Numerical investigations of heat transfer and pressure drop characteristics in multiple jet impingement system

Jet impingement is one of the best methods for achieving high heat transfer coefficient in single phase and has been a topic of active research for several decades, involving both experiments and computations. Most of the research on multiple jets have been carried out for an array of jets in the high Reynolds number regime. To increase the application of jet impingement in micro turbines, cooling of electronic chips, etc., the current paper discusses the physics of impinging jets in large array in low Reynolds number regime. Furthermore, the pressure drop incurred in impinging jets has not been addressed in the open literature and the current paper provides some vital insights into the pressure drop characteristics. Numerical simulations are carried out on an array of impinging jets using various approaches such as Reynolds averaged Navier-Stokes (RANS) and Large Eddy Simulations (LES). The results obtained from these simulations are validated with the experimental results. LES simulations have been carried out to get a better understanding of the flow physics in multiple jet impingement array. The simulations show that the major pressure loss in the system is due to contraction effect at the nozzle entrance and due to viscous losses. Furthermore, simulations have been carried out to establish the sensitivity of the pressure drop and heat transfer characteristics to the manufacturing tolerances expected in practical engineering applications of these jet arrays. (C) 2016 Elsevier Ltd. All rights reserved.