Engineering Commons^™

Numerical Investigation Of Pyrolysis Gas Blowing Pattern And Thermal Response Using Orthotropic Charring Ablative Material, Haoyue Weng, Alexandre Martin

Mechanical Engineering Faculty Publications

An orthotropic material model is implemented in a three-dimensional material response code, and numerically studied for charring ablative material. Model comparison is performed using an iso-Q sample geometry. The comparison is presented using pyrolysis gas streamlines and time series of temperature at selected virtual thermocouples. Results show that orthotropic permeability affects both pyrolysis gas flow and thermal response, but orthotropic thermal conductivity essentially changes the thermal performance of the material. The effect of orthotropic properties may have practical use such that the material performance can be manipulated by altering the angle of orthotropic orientation.

Numerical Study Of Spallation Phenomenon In An Arc-Jet Environment, Raghava Davuluri, Alexandre Martin

Mechanical Engineering Faculty Publications

The spallation phenomenon might affect the aerodynamic heating rates of re-entry vehicles. To investigate spallation effects, a code is developed to compute the dynamics of spalled particles. The code uses a finite-rate chemistry model to study the chemical interactions of the particles with the flow field. The spallation code is one-way coupled to a CFD solver that models the hypersonic flow field around an ablative sample. Spalled particles behavior is numerically studied for argon and air flow field. The chemistry model is compared with that of Park's model which complies with oxidation and sublimation and shows disagreement for nitridation.

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.

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

Ablation Workshop: Code Comparison

Numerical simulation of ablative-material response: code and model comparisons

Tacot V3.0, Jean Lachaud, Tom Van Eekelen, Daniele Bianchi, Alexandre Martin

Ablation Workshop: Code Comparison

No abstract provided.

Experimental And Numerical Study Of Carbon Fiber Oxidation, Francesco Panerai, Nagi N. Mansour, Jean Lachaud, Alexandre Martin

Mechanical Engineering Faculty Publications

The oxidation at high Knudsen number of FiberForm® , the matrix material of NASA's Phenolic Impregnated Carbon Ablator, is investigated both experimentally and numerically. The experimental setup consists of a quartz tube through a clamshell heater. Mass loss and recession of carbon preform samples are measured at temperatures between 700 and 1300 K and pressures around 2000 Pa. A volume average fiber-scale oxidation model is used to model the setup and extract the effective reactivity of the material. New values for carbon fiber reactivity are suggested and discussed.

A Design Pathfinder With Material Correlation Points For Inflatable Systems, Jared T. Fulcher

Theses and Dissertations--Mechanical Engineering

The incorporation of inflatable structures into aerospace systems can produce significant advantages in stowed volume to mechanical effectiveness and overall weight. Many applications of these ultra-lightweight systems are designed to precisely control internal or external surfaces, or both, to achieve desired performance. The modeling of these structures becomes complex due to the material nonlinearities inherent to the majority of construction materials used in inflatable structures. Furthermore, accurately modeling the response and behavior of the interfacing boundaries that are common to many inflatable systems will lead to better understanding of the entire class of structures. The research presented involved using nonlinear …

Multidimensional Modeling Of Pyrolysis Gas Transport Inside Orthotropic Charring Ablators, Haoyue Weng

Theses and Dissertations--Mechanical Engineering

During hypersonic atmospheric entry, spacecraft are exposed to enormous aerodynamic heat. To prevent the payload from overheating, charring ablative materials are favored to be applied as the heat shield at the exposing surface of the vehicle. Accurate modeling not only prevents mission failures, but also helps reduce cost. Existing models were mostly limited to one-dimensional and discrepancies were shown against measured experiments and flight-data. To help improve the models and analyze the charring ablation problems, a multidimensional material response module is developed, based on a finite volume method framework. The developed computer program is verified through a series of test-cases, …

Precipitation, Orientation And Composition Effects On The Shape Memory Properties Of High Strength Nitihfpd Alloys, Emre Acar

Theses and Dissertations--Mechanical Engineering

NiTiHf high temperature shape memory alloys are attractive due to their high operating temperatures (>100 ^oC) and acceptable transformation strain compared to NiTi. However, NiTiHf has limitations due to their lack of ductility and low strength, resulting in poor shape memory properties. In this study, Pd has been added to NiTiHf alloys in an attempt to improve their shape memory behavior. A combined approach of quaternary alloying and precipitation strengthening was used.

The characterization of a Ni_45.3Ti_29.7Hf₂₀Pd₅ (at. %) polycrystalline alloy was performed in compression after selected aging treatments. Transmission electron …

Filtered-Dynamic-Inversion Control For Fixed-Wing Unmanned Aerial Systems, Jon Mullen

Theses and Dissertations--Mechanical Engineering

Instrumented umanned aerial vehicles represent a new way of measuring turbulence in the atmospheric boundary layer. However, autonomous measurements require control methods with disturbance-rejection and altitude command-following capabilities. Filtered dynamic inversion is a control method with desirable disturbance-rejection and command-following properties, and this controller requires limited model information. We implement filtered dynamic inversion as the pitch controller in an altitude-hold autopilot. We design and numerically simulate the continuous-time and discrete-time filtered-dynamic-inversion controllers with anti-windup on a nonlinear aircraft model. Finally, we present results from a flight experiment comparing the filtered-dynamic-inversion controller to a classical proportional-integral controller. The experimental results show …