Heat Transfer on a Hypersonic Sphere with Diffuse Rarefied-Gas Injection

Abstract

The interaction of a diffusing outgas flow from a sphere nose opposing a hypersonic free stream is studied numerically by the direct simulation Monte-Carlo technique under the transitional rarefied-gas-flow regime conditions at Knudsen numbers from 0.016 to 1.5 and blowing factors from 0.15 to 1.5. Strong influences of the blowing factor (the ratio of outgas mass flux to upstream mass flux) and the Knudsen number on the flow structure about a sphere (temperature fields, the configuration of mixing flow zones) and on heat distributions along the spherical surface have been found. At large blowing factors, the injected gas significantly reduces heat flux in wide area near the spherical nose. This effect is more pronounced for light gas (helium) injection in the near-continuum flow. Nomenclature d = orifice diameter, 0.002 m f = mole fraction of helium G w = mass injection rate ratio ("blowing" factor) Kn ∞,R = Knudsen number M = Mach number p = pressure, N/m 2 R = sphere radius, 0.015 m Re 0,R = Reynolds number St = Stanton number s = coordinate along a spherical surface T = temperature t w = temperature factor, T w /T 0 x = coordinate along an axis of body symmetry subscripts R = sphere radius as a length-scale parameter w = wall condition 0 = stagnation flow condition ∞ = freestream parameter

Simulation of effects of the MHD-interaction of bodies with the Earth’s atmosphere in a rarified plasma flow

“…Для сферы зависимость (Kn M ) [36], темные треугольники -результаты измерений [12] в сверхзвуковом потоке воздуха при 2 ≤ ≤ M n ≤ 6, квадраты -данные [13] для воздуха при 2 ≤ ≤ M n ≤ 8, крестики -данные [9], кружки -данные [37] для M n ≈ 6.5, кривая 2 -аппроксимация (4) авторов для сверхзвуковых потоков…”