Aerothermodynamic Optimization of Reentry Heat Shield Shapes for a Crew Exploration Vehicle

Johnson, Joshua E.; Starkey, Ryan P.; Lewis, Mark J.

doi:10.2514/1.27219

Cited by 31 publications

(17 citation statements)

References 7 publications

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“…Johnson et al 8,9 adopted some different multidisciplinary strategies for the optimization of entry heat shield of vehicles devoted to trajectories through Martian or terrestrial atmospheres.…”

Section: Introductionmentioning

confidence: 99%

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Harouni

Mehne

2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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Multi-disciplinary shape optimization of a re-entry capsule with aero-thermodynamic, trajectory, stability and the geometry considerations is presented in this research. The method is based on decomposition of the underlying problem into disciplinary routines performing separated analysis for each goal. The objectives of the optimization are maximizing volumetric efficiency, minimizing longitudinal stability derivative and minimizing the ballistic coefficient, subject to constraints on geometry, heating load and deceleration. Utilizing a multi-objective genetic algorithm will result in a collection of Pareto optimal solutions. Then, the multi-disciplinary multi-objective optimization process allows finding a Pareto front of the best shapes. Resulting optimal solutions obviously show the compromises among volumetric efficiency, longitudinal stability and ballistic coefficient. In the end, the results containing dimension's characteristics of the re-entry capsule are presented.

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Section: Introductionmentioning

confidence: 99%

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Harouni

Mehne

2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…Previous work [12] applied the modified method of feasible directions gradient-based method to optimize over the geometric design space (without trajectory analysis) for a single objective. There were numerous local optima; over 200 runs were required to locate the global optima for four objective functions.…”

Section: Optimization Methodsmentioning

confidence: 99%

“…Table 2 indicates predictions of maximum total heat transfer within 9.2% of reported values. Further descriptions of the method and validation are provided in [12]. All of these heat transfer correlations are limited to the stagnation area, and while this is appropriate for this level of analysis, this work does not account for acreage heating, which could have a significant impact on thermal protection system (TPS) design and requirements.…”

Section: Radiative Heat Transfermentioning

confidence: 99%

“…A maximum eccentricity of 0:968 was chosen to limit the axes ratio j=k to four. Additional reasons for the chosen side constraints that are geometry-related have been detailed in [12]. A mesh convergence study was completed in [19] to reduce computational time; for optimization, the geometry's mesh is j max 45, k max 101.…”

Section: Design Variablesmentioning

confidence: 99%

“…Properly broadening the design space would allow the optimizer to determine which geometric features improve performance. Recent work completed by the authors [12] introduced nonspherical designs consisting of elliptical and polygonal base cross sections. Single design-condition optimization indicated improvements in aerodynamic performance by generating oblate heat shields with parallelogram cross sections, increasing the hypersonic lift-todrag ratio significantly.…”

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confidence: 99%

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Multiobjective Optimization of Earth-Entry Vehicle Heat Shields

Johnson

Lewis

Starkey

2012

Journal of Spacecraft and Rockets

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A differential evolutionary algorithm has been executed to optimize the hypersonic aerodynamic and stagnationpoint heat transfer performance of Earth-entry heat shields for manned and unmanned missions. Objective functions comprise maximizing cross range, minimizing heat flux, and minimizing heat load. Each considered heatshield geometry is composed of an axial profile tailored to fit a base cross section. Axial profiles consist of spherical segments, spherically blunted cones, and power law geometries. Heat-shield cross sections include oblate and prolate ellipses, rounded-edge parallelograms, and blendings of the two. Aerothermodynamic models are based on modified Newtonian impact theory with semiempirical correlations for convection and radiation. Entry velocities of 11 and 15 km=s are used to simulate atmospheric entry conditions at lunar and Mars return conditions, respectively. Results indicate that skip trajectories allow for vehicles with a low lift-to-drag ratio of 0.25 to achieve 1000 km cross range, a factor of 4 increase in capability over direct entry. For 11 km=s entry with a 6g deceleration limit, the spherical segment provides optimal performance. For 15 km=s entry with a 12g deceleration limit, the spherically blunted cone produces an 8% lower heat flux when compared with spherical segments with similar aerodynamic characteristics. This result is attributed to the blunted cone's smaller shock standoff, which reduces the heat load generated by thermal radiation, the dominant heat transfer mode.= total emitted power density, J=m 3 s e = eccentricity g w = ratio of wall enthalpy to total enthalpy g 1 , g 2 , g 3 = coefficients and exponents [Eq. (6)] H = exponent [Eq. (7)] h = length along y direction, m h t = altitude, km j = semimajor axis length of a blunt body, m j max = maximum mesh points in x direction k = semiminor axis length of a blunt body, m k max = maximum mesh points in direction L = lift, N l = length along x direction, m M 1 = freestream Mach number m = mass, kg m 1 = number of sides of the superellipsê n = normal unit vector, away from surface n crew = crew number, person n max = peak deceleration load, Earth g n 1 , n 2 , n 3 = superelliptic parameters p xrs = cross range, km Q = heat load, kJ=cm 2 q = heat flux, W=cm 2 q 1 = freestream dynamic pressure, Pa r = base radius, m r n = nose radius of blunted cone, m r s = radius of curvature of spherical segment, m S = area of base cross section, m 2 t = time, s t d = total mission duration, days V PR = pressurized volume, m 3 v 1 , v 2 = superellipse parameters V 1 = freestream velocity, m=s x, y, z = coordinate values, m = angle of attack, = sideslip angle, = trajectory flight-path angle; positive pointing away from planet, so = shock-standoff distance, m "= edge tangency angle, v = volumetric efficiency c = half-cone angle, s = half-spherical segment angle, = density, kg=m 3 2 = 1 = normal-shock density ratio = sweep angle, rad b = bank angle,axial force, N b = base cg = center of gravity conv = convective D = drag, N EI = entry int...

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Robust Optimization with Tchebysheff Decomposition for Mars Entry Probe Design

Hou

Cai

et al. 2014

Advances in Intelligent Systems and Computing

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Aerothermodynamic Optimization of Reentry Heat Shield Shapes for a Crew Exploration Vehicle

Cited by 31 publications

References 7 publications

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Multiobjective Optimization of Earth-Entry Vehicle Heat Shields

Robust Optimization with Tchebysheff Decomposition for Mars Entry Probe Design

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