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Full-Text Articles in Engineering
A Decoupled Engineering Methodology For Accurate Prediction Of Ablative Surface Boundary Conditions In Thermal Protection Systems, Justin Cooper
A Decoupled Engineering Methodology For Accurate Prediction Of Ablative Surface Boundary Conditions In Thermal Protection Systems, Justin Cooper
Theses and Dissertations--Mechanical Engineering
The main objective of the present work is to demonstrate a method for prediction of aerothermal environments in the engineering design of hypersonic vehicles as an alternative to the current heritage method. Flat plate and stagnation point boundary layer theory require multiple assumptions to establish the current engineering paradigm. Chief among these assumptions is the similarity between mass and heat transfer. Origins of these assumptions are demonstrated and their relationship to conservative engineering design is analyzed, as well as conditions where they possibly break down. An alternative approach for assessing aerothermal environments from the fluid domain is presented, which permits …
Kentucky Re-Entry Universal Payload System (Krups): Hypersonic Re-Entry Flight, John Daniel Schmidt
Kentucky Re-Entry Universal Payload System (Krups): Hypersonic Re-Entry Flight, John Daniel Schmidt
Theses and Dissertations--Mechanical Engineering
The Kentucky Re-entry Universal Payload System (KRUPS) is a small capsule designed as a technology testbed for re-entry experiments. For its first incarnation, KRUPS has been designed to test Thermal Protection Systems (TPS) and instruments in re-entry flights. Because of the unique environment a vehicle undergoes during re-entry, there is a high-demand for experimental data from re-entry experiments. KRUPS has been developed at the University of Kentucky (UK) over the past seven years to meet this demand. After completing sub-orbital campaigns, the first KRUPS hypersonic re-entry mission was attempted. The mission involved building three 11-inch diameter capsules each outfitted with …
Modeling Thin Layers In Material Response Solvers, Christen Setters
Modeling Thin Layers In Material Response Solvers, Christen Setters
Theses and Dissertations--Mechanical Engineering
Thermal Protection Systems (TPS) are a necessary component for atmospheric entry. Most TPS contain thin layers of various materials such as ceramic coatings, pore sealers and bonding agents. When modeling TPS, these thin layers are often neglected due to the difference in scale between the TPS (centimeters) and the thin layers (micrometers). In this study, a volume-averaging flux-conservation method is implemented in the governing equations of a finite volume material response code. The model proposes the addition of a volume and area fraction coefficient which utilizes a weighted-averaging between the amount of thin layer and heat shield material in a …
Development Of Universal Solver For High Enthalpy Flows Through Ablative Materials, Umran Duzel
Development Of Universal Solver For High Enthalpy Flows Through Ablative Materials, Umran Duzel
Theses and Dissertations--Mechanical Engineering
Atmospheric entry occurs at very high speeds which produces high temperature around the vehicle. Entry vehicles are thus equipped with Thermal Protection Systems which are usually made of ablative materials. This dissertation presents a new solver that models the atmospheric entry environment and the thermal protection systems. In this approach, both the external flow and the porous heat shield are solved using the same computational domain. The new solver uses the Volume Averaged Navier-Stokes Equations adapted for hypersonic non-equilibrium flow, and is thus valid for both domains. The code is verified using analytical problems, set of benchmarks and also a …
Experimental And Computational Analysis Of The Interaction Of Carbon And Silicon Ablation Products In Expanding Hypersonic Flows, Brian E. Donegan
Experimental And Computational Analysis Of The Interaction Of Carbon And Silicon Ablation Products In Expanding Hypersonic Flows, Brian E. Donegan
Theses and Dissertations
Thermal protection is required for vehicles entering planetary atmospheres to protect against the severe heating loads experienced. Characterization of candidate materials is often done utilizing plasma or arc-jet facilities, which provide steady-state testing of the thermal environments experienced during hypersonic flight, but do not correctly simulate hypersonic flowfields. Conversely, impulse facilities can reproduce flight velocities and enthalpies but have extremely short test times, prohibiting testing of thermal response. Modeling ablation and heating rates, particularly in the wake region, remains a significant challenge due to the complexity of the flowfield. To better understand this complex phenomenon and provide data to validate …
Thermo-Mechanical Coupling For Ablation, Rui Fu
Thermo-Mechanical Coupling For Ablation, Rui Fu
Theses and Dissertations--Mechanical Engineering
