Session: Raymond Viskanta Memorial Symposium-06: Thermal Management and Phase Change

Paper Number: 108428

108428 - Advances in Impingement Heat Transfer- a Review and Some Recent Results 

Impingement heat transfer is commonly used in a variety of cooling applications such as electronic cooling, turbine component cooling and others. High heat transfer coefficients are obtained in the vicinity of the impingement zone, but these decay radially on the heated surface due to boundary layer development. In-line or staggered impingement jets are commonly used, and the surface heat transfer rates have been shown to depend on the jet-geometrical parameters such as the jet-to-jet spacing and jet-to-surface distance as well as Reynolds number, Prandtl number and other factors such as jet swirl, nozzle shape etc. In this presentation, we will review the extensive body of the single-phase jet-impingement literature with the goal of summarizing the key effects.

We will also present some recent experimental work from our laboratory on approaches to enhance the jet impingement heat transfer. In particular, we will present four approaches to this end that we have investigated. These include: (a) the use of return-holes in the impingement-jet nozzle plate to disrupt the crossflow and the growing boundary layer between jets (b) the use of a fractal grid (with varying fractal dimensions) downstream of the jet nozzle plate to alter the large-scale jet-flow features and the surface heat transfer (c) the role of annular micro-jets around the primary-jet on the surface heat transfer and (d) the role of passive-nozzle modifications (such as swirl trips or radial/axial trips) on the surface heat transfer. While (a) and (b) above have been explored using jet-arrays and utilizing a transient-liquid crystal based approach, studies for (c) and (d) have been done with single jets using a steady-state infra-red imaging method. Nevertheless, some generalized conclusions are drawn on the enhancements obtained with these approaches. 

Presenting Author: Sumanta Acharya Illinois Institute of Technology