Oscillating nozzle based on continuous curvature periodic center of curvature member regulation and applications thereof

Abstract

The present application relates to the technical field of combustion oscillation injection, and discloses an oscillation nozzle based on continuous curvature periodic fluctuation center component regulation and application thereof, wherein a continuous curvature periodic fluctuation center component is arranged in the main cavity and symmetrically arranged along the center symmetry axis of the oscillation nozzle; the continuous curvature periodic fluctuation center component is located in the initial expansion area after the main flow enters the main cavity, and the axial position is arranged towards the front part of the main cavity, i.e. arranged close to the side of the inlet section, through the continuous curvature periodic fluctuation structure on the surface of the continuous curvature periodic fluctuation center component; the lateral position of the continuous curvature periodic fluctuation center component is located in the central symmetry axis area of the main cavity, and keeps a symmetrical arrangement relationship with the feedback channels on both sides, combined with the continuous curvature periodic fluctuation structure on the surface of the continuous curvature periodic fluctuation center component, so as to ensure the symmetry of the disturbance effect of the continuous curvature periodic fluctuation center component on the main flow and the stability of the subsequent switching process.

Description

Technical Field

[0001] This invention relates to the field of combustion oscillation injection technology, and in particular, to an oscillation nozzle based on the control of a central component with continuous curvature periodic fluctuations and its application. Background Technology

[0002] In engineering fields such as propulsion, combustion, and thermal energy conversion, combustion injection and enhanced mixing are key steps to ensure efficient fuel conversion and reduce pollutant emissions. As a core component connecting the supply system and the reaction space, the nozzle's internal flow organization directly determines the spatial distribution of the working medium, mixing efficiency, and subsequent combustion stability.

[0003] Oscillating nozzles, as a type of structure that generates a periodic oscillating jet without external drive by utilizing the inherent instability of the fluid, have received widespread attention in industrial combustion and enhanced heat transfer in recent years. Existing oscillating nozzles typically consist of an inlet section, a main chamber, an outlet section, and feedback channels on both sides. Their working principle relies on the wall adhesion effect and pressure feedback mechanism after the jet enters the main chamber: the main stream deflects to one side upon entering the main chamber, and a portion of the fluid acts on the other side through the feedback channels, forcing the main stream to periodically switch, thus forming a large-scale oscillating jet at the outlet. This jet characteristic can effectively expand the flow field coverage, enhance turbulence intensity, and thereby improve local mixing capacity and heat and mass transfer efficiency.

[0004] However, existing oscillating nozzle structures still face significant technical bottlenecks in practical applications, mainly in the following aspects: 1. Problems of unilateral wall-attachment locking and oscillation instability. Under specific operating conditions or structural parameters, the main jet can easily and quickly attach to one side of the wall after entering the main cavity, forming a stable unilateral deflection flow, i.e., wall-attachment locking. Once in this state, the jet is unable to overcome the pressure barrier to achieve autonomous switching, leading to oscillation failure and the jet degenerating into steady-state flow, which severely weakens the mixing enhancement effect.

[0005] 2. Lack of effective control over the initial development stage of the main jet. Existing structures mainly rely on the size of the main cavity and the feedback channel to control the flow, lacking active intervention methods for the initial development process when the main jet just enters the main cavity. The main jet is often constrained by the cavity wall only after it develops into a large-scale deflection flow, making the flow evolution process difficult to control. This makes the nozzle oscillation establishment extremely sensitive to changes in operating conditions and has poor robustness.

[0006] In summary, existing technologies urgently need a novel oscillating nozzle structure that can actively regulate the flow field during the initial stage of the main jet entering the main cavity without introducing external moving parts or excessively increasing system complexity. This would effectively suppress wall-attachment locking, improve oscillation stability, and further optimize combustion injection and mixing effects. Summary of the Invention

[0007] This invention provides an oscillating nozzle based on a continuously curvature periodically undulating central component and its application. By setting a central component with a continuously curvature periodically undulating central component along the axial direction during the initial unfolding stage of the main stream entering the main cavity, and utilizing the smooth surface three-dimensional geometric disturbance, an ordered longitudinal vortex system is actively induced before the jet develops into a large-scale deflection flow. This reconstructs the unstable flow structure in the main cavity and balances the feedback pressure on both sides, solving the technical problems of existing oscillating nozzles being prone to oscillation instability due to unilateral wall attachment and lacking effective control over the initial jet.

[0008] According to one aspect of the present invention, an oscillating nozzle based on a continuously curvature periodic undulation center component is provided, comprising an inlet section, a main cavity, an outlet section, and feedback channels located on both sides of the main cavity. The working medium enters through the nozzle inlet of the inlet section, then passes through a pre-guide section and / or a contraction section of the inlet section before entering the main cavity. Under the synergistic effect of the main cavity and the feedback channels, it sequentially undergoes expansion, deflection, switching, and feedback coupling processes, and finally exits through the outlet section to form a periodic oscillating jet. A continuously curvature periodic undulation center component is provided inside the main cavity, and the continuously curvature periodic undulation center component is symmetrically arranged along the central symmetry axis of the oscillating nozzle. The component is located in the initial development zone after the main stream enters the main cavity, and its axial position is biased towards the front of the main cavity, that is, it is arranged on the side closer to the inlet section. Through the continuous curvature periodic undulation structure on the surface of the continuous curvature periodic undulation central component, the main stream is subjected to continuous and smooth three-dimensional disturbance before it has fully developed into a large-scale unilateral flow. The lateral position of the continuous curvature periodic undulation central component is located in the central symmetry axis region of the main cavity, and maintains a symmetrical arrangement with the feedback channels on both sides. Combined with the continuous curvature periodic undulation structure on the surface of the continuous curvature periodic undulation central component, the symmetry of the continuous curvature periodic undulation central component to the disturbance of the main stream and the stability of the subsequent switching process are ensured.

[0009] Furthermore, the central component with continuous curvature periodic undulations adopts a central corrugated column.

[0010] Furthermore, the two ends of the central corrugated column are fixedly connected to the corresponding wall surfaces on the main cavity wall, forming a fixed central component that runs through the radial height of the main cavity.

[0011] Furthermore, the central corrugated column is a continuous curvature column with a periodically undulating outer contour.

[0012] Furthermore, the outer contour of the central corrugated column changes continuously along the axial direction and does not have sharp edges, abrupt steps, or obvious geometric discontinuities.

[0013] Furthermore, the axial configuration of the outer contour of the central corrugated column is a sinusoidal periodic modulation configuration, a quasi-sinusoidal periodic modulation configuration, a cosine periodic modulation configuration, or a spline smooth wave periodic modulation configuration.

[0014] Furthermore, the central corrugated column adopts an axial periodic undulating shape superimposed on the basic column diameter, so that the local radius of the column continuously increases and / or decreases along the mainstream direction, thereby forming a regular transverse pressure gradient, three-dimensional shear layer and wake disturbance during the mainstream flow. It not only has the effect of local flow division and flow channel constraint, but also has excellent longitudinal vortex induction and flow reconstruction capabilities.

[0015] Furthermore, by changing the wavelength of the central component of the continuous curvature periodic fluctuation, the longitudinal vortex formation scale, the mainstream deflection rhythm, and the feedback coupling characteristics inside the main cavity are affected, thereby adjusting the nozzle oscillation frequency.

[0016] According to another aspect of the present invention, an application of an oscillating nozzle, as described above, based on a continuously curvature periodic undulation center component, in combustion injection and enhanced mixing is also provided.

[0017] Furthermore, while regulating the flow through the continuous curvature periodic undulation central component, the spatial distribution characteristics of the working medium are improved to enhance the mixing ability between the mainstream and the surrounding working medium, expand the effective action area, and to a certain extent take into account the control of internal flow loss of the oscillating nozzle. Since the continuous curvature periodic undulation central component adopts a continuous curvature periodic undulation shape, the disturbance to the mainstream is smoother than sharp protrusions or abrupt obstacles, thereby reducing the risk of strong separation and additional energy loss while maintaining the effectiveness of disturbance.

[0018] The present invention has the following beneficial effects: 1. Active flow field reconstruction during the initial development stage of the mainstream: Due to the axial position of the continuous curvature periodic undulation central component being offset towards the front of the main cavity and located in the initial development zone after the mainstream enters the main cavity, it can exert spatial forced constraint on the mainstream that has not yet formed a stable attached boundary layer; the continuous curvature periodic undulation structure on the surface of the continuous curvature periodic undulation central component causes the flow channel area to change continuously and nonlinearly when the mainstream flows through both sides of the structure, thereby exciting three-dimensional disturbance waves with specific frequency characteristics in the mainstream shear layer; the continuous curvature periodic undulation structure can destroy the uniformity of the mainstream along the spanwise direction, inducing the generation of longitudinal vortices that are periodically distributed along the flow direction. These longitudinal vortices have extremely strong momentum transport capacity and can establish a material and energy exchange channel between the mainstream core area and the near-wall area, thereby realizing the active reconstruction of the mainstream boundary layer and velocity distribution in the early stage of flow evolution, preventing the mainstream energy from being excessively concentrated on one side wall.

