A reflux circulator, compressor

Abstract

This application provides a reflux device and a compressor. The reflux device includes a base, reflux blades, and a reflux turning channel. The reflux blades are disposed on the base, and the reflux turning channel is located upstream of the reflux blades. The reflux blades include a pressure surface and a suction surface disposed opposite to each other. The pressure surface at the trailing edge of the reflux blades includes a raised surface, and the suction surface at the trailing edge of the reflux blades includes a recessed surface. This increases the flow area at the trailing edge between two adjacent reflux blades, which can better accommodate the supplementary airflow and reduce the mixing loss between the supplementary airflow and the mainstream airflow. At the same time, it reduces the tangential flow component of the airflow at the reflux device outlet, making the overall airflow closer to the axial direction. This helps to delay the stall of the impeller assembly downstream of the reflux device and reduce the occurrence of unstable flow phenomena such as surge.

Description

Technical Field

[0001] This invention relates to the field of compressor technology, and more particularly to a reflux device and a compressor. Background Technology

[0002] Multistage compressors are equipped with a reflux duct component, which guides the airflow from the outlet of the previous compression stage to the inlet of the next compression stage. This component mainly performs two functions: first, it rectifys and redirects the airflow, which has a large tangential component and a low axial component, from the outlet of the previous compression stage into a near-axial uniform airflow with a high axial component and a small tangential component, to adapt to the inlet flow conditions of the next compression stage; second, it enables interstage replenishment, allowing the replenishment airflow from components such as the economizer and flash tank to merge into the mainstream airflow.

[0003] Improving the airflow rectification and steering capabilities of the reflux condenser, as well as reducing the mixing loss between the supplementary airflow and the mainstream airflow, are key technical issues in the structural design of the reflux condenser. Summary of the Invention

[0004] This application provides a reflux device and a compressor to improve the airflow rectification and reversal capabilities of the reflux device, and to reduce the mixing loss between the supplementary airflow and the mainstream airflow.

[0005] In a first aspect, this application provides a reflux device, including a substrate, reflux blades, and a reflux turning channel. The reflux blades are disposed on the substrate, and the reflux turning channel is located upstream of the reflux blades. The reflux blades include a pressure surface and a suction surface disposed opposite to each other. The pressure surface at the trailing edge of the reflux blades includes a raised surface, and the suction surface at the trailing edge of the reflux blades includes a recessed surface.

[0006] In one embodiment, along the direction from the trailing edge of the return blade to the leading edge of the return blade, the height of the raised surface gradually decreases, and the depth of the recessed surface gradually decreases.

[0007] In one embodiment, the reflux device further includes a first connector located on the side of the reflux blade away from the substrate; the first connector is provided with an air inlet; the end of the protruding surface near the leading edge of the reflux blade is provided corresponding to the air inlet.

[0008] In one embodiment, the first connector is provided with an air supply channel; the port of the air supply channel located on the surface of the first connector near the return blade is the air supply port; the connection between the wall surface of the air supply channel near the tail edge of the return blade and the surface of the first connector near the return blade is an arc surface.

[0009] In one embodiment, the extension direction of the air supply channel forms an angle of 20°-45° with the surface of the substrate near the return blade.

[0010] In one embodiment, both the raised surface and the recessed surface are smooth curved surfaces.

[0011] In one embodiment, the recirculation blade further includes a top surface and a bottom surface disposed opposite to each other, the top surface connecting the edge of the pressure surface and the edge of the suction surface, and the bottom surface connecting the edge of the pressure surface and the edge of the suction surface; the orthographic projection of the leading edge portion of the bottom surface on the substrate is within the orthographic projection of the leading edge portion of the top surface on the substrate.

[0012] In one embodiment, the substrate includes a top plate, a bottom plate, and a side plate. The top plate and the bottom plate are opposite to each other and spaced apart. The side plate connects the periphery of the top plate and the periphery of the bottom plate. The outer surface of the side plate is curved and the curved surface protrudes away from the internal space enclosed by the side plate. The bottom surface is connected to the top plate. The orthographic projection of the bottom surface on the top plate at the leading edge of the return blade is located inside the top plate. The orthographic projection of the top surface on the top plate at the leading edge of the return blade extends out of the edge of the top plate and is located within the contour of the side plate.

