Multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure and jetting device

Abstract

The application discloses a multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure, which comprises a main mixing cavity, a nozzle inlet and a nozzle outlet coaxially arranged at two ends of the main mixing cavity, and at least three radial plate feedback chambers uniformly arranged on the outer side of the main mixing cavity in the radial direction. The application can solve the problems of the prior art, realize multi-angle self-excited sweeping of the nozzle in the millimeter scale, improve the sweeping frequency, and thus improve the fluid space dispersion uniformity and the mixing and atomization performance.

Description

Technical Field

[0001] This invention relates to the field of fluid jetting device technology, and in particular to a multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure and jetting device. Background Technology

[0002] As aero gas turbine engines evolve towards higher thrust-to-weight ratios, lower fuel consumption, and more stringent emission standards, the combustion chamber places higher demands on fuel injection and mixing quality. Achieving sufficient atomization, rapid evaporation, and uniform distribution of fuel across the combustion chamber cross-section over a wide operating range is crucial for stable combustion, improved combustion efficiency, and reduced emissions of soot, CO, and unburned hydrocarbons. Especially under conditions of limited space in afterburners or main combustion chambers, the nozzles must achieve sufficient spatial coverage and fuel-air mixing within a limited installation length; otherwise, problems such as localized overly rich / lean zones, flame swaying, or backfire / flameout can easily occur.

[0003] In existing technologies, direct-injection nozzles are widely used due to their simple structure, ease of processing, and flexible arrangement. However, direct-injection streams typically have a narrow injection cone angle, resulting in a limited fuel spatial distribution range. Furthermore, when fuel supply pressure fluctuates or operating conditions change rapidly, phenomena such as excessive penetration, localized rich fuel zones, or wall wetting can easily occur, which are detrimental to rapid mixing and stable combustion. In scenarios requiring large-area coverage or multi-point uniform injection, it is often necessary to increase the number of nozzles or use a multi-nozzle array, leading to increased structural complexity.

[0004] To improve atomization and mixing, engineering has developed solutions such as pressure swirl nozzles, pneumatic atomizing nozzles (e.g., air atomizing, pre-filming, and dual-fluid nozzles), and multi-hole distribution nozzles. While these solutions can improve atomization fineness or extend the injection angle under certain conditions, they are generally sensitive to fuel supply pressure, air supply conditions, or component machining precision. For example, pressure swirl nozzles experience reduced atomization capacity under low flow rates or low pressure differentials; pneumatic atomizing nozzles rely on additional high-pressure air or bleed air, resulting in complex systems and pressure losses; and multi-hole distribution nozzles are prone to clogging risks, heat-resistant carbon buildup, and increased maintenance costs when the number of orifices increases. Therefore, improving injection coverage and mixing efficiency without introducing moving parts and minimizing additional energy consumption remains a key technological focus in the fuel injection field.

[0005] In recent years, swept jet technology based on the principle of fluid oscillators has attracted attention in fields such as flow separation control, fluid heat transfer, and fuel injection due to its elimination of mechanical oscillation mechanisms and the ability to generate periodic deflections through internal flow self-excitation. Sweeped jets can form a jet direction that oscillates over time at the outlet, maintaining sufficient jet depth in the time domain and effectively increasing the effective coverage angle, enhancing shear layer disturbance, and promoting mixing in the time-averaged manner. When combined with fuel injection, it is expected to improve fuel distribution uniformity and atomization and evaporation processes under lower momentum or lower supply pressure conditions, reducing emissions and heat load problems caused by local high temperatures and oil-rich areas.

[0006] However, existing nozzle structures based on fluid oscillators still have certain limitations. On the one hand, common structures often employ planar dual-feedback channels or single-feedback loops. The sweep angle and sweep frequency are constrained by factors such as the size of the mixing chamber, the structural design of the fluid oscillator, and the wall adhesion effect, making it difficult to achieve large circumferential coverage and high sweep frequency. On the other hand, to expand the sweep angle or achieve multi-directional jetting, some schemes attempt to increase the number of feedback channels or expand the mixing chamber space. However, as the number of channels and cavities increases, the stability of the internal flow may increase, the wall adhesion effect may weaken, or an asymmetric flow distribution may occur, leading to phenomena such as no oscillation, fixed bias, or degeneration into a stable straight jet. At the millimeter scale or smaller, the effects of viscosity, manufacturing tolerances, and supply disturbances on oscillation formation are more significant, making it difficult to guarantee stable and repeatable self-excited sweeping.

