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Veronica M Hawke

Publications and source records attributed to Veronica M Hawke.

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

Model Design and Pre-Test CFD Analysis for a Supersonic Retropropulsion Wind Tunnel Test

Future Mars human lander missions will require using powered descent beginning at supersonic conditions, something which has never been done before at Mars. Significant aerosciences challenges exist due to interactions between the retrorocket exhaust plumes and the freestream flow that alter the aerodynamic behavior of the powered descent vehicle. Historically, wind tunnel tests have been used to study supersonic retropropulsion with inert gas exhaust simulants. Also, SpaceX has successfully decelerated the Falcon 9 first stage numerous times by using powered flight at supersonic conditions. On the computational side, Reynolds-Averaged Navier-Stokes flowfield simulations are regularly completed at full-scale conditions. However, the available ground and flight data do not provide a basis for calibrating the computational uncertainties for aerodynamic interference forces and moments on proposed Mars descent vehicles, either because of insufficient data or dissimilar vehicles geometries and/or conditions. Thus, additional ground testing is needed to continue addressing the aerosciences risks for large-scale human Mars landers. To that end, a retropropulsion wind tunnel test will be conducted in the NASA Langley Unitary Plan Wind Tunnel in 2020. The test is designed to improve upon similar past tests, both in terms of model design and measured data. The test campaign will use subscale model geometries derived from the two current NASA powered descent reference vehicles: a blunt low lift-to-drag vehicle and a more slender geometry. This paper covers the reference vehicles, test objectives, model design, scaling parameters, test matrix, and computational analysis to date.

Karl T Edquist↗
NASA NTRSDate not supplied

Pterodactyl: Aerodynamic and Aerothermal Modeling for a Symmetric Deployable Earth Entry Vehicle with Flaps

NASA’s Pterodactyl project has investigated a deployable atmospheric entry vehicle integrated with a flap control system that provides precision targeting during reentry. The control system consists of eight flaps mounted at the edge of a heatshield that can deflect in and out of the flow. An aerodynamic and aerothermodynamic analysis process was developed for preliminary vehicle design and aerodynamic database generation using engineering and CFD tools with varying levels of fidelity. The objective of this analysis was to: 1) understand the inherent aerodynamics, 2) provide an aerodynamics database for stability and control analysis, and 3) provide qualitative and quantitative aeroheating analysis for Thermal Protection System modeling of the flaps. A high fidelity Euler code, Cart3D, was used to resolve complex flow features such as secondary shocks and shock impingement. A wide range of supersonic (Mach 2) and hypersonic Mach numbers (up to Mach 40) were tested with an Earth atmosphere model. A process was developed to utilize the adaptive volume mesh generator utility of the perfect gas model of Cart3D to create meshes with high cell efficiency and numerical stability prior to running a 2nd order accurate solution with a real gas model. High-fidelity aerothermal CFD simulations were performed using US3D to further improve the aerothermal analysis on hypersonic flow around a complex entry vehicle shape including viscosity, chemical reactions of air species, vibrational energy, and catalytic surface reactions. In this process, it was found that the flap control system provided multi-axis control that can be utilized for entry precision targeting. Additionally, the Pterodactyl vehicle can achieve up to a trim L/D of 0.2. Finally, the increased fidelity of the aerothermal heating environments revealed that the shear stress contributes to increasing the heating on the flaps.

Deployable Entry Vehicle↗
NASA NTRSDate not supplied

A New Flow-Through Balance for Retropropulsion Testing

Supersonic retropropulsion is believed to be an enabling technology for large-scale human Mars lander vehicle concepts. Ground testing of such vehicles requires the development of new flow-through wind tunnel balances because no suitable balances exist. A new flow-through balance is designed that employs membranes in place of bellows, which have historically been used, and that passes the flow through load bearing parts of the balance. Flow through the balance is optimized via the addition of flow guides, which are manufactured as separate parts, and attached to the balance. Calibration of this new flow-through balance demonstrates that it can suitably characterize the load and pressure ranges it was designed for, which provides aero researchers a new tool to directly measure supersonic retropropulsion performance of powered descent vehicles.

Flow through balance↗
NASA NTRSDate not supplied

Pterodactyl: Thermal Protection System Design Methodology for a Flap Control System

As interest in non-traditional entry vehicles continues to grow, the need for a Thermal Protection System (TPS) analysis approach that can account for entry solutions with changing geometry and complicated flow dynamics becomes invaluable. The NASA Space Technology Mission Directorate (STMD) Pterodactyl project aims to accomplish this through examination of a flap controlled Adaptable, Deployable Entry Placement Technology (ADEPT)-style Deployable Entry Vehicle (DEV). This paper details an improved methodology for modeling the aerothermodynamic environment and initial TPS design for a flap control system integrated with a symmetric DEV. Improvements include i) the addition of an anchoring process that uses an increased fidelity aerodynamic solution to anchor the aerothermal environment predictions and ii) increased surface resolution, for the 1D heat transfer analysis, to isolate the hottest area on the flap that will require the thickest TPS. It was found that the anchoring process provided an improved aerothermal environment prediction. Additionally, this analysis demonstrated that there is a need for increased surface resolution in the 1D thermal analysis since the predicted location of the hottest point was significantly different than the location identified using very coarse surface resolution.

Zane B Hays↗