CN115949625A - Self-circulating treatment casings and centrifugal compressors for centrifugal compressors - Google Patents

Abstract

The application provides a self-loopa processing machine casket and centrifugal compressor of centrifugal compressor, includes: the centrifugal compressor comprises a casing, a centrifugal compressor and a power transmission mechanism, wherein the casing comprises an air inlet passage casing and an impeller casing, the air inlet passage casing surrounds an air inlet passage, the air inlet passage is tapered in the direction from the upstream of the centrifugal compressor to the downstream, and the air inlet passage casing is connected to the upstream side of the impeller casing; the impeller hubs can rotate relative to the casing, and the impeller casing surrounds the impeller; and the casing processing groove surrounds the casing, the casing processing groove is connected to the casing, and openings are formed in the air inlet casing and the impeller casing at two axial ends of the casing processing groove respectively, so that air flow in the casing can enter the casing processing groove through the opening at one axial end of the casing processing groove and then returns to the casing from the opening at the other axial end of the casing processing groove.

Description

Self-circulating treatment casings and centrifugal compressors for centrifugal compressors

technical field

The application belongs to the field of compressors, and in particular relates to a self-circulation treatment casing of a centrifugal compressor and the centrifugal compressor.

Background technique

The compressor is a key component in the field of aero-engines that urgently needs a technological breakthrough. Centrifugal compressors occupy an important position in small and medium-sized aeroengines due to their advantages such as high single-stage booster compression ratio, wide stable operating range, compact structure, and light weight. However, the technical difficulty of the centrifugal compressor is high, and the investment is high. The internal flow of the transonic centrifugal compressor is extremely complicated, and both the shock wave structure and the vortex structure will lead to a decrease in its stability margin and efficiency. The design requirements of high compression ratio, high load and high efficiency bring many technical challenges to the design of centrifugal compressor.

Especially under the conditions of large flow rate (greater than 4kg/s) and high compression ratio (greater than or equal to 10), compared with the environment of small flow rate and low compression ratio, the blade load is higher, resulting in complex interaction between shock wave and leakage vortex , it is more prone to blockage and stall, so that the compressor can only support the aeroengine to work at full speed in the whole airspace with a narrow stable working range.

As a compressor stability expansion technology with simple structure and high reliability, casing treatment has been widely used in engineering applications of axial flow and centrifugal compressors. Traditional casing processing methods, such as casing vent holes and grooved casings, can generally increase the stable working margin by about 10%.

In the case of small flow rate and low compression ratio, the stable working margin of the centrifugal compressor is relatively high, and generally no expansion measures are needed. With the increase of the flow rate and compression ratio, the compressor gradually enters the transonic working state, the strength of the shock wave and the strength of the leakage vortex in the headspace will gradually increase, and the instability of the compressor will increase.

The self-circulating casing of the centrifugal compressor can effectively suppress the unstable flow near the stall point, delay the occurrence of stall, and thus improve the stable working margin of the compressor. However, in the case of large flow and ultra-high compression ratio, how to There is still no effective method to further increase the margin on the basis of low efficiency loss.

The opening of the self-circulating casing of the traditional centrifugal compressor is generally located behind the throat of the impeller, and the purpose is to suck the airflow at the clogged end and the stalled end respectively, so as to increase the clogged flow and reduce the stalled flow. However, for a centrifugal compressor with a large flow rate and an ultra-high compression ratio, the impeller has a stronger working ability, and the pressure behind the throat of the impeller is higher than that at the inlet of the impeller, which makes it difficult to apply the casing of the traditional centrifugal compressor Centrifugal compressors for large flow and ultra-high compression ratio.

Contents of the invention

The purpose of this application is to propose a self-circulation processing casing of a centrifugal compressor, which is suitable for a centrifugal compressor with a large flow rate and an ultra-high compression ratio, and effectively expands the stable working margin of the compressor.

The present application also proposes a centrifugal compressor including a self-circulating process casing.

