Faculty Publications
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Item Application of green’s function to establish a technique in predicting jet impingement convective heat transfer rate from transient temperature measurements(Pleiades journals, 2019) Parida, R.K.; Kadam, A.R.; Hindasageri, V.; Madav, V.Jet impingement heat transfer has gained attention of the researchers due to its very high rate of convective heat transfer. The objective of this study is to establish an analytical technique to predict the convective heat transfer coefficient and the reference temperature over a surface being impinged. This technique is based on the fundamental mathematical concept of Green’s function. A code in MATLAB is developed to predict both local convective heat transfer coefficient and reference temperature over the impinging surface, which requires the transient temperature data at both faces of the impinging plate as input. Radiation correction is also considered to incorporate radiation losses in high-temperature applications. This code works on the principle of one-dimensional heat transfer across the impinging plate, for known dimensions, thermal diffusivity, and surface emissivity. A numerical simulation of hot jet at Reynolds number equal to 1000, over a cold plate of thickness 10 mm, is carried out for a given set of spatially varying convective heat transfer coefficient and reference temperature values, along the impinging surface. The impinging plate is considered to be orthotropic to ensure one-dimensional heat conduction across the plate thickness. Transient temperature at both the faces for a duration of 10 s with an interval of one second was recorded and used as input to the code to validate the proposed technique. Local heat transfer coefficient and the reference temperature predicted are in good agreement with those input values for numerical analysis using ANSYS, having a maximum deviation of 2 and 10%, respectively. Further, it is observed that estimated values of convective heat flux at a given location on the impinging surface varies linearly with temperature at the same location, which confirms Newton’s law of cooling. © Springer Nature Singapore Pte Ltd. 2019.Item Heat transfer characterisation of impinging flame jet over a wedge(Elsevier Ltd, 2021) Parida, R.K.; Kadam, A.R.; Madav, V.; Hindasageri, V.This paper aims to estimate two unknown parameters - Nusselt number and effectiveness – analytically and study the heat transfer characteristics of impinging flame jet over a wedge-shaped structure similar to a missile deflector plate. Experimentally obtained raw transient temperature history at the non-impinging face of a 4-mm-thick test object made of stainless steel is the only input data. An analytical Inverse Heat Conduction Technique based on Green's Function Approach is employed to estimate both parameters simultaneously. Multiple experimental cases are considered in this work by varying methane-air gas mixture Reynolds number (800, 1000, 1200, and 1500), non-dimensional nozzle tip to test object distance (2, 4, and 6), and wedge-angle (90° and 120°). The observations concerning heat transfer characteristics of the impinging flame jet are discussed in detail. The flame jet's heating effect has been observed to improve as the wedge angle is increased from 90° to 120°. Uncertainty of the estimated parameters is evaluated using the Monte Carlo technique. © 2021