Abstract
Applicability of law of the wall to turbulent boundary layers under favorable pressure gradient has been studied using direct measurement of the wall shear stress. The effect of lip pressure that would produce extra force acting on a floating element of the direct measurement has been investigated for improving reliability of measured wall shear stress. The experimental results suggest that the lip pressure is unable to be ignored in the direct measurement. The logarithmic mean velocity profile using friction velocity determined by the direct measurement is disagreed with the standard log-law. The favorable pressure gradient reduces magnitude of the streamwise turbulent intensity normalized with the friction velocity compared with that of zero pressure gradient.
