LASER DOPPLER ANEMOMETRY MEASUREMENTS IN AN ENGINE

A simple and effective technique is reported which allows measurement of the flow field in the cylinder of a motored internal combustion engine with good temporal and spatial resolution. The experiment, a real-fringe laser Doppler anemometer, uses photon counting digital autocorrelation for data capture. The experimental autocorrelation functions have been processed using curve-fitting to a Gaussian velocity profile and by direct Fourier transformation without prior assumption of the form. The ability of such a technique to tolerate poor SNRs makes it a likely choice for measurement in firing engines. © 1979 Optical Society of America.