A control structure for directing the flow of low pressure air in a diffuser

Abstract

The application discloses a control structure for guiding the flow direction of low-pressure airflow in a guide diffuser, and relates to the field of engine supercharging. A second jet port, a first jet port and a suction port are arranged on a blade of the guide diffuser; the suction port is communicated with a suction channel; the second jet port and the first jet port are communicated with the suction channel through a jet channel; the vortex generated by a pressure surface is introduced out of the suction port, mixed with high-pressure gas provided by a flow control system, and then sprayed out of the first jet port and the second jet port, so that the vortex generated by the pressure surface is continuously weakened and is caused to be fused with a main flow again; the second jet channel adopts a small included angle of 10-20 degrees in a downstream jet flow mode, so that additional loss caused by the impact of a traditional pressure surface jet on the main flow due to improper direction is avoided. In a low-flow or even zero-flow working condition, airflow circulation in the guide diffuser is maintained, the probability of surge triggering is reduced, the working efficiency of the compressor is improved, and the service life of the compressor is prolonged.

Description

Technical Field

[0001] This invention relates to the field of engine turbocharging, and in particular to a control structure for guiding the flow of low-pressure airflow within a diffuser. Background Technology

[0002] Centrifugal compressors are widely used in booster systems for marine power, aero engines, and industrial gas turbines due to their advantages such as compact structure, high single-stage pressure ratio, and wide operating range. Their core function is to increase the gas pressure by performing work on the working fluid through the impeller to meet the intake requirements under different speed and load conditions. The diffuser, as a crucial component of the compressor, is responsible for slowing down and diffuserizing the high-speed airflow at the impeller outlet, efficiently converting kinetic energy into pressure energy. Its internal flow characteristics directly determine the compressor's efficiency, stability margin, and operational reliability.

[0003] As turbocharging systems continue to evolve towards higher power density and lower fuel consumption, the single-stage load of centrifugal compressors is constantly increasing. This leads to a significant increase in the adverse pressure gradient within the diffuser channel, consequently raising the risk of flow separation. Particularly in the corner region where the diffuser blade suction surface meets the endwall, low-energy fluids easily accumulate, inducing corner separation and complex vortex structures. When the compressor operates at low flow rates, these separations and vortex structures often intensify further, resulting in a reduction in the effective flow area of ​​the channel, increased aerodynamic losses, and a significant decrease in compressor efficiency. More seriously, under extreme conditions of low or even near-zero flow, the separated flow inside the diffuser may evolve into large-scale backflow and turbulent vortex structures, thereby inducing or exacerbating compressor surge and other instability phenomena, severely threatening the safe operation of the equipment and even causing blade fatigue damage and other failures. Summary of the Invention

[0004] The purpose of this invention is to provide a control structure for guiding the flow direction of low-pressure airflow within a diffuser, thereby solving the problems existing in the prior art, reducing the risk of flow separation within the diffuser under low-flow conditions, improving compressor efficiency, and extending compressor service life.

[0005] To achieve the above objectives, the present invention provides the following solution: The present invention provides a control structure for guiding the flow direction of low-pressure airflow within a diffuser, comprising an end wall and blades disposed on the end wall, the blades comprising a pressure surface and a suction surface. A suction port is provided on the pressure side near the trailing edge of the blade, and the suction port is connected to the suction channel. A first jet port is provided on the suction side near the leading edge of the blade; a second jet port is provided on the pressure side near the leading edge. The first jet port and the second jet port are connected to the suction channel through the jet channel. Both the first jet port and the second jet port face the trailing edge, and the angle between the airflow direction ejected by the second jet port and the mainstream direction of the boundary layer of the pressure side is 10°~20°. It also includes a flow control system, the output of which is connected to the jet channel. The flow control system is used to generate high-pressure gas and actively adjust the airflow rate of the jet channel.

[0006] In one embodiment, the suction channel and the jet channel are respectively vertically arranged in the blade, and the ends near the end wall extend toward the end wall and communicate with each other after penetrating the end wall.

