Uniform Cooling of a Flat Surface by an Optimized Array of Turbulent Impinging Air Jets

Abstract

The aim of this study is to investigate the uniform cooling of a hot isothermal heated target surface, using four turbulent impinging air jets. Eight parameters including the width of jets, the space between the inner jets, the space between inner and outer jets, the distance of jets from the plate, the impingement angle of jets, and the overall volumetric flow rate of the cooling air per unit depth of the nozzle are considered as design variables. The normalized standard deviation of the local Nusselt number from the desired Nusselt number is considered as the objective function. An optimization algorithm based on pattern search method is utilized to obtain the optimum array of the jets. Two different scenarios of the problem are considered, one with fixed normal impingement angles and the other with the optimized angles. Results show an almost uniform distribution of the local Nusselt number. Increasing the amount of desired Nusselt number for the case with fixed impinging angles results in a higher Reynolds number, a wider opening for outer jets and a reduction in jet to jet and jet to surface distances. However, changes in design parameters for the case with optimum impinging angles are erratic.

Funding

The authors would like to express their gratitude to Iran National Science Foundation (INSF) for their partial financial support via grant number 94/SAD/44313.

Notes on contributors

Erfan Sedighi is a M.Sc. student at Sharif University of Technology, Iran. He received his B.Sc. degree in Mechanical Engineering in 2015 from Shiraz University, Iran. His research interests include solar energy, two-phase heat transfer enhancement, computational fluid dynamics, and optimization techniques.

Ali Mazloom is a M.Sc. student at Sharif University of Technology, Iran. He received his B.Sc. degree in Mechanical Engineering in 2015 from Tehran University, Iran. His research interests include solar energy, computational fluid dynamics, and optimization techniques.

Ali Hakkaki-Fard is an assistant professor of the school of mechanical engineering at the Sharif University of Technology. He is also the head of the Renewable and Sustainable Energy Systems lab and member of the research chair of the novel energy systems at Sharif University of Technology. He received his Ph.D. from McGill University, Montreal, Canada, in 2011. He then joined CanmetENERGY as a postdoctoral researcher and then as a research scientist until Dec. 2015. He joined Sharif University of Technology in Dec. 2015. His research interests includes renewable energies, optimization of thermal systems, and inverse heat transfer.

Additional information

Funding

The authors would like to express their gratitude to Iran National Science Foundation (INSF) for their partial financial support via grant number 94/SAD/44313.