A two-stage supersonic ejector

Abstract

The present application belongs to the field of ejector, and particularly relates to a two-stage supersonic ejector, which comprises a square suction chamber and a square-to-circle transition flow channel connected in sequence; further comprising a strut ejector arranged in the square suction chamber and a ring ejector arranged at one side of the circle segment of the square-to-circle transition flow channel. The strut ejector and the ring ejector are combined via the square-to-circle transition flow channel with specific aerodynamic reconstruction function, the flow field mismatch problem in series connection of the special-shaped ejector is solved, the two performance indexes of high mixing efficiency and high pressure ratio which are traditionally restricted to each other are successfully unified, and the synergistic effect of significantly shortening the mixing length and greatly improving the overall entrainment coefficient and the pressure ratio is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of ejector, and particularly relates to a two-stage supersonic ejector. BACKGROUND

[0002] Supersonic ejector is a kind of fluid device with simple topological structure and high energy transmission efficiency, and its core goal is to create a low pressure area in the mixing chamber by using high-speed primary flow, so as to pump the secondary flow, and finally make the two flows mixed to be discharged at a moderate pressure. It is widely used in aerospace fields such as high-altitude simulation test bench, chemical laser pressure recovery system, hypersonic wind tunnel, aerospace power system, etc.

[0003] Among the existing inventions, the closest to the present application are four-branch plate ejector and annular ejector. Both of the two kinds of ejectors can realize the injection of secondary flow and the establishment of negative pressure environment, but the structural strength and pressure increasing characteristics are obviously different.

[0004] CN108757591B is a two-dimensional configuration of multi-branch plate ejector structure design, the designed branch plate ejector is arranged with multiple groups of branch plates for dividing the injected and the injected gas flow, a flow guide section is arranged at the front end of the branch plate, and a gas guide cavity and a two-dimensional Laval nozzle are arranged inside. The injected gas flow is divided into multiple uniform gas flows by the branch plate, the contact area between the injected gas flow and the injected gas flow is increased, and better mixing effect is achieved. In addition, the structure of the nozzle gas guide cavity and the two-dimensional Laval nozzle is integrally designed, the outer contour of the branch plate is streamline, and the flow loss is small.

[0005] CN102507199A is a high-altitude environment simulation test annular ejector, which is applied to the ejector used in high-altitude simulation test bench. Based on the high pressure increasing ratio characteristic of annular ejector, a split type annular ejector is proposed. The design discards the traditional integral scheme, and only needs to adjust the size of the ejector nozzle according to the test requirements to realize the adjustment of the injection performance in a certain range, so that the working efficiency is improved, the test cost is reduced, and the structure compactness is maintained.

[0006] Among the single-stage ejector types such as two-branch plate ejector and four-branch plate ejector, the active flow and the passive flow have good mixing effect, the ejector mixing length is short, the vacuum pumping capacity is strong, but the ejector coefficient is low; the annular ejector is a common ejector scheme at present, but the mixing efficiency is low under the condition of high ejector coefficient, so that the length of the ejector pipeline is long, and it is difficult to meet the dual requirements of stability and high-efficiency mixing in high-altitude simulation test; the multi-stage sub-super ejection improves the airflow matching characteristics through stage-by-stage compression, but the inter-stage dynamic pressure loss is significant, and the total pressure recovery coefficient is low, which limits its application in high-load working conditions; the multi-stage ejection improves the total pressure recovery performance, but the mixing efficiency is low due to the limited mixing length, and the above structures are difficult to realize the coordinated optimization of the ejector efficiency, the pressure ratio and the flow uniformity. If the branch plate ejector and the annular ejector are simply physically connected in series, due to the fundamental conflict between the outlet / inlet flow field structures of the two stages, the multiple discrete, non-axisymmetric jets at the outlet of the branch plate will directly impact the axisymmetric continuous flow field required by the annular ejector, which will inevitably cause strong shock waves, flow separation and vortex shedding. This not only causes great total pressure loss, leading to a sharp decrease in the pressure ratio of the second-stage annular ejector, but also interrupts and even worsens the mixing process established by the first stage, forcing the entire system to have a longer pipeline to reestablish uniform flow, completely losing the original intention of using the branch plate ejector to shorten the mixing length. At the same time, this flow field mismatch will also cause the system operating point to drift and the performance to fluctuate, seriously affecting its reliability in high-end applications requiring high stability. It is these inherent and predictable technical obstacles that make the technical personnel in this field generally believe that it is difficult and inefficient to directly combine the two different types of ejectors, thereby forming the clear technical prejudice that the present invention aims to overcome. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a two-stage supersonic ejector. The branch plate ejector and the annular ejector are combined through a square-to-round transition flow passage with a specific aerodynamic reconstruction function, which solves the flow field mismatch problem when different types of ejectors are connected in series, successfully unifies the two performance indicators of high mixing efficiency and high pressure ratio which are traditionally mutually restrictive, and realizes the synergistic effect of significantly shortening the mixing length while greatly improving the overall ejector coefficient and pressure ratio.

