Surrounding belt type stationary blade structure with oscillation-pulse jet generator

Abstract

The invention discloses a shroud ring type stationary blade structure with an oscillation-pulse jet flow generator. According to the structure, an oscillation-pulse jet flow generator is integrated in a stationary blade shroud ring, and self-excitation driving is achieved through the static pressure difference between the shroud ring and the end wall of a blade grid. A tapered air entraining section, a main mixing chamber, an auxiliary mixing chamber, a feedback channel and an outlet flow dividing device are arranged in the generator, and introduced continuous flow is converted into unsteady sweeping jet flow and finally separated into two strands of pulse jet flow which are periodically alternated. The two jets are directionally jetted to a blade root area of a blade suction surface and an adjacent end wall area from an outlet of the side wall of the shroud to cooperatively inhibit flow separation of a corner area. An external air source and a movable part are not needed, the structure is compact and reliable, and the aerodynamic performance and the working stability of the compressor can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of airflow control for aero-engine compressors, and specifically relates to a circumferential stator structure with an oscillation-pulse jet generator. Background Technology

[0002] In the design of axial compressors for aero-engines, shrouded stator blades are widely used due to their excellent mechanical strength and significant vibration reduction characteristics. Their shroud structure effectively suppresses high-frequency vibrations and improves blade reliability by increasing blade rigidity. However, gaps inevitably exist between the rotor and stator components in the compressor, such as the gap between the hub groove and the stator blade shroud. Under the influence of the pressure difference before and after the stator blade, reverse leakage flow can form, leading to a decrease in aerodynamic efficiency. Although sealing grating structures are usually used to suppress leakage, complete sealing is difficult to achieve due to limitations in manufacturing precision and operating conditions. Within the cavity, the leakage flow, subjected to the action of the rotating walls, forms a high-swirling, high-total-temperature leakage flow, which eventually flows back to the blade channel and mixes with the mainstream. This mixing significantly worsens end-area flow, exacerbates corner separation, and thus reduces the overall performance of the compressor. Therefore, effectively controlling cavity leakage flow and corner separation has become a key issue in improving compressor efficiency.

[0003] To control this type of flow separation, the industry has explored various flow control technologies. Existing technological approaches can be mainly categorized as follows: 1. External air source active control technology: This method introduces high-pressure or low-pressure air sources through external pipelines and performs constant blowing or sucking at specific locations on the blades to directly suppress separation. However, the complex external air path system leading to each blade greatly increases the complexity and weight of the structure, and the external air source itself (whether an independent air source or drawn from other stages of the compressor) brings matching difficulties and reliability challenges, making engineering applications extremely difficult.

[0004] 2. Mechanical pulse generation technology: This involves using piezoelectrically driven vibrating grids and other mechanical moving parts to modulate airflow and generate unsteady pulse jets. Although unsteady jets may be more efficient than steady jets in terms of control, this type of solution relies on precision moving parts, and its long-term reliability and lifespan face severe challenges under the harsh operating conditions of high temperature, high speed, and strong vibration in compressors.

[0005] In summary, existing technologies face a common dilemma: either they are structurally complex and have low reliability (relying on external systems or moving parts), or their working principles and structural forms are difficult to integrate efficiently and simply with the specific, space-constrained engineering structure of a "shrouded stator." Therefore, this invention proposes a shrouded stator structure with an oscillation-pulse jet generator. Summary of the Invention

[0006] The technical problem to be solved: To overcome the shortcomings of existing technologies, this invention provides a shrouded stator structure with an oscillating-pulse jet generator. By designing a sweep generator and a pulse jet generator within the shroud of the shroud, a high-energy-density, low-loss hybrid jet device is formed. Based on the characteristics of the shroud structure, an integrated array design at the edge angle is implemented to achieve multiple efficient flow control of the blade body and endwall. This jet structure is located within the crown (shroud) of the shrouded stator. This invention aims to utilize a novel fluid oscillator to reduce corner separation, thereby improving the overall aerodynamic performance of the compressor. This method combines the advantages of the shroud structure and utilizes a novel continuous-discrete pulsed fluid oscillator to reduce leakage while weakening corner separation, providing a new technical path for high-performance compressor design.