[0007] Therefore, there is an urgent need for a nozzle structure that can achieve multi-angle, large circumferential coverage and maintain high-frequency self-excited sweeping within a compact scale, so as to improve the spatial distribution and mixing effect of fuel under a wide range of operating conditions, while taking into account structural reliability, manufacturing feasibility and stability of engineering applications. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure and injection device, which can overcome the shortcomings of the prior art, enable the nozzle to achieve multi-angle self-excited sweeping at the millimeter scale and increase the sweeping frequency, thereby improving the uniformity of fuel spatial distribution and mixing atomization performance.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows.

[0010] A multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure includes a main mixing chamber, with a nozzle inlet and a nozzle outlet coaxially arranged at both ends of the main mixing chamber, and at least three radially uniformly arranged plate-type feedback chambers on the outer side of the main mixing chamber.

[0011] Preferably, the radial plate-type feedback chamber includes a secondary mixing chamber and a feedback channel. The secondary mixing chamber is connected to the main mixing chamber. The downstream end of the secondary mixing chamber is connected to the upstream end of the main mixing chamber through the feedback channel. The inner wall of the secondary mixing chamber facing the main mixing chamber is provided with an attached wall surface.

[0012] Preferably, the feedback channel has an outlet shoulder at the end near the nozzle outlet.

[0013] Preferably, the nozzle inlet consists of a flow stabilizing section and a contraction section arranged in series. The flow stabilizing section is cylindrical, and the contraction section is connected to the main mixing chamber. The diameter of the contraction section gradually decreases from the end away from the main mixing chamber to the end closer to the main mixing chamber, and the diameter of the nozzle outlet gradually increases from the end closer to the main mixing chamber to the end away from the main mixing chamber.

[0014] Preferably, the main mixing chamber is cylindrical, prismatic, frustum-shaped, or truncated cone-shaped, with a diameter of d and a length of 5-10d.

[0015] Preferably, the length of the contraction section is 0.5-3d, and the length of the flow stabilization section is 0.5-3d.

[0016] Preferably, the length of the nozzle outlet is 0.5-3d.

[0017] Preferably, the length of the feedback channel is 4-10d, the width is 0.5-1.5d, the length of the attached wall is 3-7d, the width is 0.5-3d, and the radial angle between the outlet shoulder and the nozzle outlet is 10-60°.

[0018] An injection device includes the above-mentioned multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure, wherein the nozzle inlet is connected to a fuel supply assembly.

[0019] Preferably, it includes one or more multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structures arranged in a uniform array along the circumference.

[0020] The beneficial effects of adopting the above technical solution are as follows: (1) The circumferential multi-feedback arrangement enables the main jet to switch periodically between multiple directions, and the effective coverage of the outlet is expanded from a single fixed spray direction to a circumferential sweeping coverage. This allows for a larger spatial injection range within the same installation space, thereby reducing the need to increase the number of nozzles or multiple nozzle arrays to expand the coverage and improving the spatial uniformity of fuel distribution within the combustion chamber cross section.

[0021] (2) The multi-path feedback backflow is superimposed on the mainstream shear layer in sequence, which can form a self-excited high-frequency sweep without mechanical swing mechanism, enhance the entrainment and disturbance intensity of the jet and the surrounding flow, promote the rapid mixing and evaporation of fuel and air, and help reduce the risks of local rich oil zone, incomplete combustion and outlet temperature distortion.

[0022] (3) The combination of the central mainstream circular tube and the radial plate feedback chamber strengthens the Coanda wall attachment effect and introduces a clearly directional return flow input, which can effectively destroy the stable direct jet state that the multi-feedback structure is prone to form under specific working conditions, improve the consistency of vibration and the repeatability of the sweeping process, and reduce the occurrence of non-vibration.

