CN216589292U - Centrifugal Compressor Stage Tandem Diffuser - Google Patents

Abstract

The utility model relates to a centrifugal compressor-stage tandem diffuser, which is provided with radially front-row blades of the diffuser, which are respectively fixed with the diffuser hub and the diffuser casing along the airflow direction. The diffuser axial rear main vanes and the diffuser axial rear split vanes; the trailing edges of the diffuser radial front vanes extend to the curved section of the radial flow channel, and the diffuser diameter The forward row vanes are used to change the radial flow into axial flow in the said curved section in advance; and the trailing edge of the diffuser radially forward vane is close to the leading edge of the diffuser axially rear main vane and There is a flow channel gap between them, and the said flow channel gap enables the high-energy fluid on the pressure surface of the radial front row of the diffuser to be accelerated and blown to the suction surface of the diffuser axial rear main blade that is easy to separate. Thus, the separation of the suction surfaces of the rear main blades of the diffuser axis is suppressed or delayed; the utility model significantly suppresses the backflow at the outlet casing of the centrifugal impeller, and the flow field is more uniform.

Description

Centrifugal Compressor Stage Tandem Diffuser

technical field

The utility model belongs to the field of miniature turbojet centrifugal compressors, in particular to a compressor diffuser structure.

Background technique

The static components of the multistage centrifugal compressor have a great influence on the aerodynamic performance of the whole machine. With the deepening of the research on centrifugal compressors, the researchers found that when the static element is not designed properly, the flow loss is large, and sometimes the total pressure recovery coefficient of the centrifugal compressor diffuser is even only 0.85. To further improve the performance of the centrifugal compressor stage, it is necessary to reduce the flow loss in the stationary components as much as possible. Therefore, the design and optimization of the channels of the stationary components has also become one of the focuses of the research to improve the aerodynamic performance of the centrifugal compressor.

The existing micro-turbojet centrifugal compressor stage diffuser configuration is generally such that the radial diffuser and the axial diffuser are arranged separately, and there is flow separation after the blunt trailing edge of the radial diffuser. If the design of the pressure device is not ideal, the flow loss is often very large.

The existing traditional small turbojet centrifugal compressor stage radial diffuser and axial diffuser are two-dimensional blades, and the blade shapes at the upper and lower end walls are basically the same. The radial diffuser is generally wedge-shaped, and the axial diffuser is generally constrained by the axial size, which has a large twist to the airflow and a large difference in the inlet and outlet angles. Therefore, there is often flow separation behind the radial diffuser, and the flow in the axial diffuser channel is often complicated. Flow separation and large velocity gradients will have adverse effects on the flow field. In addition, in the traditional centrifugal compressor stage, the flow separation at the casing of the impeller outlet is large, and the radial direction of the radial flow channel is turned to the axial section with a small radius of curvature, and the turning is violent. All of the above will make the centrifugal compressor stage inefficient.

SUMMARY OF THE INVENTION

The purpose of the utility model is to avoid the deficiencies of the prior art, and to provide a centrifugal compressor stage tandem diffuser that significantly suppresses the flow separation at the centrifugal impeller outlet casing, makes the flow field more uniform, and reduces losses.

In order to achieve the above purpose, the technical solution adopted by the present invention is as follows: a centrifugal compressor stage tandem diffuser, comprising a diffuser casing and an axial section which are sequentially connected and provided in the air inlet direction of the diffuser. The casing also includes a diffuser hub and an axial segment hub connected to the rear of the diffuser hub; the diffuser casing and the diffuser hub cooperate to form a diffuser meridian flow channel. In the meridian flow channel, along the airflow direction are sequentially provided with the diffuser radial front row vanes, the diffuser axial rear main vanes and the diffuser which are respectively fixed with the diffuser hub and the diffuser casing. The splitter vanes are arranged in the rear row of the shaft;

The trailing edge of the diffuser radially forward vane extends to the curved section of the meridian flow channel, and the diffuser radially forward vane is used to change the radial flow in the curved section in advance It is an axial flow; and the trailing edge of the radially front row vanes of the diffuser is close to the leading edge of the axial rear row of the main vanes of the diffuser, and there is a flow channel gap between them, and the flow channel gap makes the diffuser After the high-energy fluid on the pressure surface of the radially front vanes is accelerated, it is blown to the suction surface of the axial rear main vanes of the diffuser which is easy to separate, thereby inhibiting or delaying the separation of the suction surface of the axial rear main vanes of the diffuser;

The radially front row blades of the diffuser are evenly arranged on the peripheral surface of the diffuser hub, and the diffuser axial rear row main blades and the diffuser axial rear split blades are alternately arranged on the diffuser hub. The axial peripheral surface of the diffuser hub.

