Effect of Fence on Linear Aerospike Plume-Induced Base-Heating Physics

Abstract

A computational heat transfer analysis is conducted to study the effect of the presence of an engine fence on the X-33 linear aerospike plume-induced base heating during vehicle ascent. A fence is an extension of the plug side wall that reduces the plume spillage. A detailed three-dimensional thermo ow eld of the entire vehicle is computed such that an accurate freestream ow environment is assured for the base-ow development. The computational methodology is based on a nite difference, viscous ow, chemically reacting, pressure-based computational uid dynamics formulation and a nite volume, spectral-line-based weighted sum of gray gases absorption computational radiation heat transfer formulation. The computed base-ow physics are analyzed and compared with those of a subscale model hot-ow test. The effect of base bleed is also analyzed. Nomenclatureturbulence modeling constants: 1.15, 1.9, 0.25, and 0.09, respectively G = geometrical metrices H = total enthalpy h = static enthalpy or altitude, km I = radiative intensity J = Jacobian of coordinate transformation K = forward rate constant k = turbulent kinetic energy M = Mach number N = total number of chemical species P = pressure PC = combustion chamber pressure Pr = Prandtl number Q = heat ux, kW/m 2 q = 1, u, v, w , H, k, e , or q i R = recovery factor r = location coordinate S q = source term for equation q T + = law of the wall temperature t = time, s U = volume-weighted contravariant velocity u, v, w = mean velocities in three directions u s = wall friction velocity u += law of the wall velocity, u / u s x, y, z = coordinate or distance y + = law of the wall distance, (y p u s q / l ) e = turbulent kinetic energy dissipation rate or wall emissivity j = absorption coef cient l = effective viscosity, l 1 + l t n = computational coordinates P = turbulent kinetic energy production q = density r q = turbulence modeling constants } = energy dissipation function Presented as Paper 99-3682 at the AIAA 33rd Thermophysics ConferenceGroup; Ten-see.Wang@ msfc.nasa.gov. Senior Member AIAA. X= direction vector x = chemical species production rate Subscripts a = ambient b = blackbody or base c = convective or center l = laminar ow p = off-wall (wall function) point r = radiative t = turbulent ow w = wall surface 0 = reference 1 = freestream