[0023] (4) The outlet shoulder set near the nozzle provides stable conditions for the generation and residence of the separation vortex, so that the separation vortex pushes and the feedback return flow term jointly drive the mainstream desorption and reversal, enhances the switching ability between different feedback channels, avoids the mainstream from being attached to one side for a long time, and thus expands the sweep amplitude and improves the oscillation stability.

[0024] (5) This structure has no moving parts and its operation depends on the internal flow self-excitation. It does not require actuators such as motors and swing mechanisms. Therefore, it has high reliability, strong resistance to high temperature and vibration environment, and low maintenance requirements, making it suitable for long-term operation in the fuel injection device of aero-engine.

[0025] (6) Compared with pneumatic atomization schemes that rely on additional air sources or large-pore array schemes that rely on multi-pore distribution, the present invention achieves sweep coverage while having a more compact structure and clear channel path. It can reduce system complexity while ensuring manufacturability and is conducive to controlling additional pressure loss and blockage risks. Attached Figure Description

[0026] Figure 1 This is a structural diagram of a three-feedback self-excited swept jet nozzle.

[0027] Figure 2 This is a cross-sectional view of the three-feedback self-excited swept jet nozzle cavity along the AA direction.

[0028] Figure 3 The diagram shows the sweeping frequency, main frequency, and Strouhal number of the three-feedback self-excited swept jet nozzle.

[0029] Figure 4 A comparison of time-averaged flow field dual-feedback and triple-feedback fluid oscillators under different conditions.

[0030] Figure 5 A comparison of the internal flow velocities of stable flow in dual-feedback and triple-feedback self-excited sweeping jet nozzles.

[0031] Figure 6 A comparison diagram of the internal flow pressure during stable flow in dual-feedback and triple-feedback self-excited sweeping jet nozzles.

[0032] Figure 7 This is a schematic diagram of the principle of a traditional dual-feedback self-excited sweeping nozzle. Detailed Implementation

[0033] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0034] The starting point for this invention's multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure design is that existing fuel nozzles, within the confined space of the combustion chamber, generally suffer from problems such as limited injection coverage, uneven spatial distribution, obvious local rich fuel zones, and insufficient mixing. Traditional direct-injection nozzles typically passively expand the injection range by increasing the fuel supply pressure, increasing the number of nozzles, or adjusting the nozzle geometry parameters; however, these methods do not address the issues of insufficient spatial coverage and uneven mixing from the perspective of flow organization mechanisms. On the other hand, while existing oscillator-type nozzles have the advantages of no moving parts and self-excited sweeping, their structures mostly adopt a dual-feedback or single-loop form, with the main jet mainly exhibiting left-right oscillation within a single plane, making it difficult to achieve a larger circumferential coverage. Therefore, how to stably break the straight-through state of the main jet within a compact scale and periodically switch it between multiple directions is the core problem to be solved by this invention.

[0035] To address the aforementioned issues, this invention, focusing on the goal of multi-directional self-excited switching, reconstructs the synergistic relationship between the central mainstream channel, circumferentially radial plate-shaped feedback chambers, attached walls, and the outlet shoulder. The basic design concept is as follows: the central mainstream channel ensures sufficient axial momentum for the main jet; multiple circumferentially arranged radial plate-shaped feedback chambers construct a multi-path feedback drive network; the attached walls enhance the attachment tendency during local deflection of the mainstream; and the outlet shoulder induces and stabilizes the formation and retention of separation vortices, thereby establishing a multi-directional self-excited switching mechanism involving feedback return momentum, attached wall effects, and separation vortex action. The purpose of this design is not simply to increase flow complexity, but to establish a repeatable, periodic, alternating dominant relationship among multiple feedback loops, allowing different feedback chambers to sequentially dominate the main jet position within one oscillation cycle, thus expanding the left-right two-state switching in the traditional dual-feedback structure into multi-directional continuous sweeping.

