Vane diffuser, vane diffuser design method, and centrifugal compressor

Abstract

The application discloses a vane-type diffuser, which comprises a diffuser hub, a diffuser cover which is enclosed outside the diffuser hub to form a meridian flow passage, and a diffuser vane group arranged in the meridian flow passage, wherein the diffuser vane group comprises first vanes, second vanes and third vanes, and a plurality of the first vanes, the second vanes and the third vanes are alternately and uniformly arranged along the circumference of the annular airflow channel, the axial length of the first vane is greater than that of the second vane, and the axial length of the second vane is greater than that of the third vane; the first vane comprises a radial vane segment and an axial vane segment; the axial cross-section edge line of the meridian flow passage close to the diffuser hub is a curve, the axial cross-section edge line of the meridian flow passage close to the diffuser cover is a curve, and the radial vane segment and the axial vane segment are integrally formed. The application further discloses a design method of the vane-type diffuser. The application further discloses a centrifugal compressor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of centrifugal compressors, in particular, to a vane diffuser. Furthermore, the present application also relates to a vane diffuser design method for designing the vane diffuser. Furthermore, the present application also relates to a centrifugal compressor comprising the vane diffuser. BACKGROUND

[0002] The diffuser is a core component of the centrifugal compressor, which is installed at a downstream position adjacent to the centrifugal impeller, and has a decisive influence on the performance of the centrifugal compressor, such as working efficiency and choked flow. The main function of the diffuser is to slow down and expand the high-speed airflow at the outlet of the centrifugal impeller, to maximize the conversion of kinetic energy into pressure energy, to provide high-pressure airflow that meets the flow field quality requirements of the subsequent components such as the combustion chamber, and to ensure that the high-pressure airflow after slowing down and expanding meets the flow field quality requirements. In high-load centrifugal compressors, the angle between the outlet airflow direction and the meridian plane is generally not greater than 15°, and the outlet airflow Mach number is not greater than 0.25, so as to ensure that the high-pressure airflow after slowing down and expanding meets the flow field quality requirements. In addition, the structure of each component in the high-load centrifugal compressor is compact, and the radial space of the diffuser is limited, so the ratio of the diffuser outlet hub side diameter to the diffuser inlet diameter is generally not greater than 1.14. The diffuser is mainly divided into a double-row vane diffuser (as shown in Figure 1 ) and a single-row vane diffuser (as shown in Figure 2 ). The radial vanes and the axial vanes of the double-row vane diffuser are arranged separately to form front and rear rows of vanes, and the radial vanes and the axial vanes of the single-row vane diffuser are integrated to form a row of vanes. The main components of the two are basically the same, and each is composed of a hub surface, vanes and a cover plate.

[0003] At present, the high-pressure airflow after slowing down and expanding of the double-row vane diffuser can meet the flow field quality requirements, but the ratio of the diffuser outlet hub side diameter to the diffuser inlet diameter is greater than 1.25, and the radial size is too large, which does not meet the assembly requirements of the diffuser in the high-load centrifugal compressor. However, the ratio of the diffuser outlet hub side diameter to the diffuser inlet diameter of the single-row vane diffuser after reasonable design can be not greater than 1.14, but the number of vanes of the single-row vane diffuser is relatively small, which makes it difficult to ensure the flow angle and Mach number of the outlet airflow of the diffuser in the high-load centrifugal compressor, and thus the single-row vane diffuser cannot be applied in the high-load centrifugal compressor. SUMMARY

[0004] The present application provides a vane diffuser and a design method thereof, to solve the technical problem that the existing diffuser cannot meet the assembly requirements of the diffuser in the high-load centrifugal compressor, or meet the performance requirements of the diffuser in the high-load centrifugal compressor.

