Centrifugal compressor with circumferentially variable installation angle coupled with asymmetric vaned diffuser

Abstract

This invention relates to the field of rotating machinery technology, specifically to an asymmetric centrifugal compressor with a variable circumferential mounting angle and a bladed diffuser. The compressor includes a diffuser, a rotating shaft, a centrifugal impeller, a diffuser mounting plate, a bladed diffuser, and multiple diffuser blades. The diffuser casing and back plate are relatively fixed, and a volute flow channel is formed at the outer end of the casing. The centrifugal impeller is driven by the rotating shaft of the centrifugal compressor, and the diffuser blades are mounted circumferentially at an mounting angle β. i The circumferential variable design allows for improvements to the existing centrifugal compressor structure. While maintaining the advantages of high pressure ratio and high efficiency of centrifugal compressors with vane diffusers, the stable operating range of centrifugal compressors is broadened to effectively reduce the non-uniformity of the internal flow field, suppress flow separation within the vane diffuser, and improve the aerodynamic stability of the centrifugal compressor.

Description

Technical Field

[0001] This invention relates to the field of rotating machinery technology, and more particularly to an asymmetric centrifugal compressor with a variable circumferential mounting angle coupled to a bladed diffuser. Background Technology

[0002] Centrifugal compressors are widely used in turbochargers due to their advantages such as high single-stage pressure ratio, wide operating range, simple and compact structure, few parts, and high reliability. The demands of modern high-performance turbochargers have led to continuously increasing compressor pressure ratios. However, high pressure ratios result in highly uneven airflow at the centrifugal impeller outlet. Furthermore, the small distance between the diffuser inlet and the centrifugal impeller outlet creates a strong unsteady interaction between them. Simultaneously, the high pressure ratio increases the Mach number at the radial diffuser inlet, even leading to ultrasonic interference, further deteriorating the matching between the centrifugal impeller and diffuser, reducing the efficiency and operating range of the centrifugal compressor. This makes the design of a compact and efficient diffuser extremely challenging.

[0003] A bladed diffuser is an effective measure to improve the efficiency of a centrifugal compressor under high pressure ratio requirements. Its flow channel uses fixed backplates and casings on both sides, with blades of a specific airfoil in the middle. First, traditional bladed diffusers are axisymmetric, meaning their blade installation angles are equal at different circumferential positions. Second, the blade installation angles of traditional bladed diffusers are determined by the design point operating conditions, ensuring optimal performance at the design point under the assumption of uniform circumferential flow, effectively converting the kinetic energy of the centrifugal impeller outlet airflow into static pressure.

[0004] In existing technologies, due to the presence of components such as the volute, the internal flow field of a centrifugal compressor is often circumferentially non-uniform. When the compressor operates at a low flow rate, the non-uniform flow field causes some local airflow angles of attack in the bladed diffuser to be too large, resulting in large-scale flow separation, causing flow losses, reducing diffuser efficiency, and generating local flow instability. When the flow rate decreases further, the flow instability worsens, leading to even larger-scale flow separation or even gas backflow, inducing compressor surge. Summary of the Invention

[0005] The purpose of this invention is to provide a centrifugal compressor with an asymmetric bladed diffuser coupled to a variable circumferential installation angle. This solves the problem that in the prior art, due to the presence of components such as the volute, the internal flow field of the centrifugal compressor is often circumferentially non-uniform. When the compressor operates at a low flow rate, the non-uniform flow field causes some local airflow angles of attack in the bladed diffuser to be too large, resulting in large-scale flow separation, causing flow losses, reducing diffuser efficiency, and generating local flow instability. When the flow rate is further reduced, the flow instability worsens, leading to even larger-scale flow separation or even gas backflow, inducing compressor surge.

[0006] To achieve the above objectives, the present invention provides an asymmetric centrifugal compressor with a variable circumferential mounting angle coupled with a bladed diffuser, comprising a diffuser, a rotating shaft, a centrifugal impeller, a diffuser mounting plate, a bladed diffuser, and multiple diffuser blades. The centrifugal impeller is mounted on the rotating shaft, the rotating shaft is mounted on the diffuser, the diffuser is bolted to the diffuser mounting plate, the diffuser has multiple volute flow channels, and the multiple diffuser blades are all fixedly connected to the diffuser. A diffuser flow channel is provided between each adjacent diffuser blade.

[0007] The device includes a diffuser, a rotating shaft, a centrifugal impeller, a diffuser mounting plate, a blade diffuser, and multiple diffuser blades. The centrifugal impeller is mounted on the rotating shaft, which is mounted on the diffuser. The diffuser is bolted to the diffuser mounting plate. The diffuser has multiple volute flow channels, and the multiple diffuser blades are fixedly connected to the diffuser. There is a diffuser flow channel between each adjacent diffuser blade.

[0008] Among them, multiple diffuser blades are fixed on the diffuser along the circumference.

[0009] The diffuser is sleeved outside the rotating shaft.

[0010] The centrifugal impeller is located on the outer wall of the rotating shaft.