[0036] Furthermore, this invention employs a structural form combining a central mainstream channel with circumferentially radial plate-type feedback chambers, rather than simply increasing the size of the mixing chamber or adding random branches. This is based on the understanding that if only the number of cavities is increased without a clear guiding mechanism and reversal triggering mechanism, the internal flow may revert to a stable straight-through state, or problems such as bias fixation and difficulty in oscillation may occur. Existing technologies, when expanding the mixing space, may lead to increased internal flow stability and weakened wall adhesion effects, thereby causing the jet to degenerate into a stable straight jet. To avoid the above situation, this invention further introduces two key structural features on the basis of the main mixing region: a radial plate-type feedback chamber and an outlet shoulder. The former is used to provide feedback drive paths in multiple directions for the mainstream and amplify the feedback effect after local deflection; the latter is used to create local geometric conditions conducive to the formation, development, and maintenance of separation vortices, so that the internal flow will not become overly stable due to overall symmetry, but can continuously complete direction switching during the process of local unstable growth. Therefore, this invention is not a simple superposition of multiple feedback structures, but a targeted configuration design centered on the goal of both reliable oscillation and stable multi-directional sweeping.

[0037] Therefore, the design basis of this invention is mainly reflected in the following aspects: First, fuel injection requires not only a larger instantaneous spray angle, but more importantly, a more efficient spatiotemporal coverage capability; second, self-excited sweeping is more suitable for the high-temperature, high-vibration, and space-constrained aero-combustion environment compared to mechanical oscillation; third, although the traditional dual-feedback structure has proven the feasibility of feedback-driven oscillation, its sweeping path is limited to two-dimensional bidirectional deflection; fourth, multi-feedback structures can only avoid degenerating into stable direct jets when the mainstream channel scale, wall attachment effect, and separation vortex induction mechanism are synergistically enhanced; fifth, by arranging multiple feedback chambers uniformly along the circumference and combining them with the central mainstream channel, inlet stabilization section, inlet contraction section, nozzle expansion section, and outlet shoulder, high-frequency, multi-angle, self-excited, and self-sustaining sweeping injection under millimeter-scale conditions without moving parts can be achieved. The above understandings together constitute the design concept and theoretical starting point of this invention.

[0038] like Figure 7As shown, a traditional dual-feedback self-excited sweeping nozzle typically contains two opposing feedback control chambers arranged at a 180° angle. The main jet alternately adheres to and desorbs from the two side walls, forming a left-right oscillating sweeping pattern. Enhanced feedback flow on one side pushes the main jet towards the other side, and as the other side gradually becomes dominant, a reverse switching occurs. Therefore, the entire system exhibits an alternating transition between two deflection states. From the perspective of existing technology, related solutions can be broadly classified into two categories: one is the traditional direct-injection or swirling fuel nozzle, whose injection direction is relatively fixed, and spatial coverage mainly relies on nozzle geometry, pressure difference, or swirling atomization; the other is the existing oscillating nozzle structure, which mainly achieves in-plane sweeping by alternating the action of the two feedback loops, causing the main jet to switch back and forth between two relative deflection states. Compared with the above two types of existing technologies, the difference of this invention is not only reflected in the increase in the number of feedback units, but also in the fundamental change in the flow organization method and oscillation driving mechanism.

[0039] Specifically, the flow organization of traditional dual-feedback structures mainly relies on the alternating changes in the strength of the deflection of the adjacent walls and the feedback return flow, and its oscillation mode is essentially a two-dimensional two-state switching. This invention, however, introduces multiple independent sub-mixing chambers and corresponding feedback channels circumferentially in the main mixing region, and arranges them symmetrically in the circumferential direction. This causes the main flow to no longer oscillate back and forth between only two directions, but to deflect and switch sequentially between multiple directions. Therefore, this invention is not simply an expansion of the number of dual-feedback structures, but rather advances the oscillation mode from the traditional two-dimensional two-state switching to a multi-directional periodic sequential switching.

[0040] From a working mechanism perspective, the commutation process of a dual-feedback structure is relatively simple, typically controlled primarily by changes in the state of the adjacent walls on both sides and variations in the strength of the feedback return flow. In contrast, the oscillation process of this invention is determined within one cycle by the evolution of vortex structures at different locations, changes in mass flow rates in different feedback chambers, and the local separation effect induced by the outlet shoulder. Taking a three-feedback structure as an example, its oscillation process manifests as a chain-like evolution process: the growth of newly formed vortices, the dominance of stability in the middle, and the dissipation after maintenance at the tail. This mechanism indicates that even under conditions of more complex geometry, the internal flow of this invention will not fall into disorder, but rather can form an identifiable and repeatable dominant state migration pattern within one cycle.