[0019] 2. Suppressing large-scale unilateral wall-attachment locking and enhancing oscillation switching stability: The central component with continuous curvature periodic undulations, due to the periodic undulation of its cross-section along the axial direction, generates a pressure gradient and flow vortex system in the mainstream that also exhibit periodic alternation characteristics. This alternation characteristic generates a dynamic and unsteady lateral force on the mainstream, making the deflection of the mainstream between the left and right walls no longer solely dependent on random disturbances, but modulated by the periodicity of the structural geometry. This effectively weakens the tendency of the mainstream to form a strong wall-attachment effect on a single side wall, suppresses the formation of large-scale unilateral deflection structures, thereby reducing the critical threshold for the flow to transition from oscillatory mode to steady-state wall-attachment mode, and significantly improving the switching sensitivity and oscillation stability of the jet across the entire operating range.

[0020] 3. Optimize the unsteady coupling mechanism between the main cavity and the feedback channel: The lateral (radial) position of the central component of the continuous curvature periodic undulation is located in the central symmetry axis region of the main cavity, and it maintains a symmetrical arrangement with the two feedback channels on both sides. This geometric symmetry ensures that the disturbance effect of the component on the mainstream is consistent on both sides, avoiding the feedback pressure imbalance caused by excessive disturbance on one side. At the same time, the longitudinal vortex system induced by the central component of the continuous curvature periodic undulation can continuously deliver orderly vorticity pulsations to the downstream of the main cavity and the inlet of the feedback channel. These vorticity pulsations superimpose with the pressure waves in the feedback channel, enhancing the intensity of the unsteady fluctuation of the pressure field inside the main cavity. This synergistic effect makes the control response of the feedback channel to the mainstream deflection more rapid, shortens the establishment time of the oscillation period, and reduces the phase lag caused by flow relaxation, thereby improving the dynamic response characteristics of the entire nozzle system.

[0021] 4. Enhanced mixing and mass and heat transfer efficiency: In combustion injection and enhanced mixing applications, the longitudinal vortex structure induced by the continuous curvature periodic undulation central component can significantly increase the contact interface area between the mainstream and the surrounding medium (such as air or secondary flow), and intensify the shearing and tearing effects at the interface. Unlike simple turbulent dissipation, the longitudinal vortex can entrain high-energy fluids to low-energy regions or penetrate reactants into the oxygen-rich region of the oxidant, thereby achieving rapid mixing at the microscale. Since the surface of the continuous curvature periodic undulation central component is a continuous curvature periodic undulation structure without sharp corners or abrupt changes, it effectively avoids the severe total pressure loss caused by flow separation while generating strong disturbances, achieving a balance between high mixing efficiency and low pressure loss.

[0022] 5. Flow control gain of geometric parameters: The geometric parameters such as wavelength, amplitude and number of cycles of the central component of continuous curvature periodic undulation directly determine the scale and intensity of the induced longitudinal vortex. By adjusting these parameters, the oscillation frequency of the nozzle can be fine-tuned within a certain range without changing the overall size of the main cavity or feedback channel. This modular design gives the nozzle the ability to adapt to different working conditions. For example, the disturbance frequency can be increased by shortening the wavelength, or the local flow area ratio can be changed by adjusting the amplitude, thereby achieving fine control of the injection characteristics.

[0023] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a cross-sectional view of an oscillating nozzle based on a central component controlled by continuous curvature periodic fluctuations according to a preferred embodiment of the present invention. Figure 2 This is a three-dimensional structural schematic diagram of an oscillating nozzle based on a central component controlled by continuous curvature periodic fluctuations, according to a preferred embodiment of the present invention.

[0025] Legend: 100, Inlet section; 200, Main cavity; 300, Outlet section; 400, Feedback channel; 500, Continuous curvature periodic undulation center component. Detailed Implementation

[0026] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0027] like Figure 1 and Figure 2As shown, the oscillating nozzle based on the continuous curvature periodic undulation center component control in this embodiment includes an inlet section 100, a main cavity 200, an outlet section 300, and feedback channels 400 located on both sides of the main cavity 200. The working medium enters through the nozzle inlet of the inlet section 100, and then enters the main cavity 200 after passing through the pre-guide section and / or contraction section of the inlet section 100. Under the synergistic effect of the main cavity 200 and the feedback channels 400, it sequentially undergoes expansion, deflection, switching, and feedback coupling processes, and finally exits from the outlet section 300 to form a periodic oscillating jet. The main cavity 200 is provided with a continuous curvature periodic undulation center component 500, which is symmetrically arranged along the central symmetry axis of the oscillating nozzle. The core component 500 is located in the initial development zone after the main stream enters the main cavity 200, and its axial position is biased towards the front of the main cavity 200, that is, it is arranged on the side closer to the inlet section 100. Through the continuous curvature periodic undulation structure on the surface of the core component 500, the main stream is subjected to continuous and smooth three-dimensional disturbance before it fully develops into a large-scale unilateral flow. The lateral position of the core component 500 is located in the central symmetry axis region of the main cavity 200, and maintains a symmetrical arrangement with the two side feedback channels 400. Combined with the continuous curvature periodic undulation structure on the surface of the core component 500, the symmetry of the continuous curvature periodic undulation core component 500 to the disturbance of the main stream and the stability of the subsequent switching process are ensured. This invention is based on an oscillating nozzle controlled by a continuously curvature periodically undulating central component. Because the axial position of the continuously curvature periodically undulating central component 500 is offset towards the front of the main cavity 200 and located in the initial expansion zone after the mainstream enters the main cavity 200, it can exert spatial forced constraint on the mainstream that has not yet formed a stable attached boundary layer. The continuously curvature periodically undulating structure on the surface of the continuously curvature periodically undulating central component 500 causes the flow channel area to change continuously and nonlinearly when the mainstream flows through both sides of the structure, thereby exciting three-dimensional disturbance waves with specific frequency characteristics in the mainstream shear layer. Unlike smooth structures (such as smooth central columns) that can only produce two-dimensional separation, the continuously curvature periodically undulating structure can destroy the uniformity of the mainstream along the spanwise direction and induce the generation of longitudinal vortices that are periodically distributed along the flow direction. These longitudinal vortices have extremely strong momentum transport capabilities and can establish a material and energy exchange channel between the mainstream core area and the near-wall area, thereby achieving active reconstruction of the mainstream boundary layer and velocity distribution in the early stage of flow evolution and preventing the mainstream energy from being excessively concentrated on one side wall. In the prior art, although a smooth central column can physically divide the flow channel, it cannot provide a sufficiently strong antisymmetric perturbation to break the jet's attachment preference.In contrast, the continuous curvature periodic undulation center member 500 in this invention, due to the periodic undulation of its cross-section along the axial direction, also exhibits periodic alternation characteristics in the pressure gradient and flow vortex system generated in the mainstream. This alternation characteristic generates a dynamic and unsteady lateral force on the mainstream, so that the deflection of the mainstream between the left and right side walls no longer depends solely on random disturbances, but is modulated by the periodicity of the structural geometry. This effectively weakens the tendency of the mainstream to form a strong wall-attachment effect on a single side wall, suppresses the formation of large-scale single-sided deflection structures, thereby reducing the critical threshold for the flow to change from oscillating mode to steady-state wall-attachment mode, and significantly improves the switching sensitivity and oscillation stability of the jet in the entire working range. The lateral (radial) position of the continuous curvature periodic undulation center component 500 is located in the central symmetry axis region of the main cavity 200, and it maintains a symmetrical arrangement with the two feedback channels 400 on both sides. This geometric symmetry ensures that the disturbance effect of the component on the mainstream is consistent on both sides, avoiding feedback pressure imbalance caused by excessive disturbance on one side. At the same time, the longitudinal vortex system induced by the continuous curvature periodic undulation center component 500 can continuously deliver orderly vorticity pulsations to the downstream of the main cavity 200 and the inlet of the feedback channel 400. These vorticity pulsations superimpose with the pressure waves in the feedback channel 400, enhancing the intensity of unsteady fluctuations in the pressure field inside the main cavity 200. This synergistic effect makes the control response of the feedback channel 400 to the mainstream deflection more rapid, shortens the establishment time of the oscillation period, and reduces the phase lag caused by flow relaxation, thereby improving the dynamic response characteristics of the entire nozzle system. In combustion injection and enhanced mixing applications, the longitudinal vortex structure induced by the continuous curvature periodic undulation central component 500 can significantly increase the contact interface area between the mainstream and the surrounding medium (such as air or secondary flow), and intensify the shearing and tearing effects at the interface. Unlike simple turbulent dissipation, the longitudinal vortex can entrain high-energy fluids to low-energy regions or penetrate reactants into the oxygen-rich region of the oxidant, thereby achieving rapid mixing at the microscale. Since the surface of the continuous curvature periodic undulation central component 500 has a continuous curvature periodic undulation structure without sharp corners or abrupt changes, it effectively avoids the severe total pressure loss caused by flow separation while generating strong disturbances, achieving a balance between high mixing efficiency and low pressure loss. The geometric parameters of the continuous curvature periodic undulation center component 500, such as wavelength, amplitude, and number of periods, directly determine the scale and intensity of the induced longitudinal vortex. By adjusting these parameters, the oscillation frequency of the nozzle can be fine-tuned within a certain range without changing the overall size of the main cavity 200 or the feedback channel 400. This modular design gives the nozzle the ability to adapt to different working conditions. For example, by shortening the wavelength to increase the disturbance frequency, or by adjusting the amplitude to change the local flow area ratio, fine control of the injection characteristics can be achieved.This invention relates to an oscillating nozzle controlled by a continuously curvature periodic undulation center component. By introducing the continuously curvature periodic undulation center component 500 into the initial expansion region of the main cavity 200, continuous, smooth, and symmetrical three-dimensional perturbations are applied to the main flow using the continuously curvature surface. This suppresses the occurrence of large-scale unilateral wall-attachment locking from the source of flow evolution. Furthermore, the unsteady coupling process between the main cavity 200 and the feedback channel 400 is optimized by utilizing the induced longitudinal vortex system. Without introducing additional moving parts, this invention effectively solves the problems of poor stability, uneven mixing, and sensitivity to operating conditions of existing oscillating nozzles, significantly improving the performance of combustion injection and enhanced mixing. It also has the advantages of simple structure, strong robustness, and ease of engineering implementation.