[0011] The diffuser has 17 blades.

[0012] The centrifugal impeller and the diffuser are coaxially mounted.

[0013] This invention discloses an asymmetric centrifugal compressor with a variable circumferential mounting angle and a diffuser coupled with a diffuser housing. The diffuser housing and back plate are fixed relative to each other, and the outer end of the housing forms the volute flow channel. The centrifugal impeller is driven by the rotating shaft of the centrifugal compressor. The diffuser is provided with a plurality of diffuser blades, and the diffuser blades are mounted circumferentially at an mounting angle β. i The circumferential variable design allows for improvements to the existing centrifugal compressor structure. While maintaining the advantages of high pressure ratio and high efficiency of centrifugal compressors with vane diffusers, the stable operating range of centrifugal compressors is broadened to effectively reduce the non-uniformity of the internal flow field, suppress flow separation within the vane diffuser, and improve the aerodynamic stability of the centrifugal compressor. Attached Figure Description

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

[0015] Figure 1A cross-sectional view of the centrifugal compressor of the present invention.

[0016] Figure 2 An axial view of the asymmetric diffuser of the present invention.

[0017] Figure 3 The distribution of the inlet airflow angle at the leading edge of each diffuser in the eight semi-circular diffusers of the present invention and the installation angle determined by the method of the present invention in the circumferential direction.

[0018] Figure 4 The distribution of the inlet airflow angle at the leading edge of each diffuser in the nine semi-circular diffusers of the present invention and the installation angle determined by the method of the present invention in the circumferential direction.

[0019] Figure 5 This is a schematic diagram of the diffuser inlet installation angle of the present invention.

[0020] 1-Rotating shaft, 2-Centrifugal impeller, 3-Diffuser mounting plate, 4-Blade diffuser, 5-Vortex flow channel, 6-Diffuser blade, 7-Diffuser flow channel, 8-Diffuser. Detailed Implementation

[0021] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0022] Please see Figures 1 to 5 This invention provides an asymmetric centrifugal compressor with a variable circumferential mounting angle coupled to a bladed diffuser 8, comprising a diffuser 8, a rotating shaft 1, a centrifugal impeller 2, a diffuser mounting plate 3, a bladed diffuser 4, and multiple diffuser blades 6. The centrifugal impeller 2 is mounted on the rotating shaft 1, and the rotating shaft 1 is mounted on the diffuser 8. The diffuser 8 is bolted to the diffuser mounting plate 3. The diffuser 8 has multiple volute flow channels 5. The multiple diffuser blades 6 are all fixedly connected to the diffuser 8, and a diffuser flow channel 7 is provided between each adjacent diffuser blade 6.

[0023] In this embodiment, the housing of the diffuser 8 is fixed relative to the back plate, and the volute flow channel 5 is formed at the outer end of the housing. The centrifugal impeller 2 is driven by the rotating shaft 1 of the centrifugal compressor. The diffuser 8 is provided with a plurality of diffuser blades 6, which are fixed circumferentially to the housing or back plate of the diffuser 8. The diffuser blades 6 are installed at an installation angle β along the circumference. i It is variable in the circumferential direction;

[0024] The diffuser blades 6 consist of a total of 17 blades, with 8 blades evenly arranged in the A half-circle and 9 blades evenly arranged in the B half-circle. The installation position of the diffuser blades 6 with the volute is: starting from the volute tongue, the first blade in the A half-circle begins downstream of the volute tongue.

[0025] The leading edge airflow angles of all diffuser blades 6 were obtained through experimental measurement or simulation. The distribution diagram of the leading edge airflow angles of the diffuser blades 6 is shown below. Figure 3 and Figure 4 The airflow angle values ​​of the leading edge of each diffuser blade 6 are obtained by circumferentially distributing the airflow angles at the leading edge of the diffuser blade 6. For diffusers with 8 half-circles and diffusers with 9 half-circles, 8 and 9 angles are calculated respectively, corresponding to the airflow angles at the i-th leading edge of the diffuser blade 6. The airflow angle at the leading edge of the i-th diffuser blade 6 is denoted as α. i Where i = 1, 2, ..., N, and the average value of these N airflow angles is denoted as , i.e. (Single line spacing, the summation symbol in this formula will be displayed completely), the installation angle β of diffuser blade 6 installed circumferentially. i Calculate β using the following formula: i =β des +k·(α i -α ave ), where i is the serial number of the diffuser blade 6, β des The theoretical installation angle of the diffuser blade 6 is determined based on the design flow rate of the centrifugal compressor. k is a correction coefficient; for an 8-blade half-circumference diffuser 8, the value ranges from -5 ≤ k ≤ 3.5; for a 9-blade half-circumference diffuser 8, the value ranges from -6 ≤ k ≤ 6. α i The airflow angle at the leading edge of the i-th diffuser blade 6 can be determined through simulation or experimental measurement, α. ave This represents the average airflow angle at the leading edge of the diffuser blade 6 described in half a cycle;

[0026] The installation angle β of the diffuser blades 6 in each half-cycle can be determined by the above steps. i In terms of circumferential distribution, the installation angle β of each diffuser blade 6 obtained by this scheme is... i Distributed in the circumferential direction as follows Figure 3 and Figure 4 As shown, due to the non-uniformity of the airflow angle at the leading edge of the diffuser blade 6 in the circumferential direction, the resulting installation angle β of each diffuser blade 6 is... i It is also variable in the circumferential direction. Since the diffuser 8 in the original design is asymmetrical in the whole circumference, and the existing bladed diffuser blade 6 has a circumferentially variable installation angle, the bladed diffuser 8 of the present invention is also asymmetrical.

