Abstract
Many-channel microphone array has been developed for turbulent wall pressure measurements. The microphone array consists of custom-made PCB boards with digital MEMS microphones and an FPGA signal controller. The digital data stream from the microphone is bundled and recorded. The pressure signals are recovered using a decimation sinc2 filter in the post-processing. The measurements have been performed in a turbulent boundary layer and in a wing–flat plate juncture flow. For the turbulent boundary layer, the instantaneous space-time distribution of the wall pressure fields exhibits negative and positive wall pressure with packets of strong intermittent fluctuations. For the wing–flat plate juncture flow, the wall pressure fluctuations at 672 points on the flat plate and the velocity field in the stagnation plane have been measured simultaneously. The distribution of the RMS values of the wall pressure fluctuation indicates the trace of the strong wall pressure fluctuations. In the presentation, the future possibilities of the microphone array will be discussed.