[0005] According to one aspect of the present application, a vane-type diffuser is provided, comprising a diffuser hub, a diffuser cover enclosing outside the diffuser hub to form a meridian flow channel, and a diffuser vane set arranged in the meridian flow channel to form a diffuser passage, the diffuser hub comprises a disc radial section and a disc axial section, the diffuser cover comprises a cover radial section corresponding to the disc radial section and a cover axial section corresponding to the disc axial section, the diffuser vane set comprises first vanes, second vanes and third vanes, the first vanes, the second vanes and the third vanes are provided in plurality, the plurality of first vanes, the plurality of second vanes and the plurality of third vanes are alternately and uniformly arranged along the circumference of the annular airflow channel, the axial length of the first vane is greater than the axial length of the second vane, and the axial length of the second vane is greater than the axial length of the third vane, the first vane comprises a radial vane section arranged between the disc radial section and the cover radial section and an axial vane section arranged between the disc axial section and the cover axial section, the axial section edge line of the meridian flow channel close to the diffuser hub is a curve, the axial section edge line of the meridian flow channel close to the diffuser cover is a curve, and the radial vane section and the axial vane section are integrally formed.

[0006] As a further improvement of the above technical solution:

[0007] Further, the inlet flow angle of the upper tip of the first vane is greater than the inlet flow angle of the root, the inlet flow angle of the upper tip of the second vane is greater than the inlet flow angle of the root, and the inlet flow angle of the upper tip of the third vane is less than the inlet flow angle of the root.

[0008] Further, when the inlet flow angle of the upper tip of the first vane is -76--70°, the angle change rule of the upper tip profile of the first vane is linearly increased to 0°, when the inlet flow angle of the upper root of the first vane is -73°--67°, the angle change rule of the upper root profile of the first vane is first slowly increased and then rapidly increased to 0°; and / or when the inlet flow angle of the upper tip of the second vane is -66--60°, the angle change rule of the upper tip profile of the second vane is linearly increased to 0°, when the inlet flow angle of the upper root of the second vane is -63°--57°, the angle change rule of the upper root profile of the second vane is first kept unchanged and then rapidly increased to 0°; and / or when the inlet flow angle of the upper tip of the third vane is -50--44°, the angle change rule of the upper tip profile of the third vane is linearly increased to 0°, when the inlet flow angle of the upper root of the third vane is -55°--49°, the angle change rule of the upper root profile of the third vane is first kept unchanged and then rapidly increased to 0°.

[0009] Further, the thickness of the first blade first increases rapidly, then increases slowly, then decreases slowly, and finally decreases rapidly; and / or the thickness of the second blade first increases rapidly, then increases slowly, then decreases slowly, and finally decreases rapidly; and / or the thickness of the third blade first increases rapidly, then increases slowly, then decreases slowly, and finally decreases rapidly.

[0010] Further, the first blade is a straight blade; and / or the second blade is a straight blade; and / or the third blade is a straight blade.

[0011] Further, the radial distance between the leading edge line of the first blade and the axial center line of the diffuser hub is the same; and / or the radial distance between the leading edge line of the second blade and the axial center line of the diffuser hub is the same; and / or the radial distance between the leading edge line of the third blade and the axial center line of the diffuser hub is the same.

[0012] Further, the axial position of the trailing edge line on the first blade, the axial position of the trailing edge line on the second blade, and the axial position of the trailing edge line on the third blade are the same.

[0013] According to another aspect of the present application, there is also provided a method for designing a vane diffuser, which comprises the following steps: first, a meridian flow passage in a diffuser hub is given, and the meridian flow passage is determined as a continuous curved surface; then, a virtual modeling plane is obtained according to the meridian flow passage, and a plane coordinate system is established; then, a blade profile of a blade in a vane diffuser is generated on the modeling plane according to a given angle variation law and a thickness variation law, so as to obtain blade profile data in the plane coordinate system; then, the blade profile on the modeling plane is transformed to a three-dimensional surface formed by the meridian flow passage according to a conformal mapping relationship between the modeling plane and the surface, and a cylindrical coordinate system is established, so as to obtain blade profile data in the cylindrical coordinate system; finally, the blade profile data in the cylindrical coordinate system is converted to blade profile data in a Cartesian coordinate system, and the first blade, the second blade, and the third blade in the vane diffuser are generated in the meridian flow passage based on the blade profile data in the Cartesian coordinate system, so as to obtain the vane diffuser.