[0008] The present application provides a two-stage supersonic ejector, comprising a square suction chamber and a square-to-round transition flow passage connected in sequence;

[0009] It also includes a branch plate ejector arranged in the square suction chamber, the branch plate ejector comprising a plurality of branch plates with Laval nozzles arranged inside, for dividing the main flow into multiple jets and performing primary mixing with the secondary flow;

[0010] The annular ejector is arranged on one side of the circular segment of the square-to-circle transition flow channel, and comprises annular Laval nozzles arranged in the circumferential direction, which are used for secondary ejecting and pressurizing the mixed gas flow after being ejected by the strut ejector.

[0011] The cross-sectional shape of the square-to-circle transition flow channel gradually changes from square to circle to achieve smooth transition of the gas flow and suppress flow separation.

[0012] The high mixing efficiency of the strut ejector and the high pressure ratio of the annular ejector are combined, and the square-to-circle transition flow channel is connected and transitioned, so that the ejector can shorten the mixing length while improving the overall ejector coefficient and pressure ratio.

[0013] Further, a first straight section with a circular cross-section is connected between the outlet of the square-to-circle transition flow channel and the annular ejector.

[0014] Further, the annular ejector and the first straight section are connected by a section of metal bellows.

[0015] Further, the annular Laval nozzles of the annular ejector are uniformly distributed in the circumferential direction, and the upper profile of the nozzle profile is a straight line, and the lower profile is an arc designed by the characteristic line method.

[0016] Further, the annular ejector further comprises:

[0017] a ring-shaped gas collecting chamber for receiving and uniformly distributing the ejected gas flow;

[0018] and a plurality of gas conveying channels uniformly distributed in the circumferential direction, the inlet of each gas conveying channel is in communication with the ring-shaped gas collecting chamber, and the outlet is connected to the gas inlet end of the annular Laval nozzle, for conveying the ejected gas flow to the corresponding annular Laval nozzle.

[0019] Further, the outlet gas flow direction of the annular Laval nozzle is parallel to the axial direction of the ejector.

[0020] Further, the annular ejector further comprises a first diffuser section with a gradually expanding shape, which is connected downstream of the annular Laval nozzle, for converting the kinetic energy of the mixed fluid into pressure potential energy.

[0021] Further, the front end of each strut of the strut ejector is further provided with a flow guide cone, and the flow guide cone and the wall surface of the adjacent strut form a convergent channel together, which is used for guiding and pre-organizing the secondary flow to smoothly enter the gas flow channel between the struts.

[0022] Furthermore, downstream of the annular Laval nozzle of the annular ejector, a converging section, a second straight section, and a gradually expanding second diffuser section are sequentially arranged along the airflow direction;

[0023] The contraction section is used to accelerate the mixed airflow after the second stage ejection and improve the mixing uniformity; the second straight section is used to allow the airflow to develop fully and flow stably; and the second diffusion section is used to convert the kinetic energy of the airflow into pressure potential energy.

