Modeling of non-stationary modes of operation of turbo compressors taking into account deposits formed in the interblade channels of the fl ow part

Source abstract

The classical Moore-Greitzer model, which describes the non-stationary modes of turbo compressors, does not take into account the uneven distribution of deposits in the interblade channels, which limits its application in diagnostic tasks. In this paper, a modification of the model is proposed based on the division of the channels into two groups: clean channels and channels containing deposits. A third-order system of equations is obtained, which takes into account the redistribution of flows between the groups. Numerical integration by the Runge-Kutta method and the analysis of Poincaré sections showed that at a fixed number of contaminated channels, there is a drift of the phase trajectory while maintaining the amplitudes of the pressure ratio. A diagnostic parameter is introduced, equal to the ratio of the amplitudes of the pressure ratio in the contaminated channels to the similar value in the clean channels. A quantitative relation of the diagnostic parameter with the number of contaminated channels is established. For practical implementation, a simulation model of the pressure signal recorded by the sensor on the stator is developed. Spectral analysis of the signal by the fast Fourier transform allows distinguishing two frequency components, the amplitude ratio of which corresponds to the value of the diagnostic parameter. The proposed approach provides a basis for the operational diagnostics of the flow path of a turbo compressor during operation without stopping the unit.