[0028] Optionally, the maximum circumscribed circle diameter of the continuous curvature periodic undulation center member 500. Net internal dimensions of the main cavity 200 along this direction satisfy: Preferred The diameter ratio range defines the degree of obstruction of the central component within the main cavity 200; when Less than 0.15 At this time, the presence of the central component has an extremely weak constraint effect on the mainstream, and cannot effectively induce the generation of a longitudinal vortex structure with sufficient strength, resulting in insufficient flow control capability; when Greater than 0.6 At that time, the excessive reduction in the area of ​​the 200mm annular flow channel in the main cavity leads to a sharp increase in the mainstream flow velocity, causing severe frictional resistance and impact loss, and even making it difficult for downstream pressure to recover. Designed to be 0.15 Up to 0.6 Within the range, 0.25 is preferred. Up to 0.45 This design ensures sufficient momentum flux in the main stream to maintain jet penetration while appropriately increasing the instability of the shear layer through the contraction effect of the annular channel. This achieves an optimal balance between low resistance and strong disturbance, ensuring the working medium enters the main cavity 200 with a suitable energy state. The diameter ratio directly determines the gap size between the main stream and the outer surface of the central component, thus controlling the thickness and development space of the shear layer. A preferred diameter of 0.25... Up to 0.45 Within the range, when the mainstream flows through the central component, its shear layer has sufficient radial space to fully develop, allowing the continuously curvature periodically undulating surface to fully act on the shear layer, inducing the generation of longitudinal vortices of moderate scale and structural stability; if the gap is too large ( If the gap is too small, the shear layer cannot reach the component surface and cannot be effectively modulated; if the gap is too small ( (Too large), the shear layer is excessively compressed, which can easily lead to flow congestion or premature separation; this ratio range ensures that the longitudinal vortex-induced process occurs in the region where the shear layer energy is most concentrated, maximizing the utilization of the main kinetic energy to convert into ordered vortex transport. In the oscillating nozzle, the main cavity 200 is not only a flow space but also an acoustic resonant cavity; diameter ratio / Essentially, this defines the acoustic characteristic dimensions and volume of the main cavity 200. Controlling this ratio within a certain range helps ensure that the acoustic resonant frequency of the main cavity 200 and the hydrodynamic frequencies induced by the central component (such as longitudinal vortex shedding frequency or jet switching frequency) are within a coupleable frequency band. This geometric constraint avoids acoustic short circuits or anti-resonance phenomena caused by improper component dimensions, ensuring that pressure pulsations within the main cavity 200 can effectively propagate and couple through the feedback channel 400, thereby maintaining the stability and repeatability of the full-cycle oscillation. The ratio range also ensures the geometrical center position of the continuous curvature periodic undulation central component 500 on the cross-section of the main cavity 200; preferably 0.25. Up to 0.45 The diameter ensures that the component surface maintains a sufficient distance from the 200mm walls of the main cavities on both sides. This prevents local flow dead zones or overheating caused by the component surface being too close to the walls, and also ensures the symmetry of the flow channels on both sides of the component. This symmetrical geometric layout is the structural basis for maintaining the feedback pressure balance on both sides and preventing the jet from generating asymmetrical flow due to geometric eccentricity. It further consolidates the suppression effect of unilateral wall-attached locking.

[0029] Optionally, the axial wavelength of the continuous curvature periodic undulation center member 500 satisfy: And preferred ,in This refers to the axial length of the initial unfolding zone after the main stream enters the main cavity. The axial wavelength λ is related to the maximum circumscribed circle diameter of the central component 500, which experiences continuous curvature periodic undulations. satisfy ≥0.3 The relationship establishes the lower limit of the spatial frequency of ripple undulations; if the wavelength is too short (i.e. <0.3 This means that a drastic change in curvature occurs on the surface of the cylinder within an extremely short axial distance, leading to a geometry that resembles a structure with sharp edges or abrupt changes. Such abrupt changes disrupt the continuous curvature characteristics of the surface, inducing flow separation rather than body-fitting flow, resulting in fragmented and disordered induced vortex structures that lose their transport capacity in the longitudinal direction. Through design... ≥0.3 This ensures that the corrugated surface has a sufficiently smooth transition region, allowing fluid micro-elements to smoothly accelerate and decelerate along the surface, thereby inducing the generation of longitudinal vortices with high spatiotemporal coherence and structural stability, and avoiding additional energy dissipation introduced by geometrical abrupt changes. Axial wavelength The axial length of the initial development zone after the main stream enters the main cavity 200 Satisfying λ≤0.8 The relationship defines the effective spatial range of disturbance occurrence; the initial expansion region is the key area where the mainstream has not yet formed a stable wall-attached flow and is most sensitive to external disturbances; if this wavelength is too long (i.e., >0.8 The length of a single ripple cycle will exceed the axial range of the initial development zone, causing the central component to be unable to complete at least one full curvature change cycle in this critical region. This will prevent the component from applying effective periodic modulation before flow instability, weakening its active control over the mainstream deflection rhythm; through design ≤0.8 This ensures that the central component can provide at least one complete cycle of geometric modulation before the mainstream evolves into a large-scale unilateral flow, thus guaranteeing the effectiveness of flow reconstruction within the time window and significantly improving the sensitivity of oscillation triggering. The aforementioned wavelength range design indirectly controls the frequency characteristics of the longitudinal vortices induced by the central component; ≥0.3 This ensures that the disturbance frequency is not too high, preventing high-frequency disturbances from being quickly dissipated by the mainstream and unable to be transmitted to the feedback channel 400. ≤0.8 This ensures that the disturbance frequency is not too low, preventing the low-frequency disturbance period from exceeding the response time of the feedback system of the main cavity 200. This wavelength design allows the hydrodynamic disturbance induced by geometric fluctuations to form a good frequency match with the acoustic feedback loop composed of the main cavity 200 and the feedback channel 400, strengthening the unsteady coupling effect, thereby maintaining the oscillation stability and switching regularity of the nozzle in the entire operating range. ≥0.3 This avoids processing difficulties caused by excessively dense corrugations (such as tool interference or difficulty in removing additive manufacturing supports), and also prevents stress concentration or material fatigue risks caused by excessively small local curvature radii. It ensures that the central component maintains good mechanical structural strength and manufacturing feasibility while having complex fluid control functions, meeting the requirements of industrial applications for the reliability and manufacturability of parts.

[0030] Optionally, the amplitude of the continuous curvature periodic undulation center member 500 That is, the difference between the maximum outer radius and the minimum outer radius satisfies: .amplitude Satisfying 0.05 The lower limit requirement ensures that the surface of the central component has sufficient geometric undulations to overcome the viscous damping of the mainstream shear layer and excite two-dimensional and three-dimensional unstable waves with significant amplitudes in the initial stage of flow; if the wave amplitude Less than 0.05 The geometric undulations will degenerate into minute roughness of a nearly smooth surface, and their disturbance energy to the mainstream is insufficient to induce the generation of longitudinal vortex structures with practical strength, leading to flow control failure and the inability to achieve the expected effect of suppressing wall-attached locking; by setting 0.05 The lower limit ensures that the geometric configuration has the ability to agitate beyond the flow stability threshold, thus intervening in flow field reconstruction at the earliest stage of flow evolution. Amplitude Satisfies 0.25 The upper limit requirement is designed to prevent excessively drastic geometric undulations from causing local surface curvature radii to become too small, thereby triggering flow separation; when the amplitude exceeds 0.25... At this point, the radius of curvature in the crest region decreases sharply, and boundary layer separation easily occurs in the mainstream, forming a significant wake vortex street and energy dissipation region, which disrupts the body-fit flow state pursued by continuous curvature design; through design This ensures that fluid particles can smoothly transition along the component surface, maintaining low-resistance flow characteristics and avoiding a surge in total pressure loss due to drastic fluctuations, thus achieving an optimal trade-off between disturbance intensity and flow efficiency. Amplitude This directly determines the degree of contraction and expansion of the flow channel area when the mainstream flows through the corrugated column; within the above-mentioned proportional range, the change in wave amplitude can effectively modulate the normal velocity gradient of the shear layer; a moderate wave amplitude (0.05) Up to 0.25 This causes the mainstream to accelerate at the crests and decelerate at the troughs, thus establishing regular pressure pulsations in the shear layer. These pulsations enhance velocity slip between different fluid layers, promoting momentum transport from high-potential-energy regions to low-potential-energy regions, thereby improving macroscopic mixing efficiency. This range avoids weak momentum exchange due to excessively small amplitude, and also avoids flow congestion and energy waste due to excessively large amplitude. Excessively large geometric amplitude introduces strong geometric nonlinear effects, causing the flow field response to become chaotic and uncontrollable. By... Limit to 0.25 Within this range, the flow control is maintained within a weakly nonlinear or quasi-linear range, ensuring a good linear relationship between the longitudinal vortex behavior induced by the central component and the geometric configuration. That is, the change in wave amplitude can predictably correspond to the change in disturbance intensity. This predictability is beneficial for performance calibration and operating condition adaptation in engineering applications, ensuring that the nozzle can exhibit stable and consistent flow control characteristics under different operating conditions.

