Method for obtaining sensitivity coefficients of overall environmental compression components

Abstract

The whole machine environment compression component sensitive coefficient acquisition method of the present application relates to the field of turbomachinery. In the unsteady numerical simulation of a turbine engine, the compressor or fan is destabilized by different ways, such as the fan is destabilized by reducing the nozzle area, or the compressor is destabilized by the main combustion chamber air supply, so as to realize the acquisition of the fan / compressor component sensitive coefficient under the whole machine environment.

Description

Technical Field

[0001] This invention belongs to the technical field of aero-engines, and particularly relates to a method for obtaining the sensitivity coefficient of the environmental compression components of the whole engine. Background Technology

[0002] Rotating stall and surge are two unstable flow states unique to compressor components, leading to reduced compressor performance and, in severe cases, engine shutdown. In turbine engines, rotating stall and surge (collectively referred to as "instability") in the compressor components are usually caused by some form of intake distortion. Therefore, in the development of turbine engines, it is necessary to investigate the relationship between intake distortion and the stability of the compressor components. The stability margin represents the distance between the operating point of the compressor component and the stability boundary, while the distortion index represents the intensity of the intake distortion. The sensitivity coefficient characterizes the rate of change of the stability margin with the distortion index at a certain speed and is an important indicator for evaluating the compressor components of a turbine engine. The ratio of the stability margin to the distortion index is the sensitivity coefficient.

[0003] The sensitivity coefficient of an isolated compression component can be obtained experimentally and is currently conventionally used as the sensitivity coefficient under the overall system environment. However, it has been found that after the compression component is installed in the overall system, its stability boundary and sensitivity coefficient will change due to the influence of upstream and downstream flow fields. Currently, there are very few comparative studies in the literature. Existing methods involve establishing a one-dimensional aerodynamic small-disturbance model of the entire system and determining the system's instability point based on Lyapunov stability theory, such as in "Research on Numerical Simulation Method of Stability Margin of Gas Turbine Engine" (Liu Chao, Master's Thesis, Nanjing University of Aeronautics and Astronautics, 2012). However, because this method is one-dimensional, it cannot calculate the stability boundary under inlet distortion conditions and therefore cannot be used to obtain the component's sensitivity coefficient. Summary of the Invention

[0004] In view of this, the method for obtaining the sensitivity coefficient of the compression component in the whole machine environment provided by the present invention solves the technical problem of low accuracy in calculating the sensitivity coefficient of the compression component in the prior art.

[0005] A method for obtaining the sensitivity coefficient of a compression component in a machine environment is provided, characterized in that the method includes:

[0006] S1: Obtain the stability margin of the compressor component under uniform intake conditions. ; S2: Determine the stability margin of the compression component under study under intake conditions with a preset distortion index W. ; S3: Based on stability margin Stability margin The sensitivity coefficient of the compression component is calculated using the preset distortion index W.

[0007] The beneficial effects of this invention are: In unsteady numerical simulations of turbine engines, the compressor or fan is made unstable by different pressure methods, such as by reducing the nozzle area to make the fan unstable, or by making the compressor unstable by injecting air into the main combustion chamber, thereby obtaining the sensitivity coefficients of the fan / compressor components under the whole engine environment. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 The trajectory of the fan's operating point during the process of shrinking the nozzle; Figure 2 The trajectory of the compressor's operating point during the process of shrinking the nozzle; Figure 3 The trajectory of the fan operating point during the main combustion chamber air injection process; Figure 4 The compressor's operating point trajectory during the main combustion chamber injection process. Detailed Implementation

[0010] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0011] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0012] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this invention, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0013] The method for obtaining the sensitivity coefficient of a machine's environmental compression component provided by this invention is characterized in that the method includes: S1: Obtain the stability margin of the compressor component under uniform intake conditions. Specifically: Under uniform intake conditions, numerical simulations are performed based on an engine unsteady numerical simulation program to obtain the flow rate and total pressure ratio of the compression component; Determine the stability margin based on the flow rate to total pressure ratio under uniform intake conditions. ,satisfy: Determine the stability margin based on the flow rate to total pressure ratio under uniform intake conditions. ,satisfy:

[0014] in, It is the ratio of the compression component pressure to the flow rate before the onset of shortness of breath under uniform intake conditions. It is the ratio of the compression ratio to the flow rate of the compression components when the engine is forced to surge under uniform intake conditions.

[0015] S2: Determine the stability margin of the compression component under study under intake conditions with a preset distortion index W. Specifically: The appropriate pressure reduction method is selected based on the type of component. For example, when studying the sensitivity coefficient of a fan, pressure reduction is achieved by decreasing the nozzle size. Specifically, after obtaining a steady-state solution over time, the nozzle area is gradually reduced at a proportional rate until a preset limit is reached. This preset limit is determined according to engine specifications or design requirements. The preset limit is 50%-80% of the initial area, and the initial rate is 0.2.