The embodiment of the present application proposes a self-circulation treatment casing of a centrifugal compressor, including:

casing, the casing includes an inlet casing and an impeller casing; is tapered, the inlet casing is connected to the upstream side of the impeller casing;

a plurality of impellers connected at intervals along the circumference of the centrifugal compressor to an impeller hub rotatable relative to the casing surrounding the impeller; and

A casing processing groove, the casing processing groove surrounds the casing, the casing processing groove is connected to the casing, and the two axial ends of the casing processing groove are respectively in the inlet casing Form an opening on the casing of the impeller, so that the airflow in the casing can enter the casing processing groove through the opening at one end of the casing processing groove in the axial direction, and then flow from the shaft of the casing processing groove The opening to the other end goes back into the receiver.

In at least one possible implementation, the casing treatment groove is tapered in a direction in which the impeller casing points to the inlet casing.

In at least one possible implementation, the cross-section of the inlet is circular, and when viewed from the meridian plane of the centrifugal compressor, the inner and/or outer peripheral surfaces of the inlet include a Bessel Seoul curve.

In at least one possible implementation manner, the opening of the casing processing groove on the casing of the air inlet is located in an airflow stagnation area of the air inlet.

In at least one possible implementation manner, the opening of the casing treatment groove on the impeller casing is located between two axial ends of the throat of the impeller.

In at least one possible implementation, the casing processing tank includes a circular arc section and a connecting section, the circular arc section is connected to the casing through the connecting section, and the connecting section is perpendicular to the casing and the connecting position of the connecting segment.

In at least one possible embodiment, the connecting section extends along a straight line.

In at least one possible implementation manner, the casing processing tank includes an inner wall and an outer wall, and the inner wall and the outer wall are connected by a rigid support structure.

Embodiments of the present application also propose a centrifugal compressor, which includes the self-circulation processing casing of the centrifugal compressor described in any one of the above technical solutions.

In at least one possible implementation, the operating environment of the centrifugal compressor is that the flow rate is greater than 4 kilograms per second, and the compression ratio is greater than or equal to 10.

By adopting the above-mentioned technical solution, the casing of the present application enables the centrifugal compressor to be suitable for large flow and ultra-high compression ratio, and maintains a relatively high stable working margin.

Description of drawings

Fig. 1 shows a schematic diagram of a meridional flow path of a centrifugal compressor according to an embodiment of the present application.

FIG. 2 shows a partially enlarged view of FIG. 1 .

Fig. 3 shows a schematic structural view of a centrifugal compressor according to an embodiment of the present application.

Fig. 4 shows a schematic diagram of the internal structure of a centrifugal compressor according to an embodiment of the present application.

FIG. 5 shows a flow-efficiency graph of a centrifugal compressor according to an embodiment of the present application.

FIG. 6 shows a flow-compression ratio graph of a centrifugal compressor according to an embodiment of the present application.

Explanation of reference signs

1 air intake

2 main blade 21 leading edge of main blade

3 The first splitter vane 31 The leading edge of the first splitter vane

4 Second splitter vane 41 Second splitter vane leading edge

5 first diffuser

6 Second diffuser

7 air outlet

8 casings 81 inlet casings 82 impeller casings

9 Case processing slot 91 Arc segment 92 Connecting segment

10 impeller hub

A Axial C Circumferential

Detailed ways

In order to more clearly illustrate the above purpose, features and advantages of the present application, specific implementation methods of the present application will be described in detail in this part with reference to the accompanying drawings. In addition to the various implementations described in this section, the present application can also be implemented in other different ways. Without departing from the spirit of the present application, those skilled in the art can make corresponding improvements, deformations and replacements. Therefore, the present application Do not be bound by the specific embodiments disclosed in this section. The scope of protection of this application should be based on the claims.

As shown in Figures 1 to 4, the embodiment of the present application proposes a centrifugal compressor, which includes an air inlet 1, an impeller, a first diffuser 5, a second diffuser 6, an air outlet 7 and Receiver 8.

In Fig. 1, the left side is upstream of the centrifugal compressor, and the right side is downstream of the centrifugal compressor, and the gas flow flows from the upstream side to the downstream side.

The impeller includes main blades 2 , first splitter blades 3 and second splitter blades 4 . The main blade 2, the first splitter blade 3 and the second splitter blade 4 are connected to the impeller hub 10, the impeller hub 10 can rotate relative to the casing 8, and the main blade 2, the first splitter blade 3 and the second splitter blade 4 can all be relatively The casing 8 is rotatably arranged inside the casing 8 .

