ACOUSTIC MEASUREMENTS IN FLOWS USING PHOTON-CORRELATION SPECTROSCOPY

Laser doppler anemometry using the photon correlation method of signal processing has been used to measure a velocity field in which sinusoi dal fluctuations generated acoustically are superimposed on a steady f low. A stochastic model has been developed for the form of the correla tion function, and it is shown to be consistent with previous models f or a steady flow and for sinusoidal fluctuations in an acoustic field. Measurements have been made of the velocity field associated with ste ady flow in a tube with a superimposed acoustic field, the results wer e shown to be consistent with the theoretical predictions.