Prediction Method of Stall Boundary of Multistage Axial Compressor Based on Eigenvalue Theory

Abstract

The invention relates to a prediction method of a multistage axial-flow compressor stall margin. The prediction method comprises the following steps: according to a situation of the rotating stall inception of an axial-flow compressor, adopting a small perturbation theory to establish a three-dimensional compressible Euler equation which describes a flow field; applying harmonic decomposition and a dispersion relation to establish a boundary condition on the hub and the leaf opex of each drainage basin; adopting a three-dimensional semi-actuator model to carry out modelling on a stator and a rotor, and adopting a mode matching technology, the conservation law and the representation condition of compressor loss characteristics on an interface to obtain a characteristic value problem which solves a linearized flow field; and solving the characteristic value problem to obtain the characteristic disturbance frequency of a compression system, and judging system stability through the characteristic disturbance frequency, wherein a judgement standard is that the disturbance frequency [Omega] is a complex number, [Omega] is [Omega]R+i[Omega]I, disturbance is attenuated along with time evolution when the imaginary part [Omega]I of the frequency is greater than 0, the system is stable, otherwise, [Omega]I is less than 0, the disturbance is amplified along with time, and the system loses stability. The prediction method can be used for predicting the rotating stall inception of the multistage axial-flow compressor.

Description

technical field [0001] The invention relates to a method for predicting the stall boundary of a multistage axial flow compressor, in particular to a method for predicting the stall boundary of a multistage axial flow compressor based on eigenvalue theory, and belongs to the technical field of turbines. Background technique [0002] In the prior art, common rotating stall stability models are usually two-dimensional models that do not consider radial disturbances. However, the available three-dimensional stability models are very limited, and most of them are three-dimensional incompressible stability models, which cannot meet the needs of high-speed compressors / fans. [0003] In order to establish a three-dimensional stability model, some researchers have also made many attempts. It should be emphasized that in addition to the difficulty of the model itself, its numerical solution method also hinders the development of the three-dimensional stability model. It's all over. ...

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Problems solved by technology

It should be emphasized that in addition to the difficulty of the model itself, its numerical solution method also hinders the development of the three-dimensional stability model. it's over

Because the stability characteristic equation is a determinant of a complex characteristic matrix, there is no analytical expression, and the derivative of the independent variable cannot be expressed, and the Newton-Raphson method, When traditional iterative methods such as the traditional iterative method are used to solve the problem, the direction of convergence of the solution is not controlled. Since the characteristic equation often has multiple solutions, and some solutions are beyond the scope of the physical meaning, even if the initial value of the iteration is adjusted, it is very difficult. Difficult to control the direction of convergence of calculation results

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