Real-time hot-wire measurements in three-dimensional flows.

A real-time hot-wire method has been developed to make measurements in three-dimensional turbulent flow fields where the fluctuations are high and flow direction is unknown (w ithin limits). An analog device has been built to obtain the three instantaneous real velocity components in laboratory coordinates in real time. The components are then processed to obtain the mean velocity components and six Reynolds stresses. Extensive qualification tests were made in a 2-D channel flow. The method has been shown to be quite fast and therefore practical for acquisition of large amounts of data in three-dimensional turbulent flows. (A)