Compact transonic centrifugal compressor structure

Abstract

The application provides a compact transonic centrifugal compressor structure, and belongs to the technical field of micro small aviation engine compressors, and specifically comprises a hub, a casing, a centrifugal impeller, a radial diffuser and an axial diffuser, the radius ratio of the hub to the casing at the inlet position of the centrifugal impeller ranges from 0.3 to 0.4, the radius ratio of the casing at the inlet position of the centrifugal impeller to the outlet radius of the centrifugal impeller ranges from 0.6 to 0.8, the inlet radius of the radial diffuser to the outlet radius of the centrifugal impeller ranges from 1.03 to 1.05, the radial diffuser comprises radial diffuser blades, the radial diffuser blades are constructed by adopting a method of arbitrary polynomial mean camber line and product superposition of blade thickness, the outlet radius of the radial diffuser to the outlet radius of the centrifugal impeller ranges from 1.2 to 1.3, and the axial diffuser adopts an outlet equal-width blade profile design. Through the processing scheme, the aerodynamic efficiency of the entire centrifugal compressor is improved.

Description

Technical Field

[0001] This application relates to the field of micro-sized aero-engine compressors, and more particularly to a compact transonic centrifugal compressor structure. Background Technology

[0002] Centrifugal compressors are widely used in micro-turbojet engines due to their advantages such as high single-stage pressure ratio, fewer parts, ease of manufacturing, and high reliability. With increasingly stringent performance requirements for aero-engines, the demands on compressor pressure ratio and radial and axial dimensions are becoming increasingly stringent. The outlet linear velocity of high-pressure centrifugal impellers often reaches 530 m / s or even higher. At this point, the centrifugal impeller outlet experiences supersonic airflow, significantly increasing the matching difficulty between the centrifugal impeller and the radial diffuser, worsening gas flow within the radial diffuser, and reducing the efficiency and surge margin of the centrifugal compressor. This makes the design of high-pressure, transonic, compact, and high-efficiency centrifugal compressors extremely challenging.

[0003] The commonly used radial diffuser structure is the wedge-shaped diffuser, which exhibits significant airflow separation at the blade trailing edge, reducing efficiency. Furthermore, the thickness distribution and throat area parameters are strongly coupled, making adjustment difficult. Existing centrifugal compressors have long radial dimensions and are heavy. Matching the centrifugal impeller and radial diffuser is challenging, and shock wave losses and gas separation within the radial diffuser are substantial, resulting in low efficiency and a lack of compactness for centrifugal compressors with high pressure ratios and transonic speeds. Summary of the Invention

[0004] In view of this, this application provides a compact transonic centrifugal compressor structure, which solves the problems in the prior art and improves the aerodynamic efficiency of the entire centrifugal compressor.

[0005] The centrifugal compressor provided in this application adopts the following technical solution:

[0006] A centrifugal compressor includes a hub, a casing, a centrifugal impeller, a radial diffuser, and an axial diffuser. The ratio of the hub radius to the casing radius at the impeller inlet position is in the range of 0.3-0.4. The ratio of the casing radius to the impeller outlet radius at the impeller inlet position is in the range of 0.6-0.8. The ratio of the radial diffuser inlet radius to the impeller outlet radius is in the range of 1.03-1.05. The radial diffuser includes radial diffuser blades, which are constructed using an arbitrary polynomial method of stacking arcs and blade thicknesses. The ratio of the radial diffuser outlet radius to the impeller outlet radius is in the range of 1.2-1.3. The axial diffuser adopts an outlet-wide blade design.

[0007] Optionally, the centrifugal impeller includes main blades and diverter blades. The inlet installation angle of the main blades ranges from 28 to 58°. The inlet installation angle of the main blades at the hub is 28°, and the inlet installation angle of the main blades at the casing is 58°. The outlet installation angle of the main blades ranges from 15 to 23°. The outlet installation angle of the main blades at the hub is 15°, and the outlet installation angle of the main blades at the casing is 23°.

[0008] Optionally, a portion may be cut off from the main blade and used as the diverter blade.

[0009] Optionally, the step of constructing the radial diffuser blade using a method that combines arcs and blade thicknesses in an arbitrary polynomial includes: Obtain the mid-arc installation angle and the thickness of the radial diffuser blade at different positions; The installation angle of the mid-arc line at different positions of the radial diffuser blade and the thickness at different positions of the radial diffuser blade generate the basic blade shape of the radial diffuser blade. The tilt angle of the radial diffuser blade is set to 0, and the blade root to the blade tip are linearly stacked to generate the complete blade shape of the radial diffuser blade.

