RESUMO

A novel measurement method for local wall shear stress is proposed for the measurement in a high Reynolds number flow. The method utilizes the light interference created by a Fresnel's biprism. The biprism method can be applied to the flow where a conventional slit-type method can not be applied. In this paper, we propose two types of optical configurations for the biprism sensor. The principle is investigated with respect to the light interference and the measurement volume. The interference patterns created by the two types of configurations are calculated by electromagnetic theory. The results show the interference pattern created by the proposed configurations is not suitable for the local wall shear stress measurement. Considerations are required before the method is applied to the measurement in a flow.