[0027] Therefore, the structure of the existing centrifugal compressor is improved. While ensuring the advantages of high pressure ratio and high efficiency of the centrifugal compressor with vane diffuser, the stable operating range of the centrifugal compressor is widened. This effectively reduces the non-uniformity of the internal flow field of the centrifugal compressor, suppresses flow separation inside the vane diffuser, and improves the aerodynamic stability of the centrifugal compressor.

[0028] Furthermore, the diffuser 8 is located on one side of the diffuser mounting plate 3.

[0029] Furthermore, multiple diffuser blades 6 are fixed circumferentially on the diffuser 8.

[0030] Furthermore, the diffuser 8 is sleeved outside the rotating shaft 1.

[0031] Furthermore, the centrifugal impeller 2 is located on the outer wall of the rotating shaft 1.

[0032] Furthermore, the diffuser blades 6 number 17.

[0033] Furthermore, the centrifugal impeller 2 and the diffuser 8 are coaxially mounted.

[0034] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. An asymmetric centrifugal compressor with a variable circumferential mounting angle coupled to a bladed diffuser, characterized in that, The device includes a diffuser, a rotating shaft, a centrifugal impeller, a diffuser mounting plate, a blade diffuser, and multiple diffuser blades. The centrifugal impeller is mounted on the rotating shaft, which is mounted on the diffuser. The diffuser is bolted to the diffuser mounting plate. The diffuser has multiple volute flow channels, and the multiple diffuser blades are fixedly connected to the diffuser. There is a diffuser flow channel between each adjacent diffuser blade. The casing of the diffuser is fixed opposite to the back disc, and the outer end of the casing forms the volute flow passage. The centrifugal impeller is driven by the rotating shaft of the centrifugal compressor. The diffuser is provided with a plurality of diffuser blades which are fixed on the casing or the back disc of the diffuser in a circumferential direction. The mounting angle of the diffuser blades in the circumferential direction is In the circumferential direction; The diffuser blades 6 consist of a total of 17 blades, with 8 blades evenly arranged in the A half-circle and 9 blades evenly arranged in the B half-circle. The installation position of the diffuser blades 6 with the volute is: starting from the volute tongue, the first blade in the A half-circle begins downstream of the volute tongue. The airflow angles at the leading edges of all diffuser blades were obtained through experimental measurements or simulations. The airflow angle values ​​at the leading edges of each diffuser blade were obtained by circumferentially distributing these angles. For diffusers with 8 and a half blades and 9 and a half blades, 8 and 9 angles were calculated respectively, corresponding to the airflow angles at the i-th leading edge of diffuser blade 6. The airflow angle at the i-th leading edge of the diffuser blade is denoted as... Where i = 1, 2, ..., N, and the average value of these N airflow angles is denoted as , i.e. The installation angle of the diffuser blades along the circumference Calculate using the following formula: Where i is the diffuser blade number, The theoretical installation angle of the diffuser blades is determined based on the design flow rate of the centrifugal compressor. k is a correction factor; for an 8-blade half-circumference diffuser, the value ranges from -5 to k ≤ 3.5, and for a 9-blade half-circumference diffuser, the value ranges from -6 to k ≤ 6. The airflow angle at the leading edge of the i-th diffuser blade can be determined through simulation or experimental measurement. This represents the average airflow angle at the leading edge of the diffuser blades during half a cycle.

2. The asymmetric centrifugal compressor with a variable circumferential mounting angle coupled to a vaned diffuser as described in claim 1, characterized in that, The diffuser is located on one side of the diffuser mounting plate.

3. The asymmetric centrifugal compressor with a variable circumferential mounting angle coupled to a vaned diffuser as described in claim 2, characterized in that, Multiple diffuser blades are fixed circumferentially on the diffuser.

4. The asymmetric centrifugal compressor with a variable circumferential mounting angle coupled to a vaned diffuser as described in claim 3, characterized in that, The diffuser is fitted outside the rotating shaft.

5. The asymmetric centrifugal compressor with a variable circumferential mounting angle coupled to a vaned diffuser as described in claim 4, characterized in that, The centrifugal impeller is located on the outer wall of the rotating shaft.

6. The asymmetric centrifugal compressor with a variable circumferential mounting angle coupled to a vaned diffuser as described in claim 5, characterized in that, The centrifugal impeller and the diffuser are mounted coaxially.

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