WO2023050693A1

WO2023050693A1 - Axial-flow compressor and method for improving full-circumference flow field

Info

Publication number: WO2023050693A1
Application number: PCT/CN2022/077490
Authority: WO
Inventors: 孙鹏
Original assignee: 中国民航大学
Priority date: 2021-09-10
Filing date: 2022-02-23
Publication date: 2023-04-06
Also published as: CN113864243A

Abstract

An axial-flow compressor for improving a full-circumference flow field. In full-circumference stator blades of a stator, large attack angle blades A and small attack angle blades B are alternately arranged. The flow channel gaps between the blades are all the same. In the full-circumference stator blades of the stator, original blades and modified blades are alternately arranged, the gaps between the original blade and two adjacent modified blades are the same, and the attack angle of the modified blade is smaller than an attack angle of the original blade. According to the axial-flow compressor, some or all of the original blades in an original stator are replaced with modified blades that can inhibit the separation of a corner region of a suction face, so that a full-circumference flow field structure is improved, and the flow-through capability is increased. Not only can the stable operation of the axial-flow compressor under a working condition of an original stator blade type being operable be ensured, but a flow field structure during a near-stall working condition can also be improved, and a flow separation range of the corner region of the suction face is reduced.

Description

Axial flow compressor and method for improving full-circumference flow field

technical field

The invention belongs to the technical field of aero-engine design and research, and in particular relates to an axial flow compressor and a method for improving a flow field around the entire circumference.

Background technique

Compressor is one of the three core components of contemporary aero-engines, among which axial-flow compressors are widely used in large aero-engines. In order to meet the high performance requirements of contemporary aero-engines, it is necessary to improve the compressor's anti-load capacity, efficiency and stability margin. The stator of a conventional axial flow compressor is arranged by the blades of the same blade shape with a certain consistency. When the incoming flow is uniform, the angle of attack of the incoming flow of each stator blade is approximate. The state is close. When the compressor is in a high-load operation state, due to the large reverse pressure gradient, the flow separation in the corner area of the stator vane is prone to flow separation and blockage of the flow channel. This blockage of the flow channel occurs in the entire circumferential flow channel, which will reduce the performance of the engine. , and even cause the engine to spin stall and surge. Therefore, improving the load resistance and stability of the compressor has great practical significance for the normal and stable operation of the engine.

Existing studies have shown that the separation regions in the flow path of the stationary blade mainly exist in the upper and lower corner regions, and due to the high-speed rotation of the moving blade and the influence of the tip clearance of the moving blade, the separation of the upper corner region in the flow path of the stator blade is often stronger than that of the lower corner region , the upper corner area is prone to large-scale flow separation, which seriously affects the mainstream flow. Although there are studies in the prior art aimed at improving the flow field by changing the profile of the vane, the research direction is mainly on the axial-flow compressor with non-axisymmetric vane distribution. Replace the original vane with a modified vane that can suppress flow separation or increase the cascade consistency in this area to reduce or even eliminate the separation of the suction surface of the vane in the area affected by the distortion, and improve the flow of the compressor under the local distortion state ability. This non-axisymmetric distribution vane axial flow compressor is mainly aimed at the situation where the incoming flow is uneven and there is local distortion.

However, the location of local distortion needs to be predicted according to the actual situation. In practical applications, the distortion area may change; and, when it is in the middle stage of the compressor and later, after the diversion of the previous stages, the airflow distribution in the circumferential direction has become relatively The scheme of uniform, partial vane modification is no longer applicable. Therefore, there are limitations in the application of the above-mentioned non-axisymmetric distributed vane axial-flow compressor, and it is impossible to ensure the optimization of the performance of the compressor all the time.

Contents of the invention

In view of this, the invention aims at overcoming the defects in the prior art, and proposes an axial flow compressor and method for improving the flow field around the entire circumference.

In order to achieve the above object, the technical solution created by the present invention is achieved in this way:

An axial flow compressor for improving the flow field around the circumference. In the stator vanes around the stator, blades with large attack angles and blades with small attack angles are arranged alternately.

