Error in hot-wire X-probe measurements induced by unsteady velocity gradients

Authors: Fransson, J. H. M., Westin, K.J.A.
Document Type: Article
Pubstate: Published
Journal: Expriments in Fluids
Volume: 32   413-415
Year: 2002


Errors in hot-wire X-probe measurements due to unsteady velocity gradients are investigated by a comparison of hot-wire and LDV-measurements (Laser Doppler Velocimetry). The studied flow case is a laminar boundary layer subjected to high levels of free stream turbulence, and the hot-wire data shows a local maximum in the wall-normal fluctuation velocity inside the boundary layer. The observed maximum is in agreement with existing hot-wire data, but in conflict with the present LDV-measurements as well as existing results from numerical simulations. An explanation to the measurement error is suggested in the paper.