METHOD FOR MEASURING ACOUSTIC PULSATIONS OF A GAS STREAM Russian patent published in 2019 - IPC G01H15/00 

FIELD: measuring equipment.

SUBSTANCE: invention relates to measurement equipment, namely to methods of measuring acoustic pulsations of gas flow, mainly for investigation of acoustic noise of aircraft gas turbine engines, specifically for investigation of generation of acoustic noise by fans and / or compressors of turbojet two-circuit engines. In the method of measuring gas flow pulsations, in which the gas flow rate is measured, static and total pressure of the stream, data are collected and recorded from the measurement sensors, the readings of the sensors are processed, the Mach number (M) is determined (calculated), performing spectral analysis of measured data, wherein temperature of T₀ braking of gas flow, and as sensor of pulsations of acoustic pressure and flow rate there used is thermal anemometer, according to certain (calculated) Mach number (M) value value of gas-dynamic function is determined β, the thermal anemometer sensor is calibrated by determining the dependence of the output signal of the thermal anemometer as a function of mass flow rate m and temperature T₀ gas flow braking for different values of relative heating a, ratio of r sensitivity coefficients of filament of thermal anemometer to mass flow rate m and temperature T₀ is determined braking, also for number M, corresponding to conditions of aerodynamic experiment, determining the required value of a, at which the equality condition r=β; wherein to exclude the effect of gas flow pulsations of hydrodynamic nature, acoustic noise is measured at a selected value of relative heating a.

EFFECT: high accuracy of measuring sound pressure level and frequency spectrum of acoustic noise of aircraft gas turbine engines by excluding the effect of gas flow pulsations of hydrodynamic nature on readings of measurement equipment using additional measurements and calibration graphs.

1 cl, 2 dwg