[0041] Furthermore, the existing dual-feedback technology mainly aims to achieve jet deflection, while the present invention aims to enable multiple feedback units to sequentially dominate within a cycle. The former achieves left-right sweeping in the plane through the alternating action of the feedback chambers on opposite sides, but its sweeping path and coverage form have obvious directional limitations; the latter, through the coordinated design of circumferential multi-feedback arrangement, wall-mounted guidance, and outlet shoulder-induced separation vortex, enables different feedback chambers to sequentially dominate the deflection of the main jet within a cycle, thereby achieving multi-directional continuous sweeping coverage.

[0042] In terms of specific structural functions, the central mainstream channel is used to form the main jet core with sufficient axial momentum, providing a foundation for subsequent sweeping; multiple radially arranged plate-type feedback chambers introduce lateral momentum input in multiple directions into the mainstream through feedback channels, enabling the main jet to have multi-directional deflection conditions; the attached wall surface is used to enhance the Coanda attachment effect, making the mainstream more likely to deflect towards a specific feedback direction under local disturbances, thereby improving the oscillation initiation capability; the outlet shoulder is used to form a local structure near the nozzle that is conducive to the generation and residence of separation vortices, so that the separation vortices and feedback return flow jointly drive the mainstream desorption and reversal, enhancing the switching capability between different feedback chambers; the inlet stabilization section and the inlet contraction section are used to weaken the influence of inlet pulsation and form a stable mainstream core, while the nozzle expansion section is used to further expand the outlet sweep coverage angle. Based on the above-mentioned structural synergy, the present invention can achieve high-frequency, multi-angle, self-excited, and self-sustaining sweeping injection without moving parts, thereby improving the uniformity of fuel spatial distribution, promoting rapid mixing and evaporation of fuel and air, reducing the risk of local oil-rich areas and incomplete combustion, while taking into account structural compactness, manufacturing feasibility, and engineering application reliability.

[0043] See Figures 1-2 The multi-feedback high-frequency multi-angle self-excited swept jet nozzle structure designed in this invention includes a main mixing chamber 2. A nozzle inlet 1 and a nozzle outlet 4 are coaxially arranged at both ends of the main mixing chamber 2. Three radially uniformly arranged radially arranged plate-type feedback chambers 9 are located on the outer side of the main mixing chamber 2. Each radially arranged plate-type feedback chamber 9 includes a secondary mixing chamber 3 and a feedback channel 5. The secondary mixing chamber 3 is connected to the main mixing chamber 2, and its downstream end is connected to the upstream end of the main mixing chamber 2 via the feedback channel 5. An attached wall surface 8 is provided on the inner sidewall of the secondary mixing chamber 3 facing the main mixing chamber 2. An outlet shoulder 7 is provided at the end of the feedback channel 5 near the nozzle outlet 4. The nozzle inlet 1 consists of a stabilizing section and a contracting section arranged in series. The stabilizing section is cylindrical, and the contracting section is connected to the main mixing chamber 2. The diameter of the contracting section gradually decreases from the end furthest from the main mixing chamber 2 to the end closest to the main mixing chamber 2. The diameter of the nozzle outlet 4 gradually increases from the end closest to the main mixing chamber 2 to the end furthest from the main mixing chamber 2.

[0044] The main mixing chamber 2 is cylindrical, prismatic, frustum-shaped, or truncated cone-shaped, with a diameter of d and a length of 5-10d. The length of the contraction section is 0.5-3d, and the length of the flow stabilization section is 0.5-3d. The length of the nozzle outlet 4 is 0.5-3d. The length of the feedback channel 5 is 4-10d, and the width is 0.5-1.5d. The length of the attached wall surface 9 is 3-7d, and the width is 0.5-3d. The radial angle between the outlet shoulder 8 and the nozzle outlet 4 is 10-60°. In this embodiment, d is 8mm. The contraction angle of the contraction section is 30°, and the expansion angle of the nozzle outlet 4 is 30°. The nozzle structure can be a monolithic structure, manufactured by additive manufacturing, or it can be a split structure assembled by bonding, welding, or other methods.