Further, the flow channel gap refers to the gap between the trailing edge pressure surface of the radially front row vanes of the diffuser and the leading edge suction surface of the diffuser axial rear row main vanes.

Further, the diffuser axial rear main vanes and the adjacent diffuser axial rear split vanes are a group of diffuser axial rear vanes, and the diffuser axial rear row The airflow channel formed by the row vanes is used to reduce the included angle between the airflow and the axial direction; the number of groups of vanes in the axial rear row of the diffuser is the same as the number of vanes in the radial front row of the diffuser.

Further, the diffuser casing, the axial section casing, the diffuser hub and the axial section hub are formed to form the meridian flow channel, and the meridian flow channel is composed of The compound curve formed by the combination of the straight line and the Bezier curve; the axial section of the casing at the entrance of the meridian flow channel has a casing contraction section that contracts 1.5-2.5mm towards the diffuser hub, which significantly inhibits the diffuser inlet. Backflow at the box.

Further, an air inlet hub and a diffuser hub are arranged in sequence in the air inlet direction of the diffuser, a centrifugal impeller disc hub is arranged between the air inlet hub and the diffuser hub, and a centrifugal impeller disc hub is arranged between the air inlet hub and the diffuser hub. On the windward circumferential surface, the centrifugal impeller main blade and the centrifugal impeller shunt blade are alternately installed, and the centrifugal impeller disc hub, the centrifugal impeller main blade, and the centrifugal impeller shunt blade together form the centrifugal impeller, which rotates at a constant speed;

In the air inlet direction of the diffuser, an air inlet casing and a centrifugal impeller casing are also connected in sequence, and the air inlet hub and the centrifugal impeller disc hub are arranged on the air inlet casing and Inside the centrifugal impeller casing.

Further, the main blades of the centrifugal impeller and the shunt blades of the centrifugal impeller are evenly distributed in the circumferential direction.

The beneficial effect of the utility model is that the centrifugal compressor stage tandem diffuser provided by the utility model changes the airflow direction in the radial section and the axial section successively while decelerating and diffusing the airflow, which changes the traditional scheme. In the case where most of the steering function is performed by the axial diffuser, the load of the second row (axial section) of the tandem diffuser is reduced, making it closer to the axial direction, which greatly reduces the backflow in the axial section channel With the velocity gradient, under the given condition of the axial outlet angle requirement, the loss is reduced, and the radius of curvature of the radial passage is increased from the radial to the axial segment, which alleviates the problem of severe steering. At the impeller outlet, the casing shrinks. Section (14) can significantly suppress flow separation at the centrifugal impeller outlet casing; the above advantages have been tested by steady CFD calculations, and can fully achieve tangible loss reduction and efficiency improvement.

Description of drawings

Fig. 1 is the structural representation of the present utility model;

Fig. 2 is the meridian plane sectional structure schematic diagram of the present utility model;

Figure 3 is a schematic diagram of a 50% leaf height streamline of the diffuser of the present invention;

4 is a schematic diagram of the meridian surface streamline of the present utility model;

In the figure: 1. The radial front row of the diffuser blades; 2. The axial rear row of the main blades of the diffuser; 3. The axial rear splitter blades of the diffuser; 4. The main blades of the centrifugal impeller; Blades; 6. Intake hub; 7. Centrifugal impeller disc hub; 8. Diffuser hub; 9. Axial segment hub; 10. Inlet casing; 11. Centrifugal impeller casing; 12. Diffuser Receiver; 13. Axial section casing, 14. Receiver retraction section.

Detailed ways

The principles and features of the present invention will be described below with reference to the accompanying drawings, and the examples are only used to explain the present invention, and are not intended to limit the scope of the present invention.

Embodiment 1: As shown in Figures 1-4, a centrifugal compressor stage tandem diffuser includes a diffuser casing 12 and an axial segment diffuser connected in sequence in the air inlet direction of the diffuser. The box 13 also includes a diffuser hub 8 and an axial segment hub 9 connected to the rear of the diffuser hub 8; the diffuser casing 12 cooperates with the diffuser hub 8 to form a diffuser meridian flow channel, which diffuses the pressure. The machine casing 12, the axial section casing 13, the diffuser hub 8 and the axial section hub 9 form a meridian flow channel, and the meridian flow channel is a compound curve formed by a straight line and a Bezier curve; In the meridian flow channel, along the airflow direction are sequentially provided with the diffuser radial front row vanes 1, the diffuser axial rear main vanes 2 and the diffuser axial rear row main vanes 2, which are respectively fixed to the diffuser hub 8 and the diffuser casing 12. The diffuser is axially rear row of splitter vanes 3; the axial section casing 13 at the entrance of the radial flow channel has a casing constriction section 14 that contracts 1.5-2.5mm in the direction of the diffuser hub 8, which significantly inhibits the diffuser. Backflow at the inlet casing.