[0031] Optionally, the effective corrugated segment starting position of the continuous curvature periodic undulation center component 500 is 200 meters away from the upstream inlet end face of the main cavity. satisfy: ,in This refers to the axial length of the initial expansion zone after the mainstream enters the main cavity. The initial expansion zone is the critical area most sensitive to external disturbances after the mainstream leaves the constrained channel and enters the main cavity (200°). This is the region where the boundary layer has not yet fully developed, the streamlines have not yet undergone significant bending, and the flow is most sensitive to external disturbances. This is achieved by designing the starting position of the effective corrugated section at... Within this range, it ensures that the continuous curvature periodic undulation center component 500 can immediately intervene in the flow process before the mainstream evolves into a large-scale unilateral flow deviation or a strong wall attachment effect occurs. This pre-positioning allows the periodic disturbances generated by the geometric undulations to directly act on the linear or weakly nonlinear stages of the shear layer evolution, thereby effectively blocking the physical path of unilateral wall attachment lock-in by inducing longitudinal vortex reconstruction of the velocity profile at the incipient stage of flow instability, significantly improving the sensitivity and success rate of oscillation establishment. The upstream inlet end face of the main cavity 200 is usually accompanied by an inlet contraction section or a guide section, and this region has complex inlet effects and pressure gradient changes; if the starting position of the effective corrugated section is... Setting it too large (i.e., far from the entrance) not only misses the optimal control opportunity but may also expose the ripple segment to areas where the mainstream potential core has dissipated, preventing the disturbance from penetrating the mainstream core; design This allows the corrugated section to fully utilize the high momentum characteristics of the inlet jet, ensuring that the disturbance can penetrate to the core region of the mainstream, rather than merely acting on the low-energy fluid at the edges, thereby maximizing momentum transport efficiency and mixing enhancement effect. Distance design and wavelength ( ) and amplitude ( The design created a synergistic effect; in At this location, the radial expansion of the main flow has not yet fully unfolded, and the relative velocity gradient between the corrugated surface of the continuous curvature periodic undulation central component 500 and the main flow is at its maximum. This configuration allows the corrugated geometry to excite the strongest shear layer instability with minimal energy cost, achieving the most effective flow control "at the right time and in the right place." This precise spatiotemporal matching is something that cannot be achieved by arbitrarily arranging central columns or post-positioned disturbance structures in existing technologies. Placing the corrugated section forward helps to redistribute energy in the area where the main flow energy is most concentrated, avoiding energy loss caused by forced compression after excessive diffusion of the flow downstream. The forward-positioned corrugated section takes advantage of the space where the main flow has not yet completely filled the main cavity 200, smoothly guiding the fluid to deflect to both sides, assisting the main flow to smoothly enter the feedback coupling stage, avoiding flow blockage caused by forced disturbance downstream, and helping to maintain the pressure recovery coefficient inside the main cavity 200, ensuring the overall hydraulic performance of the nozzle.

[0032] like Figure 1 and Figure 2As shown, in this embodiment, the continuous curvature periodic undulation central component 500 adopts a central corrugated column. The central corrugated column, through its axially oriented periodic undulation structure on its outer surface, defines a continuously changing flow cross-section within the main cavity 200. When the working medium enters the initial expansion zone of the main cavity 200 as the mainstream, the crests and troughs of the central corrugated column alternately contract and expand the mainstream. This continuous change in geometric constraint leads to periodic acceleration and deceleration processes within the mainstream boundary layer, thereby exciting three-dimensional disturbance waves with specific phase relationships in the shear layer. Unlike a smooth cylindrical surface, which can only induce two-dimensional planar vortex shedding, the continuous curvature characteristics of the central corrugated column can disrupt the spanwise symmetry of the flow, inducing the generation of one or more pairs of longitudinal vortex structures with opposite rotation directions. These longitudinal vortex structures transport in a spiral manner along the mainstream direction, significantly enhancing momentum exchange and energy redistribution between the mainstream core region and the near-wall region, thus achieving active reconstruction of the mainstream velocity distribution and pressure gradient in the very early stages of flow evolution. In existing technologies, while a smooth central column can physically divide the flow channel, it cannot provide sufficient antisymmetric perturbation energy to break the jet's wall-attachment preference. In contrast, the periodicity of the surface undulations of a central corrugated column causes the local resistance and lateral forces experienced by the mainstream as it flows through both sides of the column to dynamically alternate. This unsteady lateral force mechanism effectively weakens the tendency of the mainstream to form a strong wall-attachment effect on a single side, preventing the establishment of a large-scale unilateral flow deviation structure. The longitudinal vortex system induced by the central corrugated column continuously delivers ordered vorticity pulsations downstream of the main cavity 200 and at the inlet of the feedback channel 400. These pulsations nonlinearly couple with the pressure waves within the feedback channel 400, enhancing the intensity of unsteady fluctuations in the pressure field inside the main cavity 200. This synergistic effect lowers the critical threshold for the flow to transition from an oscillating mode to a steady-state wall-attachment mode, significantly improving the switching sensitivity and oscillation period stability of the jet across the entire operating range. The central corrugated column is symmetrically arranged along the central axis of symmetry of the oscillating nozzle, and its lateral position is located in the central axis region of the main cavity 200. It also maintains a symmetrical arrangement with the two feedback channels 400 on both sides. This geometric configuration ensures a high degree of consistency in the perturbation effect of the central corrugated column on the mainstream on both sides, avoiding abnormal oscillations or stagnation caused by excessive perturbation on one side leading to feedback pressure imbalance. Because the central corrugated column is positioned axially towards the front of the main cavity 200, it can utilize the initial kinetic energy of the mainstream, which has not yet fully developed, to amplify the perturbation, thereby achieving maximum flow field control benefits while consuming minimal mainstream energy. This coordinated design of position and shape makes the nozzle's oscillation behavior more regular and controllable. In combustion injection and enhanced mixing applications, the longitudinal vortex structure induced by the central corrugated column has extremely strong penetrating power, capable of entraining and penetrating high-energy fuel jets into the surrounding oxidizer and inert gases, significantly increasing the interfacial area and intensifying interfacial shearing.Unlike simple turbulent dissipation, longitudinal vortices generate a continuous stirring effect, promoting rapid and uniform mixing of reactants and oxidants at the microscale. Given the continuous curvature of the central corrugated column surface, without sharp corners or abrupt edges, it effectively avoids severe total pressure loss and dead zones caused by flow separation while generating strong disturbances, achieving an optimized balance between high mixing efficiency and low pressure loss characteristics. The geometric parameters of the central corrugated column, such as wavelength, amplitude, and number of periods, directly determine the scale, intensity, and spatial distribution frequency of the induced longitudinal vortices. By adjusting these parameters, the oscillation frequency of the nozzle can be fine-tuned without changing the overall dimensions of the main cavity 200 or feedback channel 400. This modular design gives the nozzle adaptability to different operating conditions; for example, shortening the wavelength to increase the disturbance frequency to adapt to small-scale mixing requirements, or adjusting the amplitude to change the local flow area ratio to adapt to different flow ranges, thereby achieving precise control of injection characteristics. The continuous curvature periodic undulation central component 500 adopts a central corrugated column, which applies continuous, smooth and symmetrical three-dimensional perturbation to the mainstream by means of the corrugated surface. This suppresses the occurrence of large-scale single-sided wall-attachment locking from the source of flow evolution. Furthermore, it optimizes the unsteady coupling process between the main cavity 200 and the feedback channel 400 by using the induced longitudinal vortex system. Without introducing additional moving parts, it effectively solves the problems of poor stability, uneven mixing and sensitivity to operating conditions of existing oscillating nozzles, significantly improves the performance of combustion injection and enhanced mixing, and has the advantages of simple structure, strong robustness and easy engineering implementation.

