Unsteady Pressure Measurement on NACA0012 Model Using Global Low-Speed Unsteady PSP Technique

Pressure fluctuation field accompanied by a trailing edge noise on a 2-dimensional NACA0012 model was measured by the low-speed unsteady Pressure-Sensitive Paint (PSP) technique using a high-speed camera. Maximum pressure fluctuation on the model at U=28.0 m/s was about 150Pa p-p and its fundamental frequency was at 920Hz (St=0.985). Its global pressure fluctuation distribution around its trailing edge was measured. Anodizedaluminum PSP (AA-PSP), which is one of the fast-response PSPs, was coated on the model and illuminated by a 7W blue laser diode. AA-PSP luminescence was measured by a CMOS high-speed camera with 10k frame-per-second sampling rate and more than 50,000 images were acquired both under wind-on and wind-off condition at each case. Images were processed using FFT process including ensemble average and spectral subtraction, and reduced to the power spectrum of pressure fluctuation. The results could visualize the detailed distribution of the pressure fluctuation on the model. The difference between different test condition and flow speed were clearly detected. The results also compared with corresponding data of pressure transducers and another unsteady PSP technique, the scanning unsteady PSP technique. Both of the pressure fluctuation profile and quantitative power value measured by the high-speed unsteady PSP technique were good agreement with the other measurement data.