[0024] Furthermore, the shrinkage ratio of the flow cross-sectional area of ​​the contraction section is 0.7.

[0025] The beneficial effects of this invention are that by combining the support plate ejector and the annular ejector through a square-to-circular transition channel with specific aerodynamic reconfiguration function, the problem of flow field mismatch when irregular ejectors are connected in series is solved, and the two traditionally mutually restrictive performance indicators of high mixing efficiency and high pressure ratio are successfully unified, achieving a synergistic effect of significantly improving the overall ejection coefficient and pressure ratio while significantly shortening the mixing length. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention;

[0027] Figure 2 This is the front view of the present invention;

[0028] Figure 3 for Figure 2 A magnified view of a section at point A in the middle;

[0029] Figure 4 for Figure 2 A magnified view of a section at point B in the middle;

[0030] Figure 5 for Figure 2 A magnified view of a section at point C.

[0031] In the diagram, 1-square suction chamber; 2-square-to-round transition channel; 3-support plate ejector; 31-support plate; 32-guide cone; 4-annular ejector; 41-annular Laval nozzle; 42-first diffuser section; 43-annular gas collection chamber; 44-gas delivery channel; 5-first straight section; 6-contraction section; 7-second straight section; 8-diffuser section; 9-metal bellows; 91-guide liner tube. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0034] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0037] like Figures 1-5 As shown, the present invention provides a two-stage supersonic ejector, comprising a square suction chamber 1 and a square-to-round transition channel 2 connected in sequence;

[0038] It also includes a support plate ejector 3 disposed within the square suction chamber 1. The support plate ejector 3 comprises multiple support plates 31 with internal Laval nozzles, used to divide the main stream into multiple jets and initially mix them with the secondary stream. The arrangement of the support plate ejector 3 achieves efficient initial mixing of the main and secondary airflows. By using multiple support plates 31 with internally integrated Laval nozzles, a main stream is precisely divided and accelerated into multiple high-speed jets, greatly increasing the contact area and shearing effect with the secondary stream. Within a very short distance at the inlet section of the square suction chamber 1, sufficient mass and momentum exchange is completed, significantly shortening the length required to achieve uniform mixing, thus providing a basis for solving the shortcomings of traditional annular ejectors, such as slow mixing and long pipes.

[0039] It also includes an annular ejector 4 disposed on one side of the circular section of the square-to-circular transition channel 2. The annular ejector 4 includes an annular Laval nozzle 41 disposed along the circumferential direction, which is used to perform secondary ejection and pressurization of the mixed airflow after being ejected from the support plate ejector 3.

[0040] The square-to-circular transition channel 2 transforms the multiple discrete, rectangular jet fields at the outlet of the support plate ejector 3 into the axisymmetric, circularly distributed, uniform flow field required by the annular ejector 4 through a continuous and smooth gradual change in cross-sectional shape and channel profile. During the flow transition in the square-to-circular transition channel 2, the airflow is further mixed, providing the annular ejector 4 with uniform flow field and stable parameters for air intake. This solves the inherent flow field mutual repulsion and matching problems when irregularly shaped ejectors are connected in series, enabling efficient startup of subsequent annular ejectors.

[0041] The annular ejector 4 features a high pressure ratio and efficient energy recovery. Based on the optimized incoming flow from the support plate ejector 3 and the square-to-circular transition channel 2, its circumferentially arranged annular Laval nozzles 41 form a high-speed annular jet, effectively entraining and compressing the mixed airflow. With basic mixing completed, the system focuses on efficiently converting the kinetic energy of the airflow into pressure potential energy, achieving a significant increase in system outlet pressure (high pressure ratio), thus compensating for the shortcomings of the support plate ejector 3 in this regard.