[0014] As a further improvement of the above technical solution:

[0015] Further, the step of generating the blade profile of the blade in the vane diffuser on the modeling plane according to the given angle variation law and the thickness variation law further comprises the following step: at the same time, a circumferential stacking angle of a root tip profile of the first blade, the second blade, and the third blade is given respectively, so as to control the radial position of the leading edge line and the axial position of the trailing edge line of the first blade, the second blade, and the third blade.

[0016] According to another aspect of the present application, there is also provided a centrifugal compressor comprising the vane diffuser.

[0017] The present application has the following advantages:

[0018] The vane diffuser of the present application, by the diffuser wheel cover and the diffuser wheel hub enclosing the meridian flow passage to facilitate the airflow passage, and then arranging the diffuser vane group in the meridian flow passage to form the diffuser passage, to realize the speed reduction and expansion of the airflow, specifically by the first vane, the second vane and the third vane alternately and uniformly arranged along the circumferential direction of the annular airflow passage, and the axial length of the first vane is greater than the axial length of the second vane, and the axial length of the second vane is greater than the axial length of the third vane, to realize the increase of the number of vanes in a limited space, and realize the multi-dimensional control of the airflow, and the axial cross-sectional edge line of the meridian flow passage close to the diffuser wheel hub is a curve, the axial cross-sectional edge line of the meridian flow passage close to the diffuser wheel cover is a curve, and the curvature of the meridian flow passage is continuous, which is conducive to the flow direction control of the airflow at the corner in the diffuser passage, to reduce the airflow separation, so that the high-pressure airflow after the speed reduction and expansion of the diffuser meets the requirement of the high-load centrifugal compressor on the flow field quality of the diffuser outlet, that is, the outlet airflow direction and the meridian plane angle is not greater than 15°, and the outlet airflow Mach number is not greater than 0.25, and since the first vane with the longest axial length is composed of a radial vane segment and an axial vane segment, it is a radial-to-axial integrated vane, and the first vane, the second vane and the third vane are arranged in the same row in the circumferential direction, so that the ratio of the diffuser outlet wheel hub diameter to the diffuser inlet diameter is not greater than 1.14, to meet the assembly requirements of the high-load centrifugal compressor on the diffuser, compared with the prior art, the vane diffuser of the present application can meet the assembly requirements of the high-load centrifugal compressor, and can also meet the performance requirements of the high-load centrifugal compressor, realizing the airflow speed reduction and expansion under the condition of limited radial assembly space, with wide application range and strong practicability, and is suitable for wide promotion and application.

[0019] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this application. The embodiments of the present application illustrated in the drawings, and their description, are presented to explain the present application and are not intended to limit the present application unduly.

[0021] Figure 1 is a partial structure schematic diagram of a double-row vane diffuser in the prior art;

[0022] Figure 2 is a partial structure schematic diagram of a single-row vane diffuser in the prior art;

[0023] Figure 3The structure diagram of the vane diffuser of the preferred embodiment of the present application is shown in the figure.

[0024] Figure 4 The angle variation diagram of the first vane, the second vane and the third vane in the vane diffuser of the preferred embodiment of the present application is shown in the figure.

[0025] Legend:

[0026] 100, diffuser hub; 200, diffuser cover; 300, diffuser vane group; 310, first vane; 320, second vane; 330, third vane. DETAILED DESCRIPTION

[0027] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following description.

[0028] Figure 1 The structure diagram of the double-row vane diffuser in the prior art is shown in the figure. Figure 2 The structure diagram of the single-row vane diffuser in the prior art is shown in the figure. Figure 3 The structure diagram of the vane diffuser of the preferred embodiment of the present application is shown in the figure. Figure 4 The angle variation diagram of the first vane, the second vane and the third vane in the vane diffuser of the preferred embodiment of the present application is shown in the figure.

