Faculty Publications
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Item Estimation of heat transfer coefficient and reference temperature in jet impingement using solution to inverse heat conduction problem(Pleiades journals, 2019) Kadam, A.R.; Hindasageri, V.; Kumar, G.N.The heat transfer estimation in case of impinging jets has been considered by mainly steady-state techniques. The present study reveals the transient technique to characterize the impinging jets. A solution to three-dimensional inverse heat conduction problem (IHCP) is used to estimate the unknown transient surface temperature distribution at the jet impinging side (front side) from known non-impingement side (backside) transient temperature distribution. Further to estimate front side heat flux distribution, the temperature gradient close to the front surface is computed by finite difference method, and then linearity between surface heat flux and corresponding surface temperature is utilized to find out heat transfer coefficient (HTC) and the reference temperature simultaneously. To validate and establish the present technique, numerical simulations are carried out in fluent. The numerically estimated back surface temperature data is used as input to the solution to IHCP. Hot as well as cold impinging jets are characterized with the help of this solution. Along with laminar jets, turbulent jets with varying Reynolds number are considered. The inversely estimated results are compared with numerically simulated data and match is within 1%. © Springer Nature Singapore Pte Ltd. 2019.Item Heat transfer distribution of premixed methane-air laminar flame jets impinging on ribbed surfaces(Elsevier Ltd, 2019) Kadam, A.R.; Parida, R.K.; Hindasageri, V.; Kumar, G.N.Heat transfer distribution of premixed methane-air laminar flame jet impinging on ribbed surfaces is presented in this work. Experiments are carried out on ribbed plates with three different geometrical shaped rib elements i.e. circular, rectangular and triangular. In addition, numerical simulations are performed to study flow field distribution near the ribs. During the experiments, Reynolds number is varied from 600 to 1800 and burner tip to target plate distance is varied from 2 to 4. An analytical inverse solution to three dimensional transient heat conduction presented in our previous work is used to obtain heat transfer parameters. Heat transfer coefficients are found lower whereas reference temperatures are observed higher on ribbed surfaces as compared with smooth surface. Obstruction to the flow, flow separation and decrease in momentum are the reasons attributed for lower heat transfer rate for ribbed surfaces. © 2019 Elsevier LtdItem Inverse estimation of heat transfer coefficient and reference temperature in jet impingement(American Society of Mechanical Engineers (ASME), 2020) Kadam, A.R.; Hindasageri, V.; Kumar, G.N.Applications of impinging jets are wide-ranging from cooling to heating in industrial as well as domestic field. Most of the reported heat transfer distribution data to and from impinging jets have been found from steady-state measurements. This study utilizes the solution to three-dimensional (3D) inverse heat conduction problem to estimate transient temperatures on the impingement side. Then, the temperature gradient is determined near the impingement wall (×0.01mm inside) with which transient heat flux is estimated on the impingement side. Instead of steady-state values, transient heat flux and corresponding wall temperatures are utilized in a thin foil technique to find out heat transfer coefficient and reference temperature simultaneously. The scope of the present technique is examined through its application to impinging jets with various configurations such as laminar jet, turbulent jet, hot jet, cold jet, and multiple jets. In all cases, estimations are reasonably close. The application of this inverse technique can be extended to any configuration of jet impingement irrespective of geometry of nozzle (circular/rectangular), the orientation of nozzle (orthogonal/inclined), the temperature of a jet (hot/cold), Reynolds numbers (laminar/turbulent), the nozzle-to-plate spacing (any Z/d), and roughness of the plate surface. The effect of plate thickness on the accuracy of the present technique is also studied. Up to 5mm thick plates can be used in impinging jet applications without worrying much on accuracy. The use of the present technique significantly reduces the experimental cost and time since it works on transient data of just a few seconds. © © 2020 by ASME.