[0007] In one embodiment, a control channel is provided on the side of the endwall away from the blade. The control channel is connected to the jet channel, and the flow control system adjusts the airflow in the jet channel through the control channel.

[0008] In one embodiment, the jet channel includes a first jet channel and a second jet channel, wherein the first jet channel is connected to a first jet port and the second jet channel is connected to a second jet port.

[0009] In one embodiment, the flow control system includes an air pump and a detection module for collecting the airflow flow rate in the diffuser. The output end of the air pump is connected to a first jet channel and a second jet channel, respectively. Solenoid valves for controlling the airflow flow rate are provided on the first jet channel and the second jet channel. The air pump, the detection module, and the solenoid valves are electrically connected to a control module. The control module controls the solenoid valves based on the signal from the detection module to independently adjust the airflow flow rate of the second jet channel and the first jet channel.

[0010] In one embodiment, the first jet port, the second jet port, and the suction port are all elongated holes, and the length of the elongated holes extends along the height direction of the blade.

[0011] In one embodiment, guide vanes are respectively provided on the first jet port and the second jet port, with the guide vanes facing the trailing edge.

[0012] In one embodiment, the width of the guide vane is 2 to 3 times the diameter of the jet channel, and the angle between the extension direction of the guide vane and the mainstream direction of the boundary layer of the pressure surface or suction surface is 10° to 20°.

[0013] In one embodiment, the guide vane extends along the profile of the pressure or suction surface.

[0014] The present invention achieves the following technical effects compared to the prior art: A second jet port, a first jet port, and a suction port are provided on the diffuser blades. The suction port is connected to the suction channel, and the second and first jet ports are connected to the suction channel through the jet channel. When the diffuser operates at low or even zero flow rates, and low-energy fluids converge and form vortices near the trailing edge and endwall corners of the suction surface, the suction port on the pressure surface draws out these vortices and guides them along the suction channel to the jet channel. After mixing with the high-pressure gas provided by the flow control system, the mixture is ejected from the first and second jet ports. Since the first jet port faces the trailing edge, it creates a pre-energy replenishment and "tearing" effect in the separation area, continuously weakening the originally easily expanding separation vortex and promoting its re-merging with the mainstream. The second jet channel adopts a small angle of 10°~20° in a downstream jet manner, allowing the jet to adhere and spread along the boundary layer of the pressure surface, dispersing and "dragging" the low-energy boundary layer of the pressure surface, avoiding the additional losses introduced by the traditional pressure surface jet due to improper direction impacting the mainstream.

[0015] Because the combined effect of "tail edge suction - fluid reuse - leading edge jet" on the suction side and the low-loss fusion of the small-angle jet at the second jet outlet with the mainstream work simultaneously, the separation trend of the diffuser inner corner region and the development trend of the global vortex are effectively suppressed. Thus, it is possible to maintain the airflow circulation in the diffuser and reduce the probability of surge triggering under low flow or even zero flow conditions, thereby improving the compressor working efficiency and extending the compressor service life. Attached Figure Description

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

[0017] Figure 1 This is a top view of the blade in one embodiment of the present invention; Figure 2 This is a schematic diagram of the suction surface of the blade in one embodiment of the present invention; Figure 3 This is a schematic diagram of the pressure surface of the blade in one embodiment of the present invention; Figure 4 This is a right view of the blade in one embodiment of the present invention; Figure 5 For the present invention Figure 4 A cross-sectional view along the AA direction; Figure 6 For the present invention Figure 5 Enlarged view of the structure at point B.

