Probe shapes for streamwise momentum and cross-stream turbulence intensity

Abstract

When the highly turbulent flowfields at the edges of jets, in augmentors, and in other jet-mixing devices are surveyed with conventional pitot probes, the values indicated by the instruments may contain a significant increment brought about by the dynamics of the eddies. Although the influence of turbulence on the measurements is usually negligible in streams where the turbulence level is 1% or less, the effect of turbulence on static and total pressure measurements can be around 20% when the turbulence level exceeds 40%. This paper describes a theoretical study that develops probe shapes that directly measure the time-averaged total pressure based on the streamwise component of the velocity vector to obtain a direct measurement of the streamwise momentum. The difference between the time-averaged pressure indicated by such a probe and one that measures the total head based on the entire velocity vector yields the cross-stream turbulence intensity. © 1991 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.