Evaluation of Aerodynamic Heating Uncertainties for Space Shuttle

Abstract

The uncertainties in heating predictions derived from ground test data correlations have been used to define the corresponding uncertainties in TPS weight for the Space Shuttle. A completely reusable Shuttle system consisting of an aluminum heat sink booster and orbiter with reusable surface insulation for thermal protection was evaluated. The largest contribution to the uncertainty in TPS weight for the orbiter occurred on lower surface areas as a result of heating and boundary-layer transition uncertainties. Extension of this work to the current Shuttle system concept showed reduced weight uncertainty for the external tank compared to the reusable booster. Nomenclature H(T), h, #(0.9TO), H = heat-transfer coefficient L m M P 4 Re ReJL Re e T V W X a 6 <t> a t A Subscripts B C.L. e L tr * oo s Ref = model reference length (body axial length) = meter = Mach number = pressure = heating rate = Reynolds number = freestream unit Reynolds number = momentum thickness Reynolds number = temperature = velocity = TPS weight = axial distance = angle of attack = local flow deflection angle = peripheral angle = population standard deviation = time = increment in parameter prefixed = booster alone = booster mated with orbiter = lower surface centerline value -edge condition = local conditions = transition location = local peripheral value = freestream = stagnation point = reference value of h or q for a unit (R = I') sphere scaled to model size = wall condition = impingement region = undisturbed Presented as Paper 73-737 at

Technology and Operational Considerations for Low-Heat-Rate Entry Trajectories

“…The initial skin temperature chosen was 311 K (100°F), a value shown in previous studies to be consistent with typical vehicle attitude, orbital inclinations, and thermal control on orbit. 9 The analytical heating methods employed in MINIVER were varied depending on the particular heating condition under consideration. Stagnation point heating was evaluated using the well-known Fay and Riddell stagnation point method.…”

Optimization of the earthreentry trajectory of a blunted body by the integral heat flux

“…Figure 6 shows quasistationary trajectories with gliding coefficients of 10 -:t and 2-10-~ m2/N [3] (solid and dashed curves with rhoInbuses, respectively), the optinml trajectory obtained in the t)resent work and corresponding to the second version (see Table 1) for rL = 10 an(1 T,','. 'ax = 1500 K (crosses), tim "Space Shuttle" trajectory [13] (triangles), and the "Buraif" trajt'ctory [20] (circles). It is evident that the ol)timal trajectory ('oInl)uted in the present work correlates well with the "'Buraif' trajectory in the altitu(le range H = 100-60 km (segment of m~uximum thermal loads).…”

“…However, the maxinmm heat fluxes at the stagnation point fall in the region of the gliding trajectory at altitudes of 80-65 kin, where the Reynokts nmnbers m'e relatively small and tile ctmmical reactions are of a strongly nonequilibrium natltre [6]. Figure 1 shows the heat fluxes to the critical point of a sphere with R* = 0.5 m obtained for an ideally catalytic surface (curves 1-3) and a noncatalytic surface (curve 4) at Tw = 1200 K (curves 1 and 2) and for the case of equilibrium surface temperature (curves 3 and 4) using the Fay-Riddel formula (curve 1) and numerical solution of the TVSL equations (curves 2-4) for the trajectory of [13] (curve 5 is the speed along tim trajectory). A comparison of curves 1 and 2 shows that calculations using the Fay-Riddel formula give an error of up to 40% on the most heat-loaded segment of tile trajectory'.…”

A hypersonic chemically nonequilibrium viscous shock layer oh wings with a catalytic surface

“…The conditions in the oncoming flow corresponded to the motion along the trajectory of entry into the Earth's atmosphere [3] (curve 7 in Fig. 1), which is assumed to be isothermic with density distribution from the height H (km) p~ = 1.225-10 -3 ex~(--0.142H) g/cm 3.…”

“…On the shock wave the generalized Rankine--Hugoniot conditions are given, and on the surface of the body conditions which allow for heterogeneous catalytic reactions of the first order with reaction rate constants depending [i] or not depending [2] on the temperature.The cases of an ideally catalytic and a noncatalytic surface are also considered.The surface of the body is assumed to be heatinsulated.A numerical study was made of the problem in a broad range of variation in the angles of attack and slip for different cases of prescribed constants representing the rates of the heterogeneous reactions.The conditions of the flow corresponded to the motion of a body which possess a lifting force along the trajectory of entry into the Earth's atmosphere [3]. The dependences are given of the equilibrium temperature of the surface along the stagnation line of the wing on the height of the flight and the distribution of this temperature along the surface of wings with parabolic and hyperbolic contours.…”