Faculty Publications

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Author: search.filters.author.Hindasageri, V.Has files: No

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    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.
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    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.
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    A numerical study on heat transfer characteristics of two-dimensional film cooling
    (Pleiades journals, 2019) Ademane, V.G.; Hindasageri, V.; Kadoli, R.
    Determination of reference temperature and heat transfer coefficient in case of three temperature problems such as film cooling is one of the fundamental tasks in the design of gas turbines. In the present work, a two-dimensional numerical simulation is carried out for flat surface with 35° angle of injection from slot in case of film cooling problem. The reference temperature, which is represented as film cooling effectiveness, and heat transfer coefficient on the flat surface for different blowing ratio are studied. Heat transfer coefficient obtained from the present simulation is compared with the experimental results from the literature and found to be matching at lower blowing ratios. Turbulence intensity is found to a major contributor in enhancing the heat transfer coefficient. There is an increase in heat transfer with the blowing ratio due to increased turbulence intensity is observed. © Springer Nature Singapore Pte Ltd. 2019.
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    Transient heat transfer characterization of impinging hot / cold jets by analytical IHCP
    (Institute of Physics Publishing helen.craven@iop.org, 2018) Kadam, A.R.; Hindasageri, V.; Kumar, G.N.
    Unknown transient surface temperature and heat flux distribution at the impingement side (front side) is estimated from known temperature distribution at non-impingement side (back side) using analytical solution to three dimensional inverse heat conduction problem (IHCP). Back side input temperature data are obtained by running forward code in Fluent. Hot as well as cold impinging jets are characterized with the help of this solution. Laminar and turbulent jets at nozzle to plate spacing (Z/d) equal to 4 are considered. Hot gas at temperature 500 K and 3000 K is impinged on a 1 mm flat plate which considered initially at temperature 300 K in case of heating application. Whereas in cooling application, flat plate is initially assumed at temperature 673 K and isothermal air jet at 293 K is impinged on it. The temperature and heat flux estimation data by present technique is in very good agreement with the simulation data. © Published under licence by IOP Publishing Ltd.
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    CFD investigation of unsteady three-dimensional savonius hydrokinetic turbine in irrigation channel with varying positions for hydro power application
    (American Institute of Physics Inc., 2021) Shashikumar, S.; Hindasageri, V.; Madav, M.
    Savonius turbines are a drag driven device, and it has high starting torque. It is a vertical axis turbine and installed in small irrigation channels to utilize the hydrokinetic energy available. Since the density of water is more and the flow of water in the channel is constrained to one direction is the advantage for a vertical axis turbine as it reduces the yaw control mechanism. In the present work, a three-dimensional conventional Savonius turbine modeled and meshed in ANSYS Fluent and unsteady transient simulations are carried out using a sliding mesh technique. The computational simulations were carried out at three different positions to analyze the effect of placing a turbine blade in the high depth of water using a conventional Savonius turbine blade with an aspect ratio of 0.7 and 0.0 overlap ratio. The turbulence model used for CFD simulation is the k-ω SST model, and the results found that the maximum coefficient of torque and coefficient of power of 0.22 and 0.17 at a tip speed ratio of 0.7 and 0.9 respectively. © 2021 Author(s).
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    Study on performance of Savonius rotor type wave energy converter used in conjunction conventional rubble mound breakwater
    (Elsevier Ltd, 2014) Bikas, G.S.; Ramesh, H.; Hindasageri, V.
    In the present study the performance characteristics of a wave energy converter used in conjunction with conventional rubble mound breakwater is investigated using physical model studies. Savonius rotor type converter is used in the present study. The rotor is placed in front of the breakwater towards seaward side can cause substantial wave attenuation and thereby reduce the impact on the breakwaters apart from generating electricity. Regular waves of wide ranging heights and periods are considered in the present study. Tests are carried out for different spacing between the breakwater and the wave energy converter (X/d=10 to 40) and for two depth cases viz. shaft of the rotor at SWL (z=0) and rotor fully submerged case (z=-55 mm). The dead weight loading (shaft power) capacity for the rotor is also optimised in the present study. From the experimental study, it is observed that at a distance of X/d=22.5 to 30 and for submerged case (z=-55 mm) the rotor is found to be most efficient. It results in a wave height attenuation of 15-33%. © 2014 Elsevier Ltd.
