Doppler Sensor Array for High-Resolution Measurements of the Wavenumber-Frequency Spectrum of the Turbulent Wall Pressure at High Reynold Numbers

摘要

The Doppler frequency shift is utilized as the basic sensing mechanism for a new unsteady-surface pressure measurement technique. The frequency shift is experienced by a focused laser beam reflected off the aluminized top of a flexible-polymer diaphragm subjected to the unsteady pressure. Prototypical sensors based on this concept, with different sizes and diaphragm material and thickness are constructed as well as evaluated. The results provide understanding of the limits of the sensor's sensitivity, bandwidth, resolution and noise-level. Moreover, analysis of typical wall-pressure spectra beneath high- and low-Reynolds-number, boundary layers in light of these limits underlines the potential advantage of the new sensor in resolving the signature of small-scale turbulent structures at high Reynolds numbers.