Evaluation of a film-based wall shear stress measurement technique in a turbulent channel flow

Mean wall shear stress in a turbulent channel flow has been measured using a film-based shear stress sensor with a working principle based on the deformation of a thin elastic film. A direct comparison was made between the elastic film measurements and those using oil-film interferometry in the same experimental facility to evaluate the capability of the novel technique to measure the mean wall shear stress. The results indicate that the film-based sensor measures the wall shear stress within the uncertainty of the oil film measurement for the range of Reynolds numbers considered here, i.e. 2100-2900 based on the friction velocity and the half channel height.