[0007] The technical solution of the present invention is: a shroud-type stationary blade structure with an oscillation-pulse jet generator, comprising a stationary blade 10 and a shroud 20 fixed to its bottom, wherein at least one oscillation-pulse jet generator 40 is integrated inside the shroud 20; The oscillating-pulse jet generator 40 is configured to generate unsteady flow by using the static pressure difference between the bottom wall of the shroud 20 and the end wall of the blade cascade as the sole driving force; it includes at least one jet air inlet, an internal oscillating flow channel, at least one blade jet outlet 1, and at least one end wall jet outlet 2. The jet air intake is located on the bottom wall of the enclosure 20 and is in fluid communication with the gap below the enclosure 20; The internal oscillating channel converts the fluid introduced through the jet air inlet into a swept jet with periodically changing characteristics; the swept jet is separated into two spatially discrete and temporally periodically alternating pulse jets by the outlet splitting structure 6 located at the end of the oscillating-pulse jet generator 40. The blade jet outlet 1 and the endwall jet outlet 2 are respectively arranged in the blade root region and endwall region of the blade suction surface, and are oriented towards the blade root corner separation region and the adjacent endwall region of the stationary blade 10, thereby suppressing corner flow separation through the synergistic effect of the dual pulse jets.

[0008] A further technical solution of the present invention is: the jet air inlet is a shroud opening groove 3 opened on the bottom wall of the shroud 20, and the shroud opening groove 3 extends circumferentially along the shroud 20. A further technical solution of the present invention is: the oscillation-pulse jet generator 40 includes a gradually narrowing air intake section 8, a main mixing chamber 4, a secondary mixing chamber 5, a feedback channel 7, and an outlet diversion structure 6, which are in sequential fluid communication.

[0009] A further technical solution of the present invention is: the maximum cross-sectional area of ​​the main mixing chamber 4 is 3.6 times the area of ​​its inlet throat, and its outlet area is 2.25 times the area of ​​its inlet throat; the inlet of the secondary mixing chamber 5 is gradually expanding, and the outlet cross-sectional area of ​​the secondary mixing chamber 5 is smaller than the outlet cross-sectional area of ​​the main mixing chamber 4.

[0010] A further technical solution of the present invention is that the feedback channel 7 is a tapered flow channel with an inlet area larger than its outlet area. A further technical solution of the present invention is: the outlet diversion structure 6 is located downstream of the sub-mixing chamber 5, and its separation wedge surface is at an acute angle to the jet flow direction, so that the swept jet adheres to different sides of the wall under the Coanda effect and switches periodically, thereby being separated into two pulse jets, which are respectively introduced into the blade jet outlet 1 and the end wall jet outlet 2.

[0011] A further technical solution of the present invention is: the blade jet outlet 1 is located at 2% to 5% of the chord length from the leading edge of the blade suction surface, and the endwall jet outlet 2 is located at 5% of the blade pitch in the circumferential direction; The angle between the axis of the blade jet outlet 1 and the endwall jet outlet 2 and the mainstream flow direction is 15° to 30°.

[0012] A further technical solution of the present invention is that the internal surface of the oscillation-pulse jet generator 40 is defined by a preset family of spatial curve functions. The family of functions includes at least independent curve functions describing the inlet section, internal separator, feedback channel, outlet section, and outlet splitting structure surface, and the specific expressions are as follows: Entrance section curve: z=38.3610405927942-0.334277857895076x+0.384544247082688y+0.00000002x 2 +0.000000026xy+0.0000000053y 2 Internal separator curve: z=38.3610285714713-0.334278919719581x+0.384543583895433y+0.000000002x 2 +0.0000000086xy+0.0000000016y 2 Feedback channel curve: z=38.3610511887699-0.334277303327631x+0.384545018927886y+0.000000052x 2-0.000000012xy+0.000000051y 2 Exit section curve: z=38.3610219553997-0.334279686716947x+0.384543441532508y-0.000000023x 2 -0.000000018xy-0.0000000002y 2 Outlet diversion structure curve: z=38.3609718976251-0.334284806946798x+0.38454223138855y-0.00000015x 2 -0.000000096xy-0.000000013y 2 Where x, y, and z are coordinates in a three-dimensional Cartesian coordinate system.

[0013] A flow control method with a banded stator blade structure featuring an oscillating-pulse jet generator includes the following steps: Step 1. Self-excited bleed air: Using the static pressure difference between the bottom wall of the shroud 20 and the end wall of the blade cascade as the driving force, the fluid in the gap below the shroud 20 is automatically introduced into the bleed air section integrated into the oscillation-pulse jet generator 40 through the opening slot 3 opened on its bottom wall. Step 2. Oscillation Conversion: The introduced fluid flows through the internal oscillation channel of the oscillation-pulse jet generator 40. The internal oscillation channel includes a tapered air intake section 8, a main mixing chamber 4, a secondary mixing chamber 5, and a feedback channel 7. Under the action of the feedback oscillation mechanism, the fluid is converted into an unsteady swept jet with periodic directional changes. Step 3. Pulse separation: The unsteady swept jet is guided to the outlet splitting structure 6 at the end of the oscillating-pulse jet generator 40. The Coanda effect is used to make the swept jet periodically switch on the separation wedge surface of the outlet splitting structure 6, thereby separating the swept jet into two spatially discrete and temporally periodically alternating pulse jets. Step 4. Cooperative control: Two pulse jets are ejected through the blade jet outlet 1 and the endwall jet outlet 2 located on the sidewall of the shroud 20, respectively; wherein, the jet from the blade jet outlet 1 is directed toward the blade root corner separation region of the suction surface of the stationary blade 10, and the jet from the endwall jet outlet 2 is directed toward the adjacent endwall region; through the synergistic effect of the two pulse jets in terms of frequency, phase and spatial distribution, three-dimensional disturbance and momentum injection are simultaneously applied to the boundary layer separation of the blade suction surface and the secondary flow of the endwall, thereby suppressing and weakening the corner flow separation at the root of the stationary blade 10.

