Autocorrelation theory-based engine instability prediction and assessment method

Abstract

The invention discloses an autocorrelation theory-based engine instability prediction and assessment method. The method comprises the steps of firstly filtering a pulsating pressure signal of a combustion chamber, separating out pressure oscillation of each order mode and performing autocorrelation calculation; secondly performing Hilbert transform on an autocorrelation result to obtain an outside envelope of the autocorrelation result; and finally fitting the outside envelope by applying a least square method to determine a first-order mode dissipation coefficient of an engine, and taking the first-order mode dissipation coefficient of the engine as an assessment tool of engine stability margin for predicting and assessing high-frequency combustion instability of the liquid rocket engine. According to the method, the engine can be subjected to instability quantitative prediction and assessment under the condition of not applying external force interference.

Description

technical field [0001] The invention relates to the field of liquid rocket engine research, in particular to an engine instability prediction and evaluation method based on autocorrelation theory. Background technique [0002] The unstable combustion of the liquid rocket engine can lead to the instantaneous destruction of the engine, and the stability margin of the engine needs to be evaluated during the development period. [0003] At present, there are mainly the following methods for evaluating the stability margin of an engine. [0004] 1. Spontaneous instability assessment method [0005] The spontaneous instability evaluation method is to evaluate the instability by the probability of the occurrence of spontaneous instability, which requires multiple tests, and the time and capital costs are relatively large. [0006] 2. Finite perturbation instability method [0007] The finite disturbance instability method is to excite high-amplitude pressure oscillations through...

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Problems solved by technology

[0005] The spontaneous instability evaluation method is to evaluate the instability by the probability of the number of occurrences of spontaneous instability, which requires multiple tests, and the time and capital costs are relatively large

[0006] 2. Finite perturbation instability method

[0008] The limitation of the finite perturbation instability method is that it cannot monitor the engine instability in real time, that is, it cannot evaluate the engine instability in working state in real time

Unable to assess the extent of steady-state engine distance instability

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