Aerothermal Shape Optimization of Hypersonic Vehicle Leading Edge by Using Genetic Algorithm

Abstract

To minimize the peak heat-flux of hypersonic blunt leading-edge, the Mini-Max optimization model is introduced for the first time for aerothermodynamics optimization. The surface heat-flux is obtained by resolving Navier-Stokes equations, and only the frozen flow is considered. The computational fluid dynamics (CFD) based Genetic Algorithm is used as the optimizer. A novel 2-D profile of leading-edge is obtained and the peak heat-flux is significantly reduced. Compared to the commonly used circular leading-edge, there is a large area of high temperature, high pressure in the front part of leading-edge, together with greater shock stand-off distance. The thickness of thermal boundary layer is increased about 40% at the stagnation point, the peak heat-flux is decreased about 20% and the heat-flux distribution is little changed in the vicinity of stagnation point. The robustness analysis shows that the favorable performance of the optimal 2-D profile is universally effective, i.e., it can effectively decrease the peak heat-flux by about 20% for various wall temperatures, Mach numbers, flight altitudes and thicknesses of the leading-edge as compared with the corresponding case of circular leading-edge. Although the reduction scope of peak heat-flux decreases with the change of angle-of-attack, but the peak heat-flux can still be decreased by more than 4% when the angle-of-attack is not greater than 15°. Several axisymmetric cases are also investigated in this paper, and the circular cone is taken as the benchmark, the peak heat-flux around an axisymmetric blunt cone, which is generated by the corresponding optimal 2-D profile, is also reduced by about 25%. Similarly, the distribution of heat-flux around the stagnation point is almost unchanged. NomenclatureC p = pressure coefficient D = thickness of the leading-edge/nose-tip H = flight altitude h 0 = total enthalpy h w = wall enthalpy h ∞ = enthalpy of the free-stream flow Ma ∞ = flight Mach number P = pressure Q = heat-flux Q 0 = heat-flux of the stagnation point Q max = peak heat-flux Q(x) = heat-flux along the leading-edge R 0= curvature radius at the stagnation point T = temperature T w = wall temperature V ∞ = velocity of the free-stream flow α = angle-of-attack θ = the induced angle with respect to the x-axis φ = angle between a tangent to the surface and the free-stream direction ρ ∞ = density of the free-stream flow ∆y n = grid thickness for the first layer near the wall 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition

Integrated Shape and Trajectory Optimisation of Hypersonic Waveriders

“…In [27], a Navier-Stokes solver was used to characterise the heat flux profile on a cylinder with a radius of 2.5 mm immersed in M ∞ = 6.5 laminar flow, at an altitude of 25 km (free-stream properties again derived using the US-76 atmosphere model), and with a wall temperature of 300 K. The Newton-Kays model adopted here yields a peak heat flux of 3.675 MW/m 2 , representing a relative difference of 2.7% with respect to the reference value of 3.579 MW/m 2 .…”

Influence of Non-Uniform Bluntness on Aerodynamic Performance and Aerothermal Characteristics of Waverider

“…As the distance from the stagnation point increases, the heat flow gradually decreases. For circular blunt to produce point ablation at the stagnation point, to reduce the peak heat flow and make the heat flow near the stagnation point become uniformly distributed, an optimized 2D (non-uniform blunt) profile is obtained by resolving Navier-Stokes equations based on the genetic algorithm in [27]. The heat flux of the optimized 2D profile is distributed relatively uniform compared to that of the circular profile in the vicinity of the stagnation point.…”