[0014] A further technical solution of the present invention is that the oscillation-pulse jet generator 40 can be self-excited to start and work stably under the condition that the static pressure ratio between the inlet and outlet is not less than 1.1, and the frequency of the generated pulse jet is positively correlated with the static pressure ratio.

[0015] Beneficial effects The beneficial effects of this invention are as follows: The shroud-type stator structure with oscillation-pulse jet generator of this invention has the function of air intake. Under the pressure difference between the shroud and the end wall, the fluid at the bottom of the shroud is introduced into the novel oscillation-pulse jet generator structure from the opening groove of the shroud, realizing the effective operation of the fluid oscillator without the need for external energy injection. At the same time, the double-pulse jet outlet in the unsteady jet structure can solve the fluid blockage problem caused by the accumulation of low-energy fluid at the blade root, effectively reducing the separation range in the blade corner region. Compared with the traditional shroud structure, the novel shroud-type stator structure with oscillation-pulse jet generator of this invention has certain optimization effects on controlling secondary flow, reducing bottom leakage loss, and improving compressor efficiency. In addition, compared with the traditional jet flow control method, the unsteady jet generated by this invention without the need for an external air source has high engineering application value. The specific effects are analyzed as follows: 1. This invention creatively miniaturizes the oscillating-pulse jet generator and integrates it directly within the shroud, making it a seamless component of the shroud structure. This design does not occupy valuable axial and radial space in the engine, requires no changes to the main structure of the blade body and casing, and has low modification costs for existing shroud-type stator blades. It ingeniously transforms the "shroud," used to enhance mechanical strength, into an intelligent structure that also possesses "flow control" functions, achieving a leap from a passive structural component to an active functional component.

[0016] 2. This invention, through a unique dual-pulse outlet design, can simultaneously apply unsteady excitation from two key dimensions: the "blade suction surface" and the "endwall." These two precisely coordinated pulse jets in time and space can "three-dimensionally attack" the blade boundary layer separation and endwall secondary flow that cause corner separation, producing a synergistically enhanced control effect. This three-dimensional intervention strategy is more effective than traditional single-point steady jets or unidirectional excitation in breaking up and sweeping low-energy fluid clumps in the corner region, thereby significantly reducing the size of the separation zone, lowering flow losses, and improving compressor efficiency and stability margin.

[0017] 3. This invention directly utilizes the pressure difference energy corresponding to the "enclosure leakage flow" that originally caused aerodynamic losses, converting it into "control energy" for suppressing corner separation. This design concept achieves the recycling and efficient reuse of existing energy forms in the system, and actively suppresses flow separation with almost no additional energy consumption, exhibiting extremely high energy utilization efficiency.

[0018] 4. The fluid oscillator is characterized by the absence of any moving parts and its ability to generate jets of various frequencies and controllable angles. This swept-type fluid oscillator offers advantages such as stable oscillation frequency and high energy efficiency, with the outlet transitioning to a continuous-discrete pulsed jet. This novel structure with an oscillating-pulse jet generator can effectively control the optimal jet angle and position of the outlet airflow. Attached Figure Description

[0019] Figure 1 This is a three-dimensional schematic diagram of a banded stationary blade structure with an oscillation-pulse jet generator according to an embodiment of the present invention; Figure 2 This is a diagram illustrating the assembly of a banded stationary blade structure with an oscillation-pulse jet generator according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of the fluid oscillator in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the specific control effect of blade cascade corner region separation in an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the control effect of blade loss in an embodiment of the present invention.

[0020] Figure reference numerals: 10. Stationary blade; 1. Blade jet outlet; 2. Endwall jet outlet; 3. Enclosure opening groove; 4. Main mixing chamber; 5. Secondary mixing chamber; 6. Outlet splitting structure; 7. Feedback channel; 8. Air intake section; 15. Inlet section curve; 16. Internal separator curve; 17. Feedback channel curve; 18. Outlet curve; 20. Enclosure; 30. Hub surface; 40. Oscillating-pulse jet generator. Detailed Implementation

[0021] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] In recent years, fluid oscillators without moving parts have attracted attention due to their high reliability. For example, DE102010010790A1 discloses a fluid oscillator for boundary layer control of turbine blades, but its design relies on an externally preset pressure distribution or air source drive, and its structure and application scenarios (such as for turbine suction surfaces) are not directly compatible with the special environment of the compressor shroud. CN111810454A proposes integrating the fluid oscillator channel within the compressor casing, driven by the pressure difference between the stators / rotors of the preceding and following stages, but this is a macroscopic layout of "cross-stage" bleed air, with a complex structure, and it does not address how to integrate it with the "shroud," a component of the blade itself, in a unified and miniaturized manner.

