Local Heat Transfer of a Smooth Flat Plate Impinged by Multiple Jets

Abstract

A smooth flat plate impinged by multiple jets is investigated for the local heat transfer using a thermal imaging technique. An inline arrangement of circular jets with all side exit scheme is implemented. Jets are introduced from a 4 mm thick orifice plate. The jet diameter is 3 mm. Reynolds numbers (based on the jet diameter) range covered in this study are from 500 to 15,000. The variation of the local, spanwise average, and overall average Nusselt numbers is investigated for nozzle exit to targeted plate spacing of 0.5 d–6 d, where d is the jet diameter. A periodic pattern is witnessed in the local Nusselt number with a drop in its amplitude in the spanwise direction. For a given Reynolds number, the local and average Nusselt numbers are influenced by nozzle exit to targeted plate spacing. The influence of Reynolds number on the local and average Nusselt number is captured using ${\mathit{\text{Re}}}^n.$ The value of $n$ is found to be 0.5 and 0.6 depending on the Reynolds number range. In comparison with a single jet, multiple jet impingement on a smooth flat plate deteriorates the local Nusselt number. A semi-empirical correlation that captures the periodic nature of local and average Nusselt numbers is suggested.

Acknowledgments

The authors acknowledge the efforts put in by Mr. Rahul Shirsat in building the experimental setup and fixing the mechanical problems during the experiments.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Ketan Yogi

Ketan Yogi is a postdoctoral research fellow in the Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, India. He received his Ph.D. degree from the Indian Institute of Technology Bombay in 2022. His research interests are experimental heat and fluid flow, jet impingement, porous media, gas turbine blade cooling, and electronics cooling.

Shankar Krishnan

Shankar Krishnan received a Ph.D. degree from Purdue University, West Lafayette, USA, in 2006. He is currently an Associate Professor of mechanical engineering, at the Indian Institute of Technology, Bombay, Mumbai, India. His current research interests include heat transfer with applications to the thermal management of electronics, internal combustion engines, and nontraditional thermal desalination techniques.

Siddini V. Prabhu

Siddini V. Prabhu earned his Ph.D. in the field of gas turbine blade cooling from the Indian Institute of Technology, Bombay, India. He is presently a professor in the Department of Mechanical Engineering at the Indian Institute of Technology, Bombay. His research interests include fire dynamics, jet impingement, premixed flames, wind turbines, hydrokinetic turbines, flow metering, two-phase flows, gas turbine blade cooling, and porous medium.