[0013] In a second aspect, this application provides a compressor including a multi-stage impeller assembly and a return flow device disposed between two adjacent impeller assemblies, the return flow device including any of the above-mentioned return flow devices.

[0014] In one embodiment, the compressor further includes a diffuser disposed between two adjacent impeller assemblies, the diffuser being located upstream of the return blades; the diffuser is a bladeless diffuser.

[0015] The beneficial effects of this application are as follows: Unlike the prior art, this application provides a reflux device and a compressor. The reflux device includes a base, reflux blades, and a reflux turning channel. The reflux blades are disposed on the base, and the reflux turning channel is located upstream of the reflux blades. The reflux blades include a pressure surface and a suction surface disposed opposite to each other. The pressure surface at the trailing edge of the reflux blades includes a raised surface, and the suction surface at the trailing edge of the reflux blades includes a recessed surface. This increases the flow area at the trailing edge between two adjacent reflux blades, which can better accommodate the supplementary airflow and reduce the mixing loss between the supplementary airflow and the mainstream airflow. At the same time, it reduces the tangential flow component of the airflow at the outlet of the reflux device, making the overall airflow closer to the axial direction. This helps to delay the stall of the impeller assembly downstream of the reflux device and reduce the occurrence of unstable flow phenomena such as surge. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the compressor provided in an embodiment of this application; Figure 2 yes Figure 1 The diagram shows a cross-sectional view of the compressor along line AA. Figure 3 yes Figure 2 A schematic diagram of the structure of the reflux unit's base and reflux blades; Figure 4 yes Figure 3 An enlarged schematic diagram of the trailing edge portion of the recirculation blades shown; Figure 5 yes Figure 3 An enlarged schematic diagram of the leading edge portion of the recirculation blade is shown. Figure 6 yes Figure 3 A schematic diagram of the matrix and recirculation blades from another perspective; Figure 7 This is a schematic diagram of the inlet airflow angle of the secondary impeller assembly provided in an embodiment of this application; Figure 8 This is a comparison diagram of the outlet flow angle of the reflux device provided in this application embodiment and the reflux devices of related technologies. Attached image description: Compressor 1, impeller assembly 11, first-stage impeller assembly 11a, second-stage impeller assembly 11b, reflux 12, reflux turning channel 121, base 122, top plate 1221, side plate 1222, reflux blade 123, pressure surface 1231, suction surface 1232, top surface 1233, first connecting piece 124, air supply channel 124a, air supply port 1241, diffuser 13, first-stage diffuser 13a, second-stage diffuser 13b, motor shaft 14, volute 15. Detailed Implementation

[0019] The technical solutions of the embodiments of this application 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 this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] The terms "first," "second," and "third" in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] Multistage compressors are equipped with a reflux duct component, which guides the airflow from the outlet of the previous compression stage to the inlet of the next compression stage. This component primarily performs two functions: first, it rectifys and redirects the airflow, which has a large tangential component and a low axial component, from the outlet of the previous compression stage into a near-axially uniform airflow with a high axial component and a small tangential component, to adapt to the inlet flow conditions of the next compression stage; second, it enables interstage makeup air, allowing makeup airflow from components such as the economizer and flash tank to merge into the mainstream airflow. Improving the airflow rectification and redirection capabilities of the reflux duct, as well as reducing the mixing losses between the makeup airflow and the mainstream airflow, are key technical issues in the reflux duct structural design.

[0024] In view of this, embodiments of this application provide a reflux device and a compressor to improve the airflow rectification and reversal capabilities of the reflux device, and to reduce the mixing loss between the supplementary airflow and the mainstream airflow.

[0025] Please see Figure 1 and Figure 2 , Figure 1This is a schematic diagram of the compressor provided in an embodiment of this application. Figure 2 yes Figure 1 The diagram shows a cross-sectional view of the compressor along line AA.