As shown in FIGS. 1 to 4 , there are multiple main blades 2 , first splitter blades 3 and second splitter blades 4 arranged at intervals along the circumferential direction C of the centrifugal compressor. In the circumferential direction C of the centrifugal compressor, the first splitter blade 3 can be arranged between two adjacent main blades 2, and the second splitter blade 4 can be arranged between the adjacent first splitter blade 3 and the main blade 2 between. Along the circumferential direction C of the centrifugal compressor, the main blade 2 , the second splitter blade 4 , the first splitter blade 3 and the second splitter blade 4 may be periodically and repeatedly arranged in this order.

The upstream end of the main blade 2 is the main blade leading edge 21 , the upstream end of the first splitter blade 3 is the first splitter blade leading edge 31 , and the upstream end of the second splitter blade 4 is the second splitter blade leading edge 41 . The leading edge 21 of the main blade is located at the front side of the leading edge 31 of the first splitter vane, and the leading edge 31 of the first splitter vane is located at the front side of the leading edge 41 of the second splitter vane.

It can be understood that the specific blade shapes of the main blade 2 , the first splitter blade 3 and the second splitter blade 4 can be designed according to the basic theory of turbomachinery, so as to meet the performance requirements of the centrifugal compressor.

The first splitter blade 3 and the second splitter blade 4 rotate together with the main blade 2 to perform work, which can improve the working capacity of the centrifugal compressor and reduce the possibility of compressor blockage.

The casing 8 includes an inlet casing 81 and an impeller casing 82 , and the upstream side of the leading edge 21 of the main blade and the impeller casing 82 may be flush. The impeller casing 82 may surround the main blade 2 , the first splitter blade 3 and the second splitter blade 4 , and the inlet casing 81 is connected to the upstream side of the impeller casing 82 . The inlet casing 81 can form an inlet passage 1 extending along the axial direction A of the centrifugal compressor, and the inlet passage 1 is tapered in a direction from upstream to downstream of the centrifugal compressor. Such an air inlet 1 can form an airflow stagnation zone in the air inlet 1 near the air inlet casing 81, in order to increase the static pressure of the airflow, balance the airflow in the casing processing tank 9, and avoid near blockage The end causes excessive flow loss.

Further, the cross section of the air inlet 1 can be circular, the inner peripheral surface of the air inlet 1 is the outer peripheral surface of the impeller hub 10, and the outer peripheral surface of the air inlet 1 is the inner peripheral surface of the inlet casing 81 .

Viewed from the meridian plane of the centrifugal compressor, the profile slope of the inlet casing 81 and the profile line slope of the impeller hub 10 can first increase and then decrease, and the inner peripheral surface and/or outer peripheral surface of the inlet channel 1 can be Including Bézier curves. In the direction from the upstream to the downstream of the centrifugal compressor, the part of the impeller hub 10 on the upstream side of the main blade 2 may be in the shape of a diverging cone, and the inlet casing 81 may be in the shape of a tapering cone.

The profile slope of the inlet casing 81 can gradually and smoothly transition from 0° to 55°, and then smoothly transition to 0°. The profile slope of the impeller hub 10 can gradually and smoothly transition from 0° to 22°, and then smoothly transition to 0°. The radial dimension of the inlet passage 1 is gradually reduced in the axial direction to be the same as the radial dimension of the impeller leading edge 21 .

The casing 8 is provided with a casing processing groove 9, the casing processing groove 9 can surround the radially outer side of the casing 8, and the axial ends of the casing processing groove 9 can form an annular opening around the entire circumference of the casing 8, The casing processing tank 9 is communicated with the inside of the casing 8 to realize gas backflow.

The casing processing groove 9 includes an inner wall and an outer wall, the inner wall is located at the radial inner side of the outer wall, and the inner wall and the outer wall can enclose a channel. As shown in Figures 1 and 2, viewed from the meridian plane of the centrifugal compressor, both the inner wall and the outer wall are arc-shaped, and the casing processing groove 9 may be an arc-shaped channel.

On the axial direction A of the centrifugal compressor, the two openings of the casing treatment tank 9 on the casing 8 are respectively located at the inlet casing 81 and the impeller casing 82 . The casing treatment tank 9 can form a gas return tank.

