Simultaneous Measurement of Wall Pressure Fluctuations in a Turbulent Boundary Layer using 168ch MEMS Microphone Array
We have developed MEMS microphone arrayfor turbulent wall pressure fluctuation measurement. Figure 1 shows amicrophone array designed for the present measurement.56 microphones are implemented in two rows. The dimension of the microphone is 4×3×1 mm, and it has a pressure port with the diameter of 0.25 mm in the bottom surface. Three such microphone arrays havebeen synchronized to achieve 168ch wall pressure fluctuation measurement.Figure 2 indicates a space–time fluctuating pressure fieldwith 56 microphones aligned in the spanwise direction. The distribution clearly visualizes the instantaneous structure of the wall pressure fluctuations. The negative and positive structures tend to spread both in the spanwise and the streamwise directions. The activeintermittent small scale fluctuations can be observed.It is confirmed that the present method provides a novel flexible method for measuring wall pressure fluctuations with a good spatial and temporal resolutions. The time resolved fluctuating wall pressure fields will give new experimental insights of the relationship between the wall pressure fluctuation pattern and the wall turbulence structures.