[0045] Unlike traditional dual-feedback self-excited sweeping jet nozzles, the multi-feedback self-excited sweeping jet nozzle designed in this invention, due to its unique multi-feedback structure, transforms the exit jet from a simple left-right sweeping to a more complex multi-directional sweeping that repeatedly passes clockwise past the jet center. For a three-feedback fluid oscillator, such as... Figure 5 , 6 Within a cycle, based on location and characteristics, the vortex can be mainly divided into the following stages: vortex growth stage, mid-stage stabilization stage, and tail-stage stabilization and dissipation stage. The characteristics of each stage are mainly determined by the vortex stabilization location, the cause of the flow, and the location of the main current.

[0046] 1. Separation Vortex Growth Stage At the initial moment of this stage, the mass flow rate in the corresponding feedback cavity channel is 0, such as at 1 / 8T. This is because the mainstream flow is biased towards the other two feedback channels at this moment. Under the combined action of the separation vortex at the feedback cavity outlet and in the mixing cavity, the mainstream flow is deflected towards the sub-mixing cavity, and some fluid enters the feedback channel, causing the separation vortex to begin to grow on the inclined wall of the mixing cavity. As the mainstream deflection angle increases, at 3 / 8T, the flow rate entering the feedback channel gradually increases, and the separation vortex in the sub-mixing cavity also grows. At the same time, the feedback flow rate that maintains vortex stability in the feedback channel gradually decreases, and finally the mass flow rate entering the feedback channel reaches its peak. Due to the reduction in feedback flow rate, the tail stabilizing vortex in the sub-mixing chamber cannot maintain its own stability and eventually dissipates. The growth of the separation vortex in the sub-mixing cavity and the dissipation of the tail stabilizing vortex in the sub-mixing cavity together drive the vortex in the sub-mixing cavity to move upward. The separation vortex in the sub-mixing cavity becomes one of the dominant structures driving the mainstream deflection. When the flow field in the self-excited swept jet nozzle reaches stability again, the separation vortex enters the middle stabilization stage.

[0047] 2. Central Stable Phase At this stage, such as at time 5 / 8T in the feedback channel, the separation vortex has fully grown and formed a stable vortex structure in the middle of the mixing chamber. The dominant factor maintaining the stability of this vortex is the mass flow rate provided by the feedback channel. In the early stage of this stage, the mainstream begins to deflect in the direction of its resultant force due to the effect of the feedback channel. The upward deflection is caused by the tail vortex structure in the sub-mixing chamber, the middle deflection by the middle vortex structure in the sub-mixing chamber, and the inlet deflection by the combined force of the three feedback channel outlets. These forces jointly push the mainstream to deflect to the other side. As the vortex on the other side begins to grow, the feedback flow rate decreases due to the shift in the mainstream position, and the flow rate maintaining the existence of the vortex decreases. In particular, the sub-mixing chamber experiences the same dissipation of the tail stabilizing vortex. These factors cause the middle stabilizing vortex to be unable to maintain its position, and the vortex is pushed upward to the tail.

[0048] 3. Tail stabilization and dissipation stage In this stage, the flow in the feedback channel of the tail-end stable vortex weakens due to the degree of mainstream deflection. However, some flow continues to flow into the vortex structure through the outlet shoulder structure, thus maintaining the tail-end stable vortex structure. The main reason for vortex maintenance shifts from the feedback channel flow of the middle stable vortex to the mainstream directly providing feedback flow to the vortex after passing through the outlet shoulder structure. After this vortex stabilizes, similar to the middle stable stage, with the combined effect of changes in the mass flow rates of the mainstream, the newly formed vortex, and the maintaining vortex, the vortex structure eventually shrinks and dissipates. At the same time, the other two vortices enter the stable stage.

[0049] The three-feedback self-excited swept jet nozzle introduces three independent sub-mixing chambers and corresponding feedback channels on top of the main mixing chamber. This design differs significantly from the traditional DFO (Dual-Feed Self-Excited Fluid Oscillator). Dual-feedback self-excited swept jet nozzles typically contain only two FBCs (Fluid Chambers) with a 180° chamber arrangement. Separation vortices act alternately between the two side walls, driving the jet to oscillate left and right within a range of approximately 180 degrees, with its oscillations deflecting left and right in the plane. In contrast, the three-feedback self-excited swept jet nozzle in this work introduces three spatially symmetrical sub-mixing chambers and feedback channels arranged at 120-degree angles. This allows the main stream to undergo three different stages under the combined action of three paths, unlike the two-feedback fluid oscillator. During the flow, the states of different feedback chambers alternately dominate the main stream position, driving the outlet jet to periodically deflect and sweep in three directions. This achieves in-plane multi-directional coverage and higher spatial sweep uniformity, which are difficult to obtain with traditional oscillators.

