Pilot study of frequency characteristics of an acoustic probe for measuring pressure pulsations in the gas turbine engine inlet device

Abstract

Special tests are carried out to determine the effect of heterogeneity of the air flow at the engine intake to the gas-dynamic stability margin of the compressor. There are acoustic probes mounted in the engine air flow meter manifold to measure pressure pulsations for this purpose. The probes are installed around the circumference of the collector at an angle of 90° relative to its axis. There is a differential pressure sensor installation in the acoustic probe due to the smallness of the amplitudes of velocity head pulsations in the manifold. Stagnated pulsed-flow of air is directed to the main input of the sensor and its damped component to the discharge chamber. In the paper on the basis of electrodynamics’ analogies the method of calculation of acoustic RC-damper to eliminate the constant and low frequency components of the flow speed pulsations is presented. To confirm compliance of the measuring probes characteristics to the design specification requirements acoustic probes’ frequency tests are conducted. Test results show that the developed acoustic probe can measure pressure fluctuations in the gas turbine engine inlet flow meter manifold with dynamic accuracy of ± 10% in the frequency range of 2-300 Hz.