High-Reynolds Number Aeroacoustic Testing Under Pressurised Cryogenic Conditions in PETW

This paper presents an experimental investigation of flow noise around a cylinder under combined cryogenic (290 to 120 K) and pressurized (110 to 400 kPa) conditions. The study consists of data acquired with a microphone array in the Pilot-ETW (PETW), a small scale wind tunnel for preliminary testing at the ETW site. To our knowledge, this is the first time that the microphone array measurement technique has been used under these combined pressurized and cryogenic conditions. The Mach number was in the range 0.15 to 0.3, and the Reynolds number (based on the cylinder diameter of 2 mm) was in the range of 7.6 · 103−1.9 · 105. The experiments demonstrate the technical feasibility of performing aeroacoustic measurements within the operated total static pressure and temperature range. The measured sound pressure shows a significant Reynolds number dependency. Additionally, a decibel correction, which takes account of the pressure and temperature effect in the test section on the radiated noise from the cylinder, is introduced and shows very good agreement with the measured data. Preliminary sensor tests have been performed to obtain the frequency response at different static pressures and different temperatures. The resulting amplitude response was shown not to be a linear combination of the amplitude response caused by varying the static pressure or temperature separately.