A centrifugal compressor diffuser and flow guide fusion channel

Abstract

A centrifugal compressor diffuser, guide and fusion flow channel, which is particularly suitable for industrial centrifugal compressors or aviation centrifugal compressors with limited radial dimensions. It has the following key technologies: the radial blades in the centrifugal compressor diffuser and the blades in the return flow are integrated into one, running through the entire stationary component; the radial inlet section of the diffuser, guide and fusion flow channel is similar to an airfoil diffuser. Starting from entering the bend, the pressure surface, suction surface and inner casing surface of the blade transform and merge with each other, and eventually part of the pressure surface is transformed into the inner casing surface, and the inner casing surface is transformed into the suction surface of the blade. This design method allows the centrifugal compressor to ensure that the airflow completes a 180° deflection under the condition of limited radial dimensions. The reasonable diffusion pressure distribution in the flow channel can suppress the occurrence of flow separation, reduce flow losses in the flow channel, and eliminate the vortex generated by the rotating impeller to ensure axial air intake at the next stage of the inlet, thereby improving the efficiency and operating range of the entire machine.

Description

Technical Field

[0001] This patent belongs to the field of centrifugal compressor technology and relates to a novel stationary component structure. This structure, through the integration of diffuser and return vanes, guides the airflow through a 180-degree deflection to minimize the vortex caused by the impeller. It is particularly suitable for industrial centrifugal compressors or aviation centrifugal compressors with limited radial dimensions. Background Art

[0002] Centrifugal compressors are developing in the direction of large flow, high pressure ratio, compactness, high efficiency and high reliability. When the performance improvement of centrifugal impellers has reached its limit, the improvement of the performance of stator components and the reduction of overall size are becoming increasingly important, which is one of the future trends in the development of centrifugal compressor technology. The basic stage or intermediate stage of a multi-stage centrifugal compressor is composed of a centrifugal impeller, a diffuser, a bend and a return flow collector. Among them, the impeller is the only working component and plays a decisive role in the aerodynamic performance of the entire stage (machine). The stator components such as the diffuser, bend and return flow collector also play a vital role in affecting the performance of the entire stage (machine). The stator components not only affect the aerodynamic performance of the entire machine, but also determine the overall (radial and axial) dimensions. Improving aerodynamic performance helps reduce consumption and energy, and reducing size helps reduce costs and increase efficiency.

[0003] In the prior art, some small aircraft engines also integrate the radial, turning, and axial sections of the diffuser (e.g., CN201410453415.4 and CN200810196137.3). This structure connects the radial and axial blades of the diffuser to form an integrated blade. This structure is characterized by the geometric properties of the blades and inner and outer casings that make up the flow path remaining unchanged before and after a 90-degree turn. That is, the disc after the turn is an extension of the disc before the turn, and the suction and pressure surfaces of the blades after the turn are also extensions of the disc before the turn. While this structure helps reduce the radial and axial dimensions of the diffuser, because the blade structure within the turn is merely an extension of the front and rear blades, it provides poor airflow guidance and is prone to flow separation at the turn due to the high degree of diffusion, which reduces diffuser performance. In multi-stage centrifugal compressors, there is also a structure that integrates the diffuser blades and the return flow blades (such as CN209704925U). This structure is similar to the integrated blades in aircraft engines. The geometric structure of the blades is not changed. Although the performance is improved under the design conditions, the operating range under large flow conditions is greatly reduced.

[0004] Another example is a centrifugal compressor diffuser structure for aviation, in which blades and hubs are transformed into each other. Patents CN108386389A and CN113756951B disclose a structure that integrates radial and axial blades. The radial blades' pressure, suction, and hub surfaces are twisted to form the pressure surfaces of the axial blades. This structure can better guide airflow in curves and reduce flow separation, significantly improving diffuser performance while reducing radial and axial dimensions. Summary of the Invention

[0005] Centrifugal compressors are developing in the direction of large flow, high pressure ratio, compactness, high efficiency and high reliability. When the performance improvement of centrifugal impellers has reached its limit, the improvement of the performance of stator components and the reduction of the overall size are becoming more and more important. The improvement of aerodynamic performance helps to reduce energy consumption, and the reduction of size helps to reduce costs and increase efficiency. The present invention cleverly integrates the diffuser, U-shaped bend and return flow channel into an integrated design. At the same time, the diffuser blades are extended into the bend and connected to the return flow blades to achieve the fusion transformation of the blades and the casing. The use of this structure can ensure that the airflow completes a 180° deflection when the radial size of the centrifugal compressor is limited. At the same time, the reasonable distribution of diffusion pressure in the flow channel can suppress the occurrence of flow separation, reduce flow losses in the flow channel, and eliminate the vortex generated by the rotating impeller to ensure axial air intake at the next stage, thereby improving the efficiency and operating range of the whole machine.

