HEAT TRANSFER MECHANISM AND ASSOCIATED TURBULENCE STRUCTURE IN THE NEAR-WALL REGION OF A TURBULENT BOUNDARY LAYER.

Abstract

Heat transfer mechanism and associated turbulence structure in the near-wall region of a turbulent boundary layer have been investigated experimentally. With the aid of temperature-sensitive liquid crystal and hydrogen bubble method, the wall temperature fluctuation and the flow structure are visualized simultaneously to study directly the heat exchange between the fluid and the wall. The structure of the temperature field near the wall is further studied by the measurement of cross correlation of temperature fluctuations in the spanwise and streamwise directions. All of these experimental results show that the turbulent temperature field near the wall has a feature very much similar to the flow structure in the viscous wall region.