[0026] The compressor 1 includes a multi-stage impeller assembly 11 and a return flow device 12 disposed between two adjacent impeller assemblies 11. The impeller assembly 11, as the core component of the compressor 1, performs work on the gas through high-speed rotation, enabling it to simultaneously gain kinetic and pressure energy. Each stage of the impeller assembly 11 increases the gas pressure, temperature, and flow velocity. The series connection of the multi-stage impeller assemblies 11 achieves step-by-step pressurization, ultimately resulting in a higher outlet pressure. The return flow device 12 transforms the highly rotating airflow discharged from the previous stage impeller assembly 11 into an airflow more suitable for the inlet flow conditions of the next stage impeller assembly 11. The highly rotating airflow refers to an airflow with high tangential velocity and low lateral velocity (i.e., low axial velocity), while the airflow suitable for the inlet flow conditions of the next stage impeller assembly 11 refers to an airflow with high lateral velocity (i.e., high axial velocity) and low tangential velocity. The return flow device also integrates fluids (secondary fluids, generally referred to as makeup gas flow) from components such as the economizer and flash tank into the mainstream airflow.

[0027] In one embodiment, see further. Figure 2 The compressor 1 also includes a diffuser 13 disposed between two adjacent impeller assemblies 11, with the diffuser 13 located upstream of the return flow recirculator 12. The diffuser 13 being upstream of the return flow recirculator 12 means that the airflow exiting the impeller assembly 11 first passes through the diffuser 13 before flowing into the return flow recirculator 12; in other words, the diffuser 13 is in the flow direction between the outlet of the impeller assembly 11 and the inlet of the return flow recirculator 12, and is located before the return flow recirculator 12. The main function of the diffuser 13 is to decelerate and diffuse the high-speed airflow at the outlet of the impeller assembly 11, efficiently converting the kinetic energy of the airflow into pressure energy, reducing the airflow velocity and increasing the gas pressure. Simultaneously, it makes the outflowing airflow more uniform and stable, creating favorable flow conditions for the subsequent airflow guidance and intake of the return flow recirculator 12, reducing airflow impact and energy loss, and improving the overall operating efficiency of the compressor.

[0028] In one embodiment, the diffuser 13 is a bladeless diffuser; in other words, the diffuser 13 has no blades. By setting the diffuser 13 as a bladeless diffuser, the structure is simple and easy to manufacture. It does not have the blade boundary layer separation problem inherent in bladed diffusers, and has a wider range of stable operating conditions. At the same time, it is not sensitive to changes in the airflow inlet angle, has strong adaptability to operating conditions, is not prone to airflow impact and surge, can maintain good flow performance under different flow rates and speeds, and is not prone to airflow excitation, resulting in higher operational reliability.

[0029] In one embodiment, the diffuser 13 is a bladeless diffuser. Along the flow direction from the impeller assembly 11 to the return flow device 12, the channel of the diffuser 13 is set to a cross-sectional shape that gradually decreases and then remains unchanged. On the one hand, it can moderately constrain the high-speed airflow at the outlet of the impeller assembly 11 in the front section, suppress the separation and eddies caused by excessive airflow diffusion, and reduce flow losses. On the other hand, in the constant cross-section region in the rear section, the airflow velocity and pressure tend to be uniform and stable, avoiding drastic fluctuations in airflow parameters. This ensures the efficient conversion of kinetic energy into pressure energy and provides uniform and smooth intake conditions for the downstream return flow device 12, thereby improving the overall working stability and efficiency of the compressor.

[0030] In one implementation, such as Figure 2 As shown, the compressor 1 also includes a motor shaft 14. The motor shaft 14 extends axially along the compressor 1 and is coaxially and fixedly connected to the multi-stage impeller assembly 11, and is directly driven to rotate by the torque output of the drive motor. The motor shaft 14 smoothly transmits the torque generated by the drive motor to each stage of the impeller assembly 11, driving the impeller assembly 11 to rotate at high speed, thereby performing work on the gas to achieve compression and pressure increase; at the same time, through high-precision coaxial support and positioning, it ensures that the multi-stage impeller assembly 11, diffuser 13, and return flow device 12 maintain a stable axial position, avoids interference between moving and stationary parts, and ensures that the compressor 1 operates stably and reliably under high-speed conditions.

[0031] In one implementation, such as Figure 2 As shown, the compressor 1 also includes a volute 15. The volute 15 is located downstream of the impeller assembly 11 and has an overall spiral or snail-shaped cavity structure, smoothly connecting with the internal flow channel to form the overall gas flow path of the compressor 1. The volute 15 collects the pressurized airflow from the final stage impeller assembly 11 and further converts the remaining kinetic energy of the airflow into pressure energy through the gradually expanding spiral flow channel, achieving pressure equalization, flow stabilization, and converging effects. It also smoothly guides the compressed high-pressure gas to the compressor 1 outlet for discharge. Simultaneously, it seals and reduces noise from the internal airflow, minimizing gas leakage and flow noise, ensuring efficient and stable output of high-pressure gas, and improving the overall working efficiency and operational stability of the compressor 1.