[0018] Among them, 1. trailing edge; 2. leading edge; 3. pressure surface; 4. suction surface; 5. jet channel; 6. suction channel; 7. first jet port; 8. guide vane; 9. suction port; 10. second jet port; 11. first jet channel; 12. second jet channel. Detailed Implementation

[0019] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The purpose of this invention is to provide a control structure for guiding the flow direction of low-pressure airflow within a diffuser, thereby solving the problems existing in the prior art, reducing the risk of flow separation within the diffuser under low-flow conditions, improving compressor efficiency, and extending compressor service life.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Please refer to Figures 1 to 6This embodiment provides a control structure for guiding the flow direction of low-pressure airflow within a diffuser, including an end wall and blades disposed on the end wall. Each blade includes a pressure surface 3 and a suction surface 4. A suction port 9 is disposed on one side of the pressure surface 3 near the trailing edge 1 of the blade and in areas prone to vortex accumulation, such as the corner region corresponding to the trailing edge 1. The suction port 9 is connected to a suction channel 6. A first jet port 7 is disposed on one side of the suction surface 4 near the flow separation sensitive area of ​​the leading edge 2 of the blade, and a second jet port 7 is disposed on one side of the pressure surface 3 near the flow separation sensitive area of ​​the leading edge 2. The second jet port 10 and the first jet port 7 are connected to the jet channel 5, which is connected to the suction channel 6. In this embodiment, to ensure the transmission efficiency of the airflow in the jet channel 5 and the suction channel 6, the depth of the second jet port 10 and the first jet port 7 is designed to be 1.1-1.2 times the diameter of the jet channel 5. Both the first jet port 7 and the second jet port 10 face the direction of the trailing edge 1, and the inner walls of the second jet port 10 and the first jet port 7 have a smooth transition. The airflow in the jet channel 5 enters the second jet port. There is a large buffer space after the second jet 10 and the first jet 7. After deceleration in the second jet 10 and the first jet 7, a uniform airflow is formed on the pressure surface 3 and the suction surface 4 according to the shape of the second jet 10 and the first jet 7. That is, the inner wall is arc-shaped, forming a synergistic effect of "tail edge 1 suction - internal reuse - leading edge 2 jet". Furthermore, the angle between the airflow ejected from the second jet 10 and the mainstream direction of the boundary layer of the pressure surface 3 is 10°~20°. The "dragging" effect of the ejected airflow guides the low-energy airflow to flow downstream and merge into the mainstream. The system includes boundary layer dispersion and flow field energy level supplementation. Simultaneously, it also incorporates a flow control system, which connects the high-pressure gas generated by the flow control system to the second jet port 10 and the first jet port 7. The flow control system actively regulates the gas flow rate entering the second jet port 10 and the first jet port 7 to achieve adaptive and active control of the low-pressure airflow direction within the diffuser under different operating conditions. This reduces the risk of flow separation within the diffuser under different operating conditions, improves compressor efficiency, avoids diffuser surge, and extends compressor service life.

[0023] In this embodiment, the suction channel 6 and the jet channel 5 are vertically arranged in the blade, and the ends near the end wall extend towards the end wall and are connected to each other after penetrating the end wall. In this scheme, the suction channel 6 is connected to the suction port 9 near the end wall through the suction port 9. The airflow drawn by the suction port 9 can directly enter the suction channel 6, reducing the obstruction when the airflow enters the suction channel 6 from the suction port 9. The jet channel 5 is set in the same way as the suction channel 6. The jet channel 5 is connected to the second jet port 10 and the first jet port 7 near the end wall, so that the airflow in the suction channel 6 can smoothly enter the jet channel 5, reducing the flow of airflow in the suction channel 6 and the jet channel 5, ensuring the transmission efficiency of airflow in the process of flowing from the suction port 9 to the second jet port 10 and the first jet port 7, and improving the synergistic effect of "tail edge 1 suction - internal reuse - leading edge 2 jet".

[0024] The synergistic effect of "tail edge 1 suction - internal reuse - leading edge 2 jet" formed by suction port 9, second jet port 10 and first jet port 7 is a passive adjustment process through the pressure difference between the tail edge 1 and leading edge 2 of the blade. In the control structure provided in this embodiment, an active adjustment process is also included, which extends suction channel 6 and jet channel 5 to the outside of the end wall, maintains the original structure of the flow channel inside the diffuser, and avoids additional flow resistance in the flow channel. Therefore, a control channel is provided on the side of the end wall away from the blade. The control channel is connected to the jet channel 5. The flow control system actively adjusts the airflow in the jet channel 5 through the control channel, thereby controlling the airflow intensity of the second jet port 10 and the first jet port 7.