[0029] As Figure 1 and Figure 2As shown, the vane diffuser of the embodiment comprises a diffuser hub 100, a diffuser cover 200 surrounding the diffuser hub 100 to form a meridian flow passage, and a diffuser vane set 300 arranged in the meridian flow passage to form a diffusing passage. The diffuser hub 100 comprises a disc radial section and a disc axial section. The diffuser cover 200 comprises a cover radial section corresponding to the disc radial section and a cover axial section corresponding to the disc axial section. The diffuser vane set 300 comprises first vanes 310, second vanes 320 and third vanes 330. The first vanes 310, the second vanes 320 and the third vanes 330 are alternately and uniformly arranged along the circumferential direction of the annular airflow passage. The axial length of the first vanes 310 is greater than the axial length of the second vanes 320, and the axial length of the second vanes 320 is greater than the axial length of the third vanes 330. The first vanes 310 comprise radial vane sections arranged between the disc radial section and the cover radial section, and axial vane sections arranged between the disc axial section and the cover axial section. The axial section edge line of the meridian flow passage close to the diffuser hub 100 is a curve, and the axial section edge line of the meridian flow passage close to the diffuser cover 200 is a curve. The radial vane sections and the axial vane sections are integrally formed.Specifically, the vane diffuser of the present application forms a meridian flow passage by enclosing the diffuser wheel cover 200 and the diffuser wheel hub 100, so as to facilitate the airflow passage, and then forms a diffusing passage by arranging the diffuser vane group 300 in the meridian flow passage, so as to realize the speed reduction and diffusion of the airflow. Specifically, the first vane 310, the second vane 320 and the third vane 330 are alternately and uniformly arranged along the circumferential direction of the annular airflow passage, the axial length of the first vane 310 is greater than that of the second vane 320, and the axial length of the second vane 320 is greater than that of the third vane 330, so as to increase the number of vanes in a limited space and realize the multi-dimensional control of the airflow. The axial cross-sectional edge line of the meridian flow passage close to the diffuser wheel hub 100 is a curve, the axial cross-sectional edge line of the meridian flow passage close to the diffuser wheel cover 200 is a curve, and the curvature of the meridian flow passage is continuous, which is conducive to the flow direction control of the airflow at the corner in the diffusing passage, so as to reduce the airflow separation and make the high-pressure airflow after the speed reduction and diffusion of the diffuser meet the requirements of the high-load centrifugal compressor on the outlet flow field quality of the diffuser, that is, the outlet airflow direction and the meridian plane have an angle not greater than 15°, and the outlet airflow Mach number is not greater than 0.25. Since the first vane 310 with the longest axial length is composed of a radial vane segment and an axial vane segment, it is a radial-to-axial integrated vane. The first vane 310, the second vane 320 and the third vane 330 are arranged in the same row in the circumferential direction, so as to make the ratio of the diffuser outlet hub diameter to the diffuser inlet diameter not greater than 1.14, so as to meet the assembly requirements of the high-load centrifugal compressor on the diffuser. Compared with the prior art, the vane diffuser of the present scheme can meet the assembly requirements of the high-load centrifugal compressor and the performance requirements of the high-load centrifugal compressor, realizes the airflow speed reduction and diffusion in the limited radial assembly space, has a wide range of applications, high practicability, and is suitable for wide promotion and application. Optionally, the first vane 310 is a large vane, the second vane 320 is a medium vane, and the third vane 330 is a small vane. The large, medium and small vanes are alternately and uniformly arranged along the circumferential direction of the meridian flow passage. The large vane is a radial-to-axial integrated vane, the medium vane is an axial vane or a radial-to-axial integrated vane, and the small vane is an axial vane or a radial-to-axial integrated vane.