[0032] In one embodiment, a final-stage diffuser 13 is disposed downstream of the final-stage impeller assembly 11, and no return flow device 12 is disposed between the final-stage diffuser 13 and the inlet of the volute 15. In one embodiment, the structural design of the final-stage diffuser 13 can be the same as the structural design of other diffusers 13.

[0033] In one embodiment, compressor 1 is a centrifugal compressor.

[0034] In one specific embodiment, the compressor 1 is a centrifugal compressor. The compressor 1 includes two-stage impeller assemblies 11, defined as a first-stage impeller assembly 11a and a second-stage impeller assembly 11b. The first-stage impeller assembly 11a is located upstream of the second-stage impeller assembly 11b; that is, the airflow is first compressed by the first-stage impeller assembly 11a before entering the second-stage impeller assembly 11b for further compression. A first-stage diffuser 13a and a return flow device 12 are arranged between the first-stage impeller assembly 11a and the second-stage impeller assembly 11b. The airflow from the first-stage impeller assembly 11a passes through the first-stage diffuser 13a and the return flow device 12 before entering the second-stage impeller assembly 11b. The airflow from the second-stage impeller assembly 11b passes through the second-stage diffuser 13b before entering the volute 15. In the return flow device 12, the supplementary airflow merges with the mainstream airflow, and the two mix before flowing together into the second-stage impeller assembly 11b. The first-stage impeller assembly 11a and the second-stage impeller assembly 11b are driven to rotate by the same motor shaft 14. Both the first-stage diffuser 13a and the second-stage diffuser 13b are bladeless diffusers.

[0035] Since the outlet of the first-stage impeller assembly 11a is a high-speed rotating airflow, and ideally the inlet airflow of the second-stage impeller assembly 11b should be close to the axial direction, otherwise it will lead to a decrease in compression efficiency and a narrowing of the stable operating range, the design of the return flow device 12 needs to eliminate the circumferential velocity component of the airflow flowing out of the first-stage impeller assembly 11a as much as possible. At the same time, in the return flow device 12, the make-up airflow merges into the mainstream airflow, and there is an angle between the make-up airflow and the mainstream airflow. Flow losses may occur during the mixing process, and the design of the return flow device 12 should make the mixing process as efficient as possible. In view of this, the embodiment of this application designs the return flow device 12.

[0036] Please see Figures 3 to 6 , Figure 3 yes Figure 2 A schematic diagram of the structure of the reflux unit's base and reflux blades. Figure 4 yes Figure 3 The diagram shows an enlarged view of the trailing edge of the recirculation blade. Figure 5 yes Figure 3 The diagram shows an enlarged view of the leading edge portion of the recirculation blade. Figure 6 yes Figure 3 The diagram shows the structure of the substrate and the return flow blades from another perspective.

[0037] The return flow device 12 includes a return flow turning channel 121, a base 122, and return flow blades 123. The return flow blades 123 are disposed on the base 122; the base 122 serves as the supporting structure for the return flow blades 123, and the return flow blades 123 are fixed to the surface of the base 122. The return flow turning channel 121 is located upstream of the return flow blades 123; that is, the airflow from the impeller assembly 11 is guided and turned through the return flow turning channel 121 before entering the area of ​​the return flow blades 123. During the turning process, the return flow turning channel 121 rectifyes and stabilizes the airflow, weakens eddies and flow separation, reduces flow losses, and ensures that the airflow enters the area of ​​the return flow blades 123 uniformly and stably, thereby improving the interstage efficiency and overall operational stability of the compressor.

[0038] The return vane 123 includes a pressure surface 1231 and a suction surface 1232 arranged opposite to each other. The pressure surface 1231 refers to the working surface of the return vane 123 facing the side impacted by the mainstream airflow, where the surface static pressure is relatively high; the suction surface 1232 refers to the working surface of the return vane 123 away from the side impacted by the mainstream airflow, where the surface static pressure is relatively low. During the flow of airflow through the area of ​​the return vane 123, the pressure surface 1231 and the suction surface 1232 together guide and deflect the airflow, allowing the airflow to smoothly enter the next stage impeller assembly 11 along the preset flow channel.

