Determination of local heat transfer coefficients at the entrance region of streamlined bodies

Abstract

Prandtl’s two-layer model of the turbulent boundary layer is considered and the expression obtained through the use of the model is applied to calculate the heat transfer coefficient, calculations for which agree well with experimental data on mean values of the coefficients for various bodies. Determination of parameters of this expression is shown for the case of calculating local heat transfer coefficients in the entrance regions of the channels. The main parameters are dynamic velocity, dimensionless thickness of the boundary layer and dimensionless thickness of the viscous sublayer. Based on the power-law and logarithmic velocity profiles, expressions are obtained for calculating the dimensionless parameters of the turbulent boundary layer. A satisfactory agreement of the results of calculations of loc al heat transfer coefficients for the flow over a flat plate and the pipe flow is shown. The presented approach represents a theoretical basis for modeling the local heat transfer for bodies of more complex shapes, if the friction coefficients are known.

Keywords

• local heat transfer
• boundary layer
• turbulence
• entry region