[0025] In the diffuser of the compressor, the pressure on the pressure surface 3 of the blade is greater than the pressure on the suction surface 4. When the airflow rate of the second jet port 10 and the first jet port 7 is controlled by active adjustment, the required airflow rates of the second jet port 10 and the first jet port 7 are different. Therefore, in this embodiment, the jet channel 5 includes a first jet channel 11 and a second jet channel 12. The first jet channel 11 is connected to the first jet port 7, and the second jet channel 12 is connected to the second jet port 10. The flow control system is connected to the first jet channel 11 and the second jet channel 12 respectively, and the airflow rate in the first jet channel 11 and the second jet channel 12 is adjusted by the flow control system.

[0026] This embodiment provides a specific solution for a flow control system.

[0027] The flow control system includes an air pump and a detection module. The detection module uses a flow sensor to detect the airflow in the diffuser in real time and transmits the detected flow signal to an Arduino microcontroller, which acts as the control module. The Arduino microcontroller generates adjustment commands based on a PID control algorithm and controls the opening of the solenoid valves set on the second jet channel 12 and the first jet channel 11, as well as the output power of the air pump, thereby changing the airflow in the second jet channel 12 and the first jet channel 11. This changes the intensity of the jet airflow at the second jet port 10 and the first jet port 7, enhancing the tearing effect on the vortex of the suction surface 4, and achieving the dispersal of the boundary layer of the pressure surface 3 and the replenishment of the flow field energy level.

[0028] The specific industrial control logic of the Arduino microcontroller is as follows: Under low flow conditions: Increase the jet intensity of the first jet port 7, tear apart the separation vortex through the jet at the leading edge 2, and at the same time use the suction port at the trailing edge 1 to suction and remove the vortex in the accumulation angle region. Under zero flow conditions: By increasing the intensity of the dual-jet flow, the working fluid circulation in the flow channel is forcibly maintained, preventing the compressor from entering a surge state; Under design conditions: The system automatically lowers or shuts down the jet flow, which is passively adjusted by the suction channel 6, the first jet channel 11, and the second jet channel 12 to reduce additional energy consumption.

[0029] In this embodiment, the suction port 9 is configured as an elongated hole, and the length of the elongated hole extends along the height direction of the blade until the suction range of the elongated hole covers the height direction of the blade, ensuring that the suction port 9 can completely eliminate the vortex of flow separation in the corner region; similarly, the first jet port 7 and the second jet port 10 are also configured as elongated holes, and the length range of the elongated hole also extends along the height direction of the blade, so that the airflow ejected from the first jet port 7 and the second jet port 10 covers the entire height direction of the blade, thereby suppressing flow separation when the airflow flows in the entire height direction of the blade.

[0030] Since this embodiment adopts the method of "tail edge 1 suction - internal reuse - leading edge 2 jet" to reduce the flow separation problem generated by the diffuser under low flow conditions, in order to avoid the airflow ejected from the second jet port 10 and the first jet port 7 impacting the main airflow and causing impact loss, guide vanes 8 are respectively provided on the first jet port 7 and the second jet port 10, and the guide vanes 8 face the direction of the tail edge 1, thereby limiting the jet direction of the airflow.

[0031] In this embodiment, the width of the guide vane 8 is 2 to 3 times the diameter of the jet channel 5. The guide vanes 8 are respectively disposed on the side of the first jet port 7 and the second jet port 10 near the leading edge 2 of the blade. The extension direction of the guide vane 8 disposed on the first jet port 7 is at an angle of 10° to 20° with the mainstream direction of the boundary layer of the suction surface 4. The extension direction of the guide vane 8 disposed on the second jet port 10 is at an angle of 10° to 20° with the mainstream direction of the boundary layer of the pressure surface 3. The guide vane 8 is used to control the jet direction of the first jet port 7 and the second jet port 10, so that the airflow ejected from the first jet port 7 and the second jet port 10 can be guided by the "dragging" effect within this angle range to integrate the low-energy fluid into the mainstream, thereby realizing boundary layer dispersion and replenishment of flow field energy level.