[0016] When studying the compressor's sensitivity coefficient, surge can be induced by injecting air into the main combustion chamber. This injection involves injecting air into the main combustion chamber after obtaining a steady-state solution via time progression, ensuring the total pressure and temperature meet design requirements until compressor surge occurs. The recommended total temperature is ambient, and the recommended total pressure is 8 to 12 times the total pressure after the compressor. Simultaneously, to prevent fan surge, it is recommended to increase the nozzle area by approximately 10%. Based on the distortion mode to be studied, a distortion inlet boundary condition with a preset distortion index W is applied to the engine inlet to cause the compression component to become unstable. The flow rate and total pressure ratio at the time of instability are obtained, and the stability margin is calculated. ,satisfy:

[0017] in, It refers to the ratio of the compression component pressure to the flow rate before the onset of shortness of breath under distorted intake conditions. It is the ratio of the compression component pressure to the flow rate when the engine is forced to surge under distorted intake conditions.

[0018] S3: Based on stability margin Stability margin The sensitivity coefficient of the compression component is calculated based on the preset distortion index W. Specifically: The sensitivity coefficient α satisfies: .

[0019] Compared with the prior art, the present invention can use a targeted breathing method to destabilize the compression component to be studied in numerical simulation, thereby obtaining the sensitivity coefficient of any compression component in a turbine engine with multiple compression components. Furthermore, the present invention is based on unsteady numerical simulation of turbine engines and is applicable to engines of various configurations and various forms of intake distortion.

[0020] For example: Numerical simulation of an aero-engine was performed using the sensitivity coefficient acquisition method described in this invention. Two-dimensional (axial and circumferential), unsteady, inviscid integral Euler equations were used as the governing equations, with the engine's steady-state common operating point as the initial value, and a time-progressed solution was performed. Static pressure, static temperature, mass flow rate, and circumferential velocity were used as the basic variables of the governing equations. Additionally, the high- and low-pressure rotor physical speeds and fuel mass flow rate were used as control parameters for the engine state. The finite volume method was used to approximate the equation system into a high-order ordinary differential equation system with numerical solutions obtainable using the Runge-Kutta method. The integral results represent the unsteady airflow parameters at the computational grid nodes. In the calculation of unsteady processes, the aerodynamic stability of the engine is checked. That is, if the airflow velocity at a certain circumferential position in the engine passage is negative, the engine is considered to be unstable.

[0021] First, the fan is destabilized by narrowing the nozzle. Under conditions of uniform air intake and inlet distortion, the fan's operating point trajectory is observed until instability occurs. Figure 1 The compressor's operating point trajectory is shown in the figure. Figure 2 As shown in the figure, under the condition of a smaller nozzle, the fan can become unstable, but the compressor's operating point shifts to the left along the common working line without becoming unstable. Under inlet distortion conditions, the common working line of the compression components can be observed to rise and the stability boundary to fall. This indicates that the present invention can be used to obtain the stability boundary of the fan under inlet distortion conditions, and then calculate its sensitivity coefficient.

[0022] Secondly, compressor instability is caused by injecting air into the main combustion chamber. Under conditions of uniform intake and inlet distortion, the fan's operating point trajectory continues until instability occurs. Figure 3 The compressor's operating point trajectory is shown in the figure. Figure 4 As shown in the figure, under the condition of a smaller nozzle, the compressor can become unstable, while the fan operating point rises slightly but does not become unstable. Under inlet distortion conditions, the common operating line of the compression components rises and the stability boundary falls. This indicates that the present invention can be used to obtain the stability boundary of the compressor under inlet distortion conditions, and then calculate its sensitivity coefficient.

[0023] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for obtaining a sensitivity coefficient of a machine environment compression component, characterized in that, The method includes: S1: Obtain the stability margin of the compressor component under uniform intake conditions. Among them, under uniform intake conditions, numerical simulation is performed based on an engine unsteady numerical simulation program to obtain the flow rate and total pressure ratio of the compression component; Determine the stability margin based on the flow rate to total pressure ratio under uniform intake conditions. ,satisfy: In the formula, It is the ratio of the compression component pressure to the flow rate before the onset of shortness of breath under uniform intake conditions. It is the ratio of the compression component pressure to the flow rate when the engine is forced to surge under uniform intake conditions; S2: Determine the stability margin of the compression component under study under intake conditions with a preset distortion index W. Among them, the appropriate pressure-inducing method is selected according to the type of component. When studying the sensitivity coefficient of the fan, pressure is induced by reducing the size of the nozzle; when studying the sensitivity coefficient of the compressor, pressure is induced by injecting air into the main combustion chamber. S3: Based on stability margin Stability margin The sensitivity coefficient of the compression component is calculated using the preset distortion index W, where, Based on the distortion type to be studied, a distortion inlet boundary condition with a preset distortion index W is applied to the engine inlet; To destabilize the compression component, obtain the flow rate and total pressure ratio at the point of instability; Calculate stability margin ,satisfy: in, It refers to the ratio of the compression component pressure to the flow rate before the onset of shortness of breath under distorted intake conditions. It is the ratio of the compression component pressure to the flow rate when the engine is forced to surge under distorted intake conditions.

2. The acquisition method according to claim 1, characterized in that, The method of reducing nozzle size to force a stop includes: after obtaining a steady solution over time, starting to reduce the nozzle area at a proportional rate until a preset limit value is reached, which is determined according to engine specifications or design requirements.

3. The acquisition method according to claim 2, characterized in that, The main combustion chamber replenishment method includes: after obtaining a steady solution over time, injecting air with total pressure and total temperature that meet the design requirements into the main combustion chamber until the compressor surges.

4. The acquisition method according to claim 1, characterized in that, S3 includes: The sensitivity coefficient α satisfies: 。

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