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Estimation of thermal load on the nozzle base plate from small plumes at high temperature

A numerical study is performed to estimate thermal load on the nozzle base plate, which is in the upstream direction to the flow, from three hot plumes of pure (CO2), (H2O) and 50-50 (%) composition of (CO2) and (H2O) expanding through a convergent-divergent (CD) nozzle in a quiescent medium at 1.1 bar pressure and 298K temperature. The base plate of the nozzle heats up due to thermal radiation, emitting from the hot gases in the form of plumes. The spectral radiative properties of major participating gases such as (CO2), (H2O) are calculated from HITEMP-2010 database. A small CD nozzle which is designed for the perfect expansion of air by 1D calculation with nozzle throat diameter 1.98 mm and area ratio 1.5942, is considered as the design of nozzle for present study [1]. All three plumes are in the under-expanded state for this CD nozzle and hence expands rapidly at supersonic speed as the plumes exit from the nozzle and forms a series of expansion and compression waves. The hot plumes emanating from the nozzle develop very high temperature in a small vicinity around the base plate, due to diffusion and develop very high temperature on the base plate. Barring this region, the maximum amount of radiative flux on base plate for these three plumes, i.e., CO2 plume, mixture plume and H2O plume are 4000 W/m2, 2300 W/m2 and 1300 W/m2, respectively and the maximum temperature developed due to these corresponding fluxes are 323 K, 312 K and 308 K, respectively.