METHOD OF CHECKING COMBUSTION INSTABILITY

摘要

The prevent invention provides a method for checking combustion instability at real time in multiple dimensions by calculating sound pressure, kurtosis, a damping coefficient of combustion dynamic pressure frequency components corresponding to a sound mode. The method for checking the combustion instability includes a step for measuring a combustion dynamic pressure signal generated in combustion; a step for determining a sound mode frequency by applying high speed Fourier transform to the combustion dynamic pressure signal; a step for extracting the combustion dynamic pressure signal in a sound mode frequency band by applying a wavelet filter or by passing through the band in which the sound mode frequency is a center frequency on the combustion dynamic pressure signal; a step for calculating an RMS sound pressure and the damping coefficient during a predetermined period on the combustion dynamic pressure signal in the sound mode frequency band; a step for comparing an RMS sound pressure with a first combustion instability threshold; a step for determining that the combustion instability is generated in case that the RMS sound pressure is more than the first combustion instability threshold; a step for calculating the kurtosis during the period on the combustion dynamic pressure signal in the sound mode frequency band in case that the RMS sound pressure is less than the first combustion instability threshold; a step for determining whether the kurtosis is larger than a standard value; a step for calculating the RMS sound pressure corrected by the kurtosis when the kurtosis is larger than the standard value and comparing that with a second combustion instability threshold; a step for determining that the combustion instability is generated when the corrected RMS sound pressure is larger than the first combustion instability threshold; a step for comparing the damping coefficient with the second combustion instability threshold; and a step for determining that the combustion instability is generated when the damping coefficient is under the second combustion instability threshold. [Reference numerals] (AA) Start;(BB) Pass through a band/a wavelet filter;(CC) End;(S202) Measure p(t);(S204) Determine a sound mode frequency;(S206) Extract p*(t) of the sound mode frequency band;(S208) Calculate P_rms;(S210) Calculate average movement of autocorrelation data, Determine autocorrelation;(S212) Calculate a hilbert-transform value;(S214) Calculate 瓘;(S218) Determine that the combustion instability is generated;(S220) Continue operation;(S224,S228) Calculate k