[0024] Based on the above problems, the present invention proposes a shroud-type stationary blade structure with an oscillation-pulse jet generator, including a stationary blade 10 and a shroud 20 fixed to its bottom, wherein at least one oscillation-pulse jet generator 40 is integrated inside the shroud 20. The oscillating-pulse jet generator 40 is configured to generate unsteady flow by using the static pressure difference between the bottom wall of the shroud 20 and the end wall of the blade cascade as the sole driving force; it includes at least one jet air inlet, an internal oscillating flow channel, at least one blade jet outlet 1, and at least one end wall jet outlet 2. The jet air intake is located on the bottom wall of the enclosure 20 and is in fluid communication with the gap below the enclosure 20; The internal oscillating channel converts the fluid introduced through the jet air inlet into a swept jet with periodically changing characteristics; the swept jet is separated into two spatially discrete and temporally periodically alternating pulse jets by the outlet splitting structure 6 located at the end of the oscillating-pulse jet generator 40. The blade jet outlet 1 and the endwall jet outlet 2 are respectively arranged in the blade root region and endwall region of the blade suction surface, and are oriented towards the blade root corner separation region and the adjacent endwall region of the stationary blade 10, thereby suppressing corner flow separation through the synergistic effect of the dual pulse jets.

[0025] This invention also proposes a flow control method with a circumferential blade structure containing an oscillating-pulse jet generator, comprising the following steps: Step 1. Self-excited bleed air: Using the static pressure difference between the bottom wall of the shroud 20 and the end wall of the blade cascade as the driving force, the fluid in the gap below the shroud 20 is automatically introduced into the bleed air section integrated into the oscillation-pulse jet generator 40 through the opening slot 3 opened on its bottom wall. Step 2. Oscillation Conversion: The introduced fluid flows through the internal oscillation channel of the oscillation-pulse jet generator 40. The internal oscillation channel includes a tapered air intake section 8, a main mixing chamber 4, a secondary mixing chamber 5, and a feedback channel 7. Under the action of the feedback oscillation mechanism, the fluid is converted into an unsteady swept jet with periodic directional changes. Step 3. Pulse separation: The unsteady swept jet is guided to the outlet splitting structure 6 at the end of the oscillating-pulse jet generator 40. The Coanda effect is used to make the swept jet periodically switch on the separation wedge surface of the outlet splitting structure 6, thereby separating the swept jet into two spatially discrete and temporally periodically alternating pulse jets. Step 4. Cooperative control: Two pulse jets are ejected through the blade jet outlet 1 and the endwall jet outlet 2 located on the sidewall of the shroud 20, respectively; wherein, the jet from the blade jet outlet 1 is directed toward the blade root corner separation region of the suction surface of the stationary blade 10, and the jet from the endwall jet outlet 2 is directed toward the adjacent endwall region; through the synergistic effect of the two pulse jets in terms of frequency, phase and spatial distribution, three-dimensional disturbance and momentum injection are simultaneously applied to the boundary layer separation of the blade suction surface and the secondary flow of the endwall, thereby suppressing and weakening the corner flow separation at the root of the stationary blade 10.

[0026] Preferably, the novel oscillating-pulse jet generator employs a tapered inlet at both ends to increase the inlet fluid velocity, controlling the inlet throat area to be d×0.8d. The feedback channel adopts a tapered pipe design, with an inlet area of ​​1.1d and an outlet area of ​​0.8d. This tapered design ensures that the feedback fluid reaches its maximum velocity at the inlet throat, facilitating the operation of the novel oscillating-pulse jet generator under a wide range of working conditions. The mixing chamber adopts a main and auxiliary 3.6 dual-mixing design, with a maximum cross-sectional area of ​​3.6d in the main mixing chamber and an outlet area of ​​2.25d. The mainstream fluid flows through the main mixing chamber... After a large-scale oscillation occurs in the mixing chamber, the fluid flows into the sub-mixing chamber. The sub-mixing chamber is designed with a gradually expanding inlet to increase the pressure of the fluid within it. After a small-scale oscillation occurs in the sub-mixing chamber, the fluid flows out at a certain frequency and sweep angle. The presence of the sub-mixing chamber can reduce the energy loss of the main stream and provide a more stable fluid for the feedback channel. The swept jet of fluid collides with the fluid separator in the novel structure. Under the influence of the Coanda effect, two sets of separation bubbles are generated near the separator. The separation bubbles change with the jet angle, and the fluid becomes two discrete, periodically changing pulse jets.

