Development of the Microphone-Array Measurement Technique for use in Cryogenic and Pressurized Wind Tunnels

摘要

In the development process of aircrafts and rail vehicles, the use of microphone phased arrays to acquire acoustic data on scaled models in conventional wind tunnels has become feasible. Since conventional wind tunnels cannot generally achieve full-scale Reynolds numbers, aerodynamic measurements are performed in cryogenic and/or pressurized wind tunnels which are capable of full-scale/higher Reynolds number flows. The microphone array measurement technique has been further developed for the use in cryogenic (down to 100 K) and pressurized (up to 450 kPa) wind tunnels. The comparison of aeroacoustic results obtained from wind tunnel tests with results from real flight tests shows differences. The differences can be attributed to lack of model-fidelity, installation effects, the Reynolds number and the assumptions made in phased array processing. This work focuses on the effect of the Reynolds number. This paper gives an overview of the efforts at to make microphone array measurement technique available to use in pressurized and cryogenic condition. The aim of this development is to enable acoustic measurements on scaled aircraft models in start and landing configuration at real-flight Reynolds numbers.