The opening width b _o of the casing processing groove 9 on the impeller casing 82 _is greater than the opening width bi of the casing processing groove 9 on the inlet casing 81, so that the impeller casing 82 points to the inlet casing 81. Direction, the casing processing slot 9 is tapered. This can make it easier for the gas to flow from the impeller side to the intake port 1, thereby reducing the flow at the stall end, suppressing the unstable flow near the stall point, and delaying the occurrence of stall, thereby improving the stable working margin of the compressor.

Further, the opening of the upstream end of the casing treatment tank 9 on the inlet casing 81 is located in the stagnation area of the airflow of the inlet 1 . The opening of the downstream end of the casing processing tank 9 on the impeller casing 82 is located between the axial ends of the throat of the impeller, and the throat of the impeller refers to one of the multiple sections between two adjacent main blades 21 The location of the section with the smallest area and passing through the leading edge 21 of one of the main blades.

The opening of the casing treatment tank 9 on the impeller casing 82 is located at the throat of the impeller. In the case of large flow and high compression ratio, when the blade load is high, excessive gas can be prevented from flowing out through the casing treatment tank 9 , thereby reducing the flow loss near the blocked end.

Specifically, the opening of the casing processing tank 9 on the air inlet casing 81 is located at 60% of the front and rear sides of the air inlet casing 81, and the position of the front side of the air inlet casing 81 is 0%. The position of the rear side of the air intake casing 81 is 100%. The opening of the casing processing groove 9 on the impeller casing 82 is located at the front 7.5% position between the leading edge 21 of the main blade and the trailing edge of the main blade. The position where the leading edge 21 of the main blade is located is 0%, and the position where the trailing edge of the main blade is located is 100%. Of course, there may also be a slight position difference, for example, the error amount is plus or minus 3%.

The inner wall and the outer wall of the casing processing tank 9 can be connected by a rigid support structure, the rigid support structure can include a support rod, the support rod can be nested in the outer wall, and the support rod can be arranged between the inner wall and the outer wall to support and fix the inner wall.

As shown in FIGS. 1 and 2 , the casing processing tank 9 includes an arc segment 91 and a connecting segment 92 , the connecting segment 92 can be located at both ends of the arc segment 91 , and the connecting segment 92 is connected to the casing 8 .

The connecting section 92 is perpendicular to the connection position of the casing 8, and the gas flow near the casing is relatively complicated. Under different working conditions, such as different speeds and flow rates, it is difficult to determine the gas flow direction near the casing, and the gas may flow downstream It is also possible for the flow to flow upstream. Making the connecting section 92 vertical to the connection position of the casing 8 can ensure that the opening of the casing processing slot 9 is neither facing the airflow nor facing away from the airflow under different working conditions.

The connecting section of the casing processing groove 9 can be a straight line segment, no matter how the outer shape of the casing 8 is, it is easy to make the connecting section 92 intersect vertically with the casing 8, so that the arc section 91 of the casing processing groove 9 and the casing 8 are transitioned uniform. The length of the straight line can be selected according to the specific shape of the casing, so that the length of the self-circulating treatment tank 9 along the axial direction A of the centrifugal compressor is as small as possible.

The first diffuser 5 , the second diffuser 6 and the gas outlet 7 may be arranged sequentially on the downstream side of the second splitter vane 4 , and the second diffuser 6 is located radially outside the first diffuser 5 . The first diffuser 5 may be a tapered diffuser without blades. The second diffuser 6 may be a wedge diffuser. Since the gas flow velocity and pressure are high at the downstream side of the blade 4, the use of a tapered diffuser without blades is conducive to the stable flow of the gas. Using a wedge-shaped diffuser on the downstream side of the tapered diffuser without blades can further decelerate and diffuse the gas, so that the diffuser has better diffusion capacity.

The gas outlet 7 can be bent 90 degrees as a whole, the upstream section of the gas outlet 7 can extend along the radial direction R, and the downstream section of the gas outlet 7 can extend along the axial direction A, so that the gas is discharged from the casing 8 along the axial direction A.

The centrifugal compressor of the present application works under the conditions of large flow rate (greater than 4kg/s) and high compression ratio (greater than or equal to 10), and its compression ratio far exceeds that of conventional compressors. The stability expansion effect of the centrifugal compressor is mainly reflected in the near-stall end, and has little effect on the near-blocking end. A portion of the traffic is lost.