[0006] The technical solution adopted by the present invention to achieve its technical purpose is:

[0007] A centrifugal compressor diffuser, guide and fusion flow channel comprises inner and outer casing surfaces and blades. The blades are evenly distributed along the circumference and are the intersection and fusion of diffuser blades and return flow vanes. Two adjacent blades and the inner and outer casing surfaces together form the flow channel. Each blade comprises an inlet radial section, a 180° turn section, and an outlet radial section, forming a three-section integrated design. The blade wall begins to split from the 180° turn section and transforms into the inner casing surface, ultimately converging at the outlet section to achieve connection of the blades and fusion with the inner casing surface.

[0008] The intersection and fusion includes: the number of diffuser blades is the same as the number of return flow blades, the trailing edges of the diffuser blades extend backward, and the return flow blades extend forward, and the two are integrated in the curve.

[0009] The transformation includes:

[0010] The suction surface 4 of the inlet radial section twists after entering the curve and is accompanied by a decrease in area to form a gradual suction surface 5 of the turning section. After leaving the curve, it deflects toward the wheel cover side, and the area further decreases and eventually becomes the suction surface 14 of the outlet radial section. The area of the inner casing surface 2 of the inlet radial section decreases and twists after entering the curve to form the gradual inner casing surface 6 of the turning section. After leaving the curve, the area increases and eventually becomes the outlet radial suction surface 13. The wall angle between the suction surface 4 of the inlet radial section and the inner casing surface 2 of the inlet radial section before entering the curve and twisting is 90°. After entering the curve, the angle increases to form an obtuse angle, and finally reaches 180° at the trailing edge of the outlet radial section and completely merges to form the suction surface of the outlet radial section.

[0011] After entering the curve, the inlet radial section pressure surface 3 splits into two sections starting from the wheel cover side. The turning section gradient pressure surface 2 8 near the wheel cover side continuously increases in area after entering the curve, eventually twisting to become the outlet radial section pressure surface 12. The inlet radial section pressure surface 1 7 near the wheel disc side first decreases in area after entering the curve, then increases and twists to become the outlet radial section inner casing surface 11. The angle between the two sections decreases from 180° at the inlet radial section to 90° at the outlet radial section. After entering the curve, the inlet radial section outer casing surface 1 becomes the turning section outer casing surface 9, and ultimately becomes the outlet radial section outer casing surface 10.

[0012] Furthermore, the inlet radial section and the outlet radial section are both low-consistency airfoil blades.

[0013] Furthermore, the cross-sectional shape of the diffuser, guide and merging flow channel is a quadrilateral in the inlet radial section, becomes a pentagon after entering the bend, and finally becomes a quadrilateral again at the trailing edge of the outlet radial section.

[0014] Beneficial effects of the present invention:

[0015] (1) The diffuser channel, U-shaped bend and return channel of the centrifugal compressor are integrated into a design, and the diffuser blades and return blades are connected and integrated with the casing, thereby ensuring the continuity of the airflow channel of the entire stationary component. On the premise of completing the deflection of the airflow, the flow separation phenomenon is suppressed and the uniformity of the outlet flow field is improved through the guidance of the flow channel. At the same time, the radial size of the compressor can be effectively reduced without changing the operating range of the entire stage.

[0016] (2) The blades at the radial inlet section of the diffuser, guide and fusion flow channel are low-consistency airfoil blades, which not only adapt to a wide range of working conditions, but also guide the airflow and reduce the occurrence of flow separation.