[0033] like Figure 1 and Figure 2As shown, in this embodiment, the two ends of the central corrugated column are fixedly connected to the corresponding wall surfaces on the main cavity 200, forming a fixed central component that extends through the radial height of the main cavity 200. The fixed connection between the central corrugated column and the wall surfaces of the main cavity 200 at both ends constitutes a cantilever beam or simply supported beam support structure spanning the radial height of the main cavity 200. This fixed connection method enhances the structural stiffness and natural frequency of the central corrugated column, effectively avoiding the risk of fluid-induced vibration or resonance caused by acoustic mode coupling with the main cavity 200 under high-speed scouring of the working medium. Compared to suspended or single-sided support structures, the fixed central component ensures that the geometric position of the central corrugated column remains constant under long-term operation and varying working conditions, without displacement, swaying, or fatigue fracture, thus ensuring its long-term stability and reliability against mainstream disturbances. Because the two ends of the central corrugated column are rigidly constrained, its elastic deformation under fluid load is limited to a very small range. This defined boundary condition ensures that the axis of the central corrugated column always coincides with the central axis of symmetry of the oscillating nozzle. The central corrugated column has a high degree of geometric symmetry in its disturbance effect on the mainstream. The fixed spatial position ensures that the intensity, scale and phase distribution of the longitudinal vortex system induced by the corrugated surface are consistent on both sides (relative to the 200 axis of symmetry of the main cavity), thereby avoiding flow asymmetry caused by component swaying or displacement, further consolidating the suppression effect on the large-scale unilateral flow structure, and ensuring the balance of the left and right switching of the oscillating jet. The central corrugated column forms a structure that penetrates the main cavity 200 radially. Its effective range covers the entire radial region from the near-wall area to the main flow core area. This ensures that regardless of the initial momentum distribution of the main flow (e.g., the presence of a radial velocity gradient), all flow must pass through the perturbation field of the central corrugated column, enhancing the adaptability of the component to different inlet flow patterns (e.g., fully developed flow or uniform inflow). The through-type structure eliminates potential flow dead zones or bypass flows at the component ends, forcing all working media to participate in the mixing and oscillation process induced by the corrugated column, thereby maximizing the utilization of the main cavity 200 space and improving the overall flow organization efficiency. In combustion injection and enhanced mixing applications, the working medium is typically present in a high-temperature environment. The fixed connection allows the central corrugated column and the wall of the main cavity 200 to use the same material system, and the matching of thermal expansion coefficients is considered in the design stage. This effectively absorbs or releases thermal stress caused by temperature difference through the constraint at both ends, preventing buckling instability of the component at high temperatures. The fixed structure at both ends simplifies the assembly process. The axial and circumferential positions of the central corrugated column in the main cavity 200 can be precisely controlled by the positioning pins or stop structure, ensuring the consistency of product performance in mass production and meeting the stringent requirements of interchangeability of parts for industrial applications.By setting the central corrugated column as a through-type fixed component with fixed connections at both ends, the structural safety and stability issues in high-speed flow environments are solved while performing fluid control functions. The rigid constraint ensures the constant geometric position of the central corrugated column, thereby ensuring the symmetry and effectiveness of the induced longitudinal vortex system, suppressing unilateral wall-attached locking and enhancing the mixing effect. It also has excellent mechanical robustness, thermal management capability and engineering feasibility.

[0034] In this embodiment, the central corrugated column is a continuous curvature column with a periodically undulating outer contour. The continuous curvature column has a periodically undulating outer surface along the axial direction, with continuous curvature changes and no sharp corners, broken lines, or abrupt transitions. When the main flow passes over the surface of this column, due to the continuous change in surface curvature, the normal force and pressure gradient experienced by the fluid micro-elements also undergo a continuous and smooth transition. This smooth geometric transition avoids flow separation and severe energy dissipation caused by abrupt curvature changes (such as sharp corners or steps). The periodically undulating outer contour excites three-dimensional perturbation waves with specific frequencies in the main flow shear layer, inducing the generation of stable longitudinal vortex structures. These longitudinal vortex structures have extremely strong momentum transport capabilities, enabling the establishment of ordered material and energy exchange channels between the main flow core region and the near-wall region, thereby achieving active reconstruction of the main flow boundary layer and velocity distribution in the early stages of flow evolution. In the prior art, smooth central columns or structures with sharp corners often fail to provide sufficiently strong antisymmetric perturbations to break the jet's wall attachment preference. In contrast, the periodic undulations of the continuous curvature column cause the local resistance and lateral force experienced by the mainstream as it flows through both sides of the column to exhibit dynamic alternation. This unsteady lateral force mechanism effectively weakens the tendency of the mainstream to form a strong wall-attachment effect on a single side wall, preventing the establishment of a large-scale unilateral flow deflection structure. The longitudinal vortex system induced by the continuous curvature surface can continuously deliver ordered vorticity pulsations downstream of the main cavity 200 and at the inlet of the feedback channel 400. These vorticity pulsations nonlinearly couple with the pressure wave in the feedback channel 400, enhancing the intensity of unsteady fluctuations in the pressure field inside the main cavity 200. This reduces the critical threshold for the flow to transition from the oscillating mode to the steady-state wall-attachment mode, significantly improving the switching sensitivity and oscillation period stability of the jet across the entire operating range. Because the central corrugated column is a continuously curved column, its surface lacks sharp angles or abrupt expansion structures that could cause flow separation. This allows the main flow to maintain good body-fit characteristics when bypassing the column. This smooth disturbance provides strong flow control while effectively avoiding severe total pressure loss and flow dead zones caused by flow separation. Compared to structures with sharp protrusions or abrupt obstacles, the continuous curvature design of this invention achieves an optimized balance between high mixing efficiency and low pressure loss characteristics. That is, it suppresses wall-locking and enhances mixing without excessively increasing system resistance. The geometric parameters of the continuous curvature cylinder, such as wavelength, amplitude, and number of periods, determine the scale, intensity, and spatial distribution frequency of the induced longitudinal vortex. By adjusting these parameters, the oscillation frequency of the nozzle can be fine-tuned without changing the overall size of the main cavity 200 or the feedback channel 400. This modular design gives the nozzle the ability to adapt to different operating conditions. For example, by shortening the wavelength to increase the disturbance frequency to adapt to small-scale mixing requirements, or by adjusting the amplitude to change the local flow area ratio to adapt to different flow ranges, the nozzle can achieve fine control of the injection characteristics.

[0035] In this embodiment, the outer contour of the central corrugated column changes continuously along the axial direction and has no sharp edges, abrupt steps, or obvious geometric discontinuities. The continuous axial contour of the central corrugated column, eliminating sharp edges, abrupt steps, or obvious geometric discontinuities, ensures that the streamlines of the working medium smoothly transition along the column surface during flow, avoiding flow separation and vortex shedding caused by local geometric abrupt changes. Sharp edges would cause the boundary layer to rapidly detach from the wall, generating significant energy dissipation and a wake region. The continuous curvature design of this scheme allows the mainstream to flow around the column in a body-fitting manner, thus providing effective three-dimensional disturbance while significantly reducing additional body drag and total pressure loss, achieving efficient flow control with low energy consumption. Due to the continuous change of the outer contour, the normal vector and pressure gradient at each point on the column surface also continuously evolve. This continuous geometric constraint exerts an unsteady, but non-impact modulating effect on the mainstream shear layer, causing fluid micro-particles to periodically accelerate and deflect in the spanwise direction, thereby inducing the generation of longitudinal vortices with their rotation axes along the mainstream direction. Unlike the disordered turbulence induced by sharp edges, the longitudinal vortices generated by continuous curvature configurations possess high order and stability. They can continuously transport high-momentum fluid from the mainstream core region to the near-wall region and entrain surrounding media into the mainstream, thereby significantly enhancing momentum exchange and mixing efficiency between different fluid regions without inducing severe turbulent kinetic energy dissipation. Sharp edges and geometric abrupt changes are often the main sources of stress concentration. The absence of sharp edges and geometric discontinuities in the configuration ensures that the internal stress distribution of the central corrugated column is uniform and continuously transitioning when subjected to high-speed jet impact loads or thermal loads. This avoids the risk of fatigue crack initiation and propagation caused by local stress peaks exceeding the material's yield limit, significantly improving the structural integrity and service life of the component under high pressure, high temperature, and variable operating conditions, meeting the stringent requirements of industrial combustion equipment for long-term operational reliability. Geometric continuity breaks the acoustic resonance or flow-induced vibration at specific frequencies that may be caused by periodically abrupt edge changes. Since there is no fixed-frequency vortex shedding source (such as the Karman vortex street behind the edge), the central corrugated column can effectively reduce the aerodynamic and structural noise generated during nozzle operation, while avoiding the risk of failure caused by the coupling resonance between the fluid excitation frequency and the component's natural frequency, further consolidating the stability and purity of the oscillating jet output.