[0039] In the embodiments of this application, such as Figure 4 As shown, the pressure surface 1231 located at the trailing edge of the return blade 123 includes a convex surface; wherein, the convex surface refers to the surface of the blade profile of the pressure surface 1231 located at the trailing edge of the return blade 123 that protrudes outward and is in an outwardly convex arc shape. The suction surface 1232 located at the trailing edge of the return blade 123 includes a concave surface; wherein, the concave surface refers to the surface of the suction surface 1232 located at the trailing edge of the return blade 123 that converges inward and is in an inwardly concave arc shape. It should be noted that the trailing edge is the end of the return blade 123 where the airflow leaves the blade after being guided, and is the end where the airflow flows out of the blade channel and enters the next stage impeller assembly 11; the trailing edge refers to a small section of the blade near the trailing edge (e.g., Figure 4 (As shown).

[0040] By setting the pressure surface 1231 of the trailing edge portion of the return blade 123 to have a convex surface and the suction surface 1232 to have a concave surface, the flow area of ​​the trailing edge portion between two adjacent return blades 123 is increased, which can better accommodate the supplementary airflow. The supplementary airflow can smoothly integrate into the mainstream airflow, reducing the mixing loss between the supplementary airflow and the mainstream airflow. At the same time, it can guide the airflow to turn more smoothly, reducing the tangential flow component of the airflow at the outlet of the return pipe 12, thereby making the overall airflow closer to the axial direction, reducing the flow loss of the next compression stage, which is beneficial to delay the stall of the impeller assembly 11 downstream of the return pipe 12, reducing the occurrence of unstable flow phenomena such as surge, and improving the efficiency of the compressor 1.

[0041] In one embodiment, the protrusion direction of the pressure surface 1231 located on the protrusion of the trailing edge portion of the return blade 123 is opposite to the rotation direction of the impeller of the impeller assembly 11 upstream of the return blade 123.

[0042] In one embodiment, along the direction from the trailing edge to the leading edge of the return vane 123, the height of the raised surface gradually decreases, and the depth of the recessed surface gradually decreases. This gradual design makes the flow area of ​​the flow channel formed by two adjacent return vanes 123 change more smoothly at the trailing edge, which is beneficial for efficient mixing of the supplementary fluid and the mainstream fluid and reduces mixing losses. At the same time, it can make the tangential component of the airflow at the outlet of the return device 12 smaller, thereby achieving a flow closer to the axial direction and improving the overall efficiency and operating range of the compressor 1. It should be noted that the leading edge of the return vane 123 refers to the end of the return vane 123 that first contacts the airflow, which is the starting point for the airflow to enter the vane flow channel; a small section of the vane near the leading edge is the leading edge portion (e.g., Figure 5 (As shown).

[0043] In one embodiment, both the raised and recessed surfaces are smooth curved surfaces. A smooth curved surface refers to a continuous curved surface without sharp edges or abrupt changes. As the core feature surfaces of the trailing edge portion of the return blade 123, both the raised and recessed surfaces adopt a smooth curved surface design, which makes the airflow continuous and stable in the boundary layer of the trailing edge portion, thereby reducing flow separation losses and further improving the airflow rectification effect; at the same time, it allows the supplementary airflow to smoothly integrate into the mainstream airflow, and the flow is more uniform during the mixing process, which helps to reduce mixing losses and improve the overall efficiency of the return device 12.

[0044] In one embodiment, both the raised and recessed surfaces are streamlined curved surfaces. A streamlined curved surface refers to a surface with a smooth transition and no abrupt turns or sharp angles. Its curvature changes gradually, allowing airflow to flow smoothly along the surface, effectively avoiding flow separation, eddies, and local impact losses. This ensures uniform pressure and velocity changes during fluid flow, improving flow efficiency and operational stability. As the core feature surfaces of the trailing edge of the return blade 123, the raised and recessed surfaces, by being designed as streamlined curved surfaces, can reduce mixing losses when the supplementary airflow merges into the mainstream airflow, while simultaneously improving airflow rectification.