Further, the clearances of the flow passages between the blades are the same.

Further, in the stator blades around the stator, the prototype blades and modified blades are arranged alternately, the gaps between the prototype blades and two adjacent modified blades are the same, and the angle of attack of the modified blades is smaller than that of the prototype blades.

Further, the modified blade adopts a tip-swept blade, or adopts a modified blade whose chord length is changed from the prototype blade.

Further, each remodeled blade is remodeled by changing the inlet geometric angle of the blade tip and simultaneously changing the geometric angle of the blade root inlet.

Further, each blade adopts a modified stator blade.

Further, each of the modified stationary blades adopts blade-top forward-swept blades, or adopts modified blades with changed chord lengths of the prototype blades.

Further, each modified stator blade is modified by changing the geometric angle of the inlet of the blade top and changing the geometric angle of the inlet of the blade root at the same time.

A method for improving the overall flow field of an axial flow compressor, using modified blades with a small inlet geometric angle to replace the prototype stator blades in the original stator at intervals; or,

Replace all the prototype stator blades in the original stator with modified stator blades, and ensure that the inlet geometric angles of each modified stator blade are smaller than the prototype stator blades. The leaves are arranged alternately.

Further, the gaps between the two adjacent blades are the same.

Compared with the prior art, the present invention has the following advantages:

In the axial flow compressor provided by the invention, part or all of the original blades in the original stator are replaced with modified blades that can suppress the separation of the angular area of the suction surface, thereby improving the flow field structure around the circumference and increasing the flow capacity. This structure can not only ensure stable operation under the operating conditions of the original stator blade type, but also greatly improve the flow field structure in near-stall conditions, and reduce or even eliminate the flow separation range in the corner area of the suction surface.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is the schematic diagram of the stationary vane in the embodiment of the present invention;

Fig. 2 is a schematic diagram of the arrangement of the blades of the stator in the embodiment of the invention;

Fig. 3 is a schematic diagram of blade arrangement when the stator is flattened in an embodiment of the invention;

Fig. 4 is a schematic diagram of the partial structure of the invention when the stationary vane cooperates with the moving vane;

Fig. 5 is a schematic diagram of the comparison between the prototype blade and the modified blade in the invention;

Fig. 6 is a schematic diagram of the position of the corner area in the creation of the present invention;

Figure 7 is a schematic diagram of the comparison of the pressure ratio characteristic line between the prototype and the modified single-stage compressor (the pressure ratio is the ratio of the total pressure at the outlet to the total pressure at the inlet, ori represents the prototype compressor, and opt represents the modified compressor according to this invention. );

Fig. 8 is a schematic diagram of the comparison of the efficiency characteristic line between the single-stage compressor prototype and the modification (ori represents the prototype compressor, and opt represents the modified compressor according to the invention).

Detailed ways

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention Creation and simplification of description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as limiting the invention. In addition, the terms "first", "second", etc. are used for descriptive purposes only, and should not be understood as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first", "second", etc. may expressly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be interpreted in a broad sense, for example, it can be a fixed connection or a flexible connection. Detachable connection, or integral connection; it can be mechanical connection or electrical connection; it can be direct connection or indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention based on specific situations.

The invention will be described in detail below with reference to the accompanying drawings and examples.

An axial flow compressor for improving the flow field around the circumference, as shown in Figures 1 to 6, in the stator blades around the circumference, blades A with a large angle of attack and blades B with a small angle of attack are arranged alternately. Preferably, the gaps of the flow passages between the blades are the same. The axial-flow compressor provided by the present invention can control the flow of the entire peripheral flow channel, suppress the separation of the angular area to improve the flow capacity of the whole stage engine, not only can suppress the separation of the angular area when facing a uniform incoming flow, but also can prevent the separation of the angular area when the incoming flow exists. Distortion, that is, when the incoming flow is uneven, it is guaranteed that the performance of the compressor will not deteriorate sharply, and no matter where the distortion is, it can ensure the effect of improving the flow field.

