Analysis and Design Optimization of Blunt Bodies In Hypersonic Flow

The purpose of this study is to model hypersonic flow around blunt body especially in atmospheric reentry of Earth. The more detailed model contains each energy transformation between each energy modes and all reactions. To simulate flow field region, thermal and chemical nonequilibrium must be considered all together. For the chemical nonequilibrium, species masses production of reactions must be characterized with suitable model. In this study, flow analysis based on the finite rate chemical reaction equations. Flow field region is assumed as continuum. Also flow is considered as inviscid and there is no diffusion. Computation of flow field is based on the axisymmetric Euler code. Coupled equations, chemical and thermal nonequilibrium equations are solved by using Newton's method. Jacobian matrices are calculated analytically. In the design part, aim is to obtain reduced pressure drag while keeping the body as blunt. Optimization results for various situations are represented

Analysis and Adjoint Design Optimization of Hypersonic Blunt Bodies

© 2014 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.The main purpose of this study is to analyze hypersonic flow field around the blunt bodies and to design of that bodies in order to obtain minimum pressure drag. Modeling of non-equilibrium must be done properly. In this study, non-equilibriums of thermal and chemical modes are considered. Translational and rotational energy modes are assumed that energy exchange between these modes is so fast. Vibrational and electronic energy terms are neglected. Therefore, one temperature is used to model thermo-chemical non-equilibrium. Flow field is assumed as inviscid and continuum region. Moreover, there is not diffusion. Thus, to model chemical non-equilibrium, finite rate chemistry can be used. For the thermal- nonequilibrium, enthalpy, entropy and specific heat constants are obtained from curve fitting methods. The coupled flow field equations are solved by using Newton’s methods. To solve Newton’s method, Jacobian matrices evaluation is required. In terms of convergence, Jacobian matrices are obtained by using analytical methods. At the design part, sensitivities are obtained by using adjoint design methods. The aim of design part is finding a hypersonic blunt geometry with minimum pressure drag while keeping the maximum temperature smaller than the baseline value

Aerothermodynamic Design Optimization of Hypersonic Vehicles

The objective of this study is to develop a reliable and efficient design optimization method for hypersonic vehicles focused on aerothermodynamic environments. Considering the nature of hypersonic flight, a high-fidelity aerothermodynamic analysis code is used for the simulation of weakly ionized hypersonic flows in thermochemical nonequilibrium. A gradient-based method is implemented for optimization. Bezier or nonuniform rational basis spline curves are used to parametrize the geometry or the geometry change. Linear elasticity theory is implemented for mesh deformation. Penalty functions are utilized to prevent undesired geometrical changes. The design objective is to minimize drag without increasing the total heat transfer rate and the maximum values of the surface heat flux, temperature, and pressure. Design optimizations are performed at different trajectory points of the IRV-2 vehicle. The effects of parametrizations, the number of design variables, and freestream conditions on design performance are studied