[0042] The cross-sectional shape of the square-to-circular transition channel 2 gradually changes from a square shape matching the outlet of the square intake chamber 1 to a circle shape matching the inlet of the annular ejector 4, in order to achieve a smooth transition of airflow and suppress flow separation. Its gradual design effectively eliminates corner vortices, shock waves and boundary layer separation caused by abrupt changes in cross-section, and controls the total pressure loss between the two stages to the lowest level.

[0043] By combining the high mixing efficiency of the support plate ejector 3 with the high boosting efficiency of the annular ejector 4, and through the connection and transition of the square-to-circular transition channel 2, the ejector can improve the overall ejection coefficient and boosting ratio while shortening the mixing length.

[0044] The two-stage supersonic ejector provided by this invention successfully solves the traditionally mutually restrictive problem of high mixing efficiency and high boost ratio performance.

[0045] The first-stage ejector 3 actively organizes and pre-treats the airflow. Through multiple ejectors 31 internally integrated with Laval nozzles, it precisely divides and accelerates the main stream into multiple high-speed jets. This design not only significantly increases the contact area with the secondary flow, achieving rapid and efficient initial mixing, but more importantly, it pre-constructs a complex yet controllable multi-jet system for the downstream flow field, laying the foundation for subsequent flow field reconstruction and energy transfer.

[0046] The second-stage annular ejector 4 serves as the system's pressure boosting and energy recovery terminal. Its circumferentially distributed annular Laval nozzles 41 can form a uniform, high-intensity annular supersonic jet. In this invention, its efficient operation relies on obtaining an axisymmetric and uniform incoming flow. Building upon the already largely completed mixing in the preceding stage, it focuses on the efficient entrainment of the airflow and the efficient conversion of kinetic energy into pressure potential energy, thereby achieving a high pressure ratio that is difficult to attain with a single ejector.

[0047] The square-to-round transition channel 2 is the pivotal element for achieving seamless integration and synergistic amplification of the aforementioned two-stage performance advantages. Compared to conventional square-to-round structures used only for physical connection or simple rectification, this component in the present invention is endowed with an active and crucial aerodynamic reconfiguration function:

[0048] 1. It smoothly and with low loss reconstructs the complex turbulent field of the non-axisymmetric, multi-core, high-intensity shear layer inherent in the outlet of the support plate ejector 3 into a highly axisymmetric, uniform, and stable circular cross-section flow field necessary for the efficient operation of the annular ejector 4.

[0049] 2. While completing the above-mentioned drastic flow field transformation, its optimized surface can suppress shock waves, boundary layer separation and vortex shedding to the maximum extent, thereby keeping the total pressure recovery coefficient between the two stages at the optimal level.

[0050] 3. Within the space of gradually changing cross-section, the natural stretching and reorganization of the flow field promotes further momentum and mass exchange among the fluid micro-particles from different support plates 31 channels, which is essentially a deepening of the mixing process.

[0051] In summary, the support plate ejector 3 achieves efficient mixing, the square-to-circular transition channel 2 reconstructs and adapts the flow field, and the annular ejector 4 enhances the high pressure. These three components work together to form a highly efficient functional relay. This allows the system to achieve a mixing length close to or better than that of a pure support plate ejector, while significantly surpassing the overall pressure ratio and vacuum pumping capacity of a pure annular ejector. This represents a performance breakthrough that cannot be achieved by traditional single-structure or simple physical series connection methods.

[0052] In one embodiment, a first straight section 5 with a circular cross-section is connected between the outlet of the square-to-circular transition channel 2 and the annular ejector 4.

[0053] In this embodiment, the first straight section 5 further optimizes the matching quality of the interstage flow field. It provides a stable development section for the airflow after the drastic cross-section change, allowing the flow field initially reconstructed in the square-to-circular transition channel 2 to be fully homogenized here, eliminating local velocity and pressure fluctuations. This ensures that the airflow entering the annular ejector 4 in the second stage achieves a high degree of axisymmetry and stability. This design significantly reduces the negative impact of residual non-uniformity of the incoming flow on the performance of the annular ejector 4, further reduces the total interstage pressure loss, and ensures the full utilization of the ejection efficiency of the annular ejector 4.