[0030] In the present embodiment, the inlet flow angle of the tip of the first vane 310 is greater than that of the root, the inlet flow angle of the tip of the second vane 320 is greater than that of the root, and the inlet flow angle of the tip of the third vane 330 is less than that of the root. Specifically, by respectively controlling the inlet flow angles of the root and tip of the first vane 310, the root and tip of the second vane 320 and the root and tip of the third vane 330, the direction of the airflow is adapted, the airflow flow damage is reduced, the performance of the diffuser is improved, and then the diffuser is assembled in the centrifugal compressor, so as to improve the vibration margin of the centrifugal compressor.

[0031] In the embodiment, when the inlet flow angle of the upper tip of the first blade 310 is -76°-70°, the angle variation rule of the upper tip profile of the first blade 310 is linearly increased to 0°, and when the inlet flow angle of the upper root of the first blade 310 is -73°-67°, the angle variation rule of the upper root profile of the first blade 310 is first slowly increased and then rapidly increased to 0°. After the inlet flow angle of the upper tip and root of the first blade 310 is determined, the angle variation rule of the upper tip and root profile of the first blade 310 is controlled, which is beneficial to control the expansion degree of the airflow, and then the flow field of the turning section from the radial direction to the axial direction in the diffuser passage is improved, thereby improving the performance of the diffuser. As shown in FIG. 6, preferably, the inlet flow angle of the upper tip of the first blade 310 is -73°, the angle variation rule of the upper tip profile of the first blade 310 is linearly increased to 0°, the inlet flow angle of the upper root of the first blade 310 is -70°, and the angle variation rule of the upper root profile of the first blade 310 is first slowly increased and then rapidly increased to 0°. Figure 4

[0032] In the embodiment, when the inlet flow angle of the upper tip of the second blade 320 is -66°-60°, the angle variation rule of the upper tip profile of the second blade 320 is linearly increased to 0°, and when the inlet flow angle of the upper root of the second blade 320 is -63°-57°, the angle variation rule of the upper root profile of the second blade 320 is first kept unchanged and then rapidly increased to 0°. After the inlet flow angle of the upper tip and root of the second blade 320 is determined, the angle variation rule of the upper tip and root profile of the second blade 320 is controlled, which is beneficial to control the expansion degree of the airflow, and then the flow field of the turning section from the radial direction to the axial direction in the diffuser passage is improved, thereby improving the performance of the diffuser. As shown in FIG. 7, preferably, when the inlet flow angle of the upper tip of the second blade 320 is -63°, the angle variation rule of the upper tip profile of the second blade 320 is linearly increased to 0°, the inlet flow angle of the upper root of the second blade 320 is -60°, and the angle variation rule of the upper root profile of the second blade 320 is first kept unchanged and then rapidly increased to 0°. Figure 4

[0033] In the embodiment, when the inlet flow angle of the upper tip of the third blade 330 is -50°-44°, the angle variation rule of the upper tip profile of the third blade 330 is linearly increased to 0°, and when the inlet flow angle of the upper root of the third blade 330 is -55°-49°, the angle variation rule of the upper root profile of the third blade 330 is first kept unchanged and then rapidly increased to 0°. After the inlet flow angle of the upper tip and root of the third blade 330 is determined, the angle variation rule of the upper tip and root profile of the third blade 330 is controlled, which is beneficial to control the expansion degree of the airflow, and then the flow field of the turning section from the radial direction to the axial direction in the diffuser passage is improved, thereby improving the performance of the diffuser. As shown in FIG. 8, preferably, when the inlet flow angle of the upper tip of the third blade 330 is -55°, the angle variation rule of the upper tip profile of the third blade 330 is linearly increased to 0°, the inlet flow angle of the upper root of the third blade 330 is -49°, and the angle variation rule of the upper root profile of the third blade 330 is first kept unchanged and then rapidly increased to 0°. Figure 4 ​​As shown, preferably, when the inlet flow angle of the upper tip of the third blade 330 is-47°, the angle variation law of the upper tip airfoil of the third blade 330 is linearly increased to 0°, the inlet flow angle of the upper root of the third blade 330 is-52°, and the angle variation law of the upper root airfoil of the third blade 330 is first kept unchanged and then rapidly increased to 0°.