[0027] The above technical solution will be further analyzed below with reference to the accompanying drawings: In one embodiment, refer to Figure 1 and Figure 2 As shown, a basic embodiment of a shroud-type stator blade structure with an oscillating-pulse jet generator is provided. The shroud-type stator blade structure mainly includes a stator blade 10 and a shroud 20 fixed to its bottom end. A novel oscillating-pulse jet generator 40 is machined inside the shroud 20.

[0028] 1. Structural integration and air intake section: A continuous circumferential opening groove 3 is formed on the bottom wall of the enclosure 20. This opening groove 3 serves as a jet air inlet, allowing the gap area below the enclosure 20 to communicate with the internal flow channel of the enclosure.

[0029] The entire oscillation-pulse jet generator 40 is integrally formed in the solid structure inside the shroud 20 using precision casting or additive manufacturing technology, forming an inseparable whole with the shroud 20 without any additional assembly parts.

[0030] An opening slot is provided at the bottom of the shroud. Due to the pressure difference between the bottom of the shroud and the endwall of the blade cascade, the air intake section introduces part of the fluid into the jet structure. Then, through a swept-frequency fluid oscillator, an unsteady jet is formed and injected into the outlet separation device. The outlet separation device divides the fluid into two discrete, periodically varying pulse jets. Because the flow inside the blade cascade produces corner separation at 0%–20% and 74%–100% of the blade height axial position, and most of the low-energy fluid accumulates at the blade root, causing flow blockage at the blade root and adverse effects, the pulse jet outlet of this invention is arranged at the blade suction surface at the blade root and the endwall region, and the jet fluid is blown towards the blade root corner separation range.

[0031] 2. Core structure of the oscillation-pulse jet generator: Reference Figure 3 As shown, the oscillation-pulse jet generator 40 includes, from upstream to downstream, a tapered air intake section 8, a main mixing chamber 4, a secondary mixing chamber 5, a feedback channel 7, and an outlet diversion structure 6.

[0032] The gradually narrowing air intake section 8 has its inlet connected to the opening slot 3, and the cross-section of the flow channel gradually narrows along the flow direction to accelerate the introduction of fluid.

[0033] The main mixing chamber 4 and the secondary mixing chamber 5: The main mixing chamber 4 has a larger volume and is used to generate large-scale initial pressure oscillations; the secondary mixing chamber 5 is connected downstream of the main mixing chamber 4, and its inlet is gradually expanding to stabilize the oscillations and increase the local pressure. Together, they form a "dual mixing chamber" structure, which enhances the stability and intensity of the oscillations.

[0034] Feedback channels 7: Two channels are provided, symmetrically connected between the outlet side of the secondary mixing chamber 5 and the inlet side of the main mixing chamber 4. The feedback channels 7 are designed as tapered channels, with an inlet area larger than the outlet area, to ensure that the feedback fluid can impact the main jet at a higher velocity, thereby enhancing the wall-attached switching effect.

[0035] Outlet diversion structure 6: Located downstream of the sub-mixing chamber 5, it is a wedge-shaped structure with a sharp edge. Its location is L from the outlet of the sub-mixing chamber 5.

[0036] The novel enclosed structure employed in this invention effectively suppresses corner flow separation through the synergistic effect of "self-excitation + enclosed integration + dual-pulse outlet". The enclosed band not only provides rigid support for the self-excitation cavity but also enhances intracavity pressure oscillation through its circumferential constraint, thereby increasing the energy density of the passive excitation. The enclosed structure facilitates the integration of the inlet and flow channel of the novel fluid oscillator, simplifying the overall structure and reducing flow channel blockage. The uniform circumferential arrangement of the enclosed band enables the dual-pulse outlet to achieve uniform circumferential jet coverage, effectively controlling corner separation within the entire annular region. The dual-pulse jet, with its transient jet effect, enhances the control capability against corner separation while increasing the frequency and intensity of self-excitation; its pulse characteristics also help maintain excitation stability. The self-excitation mechanism provides continuous and stable energy input, the enclosed band provides precise flow guidance, and the dual-pulse jet specifically enhances corner momentum, jointly suppressing secondary flow and boundary layer separation, ultimately promoting a benign coupling effect between "jet-vortex-boundary layer".

[0037] 3. Jet outlet arrangement: The generator has two jet outlets at its end: blade jet outlet 1 and endwall jet outlet 2.

[0038] The blade jet outlet 1 is located in the blade root region, pointing towards the blade root region of the suction surface of the stationary blade 10 below, specifically at a distance of about 3% of the chord length from the leading edge of the blade.

