Heat transfer and friction factor in a dimple-pin fin wedge duct with various dimple depth and converging angle
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 1 August 2016
Abstract
Purpose
The dimple is adopted into a pin fin wedge duct which is widely used in modern gas turbine vane cooling structure trailing edge region. The purpose of this paper is to study the effects of dimple depth and duct converging angle on the endwall heat transfer and friction factor in this pin fin wedge duct.
Design/methodology/approach
The study is carried out by using the numerical simulations. The diameter of dimples is the same as the pin fin diameter with an inline manner arrangement in relation to the pin fin. The ratio between dimple depth and dimple diameter is varied from 0 to 0.3 and the converging angle is ranging from 0° to 12.7°. The Reynolds number is between 10,000 and 50,000. Results of the endwall Nusselt number, friction factor, and flow structures are included. For convenience of comparison, the pin fin wedge duct with a converging angle of 12.7° without dimples is considered as the baseline.
Findings
It is found that the dimples can effectively enhance the endwall heat transfer due to the impingement on the dimple surface, reattachment downstream the dimple and recirculation in front of the pin fin leading edge. By increasing the converging angle, the heat transfer is also increased but with a large friction factor penalty. In addition, the heat transfer enhancement for deep depth cases is 1.57 times higher than that of the low depth case. The thermal performance indicates that the intensity of heat transfer enhancement depends upon the dimple depth and converging angle.
Originality/value
It suggests that the endwall heat transfer in a pin fin wedge duct can be increase by the adoption of dimples. The optimal dimple relative depth is 0.2 with low friction factor and high heat transfer performance.
Keywords
Acknowledgements
The authors acknowledge the financial support provided by the Swedish Energy Agency, and the China Scholarship Council (CSC).
Citation
Luo, L., Wang, C., Wang, L., Sunden, B.A. and Wang, S. (2016), "Heat transfer and friction factor in a dimple-pin fin wedge duct with various dimple depth and converging angle", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 26 No. 6, pp. 1954-1974. https://doi.org/10.1108/HFF-02-2015-0043
Publisher
:Emerald Group Publishing Limited
Copyright © 2016, Emerald Group Publishing Limited