[0032] Preferably, the guide vane 8 disposed on the first jet port 7 extends along the profile of the suction surface 4, and the guide vane 8 disposed on the second jet port 10 extends along the profile of the pressure surface 3, so as to ensure that the airflow ejected from the first jet port 7 and the second jet port 10 flows along the surfaces of the suction surface 4 and the pressure surface 3, thereby better suppressing the flow separation of the airflow.

[0033] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0034] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0035] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A control structure for guiding the flow direction of low-pressure airflow within a diffuser, comprising an end wall and blades disposed on the end wall, the blades comprising a pressure surface (3) and a suction surface (4), characterized in that, A suction port (9) is provided on one side of the pressure surface (3) near the trailing edge (1) of the blade. The suction port (9) is connected to the suction channel (6). A first jet port (7) is provided on one side of the suction surface (4) near the leading edge (2) of the blade. A second jet port (10) is provided on one side of the pressure surface (3) near the leading edge (2). The first jet port (7) and the second jet port (10) are connected to the suction channel (6) through the jet channel (5). Both the first jet port (7) and the second jet port (10) face the trailing edge (1). The angle between the airflow direction ejected by the second jet port (10) and the mainstream direction of the boundary layer of the pressure surface (3) is 10°~20°. It also includes a flow control system, the output of which is connected to the jet channel (5). The flow control system is used to generate high-pressure gas and actively adjust the airflow of the jet channel (5).

2. The control structure for guiding the flow direction of low-pressure airflow within the diffuser according to claim 1, characterized in that, The suction channel (6) and the jet channel (5) are respectively vertically arranged in the blade, and the ends near the end wall extend towards the end wall and communicate with each other after penetrating the end wall.

3. The control structure for guiding the flow direction of low-pressure airflow within the diffuser according to claim 2, characterized in that, A control channel is provided on the side of the end wall away from the blade. The control channel is connected to the jet channel (5). The flow control system adjusts the airflow in the jet channel (5) through the control channel.

4. The control structure for guiding the flow direction of low-pressure airflow within the diffuser according to claim 1, characterized in that, The jet channel (5) includes a first jet channel (11) and a second jet channel (12). The first jet channel (11) is connected to the first jet port (7), and the second jet channel (12) is connected to the second jet port (10).

5. The control structure for guiding the flow direction of low-pressure airflow within the diffuser according to claim 4, characterized in that, The flow control system includes an air pump and a detection module for collecting the airflow flow rate in the diffuser. The output end of the air pump is connected to the first jet channel (11) and the second jet channel (12) respectively. The first jet channel (11) and the second jet channel (12) are provided with solenoid valves for controlling the airflow flow rate. The air pump, the detection module and the solenoid valve are electrically connected to the control module respectively. The control module controls the solenoid valve based on the signal from the detection module to independently adjust the airflow flow rate of the second jet channel (12) and the first jet channel (11).

6. The control structure for guiding the flow direction of low-pressure airflow within the diffuser according to claim 1, characterized in that, The first jet port (7), the second jet port (10) and the suction port (9) are all elongated holes, and the length of the elongated holes extends along the height direction of the blade.

7. The control structure for guiding the flow direction of low-pressure airflow within the diffuser according to claim 6, characterized in that, The first jet port (7) and the second jet port (10) are respectively provided with guide vanes (8), and the guide vanes (8) are oriented toward the trailing edge (1).

8. The control structure for guiding the flow direction of low-pressure airflow within the diffuser according to claim 7, characterized in that, The width of the guide vane (8) is 2 to 3 times the diameter of the jet channel (5), and the angle between the extension direction of the guide vane (8) and the mainstream direction of the boundary layer of the pressure surface (3) or the suction surface (4) is 10° to 20°.

9. The control structure for guiding the flow direction of low-pressure airflow within the diffuser according to claim 8, characterized in that, The guide vane (8) extends along the profile of the pressure surface (3) or suction surface (4).

Images