[0039] The endwall jet outlet 2 is located in the endwall region, pointing towards the endwall region of the blade passage, specifically in the circumferential direction at a distance of approximately 5% pitch from the pressure surface of the adjacent blade.

[0040] The axial direction of both jet outlets is designed to be 20° with the axial direction of the compressor mainstream.

[0041] 4. Key geometric parameters: refer to Figure 3 According to Table 1, with the characteristic width of the inlet throat as d, the key dimensions in this embodiment are the working dimensions: inlet wedge width d1 = 1.05d, inlet throat area d × 0.8d, main mixing chamber outlet width d2 = 2.25d, generator outlet width d3 = 1.2d, and feedback channel inlet width b = 0.8d. The distance L of the outlet diversion device is designed to be 3.5d3.

[0042]

[0043] The internal three-dimensional profile of the oscillating-pulse jet generator 40 is precisely defined by a set of specific quadratic polynomial curve functions (as described in the specification), ensuring that the flow channel surface is smooth and conforms to the designed flow field characteristics. The specific expressions are as follows: Entrance section curve: z=38.3610405927942-0.334277857895076x+0.384544247082688y+0.00000002x 2 +0.000000026xy+0.0000000053y 2 Internal separator curve: z=38.3610285714713-0.334278919719581x+0.384543583895433y+0.000000002x 2 +0.0000000086xy+0.0000000016y 2 Feedback channel curve: z=38.3610511887699-0.334277303327631x+0.384545018927886y+0.000000052x 2 -0.000000012xy+0.000000051y 2 Exit section curve: z=38.3610219553997-0.334279686716947x+0.384543441532508y-0.000000023x 2 -0.000000018xy-0.0000000002y 2 Outlet diversion structure curve: z=38.3609718976251-0.334284806946798x+0.38454223138855y-0.00000015x 2 -0.000000096xy-0.000000013y 2 Where x, y, and z are coordinates in a three-dimensional Cartesian coordinate system.

[0044] 5. Working principle and effects: Reference Figure 4 and Figure 5As shown, the novel oscillating-pulse jet generator of this invention, with its surrounding stator blade structure, simultaneously jets from the endwall and blade root. During jetting, a discrete high vortex region is generated at the nozzle. When this jet enters the mainstream at a certain angle, it is entrained by the shear layer, forming multiple ordered vortex rings or flow vortices. This can entrain and send the low-energy, separated fluid from the blade root and endwall into the mainstream region, reducing the accumulation of low-energy fluid in the blade corner region. The novel oscillating-pulse jet generator structure of this invention can provide a more continuous and stable energy input. The array-style arrangement design can more effectively control the frequency of the novel oscillating-pulse jet generator and the phase matching of the mainstream vortex system structure, making the jet's optimization effect on internal corner separation superior to that of traditional fluid oscillators. Furthermore, the novel oscillating-pulse jet generator with a surrounding stator blade structure of this invention features a dual-pulse outlet design. This design can simultaneously optimize the flow deterioration in both directions: the flow direction at the blade root (where the boundary layer on the blade's suction surface thickens and separates under the adverse pressure gradient) and the flow direction at the endwall (where the endwall boundary layer accumulates and climbs along the endwall towards the blade's suction surface under the adverse pressure gradient). When these two jets work together, they produce advanced control effects that a single-point jet cannot achieve. By designing the pulse phase, angle, and intensity of the two jets, the vortex structures they generate can interact to form a more powerful composite vortex system, thereby achieving a "three-dimensional pincer attack" of low-energy fluids in the diagonal region. This dual-jet collaborative control strategy achieves systematic regulation of the diagonally separated three-dimensional flow field structure through the spatial coordination and phase coupling of the endwall jet and the blade root jet. Specifically, the endwall jet directly acts on the low-energy fluid accumulation region of the endwall boundary layer, weakening the transport of secondary flow to the suction surface through periodic strong disturbances, thus suppressing the formation of corner separation at its source. Meanwhile, the blade root jet directly excites the suction surface boundary layer, enhancing its resistance to adverse pressure gradients and preventing further development of the separation structure. Through a synergistic mechanism of unsteady vortex dynamics—such as generating phase-matched composite vortex structures—both enhance the sweeping of low-energy fluid and the injection of high-energy momentum, achieving more efficient and stable active control of complex three-dimensional corner separation structures. This scheme significantly improves flow control performance while effectively reducing the net mass flow rate and energy consumption of the control system, providing a promising flow control approach for the design of next-generation high-performance turbomachinery.

[0045] The novel fluid pulser designed and used in this invention can operate effectively at a minimum inlet-outlet pressure ratio of 1.1, and the pulse frequency changes positively with the magnitude of the pressure difference. Figure 4 , five In the example, the inlet and outlet pressure ratio of the novel fluid pulser is 1.5, the frequency is 1250 Hz, the mainstream flow velocity is about 146 ms^-1, and the average flow velocity of the two jet outlets of the pulse jet generator is 218 ms^-1.

