Space transportation system launch pad summer environmental effects

Abstract

The external tank (ET) of the space transportation system (STS) contains liquid oxygen and liquid hydrogen as oxidizer and fuel for the Space Shuttle main engines. This article describes a two-dimensional flow and thermal forced convection analysis to determine solar heat effects on the Space Shuttle launch components subsequent to the ET loading operation in extremely hot conditions. An existing computational fluid dynamics (CFD) code, parabolic hyperbolic or elliptical numerical integration code series (PHOENICS '81) was used in the study. The analysis was done for a two-dimensional slice between planes perpendicular to the longitudinal axis of the STS and passing through the lower portions of the redesigned solid rocket motors (RSRMs), the ET, and the or biter wing. The results are presented as local and average values of surface temperatures and Nusselt numbers around the RSRMs and the ET. Solar heating effects increased surface temperatures of the RSRMs by 5-6.1°C. Comparisons were based on the local Nusselt number at the forward stagnation point and on the average Nusselt number around the West RSRM. Nomenclature D = diameter of RSRM, 12.2 ft (3.72 m) or ET, 28 ft (8.54 m) Gr D = Grashof number of free convection based on outer diameter of RSRM or ET, gf3(T s -r.)D 3 /^2 g = acceleration due to gravity, ft/s 2 (m/s 2 ) h = convective heat transfer coefficient, Btu/h-ft 2 -°F (W/m 2 -°C) /y, IZ -cell numbers in domain, Fig. 2 k = thermal conductivity of air, Btu/h-ft-°F (W/m-°C) Nu D = local Nusselt number based on outer diameter, hDlk Pr = Prandtl number, 0.7 q'^ = solar heat flux, Btu/h-ft 2 (W/m 2 ), Fig. 3 Re D = Reynolds number of forced convection, U x Dlv T = temperature, °F (°C) t = half the thickness of adjacent air cell to a surface, in. (mm) U x = freestream wind velocity, ft/s (m/s) Y, Z = Cartesian coordinates, Figs. 2 and 4 /3 = coefficient of volumetric expansion of air, I/TV, OR-1 (K" 1 ) g = dissipation rate of turbulence kinetic energy per unit mass, (ft 2 /s 2 )/s (m 2 /s 2 )/s 6 = angular direction, deg (Figs. 2 and 3) K = turbulence kinetic energy per unit mass, ft 2 /s 2 (m 2 /s 2 ) fji = dynamic viscosity, Ibm/ft-s (kg/m-s) v = kinematic viscosity of air, ja/p, 0.6482 ft 2 /h (6.0221 x 10-2 m 2 /h) p = air density, lbm/ft 3 (kg/m 3 ) Subscripts c = cell adjacent to a surface D = based on diameter fsp = forward stagnation point on the west RSRM, 6 -150 deg / -inside RSRM cavity or ET fuel tank / = laminar m = arithmetic mean, measured s = surface sol = solar t = turbulent o° = freestream conditions Superscript