SKIN FRICTION MEASUREMENT IN TURBULENT BOUNDARY LAYER BY MEAN VELOCITY PROFILE METHOD
FAN Xing JIANG Nan(Department of Mechanics, Tianjin University,Tianjin 300072, China)
On the basis of finely measured logarithmic mean-velocity profile in the near wall region of turbulent boundary layer over a flat plate in a wind tunnel using hot-wire anemometer of model IFA-300, we calculate the skin friction velocity according to the relationship between inner-scale physical parameters of logarithmic mean-velocity profile in the near wall region of turbulent boundary layer, such as mean velocity, skin friction velocity and fluid dynamics viscosity, and the relationship between skin friction velocity and skin friction drag. The skin friction measurement in a turbulent boundary layer is achieved by non-perturbed or micro-perturbed technique using logarithmic mean-velocity profile method. The present experimental method is simple, cheap and precise and without the need to use any complex equipment, such as sensors or balance, and to damage the surface of the plate. What is more, the original flow condition in the near wall region of turbulent boundary layer is not disturbed. With its high automatic level and reliable experiment results, the mean-velocity profile method enjoys high efficiency and precision, for the measurement of skin friction drag-in turbulent boundary layer.