[0036] In this embodiment, the axial configuration of the outer contour of the central corrugated column is a sinusoidal periodic modulation configuration, a quasi-sinusoidal periodic modulation configuration, a cosine periodic modulation configuration, or a spline smooth wave periodic modulation configuration. Sinusoidal, quasi-sinusoidal, cosine, or spline smooth wave periodic modulation configurations all belong to continuous curvature functions with well-defined mathematical definitions. Compared to irregular rough surfaces or polygonal undulations, these analytically defined geometric configurations can produce predictable and highly controllable flow field responses. More specifically, the sinusoidal or cosine configuration provides a smooth and continuously varying radius of curvature, causing the pressure gradient and velocity distribution of the main flow to evolve periodically and smoothly as it flows through the column. This deterministic modulation can generate disturbance waves in the main flow shear layer that match the geometric frequency, thereby precisely controlling the generation location, scale, and intensity of longitudinal vortices, achieving refined organization of the unsteady flow structure inside the main cavity 200, rather than random disordered mixing. The aforementioned configuration is characterized by its second-order continuity, meaning that not only is its geometric position continuous, but its first and second derivatives are also continuous. This higher-order continuity ensures that the lateral forces experienced by fluid particles during axial motion are gradually changing, thereby inducing the generation of large-scale longitudinal vortex structures with extremely high stability. Unlike the transient and fragmented small-scale vortex structures generated by sharp edges, longitudinal vortices induced by sinusoidal or spline waves can maintain their structural integrity over a longer axial distance, continuously carrying out momentum transport and energy redistribution. This vortex system, with its high spatiotemporal coherence and structural stability, can more effectively penetrate the mainstream core, expand the mixing radius, and significantly improve the macroscopic mixing uniformity in combustion injection applications. Different periodic modulation configurations correspond to different fluid control characteristics. For example, sine and cosine configurations provide standard symmetrical antinode and node distributions, suitable for scenarios requiring uniform and standard perturbations; sine-like or spline smooth wave configurations allow for customization of peak steepness and trough flatness. This diversity gives nozzle design great flexibility: by adjusting the wavelength, amplitude, or waveform skewness, the nozzle oscillation frequency can be fine-tuned for specific inlet flow velocities or fuel properties to achieve optimal matching with the acoustic modes of the combustion chamber or avoid resonance hazards. This tuning capability based on geometric functions solves the problem that traditional structures struggle to achieve adaptability to a wide range of operating conditions. Since all the above configurations eliminate abrupt curvature changes, the fluid can always maintain a close-fitting flow state, fundamentally suppressing the severe total pressure loss and large-scale wake backflow zone caused by flow separation. In combustion injection applications, this means that while achieving the same or even stronger mixing effect, the pressure drop required by the oscillating nozzle is lower and the pump power consumption is less, thereby improving the thermal efficiency of the entire thermodynamic cycle. The smooth transition between peaks and troughs avoids fluid stagnation and overheating in local areas, reduces the risk of carbon buildup or coking, and improves the thermal management performance of the nozzle.The use of a configuration with a clear mathematical expression (such as sine, cosine, or spline curves) facilitates high-precision machining and manufacturing (such as CNC turning, additive manufacturing, or precision casting). The clarity of the mathematical definition eliminates ambiguity in drawing interpretation, ensuring high geometric consistency of each central corrugated column in mass production, and guaranteeing batch stability of the oscillating nozzle performance. Because even small geometric deviations can lead to significant performance differences under fluid amplification effects, this configuration design not only has advantages in fluid mechanics but also possesses excellent engineering feasibility and quality control potential. By designing the outer contour of the central corrugated column as a periodic modulation configuration in the form of a sine, quasi-sine, cosine, or spline smooth wave, and utilizing the continuous curvature characteristics defined by analytical functions, precise control of the mainstream shear layer disturbance and orderly induction of the longitudinal vortex structure are achieved. This effectively suppresses unilateral wall-attached locking, enhances the stability of the full-cycle oscillation, and simultaneously ensures low flow resistance loss and high thermal efficiency. Furthermore, the adjustability of the geometric parameters meets the adaptation requirements of different working conditions, combining excellent fluid control performance, structural safety, and industrial manufacturing feasibility.

[0037] In this embodiment, the central corrugated column adopts an axial periodic undulating shape superimposed on the basic column diameter, so that the local radius of the column continuously increases and / or decreases along the mainstream direction, thereby forming a regular transverse pressure gradient, three-dimensional shear layer and wake disturbance during the mainstream flow. It not only has the effect of local flow division and flow channel constraint, but also has excellent longitudinal vortex induction and flow reconstruction capabilities. By superimposing an axially periodically undulating shape onto the basic column diameter, a non-uniform flow channel with continuous variation along the flow direction is constructed. When the mainstream of the working medium flows through the region where the local radius of the column increases (crest), the cross-sectional area of ​​the flow channel shrinks, the flow velocity increases, and the static pressure decreases. Conversely, when it flows through the region where the local radius decreases (trough), the cross-sectional area of ​​the flow channel expands, the flow velocity slows down, and the static pressure rises. This regular lateral pressure gradient induced by the periodic change of the geometric shape provides a continuous and predictable lateral driving force for the mainstream fluid, breaking the monotony of the pressure distribution on the surface of the traditional smooth column. This allows the mainstream to be subjected to periodic lateral pushing before it fully develops into a large-scale unilateral deflection flow, thereby effectively suppressing the excessive adhesion of the jet to one side wall. Due to the continuous variation in the local radius of the column, the shear layer formed between the mainstream and the surrounding medium no longer maintains a single two-dimensional planar structure, but undergoes three-dimensional twisting and evolution along the spanwise and flow directions. The axial periodic undulating shape acts as a disturbance source, exciting three-dimensional unstable waves of specific frequencies in the shear layer, causing the shear layer to entrain and pair, thereby inducing the generation of longitudinal vortices with the rotation axis along the mainstream direction. Unlike vortex structures generated solely by the random shedding of blunt body wakes, the longitudinal vortex system of this invention is directly controlled by the geometric configuration, possessing a clear generation location, spatial scale, and intensity distribution. These longitudinal vortex structures have extremely strong penetrating power, capable of reaching deep into the core region of the mainstream, significantly enhancing the momentum exchange and mixing efficiency between different fluid layers. This design achieves a dual synergistic effect of local flow constraint and active flow reconstruction. On the one hand, the basic column diameter of the central corrugated column provides a basic physical flow diversion function, dividing the main stream into two or more branches and limiting the expansion envelope of the main stream to prevent excessive jet diffusion leading to energy dissipation. On the other hand, the superimposed axial periodic undulation shape performs secondary flow reconstruction on this basis. This reconstruction utilizes the accelerated jet in the crest region to enhance the entrainment of near-wall fluid and the decelerated backflow in the trough region to enhance the mixing residence time of the fluid. The synergistic effect of these two aspects ensures that the flow organization inside the main cavity 200 maintains both macroscopic order (controlled by the basic column diameter) and microscopic efficient mixing (induced by periodic undulation), thereby significantly improving the performance of combustion injection and enhanced mixing while suppressing large-scale unilateral instability.The disturbance induced by the periodic undulating shape in the wake region of the column is no longer the disordered turbulent pulsation behind the traditional blunt body, but an organized unsteady flow dominated by the longitudinal vortex system. This organized wake disturbance can continuously deliver pressure pulsations with specific frequency characteristics to the downstream of the main cavity 200 and the inlet of the feedback channel 400, which enhances the intensity of the unsteady fluctuation of the pressure field inside the main cavity 200. This process helps to maintain the full-cycle switching stability of the oscillating nozzle and avoid oscillation instability or switching delay caused by weak or disordered feedback signals.

[0038] In this embodiment, by changing the wavelength of the continuous curvature periodic undulation center component 500, the longitudinal vortex formation scale, the mainstream deflection rhythm, and the feedback coupling characteristics inside the main cavity 200 are affected, thereby adjusting the nozzle oscillation frequency. The wavelength of the continuous curvature periodic undulation center component 500 directly determines the spatial frequency of the curvature change of the column surface. When the wavelength is short, the column surface undulations are dense, the induced longitudinal vortex structure is small in scale, the vortex core spacing is narrow, and the resulting disturbance frequency is high. When the wavelength is long, the column surface undulations are gentle, the induced longitudinal vortex structure is large in scale, the vortex core spacing is wide, and the resulting disturbance frequency is low. This direct correspondence between geometric scale and vortex scale allows designers to precisely control the wavelength parameter to customize the physical size of the longitudinal vortex, thereby matching the characteristic size of the main cavity 200, achieving the best flow field filling effect and momentum transport efficiency, and avoiding energy dissipation or control failure caused by the mismatch between the vortex scale and the main cavity 200 size. The change in wavelength directly alters the path length and pressure gradient distribution period of the central component at 500° of the continuous curvature undulation of the mainstream flow. A shorter wavelength means that the mainstream needs to undergo more acceleration and deceleration cycles per unit axial distance, resulting in a higher frequency of switching of the mainstream deflection direction, i.e., a faster mainstream deflection rhythm. Conversely, a longer wavelength prolongs the residence time of the mainstream in the same deflection direction, causing the deflection rhythm to slow down. This precise modulation of the mainstream deflection rhythm allows the jet oscillation frequency of the nozzle to be actively matched with the acoustic mode or heat release pulsation of the downstream combustion chamber, thereby achieving active control or avoidance of combustion oscillations under unstable operating conditions. The longitudinal vortex system induced by the continuous curvature periodic undulation central component 500 is not only a flow structure but also a carrier of pressure pulsations. The change in wavelength affects the velocity and phase of the longitudinal vortex transported downstream, thereby altering the vortex flux and pressure pulsation spectrum at the inlet of the feedback channel 400. This change reconstructs the nonlinear coupling characteristics between the main cavity 200 and the feedback channel 400. At a specific wavelength, the longitudinal vortex may resonate with the inherent feedback loop of the main cavity 200, thus significantly enhancing the strength and stability of the feedback signal. At other wavelengths, it may play a damping or decoupling role. This mechanism gives the nozzle the ability to optimize the dynamic response of the overall system through a single geometric parameter (wavelength). Since the outlet jet frequency of the oscillating nozzle is mainly determined by the feedback coupling cycle inside the main cavity 200, and this cycle is constrained by the formation scale of the longitudinal vortex and the mainstream deflection rhythm, changing the wavelength becomes a direct and effective means of adjusting the nozzle oscillation frequency. This allows the same nozzle main structure (with the main cavity 200 and feedback channel 400 dimensions unchanged) to adapt to different flow ranges, fuel types, or combustion chamber pressure pulsation characteristics by replacing the continuous curvature periodic undulation center component 500 with different wavelengths. This modular design improves the product's versatility and adaptability to operating conditions, and reduces the R&D cost and cycle of redesigning the entire nozzle for different application scenarios.By setting the wavelength of the continuous curvature periodic undulation center component 500 as an adjustable parameter, and utilizing the multiple control effects of geometric wavelength on longitudinal vortex scale, mainstream deflection rhythm, and feedback coupling characteristics, active and continuous adjustment of nozzle oscillation frequency is achieved. This overcomes the limitations of traditional oscillating nozzles with fixed frequency and poor adaptability to operating conditions. While ensuring flow control and mixing enhancement effects, it endows the device with excellent frequency tuning capability and engineering flexibility, demonstrating significant technological advancement and practical value.