[0046] In one embodiment, based on the previous embodiment, it is shown how multiple oscillating-pulse jet generators are integrated in an array within the shroud 20 and their parameters are optimized to adapt to high-load conditions.

[0047] In this embodiment, refer to Figure 2 As shown, to address the negative effects of fluid blockage caused by low-energy fluid accumulation at the blade root, this invention presents a novel shrouded stator blade with an oscillating-pulse jet generator. The jet outlet 1 is positioned at 2%–5% of the blade's suction surface, and the jet outlet 2 is located circumferentially at 5% of the blade pitch. The three positions shown in the figure are spaced 10% of the chord length. The specific chord length can be adjusted according to the blade position array based on different operating conditions. The number of novel oscillators can also be determined based on the actual operating conditions of the compressor blade cascade. The angle between the two outlets is controlled within the range of 15°–30°. The stator blade is 10, the shroud 20 is a solid structure, and the hub surface is 30°. This invention can meet specific needs under different operating conditions and has high applicability.

[0048] Referring to Figure 2, the installation diagram of the novel oscillating-pulse jet generator enclosed vane structure includes a novel fluid oscillator 40, which is constructed inside the enclosed belt 20. The unsteady jet structure inlet 3 is arranged on the lower wall of the enclosed belt, and air is drawn in under the pressure difference between the enclosed belt and the end wall. The position is determined according to the jet outlet position and jet angle.

[0049] Reference Figure 3 As shown, the structure of the novel oscillating-pulse jet generator includes a blade jet outlet 1, an end-wall jet outlet 2, a main mixing chamber 4, a secondary mixing chamber 5, an outlet splitter 6, a feedback channel 7, and an air intake section 8 with a two-stage tapered structure to increase the inlet fluid velocity. A novel fluid oscillator 40 is also included. The structural parameters of the novel oscillating-pulse jet generator include the inlet throat width d, the inlet wedge width d1, the main mixing chamber outlet width d2, the outlet width d3, the feedback channel width b, and the distance L between the outlet separator and the swept-frequency oscillator outlet. L determines the pulse frequency of the two pulsed airflows. A longer L results in a lower frequency for the oscillating-pulse jet generator, and vice versa. However, a smaller L leads to more severe losses due to the high velocity of the main outlet stream impacting the splitter. Therefore, the novel oscillating-pulse jet generator achieves optimal frequency and overall losses when designed with a length of L = 3.5d3. Specific design ratios of the novel oscillating-pulse jet generator are shown in Table 1.

[0050] In summary, the first embodiment demonstrates the basic feasibility and significant effects of the core unit of the present invention, while the second embodiment further expands its engineering application by showcasing the great potential of the present invention in significantly improving the performance of the entire stage compressor through arraying and parameter system optimization.

[0051] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A shroud-type stator blade structure with an oscillating-pulse jet generator, comprising a stator blade (10) and a shroud (20) fixed to its bottom, characterized in that, At least one oscillation-pulse jet generator (40) is integrated inside the enclosure (20). The oscillating-pulse jet generator (40) is configured to generate unsteady flow by using the static pressure difference between the bottom wall of the shroud (20) and the end wall of the blade cascade as the sole driving force; it includes at least one jet inlet, an internal oscillating flow channel, at least one blade jet outlet (1), and at least one end wall jet outlet (2). The jet air intake is opened on the bottom wall of the enclosure (20) and is in fluid communication with the gap below the enclosure (20); The internal oscillating channel converts the fluid introduced through the jet inlet into a swept jet with periodic variation characteristics; the swept jet is separated into two spatially discrete and time-periodically alternating pulse jets by the outlet splitting structure (6) located at the end of the oscillating-pulse jet generator (40). The blade jet outlet (1) and the endwall jet outlet (2) are respectively arranged in the blade root region and endwall region of the blade suction surface, and are oriented towards the blade root corner separation region and the adjacent endwall region of the stationary blade (10), thereby suppressing corner flow separation through the synergistic effect of the dual pulse jets.

2. The circumferential stator structure with oscillation-pulse jet generator according to claim 1, characterized in that: The jet air intake is a circumferential opening groove (3) formed on the bottom wall of the circumferential band (20), and the circumferential opening groove (3) extends along the circumference of the circumferential band (20).

3. The circumferential stator structure with an oscillating-pulse jet generator according to claim 2, characterized in that: The oscillation-pulse jet generator (40) includes a sequentially fluid-connected converging air intake section (8), a main mixing chamber (4), a secondary mixing chamber (5), a feedback channel (7), and an outlet diversion structure (6).