In an optional embodiment, the prototype blades and modified blades are alternately arranged in the stator blades around the stator, the gaps between the prototype blades and two adjacent modified blades are the same, and the angle of attack of the modified blades is smaller than that of the prototype blades. angle of attack. In this embodiment, the above-mentioned modified blade adopts a tip-swept blade, or adopts a modified blade whose chord length of the original blade is changed. Moreover, each remodeled blade can also be remodeled by changing the geometric angle of the inlet of the blade top and changing the geometric angle of the inlet of the blade root at the same time.

The above-mentioned structural design can weaken the influence of corner separation, by replacing every second blade of the full-circumference stator blade with a modified blade that can suppress corner separation (as shown in Figure 2 and Figure 3, A represents the prototype blade, B represents the modified blade The last blade, two kinds of blades are arranged alternately on the whole circumference of the stator) to control the angle area range of the stator blade, especially the upper angle area with a large angle area range, and the prototype blades kept every other blade can balance the impact of the modified blade The impact of incoming air. The staggered arrangement of the two types of blades can ensure the periodic uniformity of the flow field, thereby achieving the purpose of improving the flow field and improving the performance of the entire circumference of the flow channel.

In another optional embodiment, each blade adopts a modified stator blade. In this embodiment, each modified stator blade adopts a tip-forward-swept blade, or adopts a modified blade whose chord length is changed from the original blade. Each modified stator blade is modified by changing the geometric angle of the inlet of the blade top and changing the geometric angle of the inlet of the blade root at the same time.

The following provides a method to improve the flow field around the axial flow compressor:

The performance test of the axial flow compressor is carried out first, that is, the complete compressor characteristic curve is tested, the near-stall condition is found, and the flow field in the near-stall condition is analyzed to find the corner separation area. Afterwards, blade remodeling is carried out for the corner separation area, and the remodeled stator blades are alternately arranged and combined with the original blades to form full-circumferential blades.

Usually, the modification is based on the original airfoil shape, as shown in Fig. 4 to Fig. 6, by changing the twist degree of the leading edge of the stator blade tip to reduce the inlet geometric angle b, and then reduce the angle of attack c. Especially in Figure 5, it can be clearly seen that the shape of the blade changes. The dotted line part shown in A is the prototype blade, and the solid line part shown in B is obtained by bending the front edge of the prototype blade tip toward the blade pot. Modified blades. In order to achieve the ideal fluency improvement effect and ensure wide adaptation, preferably, the leading edge of the blade tip of the modified blade is increased by 5-20° compared with the original blade. As shown in Figure 7, it is a schematic diagram of the comparison of the pressure ratio characteristic line of the single-stage compressor prototype and after modification; as shown in Figure 8, it is a comparison diagram of the efficiency characteristic line of the single-stage compressor prototype and after modification. It can be seen intuitively that the flow in the compressor tends to be more stable, and the performance of the compressor is improved.

The reason for reducing the angle of attack is that the analysis of the flow field determines that the flow separation is mainly distributed in the three-dimensional angular area e above and below the suction surface of the stator blade, especially the upper angular area. Since the size of the angle of attack can affect the separation position, when the angle of attack is large, the separation often occurs on the suction surface. Therefore, by reducing the geometric angle of the inlet to reduce the angle of attack, more mainstream high-energy fluid is introduced into the three-dimensional corner area d on the suction surface, the occurrence of corner separation is suppressed, the flow field structure is improved, and the flow capacity is increased.

Since the original blade with a large angle of attack and the modified blade with a reduced angle of attack exist at the same time, when the compressor is in different operating conditions and the intake angle a of the incoming flow changes, the two types of airfoils can be more easily matched to flow in Gas direction, in order to achieve the purpose of improving the stability margin of the compressor.