[0010] Optionally, the step of obtaining the mid-arc installation angle at different positions of the radial diffuser blade includes: Given the distribution curve of the arc installation angle in the radial diffuser blade: ; in, This refers to the mid-arc installation angle of the radial diffuser blade at the corresponding position. m Percentage of meridional distance, percentage of the meridional distance of the radial diffuser blade inlet. m =0, β (0) is the mid-arc installation angle at the inlet of the radial diffuser blade, and the percentage of the meridional distance at the outlet of the radial diffuser blade. m =100, β (100) is the mid-arc installation angle at the outlet of the radial diffuser blade. i Let be the degree of the curve polynomial. p i The coefficients of the polynomial, p 0 = 63.35 p 1 = -0.369 ，p 2 = 5.82e -3 , p 3 = -5.07e -5 , p 4 = 3.4e -7 ; Using interpolated data from 0 to 100 representing a percentage of the meridional distance, the mid-arc installation angle at different positions of the radial diffuser blade is calculated based on the formula for the distribution curve of the mid-arc installation angle of the radial diffuser blade.

[0011] Optionally, the step of obtaining the thickness at different locations of the radial diffuser blade includes: Given the thickness distribution curve of the radial diffuser blade: ; in, This represents the thickness of the radial diffuser blade at the corresponding position. m Percentage of meridional distance, percentage of the meridional distance of the radial diffuser blade inlet. m =0, h (0) represents the thickness of the radial diffuser blade inlet and the percentage of the meridional distance from the radial diffuser blade outlet. m =100, h (100) represents the thickness of the radial diffuser blade outlet. i Let be the degree of the curve polynomial. q i The coefficients of the polynomial, q 0 = 0.18. q I = 0.0747 q 2 = -2.06e -3 , q 3, = 1.54e -4 , q 4, = -3.55e -6 , q 5, = 3.57e -8 , q 6, = -1.39e -10 ; The thickness of the radial diffuser blade at different locations is calculated using interpolated data from 0 to 100, given a percentage of the meridional distance, based on the formula for the distribution curve of the radial diffuser blade thickness.

[0012] Optionally, on the meridional plane, the hub of the radial diffuser expands outward by 2-5° from the inlet to the outlet, and the hub of the axial diffuser expands outward by 2-5° from the inlet to the outlet.

[0013] In summary, this application includes the following beneficial technical effects: This application reduces the centrifugal impeller's outlet radius by decreasing the blade's outlet installation angle; it employs an arbitrary polynomial mid-curve design and blade thickness stacking method to construct the radial diffuser blade airfoil, making it more suitable for supersonic airflow, reducing shock wave losses at the radial diffuser blade inlet and suction surface, weakening flow separation and wake separation within the radial diffuser, improving inlet flow of the axial diffuser, and enhancing the overall aerodynamic efficiency of the centrifugal compressor. It is particularly suitable for centrifugal compressors in high-pressure ratio, transonic, compact micro-aero-engines. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the 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.

[0015] Figure 1 This is a schematic diagram of the meridional plane of the centrifugal compressor in this application; Figure 2 This is a schematic diagram of the overall structure of the centrifugal compressor in this application; Figure 3 This is a schematic diagram showing the distribution of the arc installation angle in the radial diffuser blade of this application; Figure 4 This is a schematic diagram showing the distribution of the radial diffuser blade thickness in this application.

[0016] Explanation of reference numerals in the attached drawings: 100, centrifugal impeller; 101, main blade; 102, splitter blade; 200, radial diffuser; 201, radial diffuser blade; 300, axial diffuser; 301, axial diffuser blade; 400, casing; 500, hub. Detailed Implementation

[0017] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0018] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0020] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0021] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0022] This application provides a compact transonic centrifugal compressor structure.

[0023] Centrifugal compressor: A compressor, also known as an air compressor, is a type of rotating machinery used to compress air. A centrifugal compressor is also called a radial compressor, where gas enters axially, is compressed, and then exits radially. Centrifugal compressors used in the field of micro-small aero-engines generally consist of an air inlet, a centrifugal impeller 100, a radial diffuser 200, and an axial diffuser 300.

