Inflatable Aerodynamic Decelerator Research Articles

Multistep Uncertainty Quantification Approach Applied to Hypersonic Reentry Flows

The objective of this study was to introduce and demonstrate a computationally efficient, multistep uncertainty quantification approach for high-fidelity, hypersonic reentry flow simulations, which may include large numbers of aleatory and epistemic uncertainties. The multistep uncertainty quantification approach included several key components, including a sensitivity-based dimension reduction process that used a local sensitivity analysis at selected sample locations to approximate global sensitivities. Other components included a method to update existing deterministic samples after dimension reduction and a modified point-collocation nonintrusive polynomial chaos method that incorporates existing local sensitivity information. The multistep uncertainty quantification approach was demonstrated on two model problems. The first was a model for stagnation point convective heat transfer in hypersonic flow. Mixed uncertainty quantification analysis results in reduced dimensions compared well with Monte Carlo simulations. The second problem was a high-fidelity, computational fluid dynamics model for stagnation point radiative heat flux on a Hypersonic Inflatable Aerodynamic Decelerator during a Mars entry. The model consisted of 93 uncertain parameters, coming from both flowfield and radiation modeling. The model was reduced to ten and five uncertain variables, accounting for 95 and 90% of the total output variance, respectively. Pure aleatory, epistemic, and mixed uncertainty quantification analyses were in agreement with previous work, proving the potential and applicability of the multistep uncertainty quantification process for complex hypersonic reentry flow models.

Deployment Analysis of Pneumatic Envelopes Including Ascending Balloons and Inflatable Aerodynamic Decelerators

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

Deployment Analysis of Pneumatic Envelopes Including Ascending Balloons and Inflatable Aerodynamic Decelerators

Deployment Analysis of Pneumatic Envelopes Including Ascending Balloons and Inflatable Aerodynamic Decelerators

Three-dimensional elliptic grid generation with fully automatic boundary constraints

A new procedure for generating smooth uniformly clustered three-dimensional structured elliptic grids is presented here which formulates three-dimensional boundary constraints by extending the two-dimensional counterpart 1 US patent 7231329. 1 presented by the author earlier. This fully automatic procedure obviates the need for manual specification of decay parameters over the six bounding surfaces of a given volume grid. The procedure has been demonstrated here for the Mars Science Laboratory (MSL) geometries such as aeroshell and canopy, as well as the Inflatable Aerodynamic Decelerator (IAD) geometry and a 3D analytically defined geometry. The new procedure also enables generation of single-block grids for such geometries because the automatic boundary constraints permit the decay parameters to evolve as part of the solution to the elliptic grid system of equations. These decay parameters are no longer just constants, as specified in the conventional approach, but functions of generalized coordinate variables over a given bounding surface. Since these decay functions vary over a given boundary, orthogonal grids around any arbitrary simply-connected boundary can be clustered automatically without having to break up the boundaries and the corresponding interior or exterior domains into various blocks for grid generation. The new boundary constraints are not limited to the simply-connected regions only, but can also be formulated around multiply-connected and isolated regions in the interior. The proposed method is superior to other methods of grid generation such as algebraic and hyperbolic techniques in that the grids obtained here are C 2 continuous, whereas simple elliptic smoothing of algebraic or hyperbolic grids to enforce C 2 continuity destroys the grid clustering near the boundaries.

Supersonic Inflatable Aerodynamic Decelerators for Use On Future Robotic Missions to Mars

The 2009 Mars science laboratory mission is being designed to place an 850 kg rover on the surface of Mars at an altitude of at least one kilometer. This is being accomplished using the largest aeroshell and supersonic parachute ever flown on a Mars mission. Future missions seeking to place more massive payloads on the surface will be constrained by aeroshell size and deployment limitations of supersonic parachutes. Inflatable aerodynamic decelerators (IADs) represent a technology path that can relax those constraints and provide a sizeable increase in landed mass. This mass increase results from improved aerodynamic characteristics that allow IADs to bedeployed at higher Mach numbers and dynamic pressures than can be achieved by current supersonic parachute technology.During the late 1960's and early 1970's preliminary development work on IADs was performed. This included initial theoretical shape and structural analysis for a variety of configurations as well as wind tunnel and atmospheric flight tests for a particular configuration, the attached inflatable decelerator (AID). More recently, the program to advance inflatable decelerators for atmospheric entry (PAI-DAE) has been working to mature a second configuration, the supersonic tension cone decelerator, for use during atmospheric entry.This paper presents an analysis of the potential advantages of using a supersonic IAD on a proposed 2016 Mars mission. Conclusions drawn are applicable to both the astrobiology field laboratory and Mars sample return mission concepts. Two IAD configurations, the AID and tension cone, are sized and traded against their system-level performance impact. Analysis includes preliminary aerodynamic drag estimates for the different configurations,trajectory advantages provided by the IADs, and preliminary geometric and mass estimates for the IAD subsystems. Entry systems utilizing IADs are compared against a traditional parachute system as well as a system employing an IAD in the supersonic regime and a parachute in the subsonic regime. Key sensitivities in IAD design are included to highlight areas of importance in future technology development programs.