In the air inlet direction of the diffuser, an inlet hub 6 and a diffuser hub 8 are arranged in sequence, and a centrifugal impeller disc hub 7 is arranged between the inlet hub 6 and the diffuser hub 8. On the windward circumferential surface of the hub 7, the centrifugal impeller main blade 4 and the centrifugal impeller shunt blade 5 are alternately installed, the centrifugal impeller disc hub 7, the centrifugal impeller main blade 4, and the centrifugal impeller shunt blade 5 together constitute a centrifugal impeller, which works at a constant speed. Rotation; the centrifugal impeller main blade 4 and the centrifugal impeller shunt blade 5 are evenly distributed in the circumferential direction; in the air inlet direction of the diffuser, the air inlet casing 10, the centrifugal impeller casing 11, the air inlet hub 6 and the centrifugal impeller casing 10 are also connected in turn. The impeller disc hub 7 is arranged in the air inlet casing 10 and the centrifugal impeller casing 11;

The trailing edge of the diffuser radial front row vanes 1 extends to the curved section of the meridian flow channel, and the diffuser radial front row vanes 1 are used to change the radial flow to the axial flow in the curved section in advance; and the diffuser The trailing edge of the vanes 1 in the radial front row of the diffuser is close to the leading edge of the main vanes 2 in the rear row of the diffuser axially, and there is a flow channel gap between them. The gap between the edge pressure surface and the leading edge suction surface of the main vanes 2 in the axial rear row of the diffuser; The suction surface of the rear row of main blades 2 in the axial direction of the compressor is easy to separate, thereby inhibiting or delaying the separation of the suction surface of the main blades 2 in the rear row of the diffuser axial direction;

The diffuser radial front row vanes 1 are evenly arranged on the peripheral surface of the diffuser hub 8, the diffuser axial rear main vanes 2 and the diffuser axial rear split vanes 3 are alternately arranged on the diffuser. The axial peripheral surface of the diffuser hub 8; the diffuser axial rear main vanes 2 and the adjacent diffuser axial rear split vanes 3 are a set of diffuser axial rear vanes, and a set of diffuser axial rear vanes. The airflow channel formed by the rear vanes in the axial direction of the diffuser is used to reduce the included angle between the airflow and the axial direction; the number of groups of vanes in the rear row of the diffuser axis is the same as the number of vanes 1 in the radial front row of the diffuser.

The working process of the utility model: when the centrifugal compressor is working, the centrifugal impeller composed of the main blades 4 of the centrifugal impeller, the branch blades 5 of the centrifugal impeller, and the hub 7 of the centrifugal impeller rotates at a high speed. The gas in the channel is thrown out of the centrifugal impeller and enters the rear structure radially. The gas in the impeller is thrown out, and due to the action of pressure, the air at the inlet of the impeller is sucked into the airflow channel of the centrifugal impeller. The gas at the front end of the centrifugal impeller flows at a high speed and the pressure is reduced, so the air in the intake port composed of the intake port hub 6 and the intake port casing 10 flows into the centrifugal impeller, and the outside air flows into the intake port.

After the gas is thrown out of the centrifugal impeller, it enters the diffuser radial front vanes 1 and the diffuser axial rear vanes of the diffuser in turn along a certain angle with the radial direction. The channel formed by the front row of vanes 1 makes the airflow advance in the curved section to change the radial flow in the meridian plane to the axial flow in the meridian plane, and at the same time decelerates the supercharging, the diffuser axial The rear row of blades further makes the airflow closer The direction of the Z axis changes the direction of the airflow, and finally enters the subsequent combustion chamber and other components.

As shown in Figures 3 and 4, at the gap between the diffuser radial front vanes 1 and the diffuser axial rear vanes, the diffuser axial rear vanes limit the diffuser radial front vanes 1 With the development of the low-velocity area on the suction surface, the backflow is significantly reduced, and the meridian-averaged streamline diagram can show that the diffuser flow field is very uniform.

