Engineering Commons^™

Characterization Of The Flow Field Over An Ablative Surface, Michael Allard, C. M. White, Y. Dubief

Ablation Workshop

No abstract provided.

Experimental Determination Of Pyrolysis Products From Carbon/Resin Ablative Materials, Hsi-Wu Wong, Jay Peck, Robin Edwards, Guillaume Reinisch, Jean Lachaud, Nagi N. Mansour

Ablation Workshop

No abstract provided.

Remote Recession Sensing Of Ablative Heat Shield Materials, Michael Winter, Margaret Stackpoole, Anuscheh Nawaz, Gregory Lewis Gonzales, Thanh Ho

Ablation Workshop

No abstract provided.

In-Situ Recession Measurements By Photogrammetric Ablator Surface Analysis, Stefan Löhle, T. Staebler, T. Reimer, A. Cefalu

Ablation Workshop

No abstract provided.

A Light-Weight Ablative Material For Research Purposes, Thomas Rothermel, C. Zuber, G. Herdrich, L. M. G. F. M. Walpot

Ablation Workshop

No abstract provided.

Ablation Test Case Series #3, Tom Van Eekelen, Alexandre Martin, Jean Lachaud, Daniele Bianchi

Ablation Workshop

No abstract provided.

Overview Of Ablation Test-Cases, Alexandre Martin, Jean Lachaud, Tom Van Eekelen, Ioana Cozmuta, Michael Wright, Nagi N. Mansour, Daniele Bianchi

Ablation Workshop

No abstract provided.

Microscale Modeling Of Ablative Thermal Protection System Materials, Eric Stern, Graham Candler, Tom Schwartzentruber, Ioannis Nompelis, Michael Barnhardt

Ablation Workshop

No abstract provided.

Material Response Characterization Of New-Class Ablators In View Of Numerical Model Calibration, Bernd Helber, Alessandro Turchi, T. E. Magin

Ablation Workshop

No abstract provided.

Uncertainty Analysis Of Carbon Ablation In The Vki Plasmatron, Alessandro Turchi, P. M. Congedo, Bernd Helber, T. E. Magin

Ablation Workshop

No abstract provided.

Investigation Of Surface Radiation In Earth Re-Entry Flows With Graphite Ablation, Christopher Alba

Ablation Workshop

No abstract provided.

Surface Effects And Phenomena On Ablative Materials, Alexandre Martin

Ablation Workshop

No abstract provided.

Ablamod: Advanced Ablation Characterization And Modelling European Project Description, Gregory Pinaud, A. Guelhan

Ablation Workshop

No abstract provided.

Overview Of Stmd’S Investments In Advanced Entry, Descent And Landing (Edl), Michael Wright

Ablation Workshop

No abstract provided.

An Adjoint Method To Determine The Effective Material Properties Of An Ablator, Emma Johnstone

Ablation Workshop

The determination of the effective thermal properties of a material from thermocouple data has always been very labour intensive. Similarly determining the Arrhenius parameters for a decomposition model from thermo-gravimetric analysis is also very time-consuming. There is little formalisation of the procedures used to determine the material properties. Despite the fact that some effort has been devoted to this topic in the literature, it is not clear whether comparable effective material properties data would result if several groups used the same experimental data. The FGE Ablation code FABL has been written in an adjoint form and has successfully been used …

Ultrasonic Thermometry For Recession Measurements In Ablative Materials, Joseph A. Lloyd, Donald E. Yuhas

Ablation Workshop

Recent developments in ultrasonic instrumentation & sensors, improved signal processing, and high speed data acquisition have rekindled interest in ultrasonic thermometry and made temperature localization feasible and economically attractive to a wider range of applications. Ultrasound-based temperature measurements offer several advantages: they are non-intrusive, have high temporal response, isolate the sensor from explosive or chemically harsh environments and do not adversely influence thermal transport. Ultrasonic thermometry techniques rely on precise measurements of ultrasonic time-of-flight (ToF) which forms the basis for many applications including measurements of flow, heat flux, temperature, ablation and strain. In this report, we characterize the ultrasonic propagation …

A Statistics-Based Material Property Analysis To Support Ablation Simulation Uq Efforts, Sean R. Copeland, Juan Alonso, Milad Mahzari, Ioana Cozmuta

Ablation Workshop

Accurate characterization of entry capsule heat shield material properties is a critical component in modeling and simulating Thermal Protection System (TPS) response in a prescribed aerothermal environment. The thermal decomposition of the TPS material during the pyrolysis and charring processes is typically poorly characterized and results in large uncertainties in material properties as inputs for ablation models. These material property uncertainties contribute to large design margins on flight systems and cloud re-construction efforts for data collected during flight and ground testing, making revision to existing models for entry systems more challenging. This work focuses on the following areas of interest …