[0045] In one embodiment, see further. Figure 2The reflux 12 also includes a first connector 124, which is located on the side of the reflux blade 123 facing away from the base 122. The first connector 124 has a supplementary air inlet 1241. A pressure surface 1231 has a raised surface at the trailing edge of the reflux blade 123, with the raised surface near the leading edge of the reflux blade 123 corresponding to the supplementary air inlet 1241. This design allows for better accommodation of the supplementary airflow, enabling the supplementary airflow to smoothly integrate into the mainstream airflow, reducing mixing losses between the supplementary airflow and the mainstream airflow. Simultaneously, it guides the airflow to a smoother direction, reducing the tangential flow component of the airflow at the outlet of the reflux 12, thus making the overall airflow closer to the axial direction and improving the efficiency of the compressor 1.

[0046] The first connector 124 is provided with an air supply channel 124a. The port of the air supply channel 124a near the surface of the first connector 124 close to the return vane 123 is the air supply port 1241. The connection between the wall of the air supply channel 124a near the trailing edge of the return vane 123 and the surface of the first connector 124 near the return vane 123 is an arc surface, which allows the air supply airflow to smoothly merge into the main airflow channel, effectively reducing the impact loss and eddy disturbance when the airflow merges; it can also reduce the problem of the port corners blocking and separating the airflow, ensuring uniform and stable air supply, and improving the mixing effect of the air supply and the mainstream.

[0047] In one embodiment, the extension direction of the supplementary air channel 124a forms an angle of 20°-45° with the surface of the substrate 122 near the return blade 123, so that the supplementary airflow and the mainstream airflow form an angle of 20°-45°, which enables the supplementary airflow to merge into the mainstream airflow in a posture that is closer to the flow direction of the main airflow, significantly reducing the impact, turbulence and mixing loss when the airflows converge; at the same time, it can effectively suppress the disturbance of the mainstream flow field by the supplementary airflow, avoid local backflow or separation, ensure the smooth fusion of the main airflow and the supplementary airflow, and improve the supplementary air conditioning effect.

[0048] In one embodiment, the first connector 124 is provided with a plurality of air inlets 1241. A flow channel is formed by two adjacent return blades 123, and multiple flow channels are formed between each pair of return blades 123. Each flow channel is provided with a corresponding air inlet 1241. The orthographic projection of the air inlet 1241 on the substrate 122 is located between two return blades 123.

[0049] In one implementation, such as Figure 3 and Figure 6As shown, the return vane 123 also includes a top surface 1233 and a bottom surface disposed opposite to each other. The top surface 1233 connects the edge of the pressure surface 1231 and the edge of the suction surface 1232, and the bottom surface connects the edge of the pressure surface 1231 and the edge of the suction surface 1232. The orthographic projection of the leading edge portion of the return vane 123 onto the substrate 122 is within the orthographic projection of the leading edge portion of the return vane 123 onto the substrate 122; in other words, the bottom surface of the return vane 123 located at the leading edge portion is recessed relative to the top surface 1233, and the end face of the leading edge of the return vane 123 is an inclined surface.

[0050] By setting the bottom surface of the leading edge portion of the return blade 123 to be projected onto the base 122 so that it is completely within the projection of the top surface 1233 onto the base 122, and the bottom surface is recessed relative to the top surface 1233, when the airflow enters the area of ​​the return blade 123 from the return turning channel 121, the recessed design of the bottom surface relative to the top surface 1233 guides the airflow to transition smoothly in the leading edge area, avoiding flow separation caused by abrupt changes in cross-section, and further improving the airflow rectification efficiency.

[0051] In one implementation, such as Figure 3 and Figure 6 As shown, the base 122 includes a top plate 1221, a bottom plate, and a side plate 1222. The top plate 1221 is opposite to and spaced apart from the bottom plate. The side plate 1222 connects the periphery of the top plate 1221 and the periphery of the bottom plate. The outer surface of the side plate is curved, and the curved surface protrudes away from the internal space enclosed by the side plate 1222. The bottom surface of the return blade 123 is connected to the top plate 1221. The orthographic projection of the leading edge portion of the bottom surface on the top plate 1221 is located within the top plate 1221; the orthographic projection of the leading edge portion of the top surface on the top plate 1221 extends beyond the edge of the top plate 1221 and is located within the contour of the side plate 1222.