[0024] like Figure 1 and Figure 2 As shown, a centrifugal compressor according to this application includes a hub 500, a casing 400, a centrifugal impeller 100, a radial diffuser 200, and an axial diffuser 300. The centrifugal impeller 100, the radial diffuser 200, and the axial diffuser 300 surround the outer periphery of the hub 500, and are arranged sequentially along the axial direction of the hub 500. The casing 400 has an annular structure surrounding the outer periphery of the centrifugal impeller 100, the radial diffuser 200, and the axial diffuser 300.

[0025] The centrifugal impeller 100 consists of a disc and blades thereon. Airflow flows along the channel formed by the disc, casing, and blades, converting the mechanical work absorbed by the impeller 100 into pressure (potential energy) and velocity (kinetic energy) during this process. The centrifugal impeller 100 is the most important component of the compressor, and its quality has a decisive impact on the compressor's characteristics. The centrifugal impeller 100 includes main blades 101 and branch blades 102. The main blades 101 and branch blades 102 perform work on the airflow and guide its direction within the centrifugal compressor. The design of the centrifugal compressor mainly involves designing the shape of the blades, including inlet and outlet structural parameters, angle distribution, and thickness distribution. The casing 400, hub 500, and centrifugal blades together constitute the gas flow channel within the centrifugal impeller 100. After exiting the working centrifugal impeller 100, the air has a high airflow velocity, meaning it possesses significant kinetic energy. To effectively utilize this energy, it must be converted into pressure energy to increase the air pressure. Therefore, a radial diffuser 200 is installed after the centrifugal impeller 100 to convert the kinetic energy of the airflow into pressure energy, achieving the function of deceleration and diffusion. After exiting the radial diffuser 200, the air enters the axial diffuser 300. The axial diffuser 300 continues to decelerate and pressurize the gas, and at the same time, it guides the airflow in an axial direction, thus allowing it to enter the combustion chamber for combustion. The hub 500, casing 400, radial diffuser blades 201, and axial diffuser blades 301 of the radial diffuser 200 and axial diffuser 300 together form the gas flow channels within the radial diffuser 200 and axial diffuser 300.

[0026] The meridional plane of a centrifugal impeller is a plane passing through the axis of the centrifugal impeller, formed by rotating each point around the axis to the same axial plane, with coordinates r and z. The r direction runs from the blade root to the blade tip, which is the blade spanwise or blade height direction, and the z direction is the compressor axial direction.

[0027] The radius ratio between the hub 500 and the casing 400 at the inlet position of the centrifugal impeller 100 ranges from 0.3 to 0.4. In one embodiment, the radius ratio between the hub 500 and the casing 400 at the inlet position of the centrifugal impeller 100 can be 0.334. The ratio between the radius of the casing 400 at the inlet position of the centrifugal impeller 100 and the outlet radius of the centrifugal impeller 100 ranges from 0.6 to 0.8, wherein the outlet radius of the centrifugal impeller 100 is the radius of the hub 500 at the outlet position of the centrifugal impeller 100. In one embodiment, the ratio between the radius of the casing 400 at the inlet position of the centrifugal impeller 100 and the outlet radius of the centrifugal impeller 100 can be 0.76. The centrifugal impeller 100 includes main blades 101 and flow divider blades 102. The inlet installation angle of the main blades 101 ranges from 28° to 58°. The inlet installation angle of the main blades 101 at the hub 500 is 28°, and the inlet installation angle of the main blades 101 at the casing 400 is 58°. The outlet installation angle of the main blades 101 ranges from 15° to 23°. The outlet installation angle of the main blades 101 at the hub 500 is 15°, and the outlet installation angle of the main blades 101 at the casing 400 is 23°. The trailing edge of the main blades 101 is swept back, which improves the flow at the outlet of the centrifugal impeller 100 at the casing 400. A portion of the main blades 101 is slightly modified to serve as the flow divider blades 102. This application reduces the outlet radius of the centrifugal impeller 100 by decreasing the outlet installation angle of the blades.

[0028] The ratio of the inlet radius of the radial diffuser 200 to the outlet radius of the centrifugal impeller 100 ranges from 1.03 to 1.05. In one embodiment, the ratio can be 1.032. The radial diffuser blades 201 are constructed using an arbitrary polynomial method of stacking arcs and blade thicknesses. The ratio of the outlet radius of the radial diffuser 200 to the outlet radius of the centrifugal impeller 100 ranges from 1.2 to 1.3. In one embodiment, the ratio can be 1.276. The distance between the outlets of the radial diffuser 200 and the centrifugal impeller 100 is only 2-3 mm.