Efficient Uncertainty Quantification & Sensitivity Analysis For Hypersonic Flow And Material Response Simulations Under Inherent And Model-Form Uncertainties, Serhat Hosder

Ablation Workshop

Accurate numerical prediction of coupled hypersonic flow fields and ablative TPS material response is challenging due to the complex nature of the physics. The uncertainties associated with various physical models used in high-enthalpy hypersonic flow and material response simulations can have significant effects on the accuracy of the results including the heat-flux and temperature distributions in various layers of ablating TPS material. These uncertainties can arise from the lack of knowledge in physical modeling (model-form or epistemic uncertainty) or inherent variations in the model inputs (aleatory or probabilistic uncertainty). It is important to include both types of uncertainty in the …

Ablative Thermal Protection System (Tps) Margin Study, Steven Rickman, Lawrence Green, Brian Remark, Stan Bouslog, Jeremy Vander Kam, Mohammad Khalessi

Ablation Workshop

Predicting the reliability of the heat shield for crewed space vehicles has been a topic of continuing interest within NASA for many years. The design of a thermal protection system (TPS) is subject to numerous large sources of uncertainty and reliability assessments of such TPS are rare. The proposed talk discusses both the application of Design Of Experiments (DOE) to developing a new arc jet testing campaign for a given TPS and the reliability assessment conducted for the same TPS for a crewed space capsule (similar to Apollo capsules) to withstand re-entry to earth from space.

The objectives of the …

Study Of Mechanical And Thermal Behavior Of Polymeric Ablator Using Md, Abhishek Kumar, Veera Sundararaghavan

Ablation Workshop

The thermal protection materials used for spacecraft heat shields are subjected to various thermal and mechanical loads during an atmospheric entry which can threaten the structural integrity of the system. This paper describes the development of a molecular dynamics approach to understand the mechanical and thermal behavior of high temperature polymers. One such material PICA has successfully flown on the Stardust spacecraft and is the TPS material chosen for the Mars Science Laboratory (MSL) and SpaceX Dragon spacecraft. Although such polymers have good structural properties at moderate temperature,they became structurally weak at extreme region of temperature and loads. In order …

Aerothermal Characterization Of Silicon Carbide-Based Tps In High Enthalpy Airflow, Francesco Panerai, Olivier Chazot

Ablation Workshop

Inductively-coupled plasma generators provide an ideal environment to reproduce the aerothermal heating experienced by a spacecraft re-entering a planetary atmosphere. The flight boundary layer chemistry is duplicated around a TPS model, ensuring a similarity between the flight and ground stagnation-point heat flux.

Experiments conducted in an induction plasmatron on silicon carbide-based thermal protection materials will be described. Several specimens are tested under a wide range of pressure and temperature conditions and investigated by means of infrared radiometry and optical emission spectroscopy. The plasma to which the materials are exposed is characterized in details by calorimetric and Pitot pressure measurements, and …

Methodology For Ablation Investigations In The Vki Plasmatron Facility: Preliminary Results With A Carbon Fiber Preform, Bernd Helber, Olivier Chazot, Annick Hubin, Thierry Magin

Ablation Workshop

Following the current developments of a new class of low-density, carbon/resin composite ablators, new efforts were initiated at the VKI on ablation research to understand the complex material response under reentry conditions and to develop and validate new material response models. Promising experimental results were obtained by testing the low-density monolytic composite ablator (MonA) in the 1.2MW inductively heated VKI Plasmatron facility. The application of a high speed camera with short exposure times (2μs) enabled in-situ analysis of both (3D) surface recession and spallation and further made it possible to demonstrate the outgassing effects of pyrolizing ablators. A change in …

Thermo-Chemical And Mechanical Coupled Analysis Of Swelling, Charring And Ablative Materials For Re-Entry Applications, Gregory Pinaud

Ablation Workshop

One of the major challenges in the design of atmospheric reentry vehicles is the optimization of the thermal protection system (TPS). During a reentry, the vehicle encounter severs heating and mechanical stress. A robust sizing is therefore essential to insure vehicle integrity and the mission success. In order to maximize the payload mass of the vehicle, lightweight charring ablators are commonly chosen as TPS materials for this one shot mission.