[0052] By setting the orthographic projection of the leading edge portion of the return vane 123 onto the top plate 1221 to be within the top plate 1221, and the orthographic projection of the leading edge portion of the top surface of the return vane 123 onto the top plate 1221 to extend beyond the edge of the top plate 1221 and to be within the contour of the side plate 1222, the bottom surface of the leading edge portion of the return vane 123 is recessed relative to the top surface 1233. When the airflow enters the area of ​​the return vane 123 from the return turning channel 121, the recessed design of the bottom surface relative to the top surface 1233 guides the airflow to smoothly transition in the leading edge area, avoiding flow separation caused by abrupt changes in cross-section, and further improving the airflow rectification efficiency.

[0053] In one implementation, such as Figure 5As shown, the leading edge end face of the return blade 123 is a circular arc surface. The circular arc surface structure of the leading edge end face of the return blade 123 can effectively reduce the impact and collision loss when the airflow enters the blade channel. The circular arc transition surface can make the airflow adhere to the blade surface more smoothly, avoiding airflow separation, eddies and local turbulence caused by sharp leading edge corners. At the same time, the circular arc surface structure can reduce the aerodynamic excitation of the airflow on the leading edge of the blade, improve the blade structural strength and impact resistance, widen the stable operating range of the compressor, and further improve the stability and flow efficiency of interstage guidance.

[0054] In one implementation, such as Figure 6 As shown, the height of the return blade 123 located at the trailing edge is relatively high (i.e., the height of the return blade 123 located at the trailing edge is higher than the height of the return blades 123 in other parts, while the height of the return blades 123 in other parts can be the same). The structure with a higher trailing edge can form a more suitable flow space, reasonably adjust the flow velocity in this area and increase the static pressure, making the airflow at the blade outlet more uniform radially, thereby providing better inlet conditions for the next stage impeller assembly 11. This height variation design matches the diffusion process, realizing the conversion of airflow kinetic energy to pressure energy while reducing flow losses in the channel and making the flow channel transition more smoothly to the next stage. In addition, the relatively high height of the return blade 123 located at the trailing edge, in conjunction with the aforementioned gradual increase and then gradual decrease in the thickness of the return blade 123, can further improve the interstage guiding efficiency and improve the overall aerodynamic performance of the compressor 1.

[0055] In one implementation, such as Figure 3 As shown, the pressure surface 1231 is generally concave, and the suction surface 1232 is generally convex. By making the pressure surface 1231 of the return blade 123 generally concave and the suction surface 1232 generally convex, the blade profile can better match the airflow turning trajectory. The airflow is smoothly guided along the concave pressure surface 1231, making it less prone to airflow impact and separation. The convex suction surface 1232 can make the airflow smooth and the velocity distribution uniform, reducing eddies and flow separation losses. This structure not only ensures stable airflow guidance and turning effect, but also reduces interstage flow resistance and improves the interstage flow efficiency and operational stability of the compressor.

[0056] In one implementation, such as Figure 3As shown, along the direction from the leading edge to the trailing edge of the return blade 123, the thickness of the return blade 123 gradually increases and then gradually decreases. This allows for a smoother transition of the blade profile, enabling the airflow to adhere stably to the surface of the return blade 123 in the leading edge region, avoiding airflow impact and separation caused by excessive thickness at the leading edge. The maximum thickness in the middle provides sufficient structural strength for the return blade 123, ensuring rigidity and stability under high-speed airflow. The thickness gradually decreases towards the trailing edge, adjusting the airflow cross-sectional area, which effectively weakens the wake vortex, reduces airflow trailing edge losses, and thus improves interstage guiding efficiency and the overall aerodynamic performance of the compressor 1. It should be noted that the thickness of the return blade 123 refers to the vertical distance between the pressure surface 1231 and the suction surface 1232.

[0057] In one implementation, such as Figure 2 As shown, the cross-sectional area of ​​the return flow turning channel 121 is the same at all positions, which can keep the airflow velocity basically constant during the turning process and avoid the acceleration, deceleration or local pressure fluctuation of the airflow due to abrupt changes in cross-section or expansion / contraction. It can effectively suppress the generation of airflow separation, eddies and secondary flows, and reduce flow losses during the turning process. At the same time, it makes the airflow more evenly distributed and more stable in the entire return flow turning channel 121, providing uniform air intake conditions for the subsequent return flow blades 123, ensuring smooth and stable interstage guidance, and thus improving the overall aerodynamic efficiency and operational stability of the compressor 1.