[0050] The cavity can be sequentially divided into an inlet stabilizing section, an inlet contraction section, a main mixing chamber, and a nozzle expansion section along the axial direction. The inlet stabilizing section is used to weaken the influence of upstream pipeline pulsation and non-uniform incoming flow on the internal self-excited oscillation and improve the consistency of oscillation start-up; the inlet contraction section is used to accelerate the incoming flow and form a relatively stable main jet core; the nozzle expansion section is used to expand the outlet sweep coverage angle while ensuring that the pressure drop is controllable.

[0051] The three sets of radial plate-type feedback chambers are all connected to the main mixing chamber and arranged around the centerline. Each set of plate-type feedback chambers preferably includes: a secondary mixing chamber adjacent to the main mixing chamber, a feedback channel connected to the secondary mixing chamber and reconnected to the upstream region of the main mixing chamber, and an attachment wall formed inside the secondary mixing chamber. The attachment wall can be a guide surface with a circular arc or a broken line transition, used to generate and maintain the Coanda attachment effect, making the mainstream more prone to unstable deflection at small scales.

[0052] The inlet of the feedback channel can be located in the middle-upper region of the main mixing chamber, and the outlet can be connected back to the side near the inlet, so that the recirculation forms a lateral momentum input that interacts with the main jet within the main mixing chamber. By adjusting the length, width, and connection position of the feedback channel with the main mixing chamber, the recirculation impedance and recirculation momentum can be adjusted without changing the nozzle diameter, thereby achieving matching between the sweep frequency and the sweep amplitude.

[0053] The outlet shoulder is a localized protrusion or step structure located upstream of the nozzle, at the intersection of the plate feedback chamber and the main mixing chamber. The outlet shoulder can form a relatively stable recirculation chamber and separation vortex core behind it. The separation vortex and recirculation momentum work together on the main jet shear layer, enhancing the switching capability of the mainstream between different feedback chambers and preventing the mainstream from being permanently biased towards a single-sided wall attachment state, thereby improving the start-up reliability under multi-feedback conditions.

[0054] Regarding dimensional parameters, d can be used as a characteristic scale of the main mixing chamber to uniformly describe the geometric proportions of nozzles of different size grades. In addition to the aforementioned preferred range, the lengths of the inlet stabilizing section, the inlet contraction section, and the nozzle expansion section can be designed to match the installation space and allowable pressure loss. When the fuel is liquid with high viscosity, the channel cross-section and fillet radius can be appropriately increased to reduce the risk of blockage. When the fuel is gas or a two-phase atomized mixture, the channel volume can be appropriately reduced to improve the response speed.

[0055] In terms of application, the nozzles can be arranged individually as fuel injection actuators at the head of the combustion chamber, or they can be arranged in a circumferential array to achieve a larger cross-sectional fuel coverage. For array applications, equal-length fuel supply branches or throttling orifice plates at the inlet can be set to ensure consistent inlet pressure fluctuations for each nozzle, thereby guaranteeing the consistency and repeatability of the sweeping behavior of each nozzle.

[0056] In addition to the three-feedback embodiment, the present invention can also employ a circumferential arrangement of four, five, or more feedback chambers: a two-feedback structure can be used to reduce structural complexity and obtain a larger reciprocating sweep amplitude; a four-feedback or higher structure can be used to further expand circumferential coverage and increase the frequency of sweep switching. When the number of feedback chambers changes, the impedance of the feedback channel and the geometry of the outlet shoulder can be adjusted accordingly to ensure that each feedback loop can be activated sequentially and form a stable periodic sweep.

[0057] Integration of the injection device: By connecting the inlet of this nozzle to the fluid pump-filter-pipeline, circumferential multi-angle sweeping injection can be achieved in the afterburner or main combustion chamber, improving fuel mixing uniformity and combustion efficiency.

