NUMERICAL ANALYSIS OF A MULTIPLE JET IMPINGEMENT SYSTEM

Jet impingement is known to provide higher heat transfer coefficients as compared to other conventional modes of single phase heat transfer. Jet impingement has been a subject of research for a long time. Single jets have been studied extensively for their heat transfer and flow characteristics. However, for practical usage, multiple jets (in the form of arrays) have to be used for increasing the total heat transfer over a given area. Most of the research on multiple impinging jets have focused on evaluating heat transfer correlations for such arrays in the turbulent regime (Re >2500). The focus of the present paper is on experimental investigation of a large array of impinging jets in the low Reynolds number regime (<1000) and subsequently numerically modeling the same array by using existing Computational Fluid Dynamics tools in order to study the physical phenomena within such a complex system. Different turbulence models were used for modeling the fluid flow within these impinging jets and it was found that the SST k-omega model is the most suitable. Results obtained from CFD analysis are in reasonable agreement with experimental values. It was observed that CFD simulations over predicted the Nusselt number and pressure drop when compared to the experimentally obtained values. It was also observed that the decrease in Nusselt number along the streamwise direction of the array was not monotonic. This could be due to the complex flow field resulting from interaction between the crossflow and the impinging jets in the wall jet region. It is anticipated that results obtained from the present work will provide greater insight into the flow behavior and the heat transfer mechanism occurring in multiple impinging jets.