In summary, for the design and arrangement of modified blades, one way is to use modified blades with small inlet geometric angles to replace the original stator blades in the original stator at intervals, that is, replace half of the stator blades in the circumferential direction with modified or, another way is to replace all the prototype stator blades in the original stator with modified stator blades, and ensure that the inlet geometric angles of each modified stator blade are smaller than the prototype stator blades. At the same time, the modified stator blades The stator blades with high angle of attack and the stator blades with small angle of attack are arranged alternately. Usually, the gaps between the two adjacent blades are the same.

The role of the alternate arrangement of the two blade types is to ensure that under different working conditions, because the inlet angle is different, in order to obtain a more suitable angle of attack for the working conditions, different inlet geometric angles are required. Therefore, when the two types of blades are arranged alternately, in the direction of the entire circumference, when the inlet angle of the incoming flow is large, there are prototype blades distributed around the entire circumference to ensure the stability of the flow state; There are also modified blades in the direction, which can still ensure a stable flow state.

Another function of the staggered arrangement of the original/modified blades in the circumferential direction is to ensure the stability of the flow in the compressor and the performance of the compressor when there is distortion at any position of the incoming air. The blade modification scheme of the present invention can be adjusted according to the specific conditions of different compressors. When the number of stator blades around the circumference is even, a modified blade is installed every other original blade, that is, half of the blades are modified, and even All the retained prototype stator blades are replaced with new modified blades matching the modified blades, that is, all blades are replaced with two modified blades arranged alternately in the original position, so as to further improve the performance of the compressor.

In the axial flow compressor provided by the invention, part or all of the original blades in the original stator are replaced with modified blades that can suppress the separation of the angular area of the suction surface, thereby improving the flow field structure around the circumference and increasing the flow capacity. This structure can not only ensure stable operation under the operating conditions of the original stator vane type, but also greatly improve the flow field structure in the near-stall condition, and reduce or even eliminate the flow separation range in the corner area of the suction surface. Without affecting the efficiency, the pressure ratio of the compressor is greatly increased, thereby expanding the stability margin of the compressor, and laying the foundation for the design and development of high-load compressors.

The above descriptions 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 Within the protection scope of the present invention.

Claims

An axial flow compressor for improving the flow field around the circumference is characterized in that: blades with large attack angles and blades with small attack angles are alternately arranged in the stator blades around the circumference of the stator.
An axial flow compressor for improving the flow field around the circumference according to claim 1, characterized in that: the gaps between the flow passages between the blades are all the same.
According to claim 1 or 2, an axial flow compressor for improving the flow field around the circumference is characterized in that: in the stator blades around the circumference, the prototype blades and the modified blades are arranged alternately, and the prototype blades and the adjacent two The modified blade clearances are the same, and the angle of attack of the modified blade is smaller than that of the prototype blade.
According to claim 3, an axial flow compressor with improved full-circumferential flow field is characterized in that: the modified blade adopts a blade-top forward-swept blade, or adopts a modified blade whose chord length is changed from the original blade.
According to claim 4, an axial flow compressor for improving the flow field around the entire circumference is characterized in that: each modified blade is modified by changing the geometric angle of the inlet of the blade tip and changing the geometric angle of the inlet of the blade root at the same time.
An axial flow compressor for improving the flow field around the circumference according to claim 1 or 2, characterized in that: each blade adopts a modified stator blade.
According to claim 6, an axial flow compressor for improving the flow field of the whole circumference is characterized in that: each modified stator blade adopts blade-top forward-swept blades, or adopts modified blades whose chord length is changed .
According to claim 6, an axial flow compressor for improving the flow field around the entire circumference is characterized in that: each modified stator blade is modified by changing the geometric angle of the inlet of the blade top and changing the geometric angle of the inlet of the blade root at the same time .
A method for improving the overall flow field of an axial flow compressor, characterized in that: using modified blades with small inlet geometric angles to replace the original stator blades in the original stator at intervals; or,

Replace all the prototype stator blades in the original stator with modified stator blades, and ensure that the inlet geometric angles of each modified stator blade are smaller than the prototype stator blades. The leaves are arranged alternately.
The axial flow compressor for improving the flow field of the whole circumference according to claim 9, characterized in that the gaps between the two adjacent blades are the same.