4. The circumferential stator structure with an oscillating-pulse jet generator according to claim 3, characterized in that: The maximum cross-sectional area of ​​the main mixing chamber (4) is 3.6 times the area of ​​its inlet throat, and its outlet area is 2.25 times the area of ​​its inlet throat; the inlet of the secondary mixing chamber (5) is gradually expanding, and the outlet cross-sectional area of ​​the secondary mixing chamber (5) is smaller than the outlet cross-sectional area of ​​the main mixing chamber (4).

5. The circumferential stator structure with an oscillating-pulse jet generator according to claim 4, characterized in that: The feedback channel (7) is a tapered flow channel with an inlet area larger than its outlet area.

6. The circumferential stator structure with an oscillating-pulse jet generator according to claim 5, characterized in that: The outlet splitting structure (6) is located downstream of the sub-mixing chamber (5). Its separation wedge surface is at an acute angle to the jet flow direction, so that the swept jet adheres to different sides of the wall under the Coanda effect and switches periodically, thereby being separated into two pulse jets, which are respectively introduced into the blade jet outlet (1) and the end wall jet outlet (2).

7. The circumferential stator structure with an oscillating-pulse jet generator according to claim 6, characterized in that: The blade jet outlet (1) is located at 2% to 5% of the chord length from the leading edge of the blade suction surface, and the endwall jet outlet (2) is located at 5% of the blade pitch in the circumferential direction. The angle between the axis of the blade jet outlet (1) and the endwall jet outlet (2) and the mainstream flow direction is 15° to 30°.

8. The circumferential stator structure with an oscillating-pulse jet generator according to claim 7, characterized in that: The internal profile of the oscillation-pulse jet generator (40) is defined by a preset family of spatial curve functions. The family of functions includes at least independent curve functions describing the profiles of the inlet section, internal separator, feedback channel, outlet section, and outlet splitting structure. The specific expressions are as follows: Entrance section curve: z=38.3610405927942-0.334277857895076x+0.384544247082688y+0.00000002x 2 +0.000000026xy+0.0000000053y 2 Internal separator curve: z=38.3610285714713-0.334278919719581x+0.384543583895433y+0.000000002x 2 +0.0000000086xy+0.0000000016y 2 Feedback channel curve: z=38.3610511887699-0.334277303327631x+0.384545018927886y+0.000000052x 2 -0.000000012xy+0.000000051y 2 Exit section curve: z=38.3610219553997-0.334279686716947x+0.384543441532508y-0.000000023x 2 -0.000000018xy-0.0000000002y 2 Outlet diversion structure curve: z=38.3609718976251-0.334284806946798x+0.38454223138855y-0.00000015x 2 -0.000000096xy-0.000000013y 2 Where x, y, and z are coordinates in a three-dimensional Cartesian coordinate system.

9. A flow control method for a circumferential stator structure with an oscillating-pulse jet generator as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1. Self-excited bleed air: Using the static pressure difference between the bottom wall of the shroud (20) and the end wall of the blade cascade as the driving force, the fluid in the gap below the shroud (20) is automatically introduced into the bleed air section integrated into the oscillation-pulse jet generator (40) through the opening slot (3) opened on its bottom wall. Step 2. Oscillation Conversion: The introduced fluid is made to flow through the internal oscillation channel of the oscillation-pulse jet generator (40), which includes a gradually narrowing air intake section (8), a main mixing chamber (4), a secondary mixing chamber (5) and a feedback channel (7). Under the action of the feedback oscillation mechanism, the fluid is converted into an unsteady swept jet with periodic directional changes. Step 3. Pulse separation: The unsteady swept jet is directed to the outlet splitter (6) at the end of the oscillating-pulse jet generator (40). The Coanda effect is used to make the swept jet periodically switch on the separation wedge surface of the outlet splitter (6), thereby separating the swept jet into two spatially discrete and periodically alternating pulse jets. Step 4. Cooperative control: Two pulse jets are ejected through the blade jet outlet (1) and the endwall jet outlet (2) set on the sidewall of the enclosure (20), respectively; wherein, the jet of the blade jet outlet (1) is directed towards the blade root corner separation region of the suction surface of the stationary blade (10), and the jet of the endwall jet outlet (2) is directed towards the adjacent endwall region; through the synergistic effect of the two pulse jets in frequency, phase and spatial distribution, the boundary layer separation of the blade suction surface and the secondary flow of the endwall are simultaneously subjected to three-dimensional disturbance and momentum injection, thereby suppressing and weakening the corner flow separation at the root of the stationary blade (10).

10. The flow control method according to claim 9, characterized in that: The oscillating-pulse jet generator (40) can be self-excited to start and work stably under the condition that the static pressure ratio between the inlet and outlet is not less than 1.1, and the frequency of the generated pulse jet is positively correlated with the static pressure ratio.

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