[0034] In this embodiment, the thickness variation law of the first blade 310 is first rapidly increased, then gently increased, then gently decreased, and finally rapidly reduced, so as to ensure that the aerodynamic performance and processing difficulty of the first blade 310 are appropriate through the appropriate thickness variation law.

[0035] In this embodiment, the thickness variation law of the second blade 320 is first rapidly increased, then gently increased, then gently decreased, and finally rapidly reduced, so as to ensure that the aerodynamic performance and processing difficulty of the second blade 320 are appropriate through the appropriate thickness variation law.

[0036] In this embodiment, the thickness variation law of the third blade 330 is first rapidly increased, then gently increased, then gently decreased, and finally rapidly reduced, so as to ensure that the aerodynamic performance and processing difficulty of the third blade 330 are appropriate through the appropriate thickness variation law.

[0037] In this embodiment, the first blade 310 is a straight blade. Specifically, when the first blade 310 is a straight blade, the first blade 310 can be processed by side milling, which is conducive to reducing the processing cost. Alternatively, the first blade 310 is generated by superimposing two cross-sectional areas of the root and the tip.

[0038] In this embodiment, the second blade 320 is a straight blade. Specifically, when the second blade 320 is a straight blade, the second blade 320 can be processed by side milling, which is conducive to reducing the processing cost. Alternatively, the second blade 320 is generated by superimposing two cross-sectional areas of the root and the tip.

[0039] In this embodiment, the third blade 330 is a straight blade. Specifically, when the third blade 330 is a straight blade, the third blade 330 can be processed by side milling, which is conducive to reducing the processing cost. Alternatively, the third blade 330 is generated by superimposing two cross-sectional areas of the root and the tip.

[0040] In this embodiment, the radial distance between the leading edge line of the plurality of first blades 310 and the axial center line of the diffuser hub 100 is the same, so as to ensure that the inlet of the plurality of first blades 310 and the outlet of the upstream centrifugal blade are equidistant, which is conducive to the airflow entering the diffuser passage.

[0041] In the embodiment, the radial distances between the leading edge lines of the plurality of second vanes 320 and the axial center line of the diffuser hub 100 are the same, so as to ensure that the inlets of the plurality of second vanes 320 and the outlets of the upstream centrifugal vanes are equidistant, which is beneficial to the air flow entering the diffuser passage.

[0042] In the embodiment, the radial distances between the leading edge lines of the plurality of third vanes 330 and the axial center line of the diffuser hub 100 are the same, so as to ensure that the inlets of the plurality of second vanes 320 and the outlets of the upstream centrifugal vanes are equidistant, which is beneficial to the air flow entering the diffuser passage.

[0043] In the embodiment, the axial positions of the trailing edge lines of the first vanes 310, the axial positions of the trailing edge lines of the second vanes 320 and the axial positions of the trailing edge lines of the third vanes 330 are the same, so as to ensure that the outlet air flow of the diffuser is more uniform, thereby improving the performance of the diffuser.

[0044] The design method of the vane diffuser in the embodiment comprises the following steps: first, the meridian flow passage in the diffuser cover 200 and the diffuser hub 100 is given, and the meridian flow passage is determined as a continuous curved surface, so as to be freely adjustable in aerodynamic design, which is beneficial to the control of air flow; then, a virtual modeling plane is obtained according to the meridian flow passage, and a plane coordinate system is established, and the blade profile of the vanes in the diffuser vane group 300 is generated on the modeling plane according to the given angle variation law and thickness variation law, so as to obtain the blade profile data in the plane coordinate system; then, the blade profile on the modeling plane is converted to the three-dimensional revolution surface formed by the meridian flow passage according to the conformal mapping relationship between the modeling plane and the revolution surface, and a cylindrical coordinate system is established, so as to obtain the blade profile data in the cylindrical coordinate system; finally, the blade profile data in the cylindrical coordinate system is converted to the blade profile data in the Cartesian coordinate system, and the first vanes 310, the second vanes 320 and the third vanes 330 in the diffuser vane group 300 are generated in the meridian flow passage based on the blade profile data in the Cartesian coordinate system, so as to obtain the vane diffuser.