[0054] In one embodiment, the annular ejector 4 is connected to the first straight section 5 via a section of metal bellows 9. Preferably, a straight flow-guiding liner 91 is coaxially disposed inside the metal bellows 9, the upper end of the flow-guiding liner 91 is fixedly connected to the metal bellows 9, and the lower end maintains a radial gap with the trough of the metal bellows 9.

[0055] In this implementation, under high load and variable operating conditions, the axial and radial thermal expansion of each component is different due to drastic temperature changes. The metal bellows 9, through its flexible characteristics, can effectively absorb these differential deformations, eliminate the huge thermal stress generated as a result, prevent structural damage or sealing failure, and ensure the long-term operational stability and reliability of the system under high temperature and high flow conditions.

[0056] While the external metal bellows 9 provides necessary flexibility, its internal trough structure, if directly exposed to the high-speed mainstream, can induce severe flow separation and pressure pulsation. This invention addresses this by providing a smooth, continuous, and ideal flow path for the core supersonic airflow through an internally straight guide liner 91, ensuring no additional flow loss or disturbance as the airflow passes through this connecting section. The radial gap between the guide liner 91 and the troughs of the metal bellows 9 forms a static secondary flow buffer chamber, balancing pressure and preventing interference between the metal bellows 9 and the liner when the bellows 9 deforms, perfectly balancing structural flexibility and aerodynamic efficiency.

[0057] In one embodiment, the annular Laval nozzles 41 of the annular ejector 4 are evenly distributed along the circumference, and the upper profile of the nozzle profile is a straight line, while the lower profile is an arc designed using the characteristic line method.

[0058] In this embodiment, the annular Laval nozzle 41 of the annular ejector 4 adopts a specific configuration with the upper profile as a straight line and the lower profile as an arc designed by the characteristic line method. This achieves isentropic smooth expansion of the supersonic airflow, effectively suppressing shock wave losses. At the same time, it ensures that the outlet airflow direction is strictly parallel to the axial direction, avoiding the impact compression of the mainstream on the downstream premixed airflow. This significantly reduces turbulent mixing losses, making the process of the annular ejector 4 more efficient and smooth. While ensuring the uniformity and high kinetic energy of the annular jet, it also takes into account the feasibility of processing.

[0059] In one embodiment, the annular ejector 4 further includes:

[0060] An annular gas collecting cavity 43 is used to receive and evenly distribute the ejector gas flow;

[0061] And multiple gas delivery channels 44 evenly distributed along the circumference, the inlet of each gas delivery channel 44 is connected to the annular gas collection chamber 43, and the outlet is connected to the air inlet of the annular Laval nozzle 41, for delivering the ejector gas flow to the corresponding annular Laval nozzle 41.

[0062] In this embodiment, the annular ejector 4 constructs a multi-stage air intake distribution system that first converges and then distributes the airflow by setting an annular gas collecting chamber 43 and multiple circumferentially uniformly distributed air delivery channels 44 connected to it. First, the annular gas collecting chamber 43 performs preliminary convergence and pressure equalization of the ejector airflow, effectively eliminating any possible flow pulsations or pressure unevenness upstream. Subsequently, the airflow is precisely and equally delivered to the air intake end of the annular Laval nozzle 41 through multiple independent air delivery channels 44. This ensures that the annular Laval nozzle 41 obtains almost completely consistent air intake conditions circumferentially, forming a uniform, stable, high-intensity, and highly axisymmetric annular supersonic jet.

[0063] In one embodiment, the outlet airflow direction of the annular Laval nozzle 41 is parallel to the ejector axis.

