Numerical Investigation of Confined Multiple-Jet Impingement Cooling Over A Flat Plate at Different Crossflow Orientaions

Abstract

This study investigates the fluid flow and heat transfer characteristics of round jet arrays impinging orthogonally on a flat-plate with confined walls at different crossflow orientations. A computational fluid dynamic technique based on a control volume method is used to compute the detailed Nusselt number distributions on the flat plate. This is achieved by solving the steady-state three-dimensional incompressible Reynolds-averaged Navier-Stoke's equations. The Reynolds stress turbulence quantities are determined by a realizable κ-ε turbulence model with an enhancement near-wall treatment. Numerical computations are performed for two types of arrangements in round jet arrays, both inline and staggered, and three different crossflow directions, parallel, hybrid, and counter. The jet Reynolds numbers ranging from 2,440 to 14,640 and three different jet-to-plate spacing ratios (Zn/d_j) of 1, 3, and 6 are investigated in this study. Results show that the flow exit crossflow direction would significantly affect the developing jet flow fields and Nusselt number distributions on the target flat-plate. Area-averaged Nusselt number increases with an increase of jet Reynolds number. Of all the cases tested, the highest average Nusselt numbers were obtained for the case with inline jets and hybrid crossflow orientation. The thermal performance of impingement multiple jets is enhanced when the value of Zn/d_j decreases from 6 to 3. Results show that further reducing the value of Zn/d_j to 1 creates a significant nonuniform distribution in local Nusselt number over the target plate regardless of the crossflow orientations. This study also provides a correlation of the area-averaged Nusselt number with the jet Reynolds number for both inline and staggered jet arrays.

Financial support for this work from NSC of Taiwan under contract NSC 93–2212-E-014–010 is deeply appreciated.

Notes

Unit: Pa.