Momentum and Heat Transfer Studies. I. Transfer of Heat and Momentum in Uniform Turbulent Air Streams. II. Continuous Velocity Measurements by the Hot Wire Method

Citation

Sherwin, Robert Mitchell (1952) Momentum and Heat Transfer Studies. I. Transfer of Heat and Momentum in Uniform Turbulent Air Streams. II. Continuous Velocity Measurements by the Hot Wire Method. Engineer's thesis, California Institute of Technology. doi:10.7907/HJ09-KX96. https://resolver.caltech.edu/CaltechTHESIS:10132017-134354937

Abstract

Part I

The thermal flux has been measured across an air stream flowing in a uniform, two-dimensional manner between horizontal parallel plates at different temperatures. Reynolds numbers ranged from 9,800 to 56,500. A macroscopic correlation shows the effect of turbulence on the thermal transfer.

A revised correlation of total conductivity as a function of position is subsequently obtained by correcting previously deter­mined values of total conductivity. A similar correlation of the total viscosity with position is revised to allow for variation in the pressure gradient with plate separation. The correlations fall off with increasing Reynolds number. The turbulent Prandtl numbers for two tests by an earlier investigator are compared with those predicted from the ratio of the revised point correlations.

Part II

Two hot-wire methods are described for determining continuously the mean velocity as a function of position in a turbulently-flowing air stream. In the constant-resistance method the mean wire temperature is automatically controlled. In the constant-current method no control is necessary. In exploratory measurements the total viscosities bridge the discontinuous gap which arises from the use of von Kármán's expression at the boundary between the buffer layer and the turbulent core. Thermal flux corresponding to a Nusselt number of 40 has no noticeable effect on the velocity profile.

Thesis Files