The Determination of the Flow Acoustic Characteristics in a Duct with Variable Cross-Section of a Laboratory Unit

When studying the influence of non-stationary and periodic processes on the fuel mixtures combustion, it is important to predict and determine the intensity of pressure and velocity oscillations near the reacting zone. When choosing the frequency and amplitude ranges of the forced influence in an experimental study, it is necessary to take into account the acoustic characteristics of the flow in the laboratory unit. In some cases, for the preliminary prediction of the acoustic characteristics of the flow in a duct with a variable cross-section, special mathematical modeling is required. The problems of mathematical modeling of the spectral characteristic of natural oscillations of the gas in a laboratory unit for studying the diffusion and kinetic combustion of fuel mixtures are considered. A mathematical model developed and implemented in a specialized module makes it possible to determine the influence of geometric and mode characteristics on the resonant frequencies. The calculated and experimental data are compared. The developed mathematical model and the calculations results can be used for choosing the configuration of experimental units and predicting resonant modes with the excitation of intense oscillations of the gas velocity in the combustion zone.

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