[0045] In the embodiment, the step of generating the blade profile of the vanes in the diffuser vane group 300 on the modeling plane according to the given angle variation law and thickness variation law further comprises the following steps: at the same time, the circumferential stacking angle of the root tip blade profile of the first vanes 310, the second vanes 320 and the third vanes 330 is given respectively, so as to control the radial positions of the leading edge lines and the axial positions of the trailing edge lines of the first vanes 310, the second vanes 320 and the third vanes 330, and further ensure that the inlets of the plurality of first vanes 310 are equidistant from the outlet of the centrifugal impeller, the inlets of the plurality of second vanes 320 are equidistant from the outlet of the centrifugal impeller, the inlets of the plurality of third vanes 330 are equidistant from the outlet of the centrifugal impeller, and the axial positions of the trailing edge lines of the first vanes 310, the axial positions of the trailing edge lines of the second vanes 320 and the axial positions of the trailing edge lines of the third vanes 330 are the same.

[0046] In the embodiment, the front end of the second blade 320 is arranged downstream of the throat line between two adjacent first blades 310. It should be understood that the arrangement position and length of the second blade 320 are associated with the first blade 310, the throat is the position with the minimum flow capacity of the diffuser, the second blade 320 increases the control and constraint ability of the diffuser to the airflow without affecting the flow capacity of the diffuser, and reduces the flow separation of the airflow in the diffuser in the case of high load and large diffuser.

[0047] In the embodiment, the front end of the third blade 330 is arranged at the starting point of the axial section after the radial turning shaft of the meridian flow passage. It should be understood that the position and length of the third blade 330 are associated with the flow separation at the starting point of the axial section after the radial turning shaft of the meridian flow passage under the action of the centrifugal force, the flow at the position is improved by the third blade 330, and the third blade 330 also increases the actual turning angle of the airflow, which is beneficial to the outlet airflow angle meeting the requirements.

[0048] The centrifugal compressor in the embodiment includes the blade diffuser. Specifically, the blade diffuser is used in the centrifugal compressor, so that the high-speed airflow can be slowed down and diffused in the case of limited radial assembly space, the requirements of the centrifugal compressor on the outlet flow field quality of the diffuser are met, the practicality is high, and the centrifugal compressor is suitable for wide promotion and application.

[0049] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A blade-type diffuser, comprising a diffuser hub (100), a diffuser cover (200) surrounding the diffuser hub (100) to form a meridional channel, and a diffuser blade assembly (300) disposed within the meridional channel for forming a diffusion channel, wherein the diffuser hub (100) includes a radial section and an axial section, and the diffuser cover (200) includes a radial section corresponding to the radial section and an axial section corresponding to the axial section, characterized in that, The diffuser blade assembly (300) includes a first blade (310), a second blade (320), and a third blade (330). Each first blade (310), second blade (320), and third blade (330) is provided in multiples. The multiple first blades (310), second blades (320), and third blades (330) are arranged alternately and evenly along the circumference of the annular airflow channel. The axial length of the first blade (310) is greater than the axial length of the second blade (320), and the axial length of the second blade (320) is greater than the axial length of the third blade (330). The first blade (310) includes a radial blade segment arranged between the radial section of the wheel disc and the radial section of the wheel cover, and an axial blade segment arranged between the axial section of the wheel disc and the axial section of the wheel cover. The edge line of the axial section of the meridional channel near the diffuser hub (100) is curved, and the edge line of the axial section of the meridional channel near the diffuser wheel cover (200) is curved. The radial blade segment and the axial blade segment are integrally formed. The inlet flow angle at the tip of the first blade (310) is greater than the inlet flow angle at the root; the inlet flow angle at the tip of the second blade (320) is greater than the inlet flow angle at the root; and the inlet flow angle at the tip of the third blade (330) is less than the inlet flow angle at the root.

