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Advancing EDL technologies for future space missions : from ground testing facilities to ablative heatshields

Citation

Rabinovitch, Jason (2014) Advancing EDL technologies for future space missions : from ground testing facilities to ablative heatshields. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:05302014-140011538

Abstract

Motivated by recent MSL results where the ablation rate of the PICA heatshield was over-predicted, and staying true to the objectives outlined in the NASA Space Technology Roadmaps and Priorities report, this work focuses on advancing EDL technologies for future space missions.

Due to the difficulties in performing flight tests in the hypervelocity regime, a new ground testing facility called the vertical expansion tunnel is proposed. The adverse effects from secondary diaphragm rupture in an expansion tunnel may be reduced or eliminated by orienting the tunnel vertically, matching the test gas pressure and the accelerator gas pressure, and initially separating the test gas from the accelerator gas by density stratification. If some sacrifice of the reservoir conditions can be made, the VET can be utilized in hypervelocity ground testing, without the problems associated with secondary diaphragm rupture.

The performance of different constraints for the Rate-Controlled Constrained-Equilibrium (RCCE) method is investigated in the context of modeling reacting flows characteristic to ground testing facilities, and re-entry conditions. The effectiveness of different constraints are isolated, and new constraints previously unmentioned in the literature are introduced. Three main benefits from the RCCE method were determined: 1) the reduction in number of equations that need to be solved to model a reacting flow; 2) the reduction in stiffness of the system of equations needed to be solved; and 3) the ability to tabulate chemical properties as a function of a constraint once, prior to running a simulation, along with the ability to use the same table for multiple simulations.

Finally, published physical properties of PICA are compiled, and the composition of the pyrolysis gases that form at high temperatures internal to a heatshield is investigated. A necessary link between the composition of the solid resin, and the composition of the pyrolysis gases created is provided. This link, combined with a detailed investigation into a reacting pyrolysis gas mixture, allows a much needed consistent, and thorough description of many of the physical phenomena occurring in a PICA heatshield, and their implications, to be presented.

Through the use of computational fluid mechanics and computational chemistry methods, significant contributions have been made to advancing ground testing facilities, computational methods for reacting flows, and ablation modeling.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Hypervelocity, Ablation, CFD, Reacting Flows, Heatshield, Ground Testing Facilities
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Awards:Ernest E. Sechler Memorial Award in Aeronautics, 2013
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Blanquart, Guillaume
Thesis Committee:
  • Shepherd, Joseph E. (chair)
  • Blanquart, Guillaume
  • McKeon, Beverley J.
  • Colonius, Timothy E.
Defense Date:16 May 2014
Non-Caltech Author Email:jason.rabinovitch (AT) gmail.com
Funders:
Funding AgencyGrant Number
U.S. Air Force Office of Scientific ResearchFA9550-12-1-0472
Record Number:CaltechTHESIS:05302014-140011538
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05302014-140011538
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8445
Collection:CaltechTHESIS
Deposited By: Jason Rabinovitch
Deposited On:31 May 2014 00:09
Last Modified:02 May 2015 00:09

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