ME Seminar: Treatment of Radiation in Hypersonic Plasma
On Nov. 16, 2012 Mechanical Engineering Department is conducting a seminar. Details are given below. All interested are invited to attend.
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Title: Treatment of Radiation in Hypersonic Plasma
Speaker: Dr. Ankit Bansal
Assistant Professor
School of Engineering
IIT Mandi
Himachal Pradesh
Date : Friday, November 16, 2012
Time : 5:15 P.M.
Venue : FB-364(ME seminar room)
Tea will be served at 5:00 p.m.
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Title:
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Treatment of Radiation in Hypersonic Plasma
Abstract:
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Prediction of nonequilibrium radiation field in plasmas around a spacecraft requires accurate spectroscopic data, efficient and accurate spectral models and databases, and radiative heat transfer model around the spacecraft. The most accurate simulation of radiative transport in the shock layer requires calculating the gas properties at a large number of wavelengths and solving the Radiative Transfer Equation (RTE) in a line-by-line (LBL) fashion over a three dimensional grid, which is prohibitively expensive for coupled simulations. k-distribution based spectral models allow efficient evaluation of radiative properties and heat loads in hypersonic shock layer plasmas. Owing to significant differences in radiation characteristics of atomic and molecular species, k-distribution models are developed separately for atomic and molecular species. There are a number of practical applications, however, where both atomic and molecular species are present; for example, the vacuum-ultra-violet spectrum in Earth’s reentry conditions is marked by emission from atomic bound-bound lines and continuum and simultaneous absorption by strong bands of N2. For such cases, a new model is developed for the treatment of gas mixtures.
Full-spectrum k-distribution method provides generally very accurate results compared to those obtained from the line-by-line method. For more extreme gradients in species concentrations and temperature, full-spectrum k-distribution model is refined by dividing the spectrum into a number of groups or scales, leading to the development of multi-scale models. To utilize the full potential of the k-distribution methods, pre-calculated values of k-distributions are stored in databases, which can later be interpolated at local flow conditions.
New spectral models and databases are applied to solve the radiative transfer equation along typical one-dimensional flow fields in Earth’s, Titan’s and Mars’ atmospheres. The k-distribution methods are vastly more efficient than the line-by-line method, showing typical reduction in computational time by a factor of more than 500 for property evaluation and a factor of about 12,000 for the solution of the RTE.
The new spectral models are assembled within OpenFOAM (an Open Source CFD code) to simulate coupled hypersonic flow–radiation over a reentry vehicle. The radiative transport is solved with the one-dimensional tangent slab and P1 solvers, and also with the two-dimensional P1 solver.
Results for uncoupled and coupled flow–radiation simulations are analyzed to study the effects of radiative cooling on flow field and wall fluxes.
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Brief Bio:
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Dr. Ankit Bansal obtained his B. Tech from IT BHU and, MS and doctoral degree from Penn State University. Dr. Bansal’s research interests are radiative heat transfer, hypersonic flows, flow-radiation interaction, spectral modeling of gas properties, solar energy, climate change and disease dynamics, and hydrology. In the past Dr. Bansal has worked with DRDO in Advanced Systems Laboratory at Hyderabad. He is recipient of BHU Gold Medal for achieving overall rank-1 in mechanical engineering and is a member of AIAA.