[0039] This embodiment describes the application of the oscillating nozzle, as described above, based on the control of the central component of continuous curvature periodic fluctuations, in combustion injection and enhanced mixing.

[0040] In this embodiment, while regulating the flow through the continuously curvature periodically undulating central component 500, the spatial distribution characteristics of the working medium are improved to enhance the mixing ability between the mainstream and the surrounding working medium, expand the effective action area, and to a certain extent, take into account the control of flow loss inside the oscillating nozzle. Because the continuously curvature periodically undulating central component 500 adopts a continuously curvature periodically undulating shape, the disturbance to the mainstream is smoother than sharp protrusions or abrupt obstacles, thus reducing the risk of strong separation and additional energy loss while maintaining the effectiveness of the disturbance. Through its periodic geometric modulation, the continuously curvature periodically undulating central component 500 applies three-dimensional disturbance to the working medium entering the main cavity 200, forcibly changing the streamline shape and velocity distribution of the mainstream. This active flow regulation breaks the traditional axisymmetric diffusion mode of jets, so that the working medium is no longer limited to a single radial expansion path, but rather moves in a spiral and divergent composite motion along the axial direction. The spatial distribution characteristics of the working medium are significantly improved, effectively avoiding excessive concentration or local depletion of jet energy on the central axis, thereby expanding the effective action area of ​​the jet on a macroscopic scale and ensuring uniform spatial coverage of fuel and oxidant in the combustion chamber. Unlike simple turbulent dissipation, the longitudinal vortex structure induced by the continuous curvature periodic undulation central component 500 has extremely strong penetrating power and transport capacity. These vortex structures can penetrate deep into the mainstream core region, entraining high-energy working medium to the low-energy near-wall region, while simultaneously entraining surrounding oxidant and inert gas into the mainstream. This bidirectional material transport process significantly increases the contact area of ​​the phase interface and intensifies the shearing and tearing at the interface, thereby achieving rapid and deep mixing of fuel and air at the microscale. This mixing enhancement method based on ordered vortex system control has higher efficiency and lower pressure loss compared to passive mixing that relies on high turbulence. Because the continuous curvature periodic undulation center component 500 adopts a shape without sharp edges or abrupt transitions, the mainstream maintains a close-fitting flow state throughout the flow process, effectively avoiding the severe total pressure loss caused by flow separation. In combustion injection applications, this means that while achieving the same or even stronger mixing effect, the nozzle requires a lower pressure drop and less pump power consumption, thereby improving the thermal efficiency of the entire thermodynamic cycle. This solves the contradiction of increased resistance accompanying enhanced mixing, which is common in traditional enhanced mixing structures, and achieves the best balance between flow control effectiveness and energy utilization. In the high-temperature and high-pressure environment of the combustion chamber, the uniformity of the working medium spatial distribution is directly related to the temperature field distribution. The continuous curvature periodic undulation center component 500, by optimizing the mixing effect, effectively eliminates the hot spot phenomenon caused by local oil-rich or oil-poor conditions, making the heat release rate in the combustion chamber more uniform. This uniform heat release distribution not only reduces the risk of local overheating but also weakens the coupling strength between the acoustic modes of the combustion chamber and the heat release pulsation, thereby suppressing the occurrence of high-frequency combustion instability and significantly improving the service life and operational safety of the combustion chamber.By applying an oscillating nozzle based on a continuously curvature periodic undulation center component to the field of combustion injection and enhanced mixing, a smooth and efficient three-dimensional disturbance is applied to the mainstream using a continuously curvature surface. This achieves the reconstruction of the spatial distribution of the working medium and the enhancement of micro-mixing. While improving combustion efficiency and temperature field uniformity, the nozzle also minimizes flow loss due to its non-separation flow characteristics. This effectively solves the technical problem of traditional nozzles in balancing mixing performance and energy loss, providing an advanced and reliable solution for high-parameter, low-pollution combustion organization.

[0041] In practice, to address the problems of unilateral deflection, significant wall-attachment locking, insufficient switching stability, and limited mixing enhancement effect in the initial development zone of the main jet in existing oscillating nozzles, an oscillating nozzle based on central corrugated column control is provided. A central corrugated column with periodic undulations and continuous curvature characteristics along the mainstream direction is set inside the main cavity 200, so that the initial development and deflection process of the main jet after entering the main cavity 200 can be actively controlled. Without excessively introducing abrupt separation and additional losses, a stable longitudinal vortex structure is induced, large-scale unilateral instability is suppressed, the initial triggering conditions of oscillation are improved, the stability of the whole cycle oscillation is improved, and the combustion injection and enhanced mixing capabilities are enhanced.

[0042] Furthermore, this application also aims to regulate the internal flow structure and oscillation frequency of the nozzle by changing the geometric configuration parameters such as the wavelength of the central corrugated column, thereby giving the nozzle structure a certain frequency adjustment capability.

[0043] The oscillating nozzle, controlled by a central corrugated column, comprises an inlet section 100, a main cavity 200, an outlet section 300, and feedback channels 400 located on both sides of the main cavity 200. The working medium enters through the nozzle inlet, passes through a pre-guided or constricted section, and then enters the main cavity 200. Within the main cavity 200, it undergoes expansion, deflection, switching, and feedback coupling processes in sequence, ultimately exiting through the outlet to form a periodic oscillating jet.

[0044] The main difference between this invention's oscillating nozzle, based on a central corrugated column, and existing technologies lies in the inclusion of a central corrugated column within the main cavity 200. This central corrugated column is symmetrically arranged along the nozzle's central axis of symmetry, located in the initial expansion zone after the main jet enters the main cavity 200. Its axial position is biased towards the front of the main cavity 200, closer to the inlet side, rather than being located near the geometric center or outlet of the main cavity 200. The lateral position of the central corrugated column is located in the central region of the main cavity 200, maintaining a symmetrical arrangement with the feedback channels 400 on both sides to ensure symmetry in its response to mainstream disturbances and stability during subsequent switching processes.

[0045] The upper and lower ends of the central corrugated column are fixedly connected to the upper and lower walls of the main cavity 200, respectively, forming a fixed central component that runs through the height of the main cavity 200. This central component is not a smooth straight column, but a continuous curvature column with a periodically undulating outer contour. A sinusoidal periodic modulation configuration is preferred; however, without departing from the basic idea of ​​this invention, quasi-sine, cosine, spline smooth waveforms, or other continuous periodic curves may also be used. Any configuration in which the outer contour of the column changes continuously along the axial direction and does not have sharp edges, abrupt steps, or obvious geometric discontinuities can be used to achieve the flow control purpose of this invention.

[0046] The central corrugated column can be understood as an axially periodically undulating shape superimposed on the base column diameter, causing the local radius of the column to continuously increase and decrease along the mainstream direction. This configuration creates a regular transverse pressure gradient, three-dimensional shear layer, and wake disturbance during the flow around the mainstream. Compared with a completely hollow form without a central component, this structure introduces a controlled central modulation effect in the critical 200 region of the main cavity; compared with the traditional smooth cylindrical central body, this structure not only has local flow division and flow channel constraint effects, but also has stronger longitudinal vortex induction and flow reconstruction capabilities.

[0047] In terms of specific arrangement, the central corrugated column is preferably placed in the initial development zone after the main jet enters the main cavity 200, so that the mainstream is subjected to continuous and smooth three-dimensional disturbance before it fully develops into a large-scale unilateral deflection flow. This arrangement is conducive to establishing an ordered longitudinal vortex structure in the early stage of flow, reducing the subsequent unilateral attachment tendency, and improving the oscillation switching triggering conditions. Since the central corrugated column is located near the inlet side of the main cavity 200, its main target is the initial deflection establishment stage of the mainstream, and it also has a continuous influence on the subsequent full-cycle oscillation maintenance process.

[0048] Research and engineering experience have verified that the formation and evolution of the flow behavior inside the oscillating nozzle are closely related to the initial deployment of the main jet, local attachment to the wall, feedback establishment, and the coupling of unsteady structures. If the main jet rapidly concentrates on one side in the initial stage after entering the main cavity 200, the subsequent feedback process often exhibits obvious asymmetry, thus forming a large-scale deflection structure that is not conducive to stable switching.