[0029] The axial diffuser blade 301 adopts an outlet equal width blade design to ensure that the outlet airflow of the axial diffuser 300 is axially discharged.

[0030] The radial diffuser blade 201 is constructed using an arbitrary polynomial method of superimposing the mid-arc line and blade thickness. Specifically, this method includes: obtaining the mid-arc installation angle and thickness of the radial diffuser blade 201 at different positions; generating the basic airfoil of the radial diffuser blade 201 using the mid-arc installation angle and thickness at different positions; setting the tilt angle of the radial diffuser blade 201 to 0°; and linearly superimposing from the blade root to the blade tip to generate the complete airfoil of the radial diffuser blade 201. The blade tip refers to the top of the blade, and the blade root refers to the root of the blade.

[0031] This application employs an arbitrary polynomial mid-curve design and a blade thickness stacking method to construct the radial diffuser blade 201 airfoil, making it more suitable for supersonic airflow. This reduces shock wave losses at the inlet and suction surface of the radial diffuser blade 201, weakens flow separation and wake separation within the radial diffuser 200, improves the inlet flow of the axial diffuser 300, and enhances the overall aerodynamic efficiency of the centrifugal compressor. It is particularly suitable for centrifugal compressors in high-pressure ratio, transonic, compact micro-aero engines.

[0032] The steps for obtaining the mid-arc installation angle at different positions of the radial diffuser blade 201 include: Given the distribution curve of the arc installation angle in the radial diffuser blade 201: .

[0033] in, The mid-arc installation angle of the radial diffuser blade 201 at the corresponding position. m The percentage of the meridional distance at the inlet of the radial diffuser blade 201. m =0, β (0) is the mid-arc installation angle at the inlet of the radial diffuser blade 201, and the percentage of the meridional distance at the outlet of the radial diffuser blade 201. m =100, β (100) is the mid-arc installation angle at the outlet of the radial diffuser blade 201. i Let be the degree of the curve polynomial. p i The coefficients of the polynomial, p 0 = 63.35 p 1 = -0.369 ，p 2 = 5.82e -3 , p 3 = -5.07e -5 , p 4 = 3.4e -7 .

[0034] Using interpolated data from 0 to 100 for a given percentage of meridional distance, the mid-arc installation angle of the radial diffuser blade 201 at different positions is calculated according to the distribution curve formula of the mid-arc installation angle of the radial diffuser blade 201.

[0035] like Figure 3 As shown, the distribution curve of the mid-arc installation angle of the radial diffuser blade 201 is plotted based on the mid-arc installation angle at different positions of the radial diffuser blade 201. The mid-arc installation angle of the radial diffuser blade 201 first decreases, reaches a minimum value near 50%, and then increases.

[0036] Given the thickness distribution curve of the radial diffuser blade 201: ; in, This refers to the thickness of the radial diffuser blade 201 at the corresponding position. m The percentage of the meridional distance at the inlet of the radial diffuser blade 201. m =0, h (0) represents the thickness of the radial diffuser blade 201 inlet and the percentage of the meridional distance of the radial diffuser blade 201 outlet. m =100, h (100) represents the thickness of the outlet of the radial diffuser blade 201. i Let be the degree of the curve polynomial. q i The coefficients of the polynomial, q 0 = 0.18. q I = 0.0747 q 2 = -2.06e -3 , q 3, = 1.54e -4 , q 4, = -3.55e -6 , q 5, = 3.57e -8 , q 6, = -1.39e -10 ; The thickness of the radial diffuser blade 201 at different locations is calculated using interpolated data from 0 to 100 based on the formula for the thickness distribution curve of the radial diffuser blade 201, given a percentage of the meridional distance.

[0037] like Figure 4 As shown, the thickness distribution curves of the radial diffuser blade 201 are plotted based on the thickness at different locations of the radial diffuser blade 201. The maximum thickness of the radial diffuser blade 201 is located near 70%, with a smaller thickness at the inlet, increasing to the maximum value and then rapidly decreasing.

[0038] The radial diffuser blade 201 of this application has a good adaptability to supersonic airflow at the inlet. Before and after entering the throat, the suction surface does not produce an extra acceleration and deceleration process. The airflow is in close contact with the radial diffuser blade 201 and no flow separation occurs. At the same time, the wake separation phenomenon of the radial diffuser blade 201 is reduced.

[0039] On the meridional plane, the hub 500 of the radial diffuser 200 expands outward by 2-5° from the inlet to the outlet, and the hub 500 of the axial diffuser 300 expands outward by 2-5° from the inlet to the outlet. This ensures a larger degree of diffusion with the same radial radius, reducing the absolute airflow velocity at the compressor outlet.