To predict the behaviour of the TPS ablative materials under pyrolysis for reentry applications, Astrium ST initiated the development of a specific module of the finite element software SAMCEF: AMARYLLIS. …

Coupled Computation Of Fluid And Material Response For Non-Charring Ablative Materials In Hypersonic Flow, Jonathan E. Wiebenga, Iain D. Boyd

Ablation Workshop

Hypersonic vehicles are subjected to high heat loads throughout their flight trajectories, and as a result, some form of thermal protection system (TPS) is required to ensure the vehicle’s survival. Accurate prediction of the behavior of these materials in a hypersonic environment is crucial to the efficient design of a hypersonic flight vehicle. It can be very costly and difficult, however, to experimentally replicate the flow conditions found in many hypersonic regimes, and for this reason it is desirable to be able to simulate the behavior of TPS materials under these flight conditions. This study aims to improve the modeling …

Uncertainty Analysis Of Reaction Rates In A Finite Rate Gas-Surface Model, Thomas E. Schwartzentruber

Ablation Workshop

A finite–rate–catalytic wall boundary condition incorporated into hypersonic flow simulations is investigated. Benchmark simulations of hypersonic flow over a cylinder are presented using the finite–rate–catalytic model parameterized with a test air–silica chemical model comprising the gas–surface reaction mechanisms and their associated rates. It is demonstrated that backwards recombination rates should not be arbitrarily set but must be consistent with the gas–phase thermodynamics, otherwise a drift from the equilibrium state may occur. The heat flux predicted by the finite rate model lies between non–catalytic and super–catalytic limits depending on the surface temperature. It is found that even for a constant surface …

Cfd Ablation Predictions With Coupled Gsi Modeling For Charring And Non-Charring Materials, Daniele Bianchi, Alessandro Turchi, F. Nasuti, M. Onofri

Ablation Workshop

To this day, a major objective of TPS design is to reduce empiricism, and to increase fundamental modeling capability through increased understanding. One of the most challenging aspect is the proper coupling between the material response and the external flow field. With this regard, the goal of this research activity is the improvement of the numerical modeling capabilities through the development of advanced CFD tools integrated with Gas-Surface Interaction (GSI) modeling.

Numerical prediction of ablation is ambitious and cpu-time demanding due to the complex multiphase physical and chemical processes that occur. With improvements in computational algorithms and advances in computer …

Radiative Transfer Equation Solver Module For Coupled Simulation Of Hypersonic Flows, Ranjan S. Mehta, Paul J. Dionne, Samuel F. Owens

Ablation Workshop

Accurate numerical modeling of the aerothermal environment around an ablation-cooled hypersonic re-entry vehicle requires high-fidelity models for processes such as non-equilibrium surface themochemistry, non-equilibrium pyrolysis chemistry, multi-scale radiation, spallation and charring. It is expected that, these models when utilized in a coupled manner will be able to accurately capture the possible nonlinear interactions between various phenomena in a computationally efficient manner. Development of a coupled radiative solver is currently being carried out as part of a joint effort between CFDRC, University of Michigan and University of Kentucky to develop a fully coupled method of simulating atmospheric entry flows and response …

Modeling Of Heat Transfer Attenuation By Ablative Gases During The Stardust Re-Entry, Alexandre Martin, Iain D. Boyd

Ablation Workshop

The great majority of modern space vehicles designed for planetary exploration use ablative materials to protect the payload against the high heating environment experienced during re-entry. In order to properly model and predict the aerothermal environment of the vehicle, it is imperative to account for the gases produced by ablation processes. In the case of charring ablators, where an inner resin is pyrolyzed at a relatively low temperature, the composition of the gas expelled into the boundary layer is complex and may lead to thermal chemical reactions that cannot be captured with simple flow chemistry models. In order to obtain …

Ablation Modeling Of A Solid Rocket Nozzle, Mark E. Ewing, Galen H. Richards, Micheal P. Iverson, Daron A. Isaac

Ablation Workshop

No abstract provided.

Definition Of Ablation Test-Case Series #3, Tom Van Eekelen, Jean R. Lachaud, Alexandre Martin, Ioana Cozmuta

Ablation Workshop

The test-case series #3 will be a further extension of the tests defined within the framework of the NASA ablation modelling workshops. In order to reduce the amount of work, all tests within test-case series #3, will use the TACOT material defined by Lachaud et al. The main goal of this new series, is to test the 3D modelling capabilities of the participating codes. The first 1D results were presented at the 4th Ablation workshop, and together with the results of the second test-case series, will be discussed and analyzed more thoroughly at the 5th Ablation Workshop, Feb. 28- March …