[0017] (3) After entering the U-shaped bend, the diffuser, guide, and fusion flow channel blades begin to twist and merge with the inner casing surface to form new return flow blades. This integrated diffuser and return flow channel blade maintains the optimal diffusion pressure distribution throughout the flow process. At the same time, the twisted flow channel shape in the bend can better adapt to flow deflection and reduce the occurrence of flow separation. The increase in the length of the blades in the flow channel brings about an increase in friction loss, but the reduction in the radial dimension offsets this loss by reducing the overall length of the flow channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a front view of the centrifugal compressor diffuser, guide and fusion flow channel of the present invention;

[0019] Figure 2 is a top view of the flow channel of the present invention;

[0020] Figure 3 The three-dimensional view of the flow channel of the present invention Figure 1 ;

[0021] Figure 4 The three-dimensional view of the flow channel of the present invention Figure 2 ;

[0022] Figure 5 The three-dimensional view of the flow channel of the present invention Figure 3 ;

[0023] Figure 6 The three-dimensional view of the flow channel of the present invention Figure 4 ;

[0024] Figure 7 is a meridian view of the flow channel of the present invention;

[0025] In the figure: 1. Outer casing surface of the inlet radial section; 2. Inner casing surface of the inlet radial section; 3. Pressure surface of the inlet radial section; 4. Suction surface of the inlet radial section; 5. Gradual suction surface of the turning section; 6. Gradual inner casing surface of the turning section; 7. Gradual pressure surface one of the turning section; 8. Gradual pressure surface two of the turning section; 9. Outer casing surface of the turning section; 10. Outer casing surface of the outlet radial section; 11. Inner casing surface of the outlet radial section; 12. Pressure surface of the outlet radial section; 13. Suction surface one of the outlet radial section; 14. Suction surface two of the outlet radial section. DETAILED DESCRIPTION

[0026] The present invention is described in detail and specifically through specific embodiments to provide a better understanding of the present invention. However, the following embodiments do not limit the scope of the present invention.

[0027] like Figures 1 to 7The present invention illustrates a centrifugal compressor diffuser, guide, and fusion flow channel. The diffuser, guide, and fusion flow channel comprises inner and outer casing surfaces and blades. Due to the channel's complex structure, a five-axis lathe is recommended for machining large industrial centrifugal compressor flow channels, while metal 3D printing is recommended for machining small aerospace centrifugal compressor flow channels. The integrated blades of the diffuser, guide, and fusion flow channel are evenly distributed circumferentially as required. Adjacent blades and the inner and outer casing surfaces together form an airflow channel, which includes a radial diffuser section, a U-turn section, and a radial recirculator section. The radial diffuser section is a low-consistency airfoil-shaped blade with a relatively small thickness. This rational blade distribution ensures efficiency while improving the operating range of the entire stage, making it suitable for high-flow coefficient compressors. Together with the inner and outer casing surfaces, the radial diffuser section forms a complete radial airflow channel. Upon entering the U-turn, the blades begin to twist, creating a new wall surface. Simultaneously, they begin to merge and transform with the inner casing surface, ultimately forming a new radial recirculator section.

[0028] The inlet radial section suction surface 4 twists after entering the curve and forms the turning section gradual suction surface 5 with the decrease in area. After leaving the curve, it deflects toward the wheel cover side and further reduces in area and eventually becomes the outlet radial section suction surface 2 14. The inlet radial section inner casing surface 2 reduces in area and twists after entering the curve to form the turning section gradual inner casing surface 6. After leaving the curve, the area increases and eventually becomes the outlet radial suction surface 13. The wall angle between the inlet radial section suction surface 4 and the inlet radial section inner casing surface 2 before entering the curve and twisting is 90°. After entering the curve, the angle increases, eventually reaching 180° at the trailing edge of the outlet radial section and completely merging to form the outlet radial section suction surface. After entering the curve, the inlet radial section pressure surface 3 splits into two sections, starting from the wheel cover side. The area of the turning section gradient pressure surface 2 8 near the wheel cover side continues to increase after entering the curve, eventually twisting to become the outlet radial section pressure surface 12. The turning section gradient pressure surface 1 7 near the disc side twists after entering the curve to become the outlet radial section inner casing surface 11. The angle between the two sections decreases from 180° at the inlet radial section to 90° at the outlet radial section. After entering the curve, the inlet radial section outer casing surface 1 becomes the turning section outer casing surface 9, and ultimately becomes the outlet radial section outer casing surface 10. The cross-sectional shape of the diffuser, guide, and merging flow channel is a quadrilateral in the inlet radial section, becomes a pentagon after entering the curve, and finally becomes a quadrilateral again at the trailing edge of the outlet radial section. This completes the construction of the diffuser, guide, and merging flow channel for a centrifugal compressor.