The centrifugal compressor stage with the above structure can significantly improve the efficiency, pressure ratio, etc. of the centrifugal compressor stage. Using the centrifugal compressor stage with the above structure for a small turbojet engine can reduce the rated rotational speed under the condition that the thrust force changes little, which is beneficial to the stable operation of the bearing. And because the efficiency of the compressor is greatly improved, the voyage of the aircraft is increased and the fuel consumption rate is saved under the condition of carrying the same quality of fuel.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection of the utility model.

Claims (6)

1. A centrifugal compressor stage tandem diffuser, characterized in that it comprises a diffuser casing (12) and an axial section casing (13) that are sequentially connected and provided in the air inlet direction of the diffuser , and also includes a diffuser hub (8) and an axial segment hub (9) connected to the rear of the diffuser hub (8); the diffuser casing (12) and the diffuser hub (8) A diffuser meridian flow channel is formed in cooperation, and in the said meridian flow channel, diffusers respectively fixed to the diffuser hub (8) and the diffuser casing (12) are arranged in sequence along the airflow direction. The radial front row vanes (1) of the diffuser, the main vanes (2) of the axial rear row of the diffuser, and the splitter vanes (3) of the axial rear row of the diffuser; The trailing edge of the radially forward vane (1) of the diffuser extends to the curved section of the meridian flow channel, and the radially forward vane (1) of the diffuser is used to advance in the bending The radial flow is changed into axial flow; and the trailing edge of the diffuser radially forward vane (1) is close to the leading edge of the diffuser axially rear main vane (2) with a flow channel therebetween. The said flow channel gap enables the high-energy fluid on the pressure surface of the radial front row vanes (1) of the diffuser to be accelerated and blown to the suction surface where the axial rear main vanes (2) of the diffuser are easy to separate, Thereby inhibiting or delaying the separation of the suction surface of the rear main vanes (2) in the axial direction of the diffuser; The diffuser radially front row vanes (1) are evenly arranged on the peripheral surface of the diffuser hub (8), and the diffuser axial rear row main vanes (2) and the diffuser shaft The backward row splitter vanes (3) are alternately arranged on the axial peripheral surface of the diffuser hub (8). 2 . The centrifugal compressor stage tandem diffuser according to claim 1 , wherein the flow passage gap refers to the difference between the pressure surface of the trailing edge of the vane (1) in the radial front row of the diffuser and the pressure surface of the trailing edge. The gap between the leading edge suction surfaces of the rear main vanes (2) in the axial direction of the diffuser. 3 . The centrifugal compressor stage tandem diffuser according to claim 1 , wherein the axial rear row main vanes ( 2 ) of the diffuser and the adjacent diffuser axial rear row splitter vanes are 3 . (3) is a set of axial rear row vanes of the diffuser, the air flow channel formed by the set of diffuser axial rear row vanes is used to reduce the included angle between the airflow and the axial direction; the diffuser The number of sets of axial rear vanes is the same as the number of radial front vanes (1) of the diffuser. 4. The centrifugal compressor stage tandem diffuser according to claim 1, wherein the diffuser casing (12), the axial section casing (13) and the diffuser The hub (8) and the axial segment hub (9) are composed and form the meridian flow channel, and the meridian flow channel is a compound curve formed by matching a straight line and a Bezier curve; at the entrance of the meridian flow channel The diffuser casing (12) at the diffuser has a casing constriction (14) that contracts 1.5-2.5 mm towards the diffuser hub (8), which significantly suppresses the flow separation at the diffuser inlet casing. 5. The centrifugal compressor stage tandem diffuser according to any one of claims 1-4, characterized in that, an inlet hub (6) and a diffuser are sequentially arranged in the air inlet direction of the diffuser The hub (8) is provided with a centrifugal impeller disc hub (7) between the air inlet hub (6) and the diffuser hub (8), and is alternately installed on the windward circumferential surface of the centrifugal impeller disc hub (7). There are centrifugal impeller main blades (4) and centrifugal impeller shunt blades (5). Speed work rotation; In the air inlet direction of the diffuser, an air inlet casing (10), a centrifugal impeller casing (11), the air inlet hub (6) and the centrifugal impeller disc hub (7) are also connected in sequence. ) are arranged in the air inlet casing (10) and the centrifugal impeller casing (11). 6 . The centrifugal compressor stage tandem diffuser according to claim 5 , wherein the main blades ( 4 ) of the centrifugal impeller and the branching blades ( 5 ) of the centrifugal impeller are evenly distributed in the circumferential direction. 7 .

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