A probabilistic sizing tool and Monte Carlo analysis for entry vehicle ablative thermal protection systems

Mazzaracchio, Antonio; Marchetti, M.

doi:10.1016/j.actaastro.2009.08.033

Cited by 34 publications

(13 citation statements)

References 13 publications

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“…These uncertainty boundaries may seem large, however it shall be noted that they represent the 99 percentile of the uncertainty distribution, and that similar uncertainty values can be found in the literature given uncertainty in material density, and thermal properties. 43 The capsules obtained with this new optimization process shall be interpreted as these capsules that do not violate the constraints with 99% of confidence and that still present efficient mean performance in terms of mass, volume, and re-usability.…”

Section: Vb Robust Optimizationmentioning

confidence: 99%

Robust Multi-Disciplinary Optimization of Unmanned Entry Capsules

Ridolfi

Mooji

Dirkx

et al. 2012

AIAA Modeling and Simulation Technologies Conference

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Uncertainties in design variables and environmental factors are common in many engineering problems, and they must be taken into account when searching for robust optimal solutions. In robust multi-objective optimization it is common practice to optimize the average performance instead of the nominal objective functions. To compute average performance, and to determine the compliance of the solutions to the constraints, sampling is needed in a neighborhood of each individual and the performance of each sample point must be evaluated. This drives the computational cost of robust optimization up. In this paper we present a repository-based approach that reduces the number of evaluations needed during robust optimization. Unlike most of the approaches available to date, we introduce methods to keep the joint probability density function of the input variables intact when pre-existing points from the repository shall be used. This allows for cheap robustoptimization also in the presence of non-uniform uncertain-variable distributions. The robust optimization of unmanned entry capsules, considering continuous shape-variation models, aerothermodynamics, flight mechanics, and thermal protection system models at the same time is a valuable test-bed for the method presented here. In this paper we discuss the results of minimizing the mass of the capsules while maximizing the internal volume and the re-usability. We demonstrate that using a double-repository archive maintenance scheme it is possible to obtain accurate results and a reduction of the computational cost that is close to 70%, if compared to classical sampling-based methods for robust optimization. The analysis of robust-optimal entry capsules demonstrates that there are design conditions for which small and fully reusable capsules for unmanned entry from low Earth orbits perform as well as capsules with ablative materials, also under uncertainties.

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Section: Vb Robust Optimizationmentioning

confidence: 99%

Robust Multi-Disciplinary Optimization of Unmanned Entry Capsules

Ridolfi

Mooji

Dirkx

et al. 2012

AIAA Modeling and Simulation Technologies Conference

View full text Add to dashboard Cite

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“…2). The model for the ablative part of the heat shield and the relevant assumptions are thoroughly described in previous work by the author (Mazzaracchio and Marchetti, 2010). However, it is worth briefly recalling here the set of equations that form the basis of the model.…”

Section: Thermal Modelmentioning

confidence: 99%

“…The developed thermal model and sizing tool were validated by the author (Mazzaracchio and Marchetti, 2010) by comparison with an industry standard high-fidelity ablation and thermal response program, namely the "Fully Implicit Ablation and Thermal" (FIAT) software of NASA Ames Research Center.…”

Section: Thermal Protection System and Trajectory Optimization For Ormentioning

confidence: 99%

Thermal Protection System and Trajectory Optimization for Orbital Plane Change Aeroassisted Maneuver

Mazzaracchio

2013

J.Aerosp. Technol. Manag.

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The aim of this paper was to identify, for a specific maneuver, the optimal combination between the trajectory and the associated heat shield configuration, namely the locations and thicknesses of the ablative and reusable zones, that maximize the allowable payload mass for a spacecraft. The analysis is conducted by considering the coupling between the trajectory's dynamics and the heat shield's thermal behavior while using a highly representative model of the heat shield. A global optimization procedure and original software were developed and implemented. The analyzed mission considers an aeroassisted transfer from two low Earth orbits with an assigned orbital plane change maneuver for a given delta wing vehicle equipped with a heat shield consisting of both ablative and reusable materials. The results indicate that the aeroassisted maneuver is more convenient than a "full propulsive" maneuver in the analyzed case, even considering the increased vehicle mass due to the presence of the heat shield.

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“…More precisely, one assumes that the propulsive phases are concentrated in three impulses in space and that the portion of atmospheric flight is performed without the use of the propulsion system. The first propulsive impulse (deorbit) at the altitude A H of the initial HEO varies the vehicle's speed by 1 to enter the atmosphere along an elliptic orbit segment. The second impulse (boost) is applied upon the exit from the atmosphere to achieve the final LEO by ascending once more along an elliptic orbit segment.…”

Section: Vehiclementioning

confidence: 99%

“…The description of the models, the governing equations, and the relevant assumptions for the problem-i.e., thermal models, aerodynamic heating, atmospheric flight mechanics, and heat shield configuration-are thoroughly presented in [1] and [2]. Reference [2] can be consulted for full details of the original optimization procedure.…”

Section: Models and Optimizationmentioning

confidence: 99%

Effect of Spacecraft Aerodynamics and Heat Shield Characteristics on Optimal Aeroassisted Transfer

Mazzaracchio¹,

Marchetti²

2012

ENG

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A spacecraft designed to operate in a planetary atmosphere must have an adequate heat shield to withstand the high heat fluxes and heat loads that are generated by aerodynamic heating. Very often, the mass of the thermal protection system is a significant fraction of the total mass of the vehicle. In contrast, performing maneuvers in the atmosphere, that would be very costly in terms of propellant consumption if they were performed completely outside of the atmosphere in a classic way, is a very attractive prospective technique. The advantages and disadvantages in terms of total mass spared must be determined. The mission investigated involves an aeroassisted coplanar transfer from a high to a low Earth orbit. The approach uses a combination of three propulsive impulses in space together with an aerodynamic maneuver in the atmosphere. The heat shield adopted is fully ablative, given the expected high values of the entering heat flux. The convenience of the aeroassisted maneuver and the influence of the parameters involved are evaluated in comparison to a conventional Hohmann transfer. In particular, a parametric analysis is performed by varying the following characteristics of the vehicle: aerodynamic efficiency, mass-to-surface ratio, deorbit impulse, and initial altitude of the orbit. The influence of the thermal protection system is examined by assessing the impact of the type of ablative material employed, the thermal safety factor, and the allowable temperature for the adhesive layer on the substructure. The analysis is conducted with a highly representative thermal model by coupling the dynamic and thermal analyses and using a genetic optimizer. The optimization methodology and the thermal model are completely original. The results indicate the importance of choosing low-density ablative materials, of adopting a suitable thermal safety factor, and of choosing high-performance adhesives. The optimal trajectories obtained correspond to a zero second propulsive impulse.

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A probabilistic sizing tool and Monte Carlo analysis for entry vehicle ablative thermal protection systems

Cited by 34 publications

References 13 publications

Robust Multi-Disciplinary Optimization of Unmanned Entry Capsules

Robust Multi-Disciplinary Optimization of Unmanned Entry Capsules

Thermal Protection System and Trajectory Optimization for Orbital Plane Change Aeroassisted Maneuver

Effect of Spacecraft Aerodynamics and Heat Shield Characteristics on Optimal Aeroassisted Transfer

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