[0058] Please see Figure 7 , Figure 7 This is a schematic diagram of the inlet airflow angle of the secondary impeller assembly provided in this application embodiment.

[0059] Figure 7 A coordinate system is established with the axial (inlet direction) and circumferential (impeller rotation direction of impeller assembly 11) as references. α is the absolute airflow angle (the angle between absolute velocity and the axial direction), and β is the relative airflow angle (the angle between relative velocity and impeller tangent). The smaller α is, the closer the airflow direction at the outlet of the return valve 12 is to the axial direction. A more axial airflow can reduce the relative airflow angle β, which is beneficial for delaying the stall of the next stage impeller and avoiding premature occurrence of unstable flow phenomena such as surge.

[0060] Please see Figure 8 , Figure 8 This is a comparison diagram of the outlet flow angle of the reflux device provided in this application embodiment and the reflux devices of related technologies.

[0061] Depend on Figure 8It can be seen that by designing the return blade 123, the outlet airflow α of the return device 12 in this embodiment is closer to 0°, which can significantly reduce the tangential flow component of the outlet airflow of the return device 12 (from over 20° to close to 0°), making the overall flow closer to the axial direction and resulting in better airflow rectification. It should be noted that... Figure 8 The only difference between the reflux device of this application embodiment and the reflux device of related technologies is the structure of the reflux blade 123. Figure 8 The vertical axis represents the different heights of the return blades.

[0062] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A reflux device, comprising a base, reflux blades, and a reflux turning channel, wherein the reflux blades are disposed on the base, and the reflux turning channel is located upstream of the reflux blades, characterized in that, The recirculation blade includes a pressure surface and a suction surface arranged opposite to each other; the pressure surface located at the trailing edge of the recirculation blade includes a raised surface, and the suction surface located at the trailing edge of the recirculation blade includes a recessed surface.

2. The reflux device according to claim 1, characterized in that, Along the direction from the trailing edge of the return blade to the leading edge of the return blade, the height of the raised surface gradually decreases, and the depth of the recessed surface gradually decreases.

3. The reflux device according to claim 1, characterized in that, The reflux device further includes a first connector, which is located on the side of the reflux blade away from the base; the first connector is provided with an air inlet. The end of the protruding surface near the leading edge of the return blade is provided corresponding to the air inlet.

4. The reflux device according to claim 3, characterized in that, The first connector is provided with an air supply channel; the port of the air supply channel located on the surface of the first connector near the return blade is the air supply port; The connection between the wall surface of the air supply channel near the trailing edge of the return blade and the surface of the first connector near the return blade is an arc surface.

5. The reflux device according to claim 4, characterized in that, The extension direction of the air supply channel forms an angle of 20°-45° with the surface of the substrate near the return blade.

6. The reflux device according to claim 1, characterized in that, Both the raised surface and the recessed surface are smooth curved surfaces.

7. The reflux device according to claim 1 or 2, characterized in that, The return blade also includes a top surface and a bottom surface disposed opposite to each other, the top surface connecting the edge of the pressure surface and the edge of the suction surface, and the bottom surface connecting the edge of the pressure surface and the edge of the suction surface; The orthographic projection of the bottom surface on the substrate of the leading edge portion of the return blade is within the orthographic projection of the top surface on the substrate of the leading edge portion of the return blade.

8. The reflux device according to claim 7, characterized in that, The substrate includes a top plate, a bottom plate, and side plates. The top plate and the bottom plate are opposite to each other and spaced apart. The side plates connect the periphery of the top plate and the periphery of the bottom plate. The outer surface of the side plate is curved and the curved surface protrudes away from the internal space enclosed by the side plate. The bottom surface is connected to the top plate; the orthographic projection of the leading edge portion of the bottom surface on the top plate is located within the top plate. The top surface, located on the leading edge of the return blade, extends out of the edge of the top plate in its orthographic projection onto the top plate and lies within the outline of the side plate.

9. A compressor, characterized in that, It includes a multi-stage impeller assembly and a return flow device disposed between two adjacent impeller assemblies, the return flow device including the return flow device according to any one of claims 1-8.

10. The compressor according to claim 9, characterized in that, The compressor further includes a diffuser disposed between two adjacent impeller assemblies, the diffuser being located upstream of the return blades; the diffuser is a bladeless diffuser.

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