Temperature and velocity characteristics of rotating turbulent boundary layers under non-isothermal conditions

Abstract

This paper describes an experimental investigation, by means of hot-wire anemometry, of the characteristics of velocity and temperature in a rotating turbulent boundary layer under isothermal and non-isothermal conditions. The ranges of experimental parameters are as follows: Reynolds number from 10 000 to 25 000, rotational speed from 0 to 150 rpm, and y+ from 1.8 to 100. The relative temperature difference is held constant at 0.1. Detailed velocity and temperature distributions in the boundary layer are measured in the rotating state, and a new criterion for boundary layer segmentation under rotation is proposed. The applicability of boundary layer theory under the rotating state is extended. The influence of Coriolis force and buoyancy on the velocity and temperature distributions in the turbulent boundary layers are analyzed. Coriolis force is found to play an important role in the behavior of the boundary layer under rotation, as it shifts the velocity and temperature boundary layers. Under isothermal conditions, such effects can be classified according to the dominant force: viscous, Coriolis, or inertial. Under non-isothermal conditions, buoyancy occurs. The buoyancy induced by the Coriolis force suppresses the effect of the Coriolis force, and the suppression effect increases with temperature difference. The variation of turbulent Prandtl number Prt under rotation is also obtained.