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    Effect of preheated mixture on heat transfer characteristics of impinging methane-air premixed flame jet
    (Elsevier Ltd, 2015) Tajik, A.R.; Kuntikana, P.; Prabhu, S.V.; Hindasageri, V.
    Energy from spent flame or other low grade energy can be used to increase the temperature of the air before mixing with fuel. This would improve the heat transfer characteristics of the impinging flame jet. The studies on impinging flame jets reported in the literature are based on the fuel-air mixture at ambient temperature. In the present work, the inlet air for mixture is heated by an electrical heater. The heat flux distribution is estimated using an inverse heat conduction (IHCP) technique. The Nusselt number (Nu) and effectiveness (?) distributions are obtained by estimating the adiabatic wall temperature (Taw) by the analytical-numerical method. A circular burner of 13.5 mm is used for impingement on quartz plate of 3 mm thickness. Reynolds number (Re) varying from 500 to 2000 for the non-dimensional burner tip to impingement plate spacing (Z/d) of 2-6 and stoichiometric condition (Ø = 1.0) is considered for varying preheated condition. The effect of equivalence ratio is studied for Ø = 0.75 to 1.5 for Re = 1000 and Z/d = 4. By increase in preheat temperature, the stagnation point heat flux increases from 20% to 50% unless the inner premixed zone touches the impingement plate. CFD simulations are carried out in FLUENT software to explain the distribution of heat flux. © 2015 Elsevier Ltd. All rights reserved.
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    A numerical investigation on heat transfer and emissions characteristics of impinging radial jet reattachment combustion (RJRC) flame
    (Elsevier Ltd, 2015) Tajik, A.R.; Hindasageri, V.
    Radial Jet Reattachment combustion (RJRC) flame jet is used in applications where the impingement surface is delicate and demands low impingement pressure. In the present study, a two dimensional axisymmetric computational fluid dynamics (CFD) simulation is carried out. The turbulence-combustion interaction in the flame field is modeled in a k-?/EDM framework. The distribution of heat flux, pressure coefficient and emissions is presented for varying Reynolds number (Re = 1000 to 30,000) and different non-dimensional nozzle tip to plate spacing (X/R = 0.5 to 3). It is found that the peak heat flux increases and pressure coefficient reduces significantly with the increase in Reynolds number. However, with the increase in the nozzle tip to plate spacing the peak heat flux and the pressure coefficient decrease. Furthermore, the concentrations of NOx and CO emissions increase with the increase in Reynolds number and the distance of the location of the nozzle tip from the impingement plate. © 2015 Elsevier Ltd. All rights reserved.
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    Heat transfer distribution of impinging flame and air jets - A comparative study
    (Elsevier Ltd, 2016) Kadam, A.R.; Tajik, A.R.; Hindasageri, V.
    Heat transfer distribution of impinging flame jet is compared with that of the impinging air jet based on the experimental data reported in literature for methane-air flame jet and air jet impingement for Reynolds number, R=600-1400 and the non-dimensional nozzle tip to impingement plate distance, Z/d=2-6. The comparative data based on mapping experimental data reported in literature suggest that there is a good agreement between the Nusselt numbers for higher Z/d near stagnation region. However, away from the stagnation region, the Nusselt number for flame jet is higher than that of air jet for similar operating conditions of Re and Z/d. A CFD simulation for impinging air jet and impinging flame jet is carried out to explain the physics and reason for the deviations observed in experimental data. A scale analysis is carried out to identify the dominant forces and their influence on the heat transfer distribution on the impingement plate. © 2015 Elsevier Ltd. All rights reserved.
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    Axis switching in impinging premixed methane-air flame jets
    (Elsevier Ltd, 2016) Hindasageri, V.; Kuntikana, P.; Tajik, A.R.; Vedula, R.P.; Prabhu, S.V.
    Axis switching in non-circular tube burner flame jets is studied. Experimental data of heat flux is obtained for square and rectangular burners of different aspect ratios: 1, 1.55, 2.1 and 3.73. A three dimensional CFD simulation is carried out to explain the phenomenon of axis switching in premixed flame jets. From the CFD simulations it is observed that the vortices formed near the corner of the tube exit are responsible for the axis switching phenomenon. These vortices control the spreading (in a preferential manner) of the flame jet along the tube axis. This preferential spreading of the flame jet is responsible for switching of contours of heat flux on the impingement plate. Furthermore, for the rectangular burner, elliptical lobes of heat flux distribution on the impingement plate are observed and this is again attributed to vortex structures. © 2016 Elsevier Ltd