[0029] The centrifugal compressor's diffuser, U-bend, and returner passages are integrated into a single design. The diffuser and returner blades are connected and integrated with the casing, ensuring continuous airflow throughout the stationary components. While deflecting the airflow, the flow channel guidance suppresses flow separation and improves the uniformity of the outlet flow field. This effectively reduces the radial dimensions of the compressor without changing the overall operating range. The radial inlet blades of the diffuser, guide, and merging passages are low-consistency airfoil-shaped blades, which not only accommodate a wide operating range but also guide the airflow and minimize flow separation. Upon entering the U-bend, the diffuser, guide, and merging passage blades begin to twist, merging with the inner casing surface to form new returner blades. This integrated diffuser and returner blade design maintains excellent diffusion throughout the entire flow process. The twisted flow channel shape within the bend better accommodates flow deflection and minimizes flow separation. While increasing the blade length within the passage increases friction losses, this loss is offset by the reduction in overall radial dimension, which reduces the overall passage length.

[0030] Furthermore, it should be noted that the specific embodiments of the present invention have been described in detail above, but these are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions of the present invention are also within the scope of the present invention. Therefore, any equivalent changes and modifications made without departing from the spirit and scope of the present invention should be included within the scope of the present invention.

Claims

1. A centrifugal compressor diffuser, guide and fusion flow channel, characterized in that: The diffuser, guide and fusion flow channel includes inner and outer casing surfaces and blades; the blades are evenly distributed along the circumference, and are the intersection and fusion of diffuser blades and return flow blades. Two adjacent blades and the inner and outer casing surfaces together form the flow channel; each blade includes an inlet radial section, a 180° turn section, and an outlet radial section, with a three-section integrated design; the blade wall begins to split from the 180° turn section and transforms into the inner casing surface, finally converging at the outlet section to achieve the connection of the blades and fusion with the inner casing surface; The intersection and fusion includes: the number of diffuser blades and the number of return flow blades are the same, the trailing edges of the diffuser blades extend backward, and the return flow blades extend forward, and the two are integrated in the curve; The transformation includes: The inlet radial section suction surface (4) twists after entering the curve and forms a turning section gradual suction surface (5) with a decrease in area. After leaving the curve, it deflects toward the wheel cover side, further reduces in area and eventually forms the outlet radial section suction surface 2 (14). The inlet radial section inner casing surface (2) reduces in area and twists after entering the curve to form a turning section gradual inner casing surface (6). After leaving the curve, it increases in area and eventually forms the outlet radial section suction surface 1 (13). The wall angle between the inlet radial section suction surface (4) and the inlet radial section inner casing surface (2) before entering the curve and twisting is 90°. After entering the curve, the angle increases to form an obtuse angle, and finally reaches 180° at the trailing edge of the outlet radial section and completely merges to form the outlet radial section suction surface. After entering the curve, the inlet radial section pressure surface (3) is divided into two sections starting from the wheel cover side. The area of the turning section gradient pressure surface 2 (8) close to the wheel cover side increases continuously after entering the curve, and finally twists to become the outlet radial section pressure surface (12); the area of the inlet radial section pressure surface 1 (7) close to the wheel disc side first decreases and then increases after entering the curve and twists to become the outlet radial inner casing surface (11); the angle between the two sections decreases from 180° at the inlet radial section to 90° at the outlet radial section; the inlet radial section outer casing surface (1) becomes the turning section outer casing surface (9) after entering the curve, and finally becomes the outlet radial section outer casing surface (10).

2. The centrifugal compressor diffuser, guide and fusion flow channel according to claim 1, characterized in that: The inlet radial section and the outlet radial section are both low-consistency airfoil blades.

3. The centrifugal compressor diffuser, guide and fusion flow channel according to claim 1, characterized in that: The cross-sectional shape of the diffuser, guide and fusion flow channel is a quadrilateral in the inlet radial section, changes to a pentagon after entering the bend, and finally becomes a quadrilateral again at the trailing edge of the outlet radial section.

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