[0058] Furthermore, this example uses Ansys Fluent 2025 to simulate the nozzle flow characteristics of this embodiment. Single-phase simulation is performed using water, and the boundary conditions required for the simulation calculation are shown in the table below.

[0059]

[0060] In the simulation, the physical field was set to "fluid dynamics", "SST-Omega turbulence model based on RANS", "URANS", and "global ordinary differential equations". The computational domain was set to the fluid domain. The mesh was made extremely fine for the structural optimization part and ultra-fine for the rest. A boundary layer was set for the fluid-solid interface, with 11 layers and a stretching factor of 1.1. The complete mesh consists of 208w elements.

[0061] In the numerical study, the sweeping frequency, main frequency, Strauhall number, and time-averaged flow field at different distances of the three-feedback self-excited swept jet nozzle were calculated for Reynolds numbers from 1W to 6W, and for the flow field at different distances at 6W Reynolds number.

[0062] The sweeping frequency is defined as the velocity frequency at the center point of the jet exit, and the dominant frequency is defined as the velocity frequency at the center point of the feedback chamber exit. The Strouhal number defines the flow field state with instabilities, oscillations, or vortices. Flow field states are defined by the Reynolds number (Re) and the Strouhal number (St):

[0063] The sweeping frequency, main frequency, and Strouhal number of the three-feedback self-excited swept jet nozzle are as follows: Figure 3 As shown, the time-averaged flow field at different distances under a Reynolds number of 6W is as follows: Figure 4 As shown.

[0064] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-feedback, high-frequency, multi-angle self-excited sweeping jet nozzle structure, characterized in that: It includes a main mixing chamber (2), with a nozzle inlet (1) and a nozzle outlet (4) coaxially arranged at both ends of the main mixing chamber (2), and at least three radial plate-type feedback chambers (9) are uniformly arranged radially on the outside of the main mixing chamber (2).

2. The multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure according to claim 1, characterized in that: The radial plate-type feedback chamber (9) includes a secondary mixing chamber (3) and a feedback channel (5). The secondary mixing chamber (3) is connected to the main mixing chamber (2). The downstream end of the secondary mixing chamber (3) is connected to the upstream end of the main mixing chamber (2) through the feedback channel (5). The inner wall of the secondary mixing chamber (3) facing the main mixing chamber (2) is provided with an attached wall surface (8).

3. The multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure according to claim 2, characterized in that: The feedback channel (5) has an outlet shoulder (7) at one end near the nozzle outlet (4).

4. The multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure according to claim 3, characterized in that: The nozzle inlet (1) consists of a flow stabilizing section and a contraction section arranged in series. The flow stabilizing section is cylindrical, and the contraction section is connected to the main mixing chamber (2). The diameter of the contraction section gradually decreases from the end away from the main mixing chamber (2) to the end closer to the main mixing chamber (2), and the diameter of the nozzle outlet (4) gradually increases from the end closer to the main mixing chamber (2) to the end away from the main mixing chamber (2).

5. The multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure according to claim 4, characterized in that: The main mixing chamber (2) is cylindrical, prismatic, frustum-shaped, or truncated cone-shaped, with a diameter of d and a length of 5-10d.

6. The multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure according to claim 5, characterized in that: The length of the contraction section is 0.5-3d, and the length of the flow stabilization section is 0.5-3d.

7. The multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure according to claim 5, characterized in that: The length of the nozzle outlet (4) is 0.5-3d.

8. The multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure according to claim 5, characterized in that: The length of the feedback channel (5) is 4-10d and the width is 0.5-1.5d. The length of the attached wall surface (8) is 3-7d and the width is 0.5-3d. The radial angle between the outlet shoulder (7) and the nozzle outlet (4) is 10-60°.

9. A spraying device, characterized in that: The nozzle structure includes the multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structure according to any one of claims 1-8, wherein the nozzle inlet (1) is connected to the fluid supply component.

10. The spraying device according to claim 9, characterized in that: It includes one or more multi-feedback high-frequency multi-angle self-excited sweeping jet nozzle structures arranged in a circumferential array.

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