DIRECT MEASUREMENT OF LASER VELOCIMETER BIAS ERRORS IN A TURBULENT FLOW.

It was suggested previously that a velocity bias might exist in measurements made with individual realization laser velocimetry (LV) systems. However, subsequent attempts by a number of investigators to experimentally verify the theory have produced conflicting results as to the magnitude and even the existence of this bias effect. In this paper, an experimental study using a signal processing technique which allowed velocity bias to be measured directly is described. The results clearly demonstate the effect of signal processing conditions on the magnitude of the velocity bias and suggest measns for eliminating it. The related problem of incomplete signal bias was also investigated.