[0064] In this embodiment, the outlet airflow direction of the annular Laval nozzle 41 is strictly set to be parallel to the ejector axis, which directly eliminates the impact and compression effect of the radial component of the jet on the premixed airflow in the downstream mixing zone, thereby significantly reducing unnecessary turbulent mixing losses and total pressure dissipation, making the energy transfer process of the second-stage ejector more direct, smooth and efficient.

[0065] In one embodiment, the annular ejector 4 further includes a gradually expanding first diffuser section 42 connected downstream of the annular Laval nozzle 41, for converting the kinetic energy of the mixed fluid into pressure potential energy.

[0066] In this embodiment, by using its gradually expanding surface to decelerate and pressurize the airflow, extremely high total pressure recovery efficiency can be achieved, thereby maximizing the kinetic energy gain obtained by the entire system and effectively increasing the outlet static pressure. This design enables the annular ejector 4 to achieve optimal energy recovery after completing the core functions of high-speed mixing and ejection, ultimately resulting in a significant enhancement in the system's vacuuming capability and operational efficiency.

[0067] In one embodiment, each of the support plates 31 of the support plate ejector 3 is further provided with a guide cone 32 at its front end. The guide cone 32 and the wall surface of the adjacent support plate 31 together form a convergence channel for guiding and pre-organizing the secondary flow so that it smoothly enters the airflow channel between the support plates 31.

[0068] In this embodiment, the guide cone 32 at the front end of the ejector 3 and the adjacent support plate walls together form a convergent inlet channel. This not only avoids the direct impact and potential erosion of the high-temperature, high-speed secondary flow on the support plate structure, but more importantly, it accelerates, organizes, and evenly distributes the secondary flow into the airflow channels between the supports 31 before it enters the mixing zone. This establishes a stable and orderly initial flow field at the starting end of the ejector 3. This greatly optimizes the boundary conditions at the encounter of the primary and secondary flows, making the high-speed shearing and mixing process more efficient and controllable. It improves the mixing efficiency and flow field quality of the ejector 3 from the source and reduces the burden on the aerodynamic reconstruction of the downstream square-to-round transition channel 2.

[0069] In one embodiment, downstream of the annular Laval nozzle 41 of the annular ejector 4, a converging section 6, a second straight section 7, and a gradually expanding second diffuser section 8 are sequentially arranged along the airflow direction.

[0070] The contraction section 6 is used to accelerate the mixed airflow after the second stage ejection and improve the mixing uniformity; the second straight section 7 is used to allow the airflow to develop fully and flow stably; and the second diffuser section 8 is used to convert the kinetic energy of the airflow into pressure potential energy.

[0071] In this embodiment, a contraction section 6, a second isostatic section 7, and a second diffuser section 8 are sequentially arranged downstream of the annular ejector 4. First, the contraction section 6 controllably accelerates the mixed airflow ejected by the annular ejector 4. The increased velocity gradient further enhances momentum exchange between micro-elements, effectively improving the final homogeneity of the mixture. Subsequently, the second isostatic section 7 provides the necessary stable development length for this accelerated airflow, allowing the flow field to fully develop and the velocity profile to become more balanced, creating ideal conditions for subsequent efficient diffuser operation. Finally, the gradually expanding second diffuser section 8 converts the kinetic energy of the airflow into pressure potential energy with maximum efficiency. This not only ensures the final perfection of the mixing quality but also maximizes the system's total pressure recovery efficiency and final outlet pressure.

[0072] In one embodiment, the flow cross-sectional area of ​​the contraction section 6 has a contraction ratio of 0.7.

[0073] In this embodiment, the flow cross-sectional area shrinkage ratio of the contraction section 6 is specifically designed to be 0.7. On the one hand, this provides a sufficient acceleration gradient to enhance the final micro-mixing and ensure optimal mixing uniformity; on the other hand, it effectively avoids unnecessary total pressure loss caused by flow separation or a sharp increase in shock wave intensity due to excessive contraction. This maximizes the total pressure recovery efficiency and energy recovery capability of the entire post-treatment system.