During the working process of the centrifugal compressor, under the condition of small flow rate, that is, near the stall end, the static pressure of the casing processing tank 9 at the opening of the impeller casing 82 is higher than that of the casing processing tank 9 at the inlet casing 81 static pressure at the opening. The air flow passes through the casing treatment groove 9 and flows from the impeller to the air inlet 1, and re-injects into the front opening of the impeller casing 82 after the air inlet 1 is mixed with the air inlet, so that the flow at the outlet of the compressor is smaller, and the compressor is actually It can still work stably under smaller flow. Under the working conditions of large flow rate (greater than 4kg/s) and high compression ratio (greater than or equal to 10), that is, near the plugged end, due to the high blade load, the static pressure at the opening of the impeller casing 82 at this time is slightly greater than or It is equal to the static pressure at the opening of the inlet casing 81, and the air flow in the casing treatment tank 9 is relatively low, so that the flow loss at the blocked end is relatively small.

Use NUMECA software to analyze the aerodynamic performance of the centrifugal compressor of this application. First, NUMECA/Autogrid is used to divide the structured grid of the compressor, diffuser and self-circulating treatment casing 8, and the wall grid meets the requirement that Y+ is less than 10. The SA turbulence model is used to calculate, the time discretization adopts the fourth-order explicit Runge-Kutta time-marching method, and the space discretization adopts the central difference scheme. Given the total inlet temperature and total pressure under the condition of standard atmosphere, the impeller wall is set as an adiabatic non-slip wall. In terms of outlet conditions, the small flow condition is the flow outlet, and the large flow condition is the pressure outlet. Multi-grid method and CPUbooster and other technologies are used to accelerate calculation convergence.

Use ANSYS/Mechanical software to check the strength of the centrifugal impeller, choose aviation TC11 titanium alloy as the impeller material, apply frictionless constraints at both ends of the shaft, cylindrical constraints on the inner surface of the shaft, and impose rotation angular velocity constraints. The result is that the maximum stress appears on the rim And near the blade tip, the safety factor is 1.16.

Fig. 5 shows the flow-efficiency curve of the centrifugal compressor of the present application, wherein the horizontal axis represents flow, and the vertical axis represents efficiency, and Fig. 6 shows the flow-compression ratio curve of the centrifugal compressor of the present application, wherein the horizontal axis represents the flow rate, and the vertical axis represents the compression ratio. n in Fig. 5 and Fig. 6 represents the rotating speed, and Fig. 5 and Fig. 6 show the working state of the centrifugal compressor under five rotating speeds (90%n to 110%n), and the two ends of the curve represent the stall end and the blocked end. The present application has a wider working range at 100% rotating speed (100% n among Fig. 5 and Fig. 6 ) compared to the scheme of the original caseless treatment tank (100% n original design among Fig. 5 and Fig. 6 ), That is to say, the curve of the present application corresponds to a larger rotation speed range on the horizontal axis, which supports the aero-engine to work at full speed in all airspaces. Especially at the stall end (the left end of Fig. 5), the centrifugal compressor of the present application has obtained a great surge margin improvement, which can meet the requirements of modern aero-engines on the stable working margin and efficiency of the compressor.

By performance comparison, it can be seen that the processing casing adopting the centrifugal compressor of the present application is relatively in the case of no casing processing (original design among Fig. 5 and Fig. 6), at the design speed (90% n to 110 among Fig. 5 and Fig. 6 ). %n), the surge margin is greatly improved with a lower efficiency loss, which can meet the requirements of modern aero-engines for the stable operating margin and efficiency of the compressor. Taking the highest efficiency point as the design point, the comprehensive surge margin at different speeds is generally increased by more than 10% compared with the case of caseless processing, and the comprehensive surge margin reaches more than 15% under some working conditions, which can meet the actual Engineering needs.

It should be understood that at least some aspects or features of the above-mentioned embodiments, embodiments or examples may be properly combined.

It can be understood that, in the present application, when the number of parts or components is not particularly limited, the number may be one or more, and a plurality here refers to two or more. For the situation that the number of components or members is shown in the drawings and/or the specification describes a specific number such as two, three, four, etc., the specific number is generally exemplary and not limiting, and may be It is understood as a plurality, that is, two or more, but this does not mean that the application excludes one case.