[0040] The centrifugal impeller 100 is made of aluminum alloy material through machining.

[0041] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A compact transonic centrifugal compressor structure, comprising a hub, a casing, a centrifugal impeller, a radial diffuser, and an axial diffuser, characterized in that, The ratio of the hub to the casing radius at the inlet of the centrifugal impeller is 0.3-0.4; the ratio of the casing radius at the inlet of the centrifugal impeller to the outlet radius of the centrifugal impeller is 0.6-0.8; the ratio of the inlet radius of the radial diffuser to the outlet radius of the centrifugal impeller is 1.03-1.05; the radial diffuser includes radial diffuser blades, which are constructed using an arbitrary polynomial method of stacking arcs and blade thicknesses; the ratio of the outlet radius of the radial diffuser to the outlet radius of the centrifugal impeller is 1.2-1.3; and the axial diffuser adopts an outlet-wide blade design. The steps involved in constructing the radial diffuser blade using an arbitrary polynomial method that combines arc lines and blade thickness include: Obtain the mid-arc installation angle and the thickness of the radial diffuser blade at different positions; The installation angle of the mid-arc line at different positions of the radial diffuser blade and the thickness at different positions of the radial diffuser blade generate the basic blade shape of the radial diffuser blade. The tilt angle of the radial diffuser blade is set to 0, and the blade root to the blade tip are linearly stacked to generate the complete blade shape of the radial diffuser blade. The steps for obtaining the mid-arc installation angle at different positions of the radial diffuser blade include: Given the distribution curve of the arc installation angle in the radial diffuser blade: ; in, This refers to the mid-arc installation angle of the radial diffuser blade at the corresponding position. m Percentage of meridional distance, percentage of the meridional distance of the radial diffuser blade inlet. m =0, β (0) is the mid-arc installation angle at the inlet of the radial diffuser blade, and the percentage of the meridional distance at the outlet of the radial diffuser blade. m =100, β (100) is the mid-arc installation angle at the outlet of the radial diffuser blade. i Let be the degree of the curve polynomial. p i The coefficients of the polynomial, p 0 = 63.35 p 1 = -0.369 ，p 2 = 5.82e -3 , p 3 = -5.07e -5 , p 4 = 3.4e -7 ; Using interpolated data from 0 to 100, representing a percentage of meridional distance, the mid-arc installation angle of the radial diffuser blade at different positions is calculated based on the distribution curve formula of the mid-arc installation angle of the radial diffuser blade. The steps for obtaining the thickness of the radial diffuser blade at different locations include: Given the thickness distribution curve of the radial diffuser blade: ; in, This represents the thickness of the radial diffuser blade at the corresponding position. m Percentage of meridional distance, percentage of the meridional distance of the radial diffuser blade inlet. m =0, h (0) represents the thickness of the radial diffuser blade inlet and the percentage of the meridional distance from the radial diffuser blade outlet. m =100, h (100) represents the thickness of the radial diffuser blade outlet. i Let be the degree of the curve polynomial. q i The coefficients of the polynomial, q 0 = 0.

18. q I = 0.0747 q 2 = -2.06e -3 , q 3, = 1.54e -4 , q 4, = -3.55e -6 , q 5, = 3.57e -8 , q 6, = -1.39e -10 ; The thickness of the radial diffuser blade at different locations is calculated using interpolated data from 0 to 100, given a percentage of the meridional distance, based on the formula for the distribution curve of the radial diffuser blade thickness.

2. The compact transonic centrifugal compressor structure according to claim 1, characterized in that, The centrifugal impeller includes main blades and branch blades. The inlet installation angle of the main blades ranges from 28 to 58°. The inlet installation angle of the main blades at the hub is 28°, and the inlet installation angle of the main blades at the casing is 58°. The outlet installation angle of the main blades ranges from 15 to 23°. The outlet installation angle of the main blades at the hub is 15°, and the outlet installation angle of the main blades at the casing is 23°.

3. The compact transonic centrifugal compressor structure according to claim 2, characterized in that, A portion is cut off from the main blade to serve as the diverter blade.

4. The compact transonic centrifugal compressor structure according to claim 1, characterized in that, On the meridional plane, the hub of the radial diffuser expands outward by 2-5° from the inlet to the outlet, and the hub of the axial diffuser expands outward by 2-5° from the inlet to the outlet.

Images