Hot-wire experimental investigation on turbulent Prandtl number in a rotating non-isothermal turbulent boundary layer

Ran Gao ^a, Haiwang Li ^b,c, Ruquan You ^b,c,*, Gangfu Li ^b,*, Shuangzhi Xia ^d

a.Department of Mechanical Engineering, The University of Melbourne, VIC 3010, Australia
         b.National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics, School of Energy and Power Engineering, Beihang University, Beijing, 100191, China
         c.Research Institute of Aero-Engine, Beihang University, Beijing, 102206, China
         d.New Era Engineering Consulting Co., Ltd, Beijing, 100088, China

Abstract: This experiment used a parallel array of hot wire probes to simultaneously measure the temperature and velocity fields in the non-isothermal turbulent boundary layer of a rotating straight channel. The Reynolds numbers are 15000 and 25000, respectively. The rotation numbers are 0, 0.07, 0.14, 0.21 and 0.28, respectively. The purpose of this study is to calculate the turbulent Prandtl number in a rotating non-isothermal turbulent boundary layer. Due to the difficulty in measuring local turbulent Prandtl numbers, this study focuses on the average turbulent Prandtl numbers in the logarithmic region instead. Under static conditions, this value is taken as 0.9 normally. This research finds that rotation conditions can affect the turbulent Prandtl number by affecting the properties of velocity and temperature boundary layers. The change range of the turbulent Prandtl number is roughly 0.6-1.1. The influence of the leading side is greater than that of the trailing side, especially at high rotation numbers. This can provide validation and guidance for numerical simulation. Other information within the turbulent boundary layer is also discussed. It is hoped that this study would enhance our understanding of the mechanism of turbulent flow in the turbulent layer at rotating conditions.

Key words: Hot-wire; Boundary layer flow; Experiment work; Rotating conditions