Faculty Publications
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Item Simultaneous estimation of heat transfer coefficient and reference temperature from impinging flame jets(Elsevier Masson SAS 62 rue Camille Desmoulins Issy les Moulineaux Cedex 92442, 2018) Kadam, A.R.; Prabhu, S.V.; Hindasageri, V.Heat transfer from impinging flame jets to a flat plate has been assumed to be one-dimensional in most of the investigations and without radiation loss treatment. In the present work, the exact nature of diffusion of heat in the plate is investigated via solution to multidimensional heat conduction problem. Two procedures have been employed – Duhamel theorem and three dimensional transient analytical IHCP. The Duhamel theorem which is analytical model for transient one dimensional heat conduction is applied but its application failed the check of linearity requirement of the convection rate equation. From the solution by analytical IHCP for transient, three-dimensional heat conduction, the distribution of wall heat flux and the wall temperature is perfectly linear. This check confirmed that three dimensional approach has to be used. Experimental data is then analyzed by the three dimensional analytical IHCP for short and larger time intervals. It is found that for short time data, heat transfer coefficient and the reference temperature have oscillatory distribution along the radial direction on the impingement plate and for larger time data the oscillations die out. However, at larger time, radiation loss from the impingement plate becomes significant. The effect of variations in thermal conductivity of the impingement plate with the temperature on heat transfer coefficient and reference temperature is discussed. A novel method is developed to correct the heat transfer coefficient and reference temperature to incorporate radiation losses. The deviation in heat transfer coefficient and reference temperature estimated without considering variable thermal conductivity and radiation loss for large time interval is upto 50%. © 2018 Elsevier Masson SASItem 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.