On the Development of a Compact Acoustic Probe for Pressure Oscillation Measurements in Gas Turbine Engine

In experimental fine-tuning of aircraft and ground-based gas turbine engines the gas-air line pressure oscillations is a highly informative parameter. Because of high temperatures and vibration levels the pressure sensors do not meet tolerances and thus they are connected to the measuring point by supply channels forming an acoustic probe. The resonant pressure oscillation amplification in the probe, reducing the accuracy of the measurement, occurs if no correction elements are used. Applicable correction elements in the form of long lines are of limited use due to their large size. The authors suggest corrective compact devices capable of measuring the acoustic pressure oscillations by the probe in a wide range of medium pressure. The corrective devices are implemented as a set of capillary channels and a porous MR throttle made of 0,09 mm diameter wire spiral by mold compression regulated by the average acoustic pressure. The technique of selecting parameters and design of the corrective devices are presented herein.