[0049] In summary, this invention applies continuous and smooth three-dimensional perturbation to the main jet by setting a central corrugated column inside the main cavity 200. Compared with a smooth central column, the continuously curvatured outer surface of the corrugated column with periodic undulations is more conducive to inducing the formation of stable and ordered longitudinal vortices on both sides of the column and in the wake region. The formed longitudinal vortices enhance momentum exchange and energy redistribution between different regions of the main cavity 200 on the one hand, and weaken the tendency of the mainstream to rapidly accumulate on one side and form a strong wall-attached deflection flow on the other, thereby suppressing the development of large-scale unilateral unstable structures.

[0050] For the initial unfolding stage after the main jet enters the main cavity 200, the central corrugated column provides a controllable disturbance source for the originally highly sensitive deflection triggering process. This disturbance source can actively reconstruct the mainstream boundary layer, shear layer, and local pressure distribution before the flow locks onto one side, making it easier for the mainstream to establish a dynamic equilibrium and switchable state between the left and right sides. This can reduce the flow lock-in phenomenon and improve the sensitivity of jet deflection and switching.

[0051] For the maintenance of the oscillation throughout the entire cycle of the oscillating nozzle, the longitudinal vortex structure induced by the central corrugated column can continue to participate in the unsteady coupling between the main cavity 200 and the feedback channel 400, weakening the dominant role of the original large-scale unstable structure on the oscillation rhythm, and transforming the internal flow of the nozzle from disordered large-scale instability to a relatively ordered, controllable small-scale unsteady structure. This process helps to improve the repeatability of the oscillation cycle and the switching stability, and improves the consistency of the spatiotemporal distribution of the outlet jet.

[0052] In combustion injection and enhanced mixing applications, the aforementioned flow regulation effects can further improve the spatial distribution characteristics of the working medium, enhance the mixing ability between the mainstream and the surrounding medium, expand the effective action area, and to a certain extent, also take into account the control of internal flow losses within the nozzle. Because the central corrugated column adopts a continuous curvature shape, its disturbance to the mainstream is smoother than that of sharp protrusions or abrupt obstacles, which can reduce the risk of strong separation and additional energy loss while maintaining the effectiveness of disturbance.

[0053] Furthermore, the central corrugated column also possesses a certain potential for oscillation frequency regulation. By changing the wavelength of the corrugated column, the longitudinal vortex formation scale, the mainstream deflection rhythm, and the feedback coupling characteristics within the main cavity 200 can be affected, thereby achieving a certain degree of adjustment to the nozzle oscillation frequency. This function is not the sole objective of this invention, but it serves as an important additional advantage of this structure, providing greater freedom for nozzle design and adaptation under different operating conditions.

[0054] In summary, compared to a central column-less oscillating nozzle, this invention, by introducing a central component 500 with continuous curvature periodic undulations in the initial development region of the main jet, can establish a more organized three-dimensional disturbance and longitudinal vortex structure in the early stage of flow, thus improving the deflection triggering mechanism from the source. Compared to a smooth central column oscillating nozzle, the central corrugated column of this invention not only has the functions of flow splitting and local constraint, but more importantly, it can actively induce stable longitudinal vortices, exhibiting stronger control capabilities in oscillation establishment, switching maintenance, and mixing enhancement.

[0055] Without departing from the basic idea of ​​this invention, the following alternative solutions can also achieve similar inventive objectives.

[0056] 1. The shape function of the central corrugated column can be replaced. In addition to the sine wave, the outer contour of the central column can also adopt a quasi-sine wave, cosine wave, smooth spline curve, or other continuous periodic undulating curve. As long as it changes continuously along the axial direction and has continuous curvature characteristics, it can achieve smooth disturbance of the main stream and longitudinal vortex induction effect.

[0057] 2. The cross-sectional shape of the central corrugated column can be replaced. Its cross-section can be circular, elliptical, or other centrally symmetrical cross-sections. As long as the overall symmetry is maintained and a periodic undulating outer contour is formed, the corresponding flow control effect can be achieved.

[0058] 3. The position of the central corrugated column can be adjusted. The central corrugated column can be finely adjusted back and forth in the initial deployment area according to the specific structure of the main cavity 200 to adapt to different inlet velocity distributions, feedback channel 400 layouts and outlet requirements, but in general, it should still be located in the key front area after the main jet enters the main cavity 200.

[0059] 4. The length and number of corrugated sections can be adjusted. The central corrugated column does not need to cover the entire 200mm length of the main cavity. Effective corrugated sections can be set only in the most sensitive initial unfolding and deflection establishment areas of the main flow to ensure the disturbance effect while taking into account the flow loss control.

[0060] 5. The central corrugated column can be further generalized as a type of centrally controlled column with continuous curvature and periodically undulating outer surface, rather than being limited to a sinusoidal corrugated column in the strict sense.

[0061] Therefore, any similar continuous undulating central column structure that can induce stable longitudinal vortices, suppress unilateral wall-attached locking, and improve oscillation switching stability within the main cavity 200 can be considered as an equivalent alternative to the present invention.

[0062] Matters not covered in this invention are common knowledge.

[0063] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An oscillating nozzle based on a continuously curvature periodic undulation center component for control, comprising an inlet section (100), a main cavity (200), an outlet section (300), and feedback channels (400) located on both sides of the main cavity (200). The working medium enters through the nozzle inlet of the inlet section (100), then enters the main cavity (200) after passing through the pre-guide section and / or contraction section of the inlet section (100), and undergoes expansion, deflection, switching, and feedback coupling processes in sequence under the synergistic effect of the main cavity (200) and the feedback channels (400), and finally exits from the outlet of the outlet section (300) to form a periodic oscillating jet, characterized in that, The main cavity (200) is provided with a continuous curvature periodic undulation center component (500), and the continuous curvature periodic undulation center component (500) is arranged symmetrically along the central symmetry axis of the oscillating nozzle. The continuous curvature periodic undulation center component (500) is located in the initial development zone after the main stream enters the main cavity (200), and its axial position is biased towards the front of the main cavity (200), that is, it is arranged on the side close to the inlet section (100). Through the continuous curvature periodic undulation structure on the surface of the continuous curvature periodic undulation center component (500), the main stream is subjected to continuous and smooth three-dimensional disturbance before it has fully developed into a large-scale unilateral flow. The lateral position of the continuous curvature periodic undulation center component (500) is located in the central symmetry axis region of the main cavity (200) and maintains a symmetrical arrangement with the two side feedback channels (400). Combined with the continuous curvature periodic undulation structure on the surface of the continuous curvature periodic undulation center component (500), the symmetry of the continuous curvature periodic undulation center component (500) to the mainstream disturbance and the stability of the subsequent switching process are ensured.

2. The oscillating nozzle based on the control of a center component with continuous curvature periodic fluctuations according to claim 1, characterized in that, The continuous curvature periodic undulation center component (500) adopts a central corrugated column.

3. The oscillating nozzle based on the control of a center component with continuous curvature periodic fluctuations according to claim 2, characterized in that, The two ends of the central corrugated column are fixedly connected to the corresponding wall surfaces on the main cavity (200) to form a fixed central component that runs through the radial height of the main cavity (200).

4. The oscillating nozzle based on the control of a center component with continuous curvature periodic fluctuations according to claim 2, characterized in that, The central corrugated column is a continuous curvature column with a periodically undulating outer contour.

5. The oscillating nozzle based on the control of a center component with continuous curvature periodic fluctuations according to claim 4, characterized in that, The outer contour of the central corrugated column changes continuously along the axial direction and has no sharp edges, abrupt steps, or obvious geometric discontinuities.

6. The oscillating nozzle based on the control of a continuous curvature periodic undulation center component according to any one of claims 2 to 5, characterized in that, The outer contour of the central corrugated column along the axial direction can be a sinusoidal periodic modulation configuration, a quasi-sinusoidal periodic modulation configuration, a cosine periodic modulation configuration, or a spline smooth wave periodic modulation configuration.

7. The oscillating nozzle based on the control of a continuous curvature periodic undulation center component according to any one of claims 2 to 5, characterized in that, The central corrugated column adopts an axial periodic undulating shape superimposed on the basic column diameter, so that the local radius of the column continuously increases and / or decreases along the mainstream direction, thereby forming a regular transverse pressure gradient, three-dimensional shear layer and wake disturbance during the mainstream flow. It not only has the effect of local flow division and flow channel constraint, but also has excellent longitudinal vortex induction and flow reconstruction capabilities.

8. The oscillating nozzle based on the control of a continuous curvature periodic undulation center component according to any one of claims 1 to 5, characterized in that, By changing the wavelength of the continuous curvature periodic undulation center component (500), the longitudinal vortex formation scale, mainstream deflection rhythm and feedback coupling characteristics inside the main cavity (200) are affected, thereby adjusting the nozzle oscillation frequency.

9. The application of an oscillating nozzle based on a continuously curvature periodic undulation center component controlled as described in any one of claims 1 to 8 in combustion injection and enhanced mixing.

10. The application according to claim 9, characterized in that, While regulating the flow through the continuous curvature periodic undulation center component (500), the spatial distribution characteristics of the working medium are improved to enhance the mixing ability between the mainstream and the surrounding working medium, expand the effective action area, and to a certain extent take into account the control of internal flow loss of the oscillating nozzle. Since the continuous curvature periodic undulation center component (500) adopts a continuous curvature periodic undulation shape, the disturbance to the mainstream is smoother than sharp protrusions or abrupt obstacles, thereby reducing the risk of strong separation and additional energy loss while maintaining the effectiveness of the disturbance.

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