2. The blade diffuser according to claim 1, characterized in that, When the inlet flow angle at the tip of the first blade (310) is -76° to 70°, the angle of the blade tip of the first blade (310) increases linearly to 0°. When the inlet flow angle at the root of the first blade (310) is -73° to 67°, the angle of the blade root of the first blade (310) increases slowly first, then rapidly to 0°; and / or When the inlet flow angle at the tip of the second blade (320) is -66° to 60°, the angle of the blade tip of the second blade (320) changes linearly to 0°. When the inlet flow angle at the root of the second blade (320) is -63° to 57°, the angle of the blade root of the second blade (320) changes initially to remain constant, then rapidly increases to 0°; and / or When the inlet flow angle at the tip of the third blade (330) is -50 to 44°, the angle of the tip of the third blade (330) changes linearly to 0°. When the inlet flow angle at the root of the third blade (330) is -55° to 49°, the angle of the root of the third blade (330) changes first by remaining unchanged and then rapidly increasing to 0°.

3. The blade diffuser according to any one of claims 1-2, characterized in that, The thickness of the first blade (310) changes rapidly at first, then increases gradually, then decreases gradually, and finally decreases rapidly; and / or The thickness of the second blade (320) changes rapidly at first, then increases gradually, then decreases gradually, and finally decreases rapidly; and / or The thickness of the third blade (330) changes rapidly at first, then increases gradually, then decreases gradually, and finally decreases rapidly.

4. The blade diffuser according to any one of claims 1-2, characterized in that, The first leaflet (310) is a straight-striated leaflet; and / or The second leaflet (320) is a straight-striated leaflet; and / or The third leaflet (330) is a straight-striated leaflet.

5. The blade diffuser according to any one of claims 1-2, characterized in that, The radial distance between the leading edge lines of multiple first blades (310) and the axial centerline of the diffuser hub (100) is the same; and / or The radial distance between the leading edge lines of multiple second blades (320) and the axial centerline of the diffuser hub (100) is the same; and / or The radial distance between the leading edge line on multiple third blades (330) and the axial center line of the diffuser hub (100) is the same.

6. The blade diffuser according to any one of claims 1-2, characterized in that, The axial positions of the trailing edge line on the first blade (310), the second blade (320), and the third blade (330) are the same.

7. A design method for a bladed diffuser, characterized in that, The design of the blade-type diffuser according to any one of claims 1-6 specifically includes the following steps: First, the meridional channels in the diffuser cover (200) and diffuser hub (100) are given, and the meridional channels are determined to be continuous curved surfaces. Then, a virtual shaping plane is obtained based on the meridional channels, and a planar coordinate system is established. On the shaping plane, the blade profiles of the blades in the diffuser blade group (300) are generated according to the given angle variation law and thickness variation law to obtain the blade profile data in the planar coordinate system. Then, according to the conformal mapping relationship between the shaping plane and the rotating surface, the blade profiles on the shaping plane are transformed to the three-dimensional rotating surface formed by the meridional channels, and cylindrical coordinates are established to obtain the blade profile data in the cylindrical coordinate system. Finally, the blade profile data in the cylindrical coordinate system is converted to the blade profile data in the Cartesian coordinate system. Based on the blade profile data in the Cartesian coordinate system, the first blade (310), the second blade (320), and the third blade (330) in the diffuser blade group (300) are generated in the meridional channels, thereby obtaining the blade diffuser.

8. The blade diffuser design method according to claim 7, characterized in that, The step of generating the blade profile of the diffuser blade assembly (300) on the modeling plane according to the given angle and thickness variation rules also includes the following steps: Meanwhile, the circumferential stacking angles of the root tip leaf shape of the first blade (310), the second blade (320), and the third blade (330) are given respectively to control the radial position of the leading edge line and the axial position of the trailing edge line of the first blade (310), the second blade (320), and the third blade (330).

9. A centrifugal compressor, characterized in that, Includes the blade diffuser as described in any one of claims 1-6.

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