In this application, unless otherwise expressly stated or limited, "mount", "assemble", "assemble", "connect", "connect", "couple", "link", "butt", "communicate" , "communication", "conduction", "fixation", "fastening" and other terms should be interpreted broadly, for example, they may be direct or indirect. For example, with regard to connection, it may be a fixed connection, or a detachable connection, or integrated; it may be a mechanical connection, or an electrical connection; it may be a direct connection or an indirect connection through an intermediary; it may be two components An internal communication or interaction relationship between two elements, unless expressly stated or limited otherwise. For example, regarding connection/conduction, etc., it may be direct connection/conduction or indirect connection/conduction via an intermediary. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations.

In this application, unless otherwise explicitly stated or limited, a component is disposed/installed/located/accommodated/placed in another component, within, inside, etc. may be any of the following two situations Situation: a part or most of the one member is located in the other member; and the one member is completely contained in the other member.

Although the present application has been described in detail using the above-mentioned embodiments, it is obvious to those skilled in the art that the present application is not limited to the embodiments described in this specification. The present application can be modified and implemented as modified embodiments without departing from the spirit and scope of the present application defined by the claims. Therefore, the description in this specification is for the purpose of illustration and does not have any restrictive meaning to this application.

Claims (10)

1. A self-circulating treatment casing for a centrifugal compressor, comprising:

the centrifugal compressor comprises a casing (8), wherein the casing (8) comprises an air inlet casing (81) and an impeller casing (82), the air inlet casing (81) is enclosed into an air inlet channel (1), the air inlet channel (1) is gradually reduced in the direction from the upstream to the downstream of the centrifugal compressor, and the air inlet casing (81) is connected to the upstream side of the impeller casing (82);

a plurality of impellers connected to an impeller hub (10) at intervals in the circumferential direction (C) of the centrifugal compressor, the impeller hub (10) being rotatable relative to the casing (8), the impeller casing (82) surrounding the impellers; and

the air inlet type engine casing structure comprises a casing processing groove (9), the casing processing groove (9) surrounds the casing (8), the casing processing groove (9) is connected to the casing (8), openings are formed in the air inlet casing (81) and the impeller casing (82) at two axial ends of the casing processing groove (9) respectively, so that air flow in the casing (8) can enter the casing processing groove (9) through the opening at one axial end of the casing processing groove (9), and then returns to the casing (8) from the opening at the other axial end of the casing processing groove (9).

2. Self-circulating treatment casing of a centrifugal compressor according to claim 1, characterized in that the casing treatment groove (9) is tapered in the direction of the impeller casing (82) pointing towards the inlet casing (81).

3. The self-circulation treatment casing of a centrifugal compressor according to claim 1, wherein the cross-section of the inlet channel (1) is circular, and the inner and/or outer circumferential surface of the inlet channel (1) comprises bezier curves, as seen in the meridian plane of the centrifugal compressor.

4. Self-circulating treatment casing of a centrifugal compressor according to claim 1, characterized in that the opening of the casing treatment groove (9) on the inlet casing (81) is located in the stagnation zone of the air flow of the inlet duct (1).

5. Self-circulating treatment casing of a centrifugal compressor according to claim 1, characterized in that the opening of the casing treatment groove (9) on the impeller casing (82) is located between the axial ends of the throat of the impeller.

6. Self-circulating treatment casing of a centrifugal compressor according to claim 1, characterized in that the casing treatment slot (9) comprises a circular arc section (91) and a connection section (92), the circular arc section (91) being connected to the casing (8) by the connection section (92), the connection section (92) being perpendicular to the connection position of the casing (8) and the connection section (92).

7. Self-circulating treatment casing of a centrifugal compressor according to claim 6, characterized in that said connecting section (92) extends along a straight line.

8. The self-circulation treatment casing of a centrifugal compressor according to claim 1, characterized in that the casing treatment tank (9) comprises an inner wall and an outer wall, the inner wall and the outer wall being connected by a rigid support structure.

9. Centrifugal compressor, characterized in that it comprises a self-circulating treatment casing of a centrifugal compressor according to any one of claims 1 to 8.

10. The centrifugal compressor of claim 9, wherein the centrifugal compressor is used in an environment where the flow rate is greater than 4 kilograms per second and the compression ratio is greater than or equal to 10.

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