In order to investigate the thermal stress and expansion as well as the associated strain effect on material properties caused by high temperature and large temperature gradient, a two-way thermo-mechanical coupling solver is developed. This solver integrates a new structural response module to the Kentucky Aerothermodynamics and Thermal response System (KATS) framework. The structural solver uses a finite volume approach to solve either hyperbolic equations for transient solid mechanics, or elliptic equations for static solid mechanics. Then, based on the same framework, a quasi-static approach is used to couple the structural response and thermal response to estimate the thermal expansion …
Verification And Validation Studies For The Kats Aerothermodynamics And Material Response Solver, Olivia Schroeder
Verification And Validation Studies For The Kats Aerothermodynamics And Material Response Solver, Olivia Schroeder
Theses and Dissertations--Mechanical Engineering
Modeling the atmospheric entry of spacecraft is challenging because of the large number of physical phenomena that occur during the process. In order to study thermal protection systems, engineers rely on high fidelity solvers to provide accurate predictions of both the thermochemical environment surrounding the heat shield, and its material response. Therefore, it is necessary to guarantee that the numerical models are correctly implemented and thoroughly validated. In recent years, a high-fidelity modeling tool has been developed at the University of Kentucky for the purpose of studying atmospheric entry. The objective of this work is to verify and validate this …
Steady State Simulation Of Pyrolysis Gases In An Inductively Coupled Plasma Facility, Nicholas C. Martin
Steady State Simulation Of Pyrolysis Gases In An Inductively Coupled Plasma Facility, Nicholas C. Martin
Graduate College Dissertations and Theses
An important step in the more efficient use of PICA (Phenolic Impregnated Carbon Ablator) as a Thermal Protection System (TPS) material for spacecraft is the understanding of its pyrolysis mechanics. The gases released during pyrolysis and their subsequent interaction with the reactive plasma environment is not yet well understood. The surface recession of PICA as it ablates during testing only makes the study and characterization of the chemical reactions more difficult. To this end, a probe has been designed for this study to simulate, in steady state, the pyrolysis gases within the UVM 30kW Inductively Coupled Plasma (ICP) Torch Facility. …
Investigation Of Pyrolysis Gas Chemistry In An Inductively Coupled Plasma Facility, Corey Tillson
Investigation Of Pyrolysis Gas Chemistry In An Inductively Coupled Plasma Facility, Corey Tillson
Graduate College Dissertations and Theses
The pyrolysis mechanics of Phenolic Impregnated Carbon Ablators (PICA) makes it a valued material for use in thermal protection systems for spacecraft atmospheric re-entry. The present study of the interaction of pyrolysis gases and char with plasma gases in the boundary layer over PICA and its substrate, FiberForm, extends previous work on this topic that has been done in the UVM 30 kW Inductively Coupled Plasma (ICP) Torch Facility. Exposure of these material samples separately to argon, nitrogen, oxygen, air, and carbon dioxide plasmas, and combinations of said test gases provides insight into the evolution of the pyrolysis gases as …
Development Of Inverse Methods For Reconstruction Of Flight Environments On Ablators, A. Brandon Oliver
Development Of Inverse Methods For Reconstruction Of Flight Environments On Ablators, A. Brandon Oliver
Open Access Dissertations
Obtaining measurements of flight environments on ablative heatshields is both critical for spacecraft development and extremely challenging due to the harsh heating environment and surface recession. Thermocouples installed several millimeters below the surface are commonly used to measure the heatshield temperature response, but an ill-posed inverse heat conduction problem must be solved to reconstruct the surface heating environment from the embedded thermocouple measurements. The material properties of typical ablators make the reconstruction process more challenging when the measurements are deep, but measurements often must be located deep to allow for surface recession. Compounding the complexity of the surface reconstruction problem, …
Modeling Of Spallation Phenomenon In An Arc-Jet Environment, Raghava Sai Chaitanya Davuluri
Modeling Of Spallation Phenomenon In An Arc-Jet Environment, Raghava Sai Chaitanya Davuluri
Theses and Dissertations--Mechanical Engineering
Space vehicles, while entering the planetary atmosphere, experience high loads of heat. Ablative materials are commonly used for a thermal protection system, which undergo mass removal mechanisms to counter the heat rates. Spallation is one of the ablative processes, which is characterized by the ejection of solid particles from the material into the flow. Numerical codes that are used in designing the heat shields ignore this phenomenon. Hence, to evaluate the effectiveness of spallation phenomenon, a numerical model is developed to compute the dynamics and chemistry of the particles. The code is one-way coupled to a CFD code that models …