[0074] The above description is merely an embodiment and does not constitute any limitation on the present invention. Any person skilled in the art can make many possible variations, modifications, or alterations to the technical solutions of the present invention without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A two-stage supersonic ejector, characterized in that, It includes a square suction chamber (1) connected in sequence and a square-to-round transition channel (2); It also includes a support plate ejector (3) installed in a square suction chamber (1), the support plate ejector (3) including multiple support plates (31) with Laval nozzles inside, for dividing the main stream into multiple jets and mixing them with the secondary streams for the first time; It also includes an annular ejector (4) set on one side of the circular section of the square-to-circular transition channel (2). The annular ejector (4) includes an annular Laval nozzle (41) set along the circumferential direction, which is used to perform secondary ejection and pressurization of the mixed airflow after being ejected from the support plate ejector (3). The cross-sectional shape of the square-to-circular transition channel (2) gradually changes from a square shape matching the outlet of the square suction chamber (1) to a circle shape matching the inlet of the annular ejector (4) to achieve a smooth transition of airflow and suppress flow separation. By combining the high mixing efficiency of the support plate ejector (3) with the high boosting efficiency of the annular ejector (4), and the connection and transition of the square-to-circular transition channel (2), the ejector can improve the overall ejection coefficient and boosting ratio while shortening the mixing length.

2. The two-stage supersonic ejector according to claim 1, characterized in that, Between the outlet of the square-to-circular transition channel (2) and the annular ejector (4), there is also a first straight section (5) with a circular cross section.

3. The two-stage supersonic ejector according to claim 2, characterized in that, The annular ejector (4) is connected to the first straight section (5) via a section of metal bellows (9).

4. The two-stage supersonic ejector according to claim 1, characterized in that, The annular Laval nozzle (41) of the annular ejector (4) is evenly distributed along the circumference, and the upper profile of its nozzle profile is a straight line, while the lower profile is an arc designed using the characteristic line method.

5. The two-stage supersonic ejector according to claim 1, characterized in that, The annular ejector (4) also includes: An annular gas collecting chamber (43) is used to receive and uniformly distribute the ejector gas flow; And multiple gas delivery channels (44) evenly distributed along the circumference, the inlet of each gas delivery channel (44) is connected to the annular gas collection chamber (43), and the outlet is connected to the air inlet of the annular Laval nozzle (41) for delivering the ejector gas flow to the corresponding annular Laval nozzle (41).

6. The two-stage supersonic ejector according to claim 1, characterized in that, The outlet airflow direction of the annular Laval nozzle (41) is parallel to the ejector axis.

7. The two-stage supersonic ejector according to claim 1, characterized in that, The annular ejector (4) also includes a gradually expanding first diffuser section (42) connected downstream of the annular Laval nozzle (41) for converting the kinetic energy of the mixed fluid into pressure potential energy.

8. The two-stage supersonic ejector according to claim 1, characterized in that, Each of the support plates (31) of the support plate ejector (3) is provided with a guide cone (32) at its front end. The guide cone (32) and the wall surface of the adjacent support plate (31) together form a convergence channel for guiding and pre-organizing the secondary flow so that it can smoothly enter the airflow channel between the support plates (31).

9. The two-stage supersonic ejector according to any one of claims 1-6, characterized in that, Downstream of the annular Laval nozzle (41) of the annular ejector (4), a converging section (6), a second straight section (7), and a gradually expanding second diffuser section (8) are arranged sequentially along the airflow direction. The contraction section (6) is used to accelerate the mixed airflow after the second stage ejection and improve the mixing uniformity; the second straight section (7) is used to allow the airflow to develop fully and flow stably; and the second diffusion section (8) is used to convert the kinetic energy of the airflow into pressure potential energy.

10. The two-stage supersonic ejector according to claim 9, characterized in that, The shrinkage ratio of the flow cross-sectional area of ​​the contraction section (6) is 0.7.

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