Heat Transfer, Combustion Commons^™

Modeling Of Spallation Phenomenon In An Arc-Jet Environment, Raghava Sai Chaitanya Davuluri

Theses and Dissertations--Mechanical and Aerospace 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 …

High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang

Theses and Dissertations--Mechanical and Aerospace Engineering

A weakly ionized hypersonic flow solver for the simulation of reentry flow is firstly developed at the University of Kentucky. This code is the fluid dynamics module of known as Kentucky Aerothermodynamics and Thermal Response System (KATS). The solver uses a second-order finite volume approach to solve the laminar Navier– Stokes equations, species mass conservation and energy balance equations for flow in chemical and thermal non-equilibrium state, and a fully implicit first-order backward Euler method for the time integration. The hypersonic flow solver is then extended to account for very low Mach number flow using the preconditioning and switch of …

Radiative Conductivity Analysis Of Low-Density Fibrous Materials, Nima Nouri

Theses and Dissertations--Mechanical and Aerospace Engineering

The effective radiative conductivity of fibrous material is an important part of the evaluation of the thermal performance of fibrous insulators. To better evaluate this material property, a three-dimensional direct simulation model which calculates the effective radiative conductivity of fibrous material is proposed. Two different geometries are used in this analysis.

The simplified model assumes that the fibers are in a cylindrical shape and does not require identically-sized fibers or a symmetric configuration. Using a geometry with properties resembling those of a fibrous insulator, a numerical calculation of the geometric configuration factor is carried out. The results show the dependency …

Low-Order Discrete Dynamical System For H2-Air Finite-Rate Combustion Process, Wenwei Zeng

Theses and Dissertations--Mechanical and Aerospace Engineering

A low-order discrete dynamical system (DDS) for finite-rate chemistry of H₂-air combustion is derived in 3D. Fourier series with a single wavevector are employed to represent dependent variables of subgrid-scale (SGS) behaviors for applications to large-eddy simulation (LES). A Galerkin approximation is applied to the governing equations for comprising the DDS. Regime maps are employed to aid qualitative determination of useful values for bifurcation parameters of the DDS. Both isotropic and anisotropic assumptions are employed when constructing regime maps and studying bifurcation parameters sequences. For H₂-air reactions, two reduced chemical mechanisms are studied via the DDS. …

Transient Thermoelectric Supercooling: Isosceles Current Pulses From A Response Surface Perspective And The Performance Effects Of Pulse Cooling A Heat Generating Mass, Alfred Piggott

Dissertations, Master's Theses and Master's Reports

With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as COP are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no …

Elementary Assessments And Simulations Based Proposals For New Heat Transfer Correlations And Flow Regime Maps For Annular/Stratified Regime Of Shear Driven Internal Condensing Flows, Siddharth Ravikumar

Dissertations, Master's Theses and Master's Reports

Contemporary cooling applications necessitate the use of mm-scale shear driven flow condenser designs which also need to ensure substantial heat transfer rates for a wide range of flow conditions. Some modern shear driven flow condensers must meet the requirements of small size and large heat flux removal capability for variety of flow conditions. For this, effective estimates of heat transfer rate correlations and correlations for estimating the length of the annular regime are essential. Existing heat transfer correlations are built based on semi-empirical approaches which are primarily supported by large data sets, which are often mixed with insufficient explanation and …

Prosthetic Thermal Management Device, Garrett Dowd

Williams Honors College, Honors Research Projects

High temperatures in lower-limb prosthetics can lead to poor user skin conditions and mechanical slippage between the user’s limb and the prosthetic. This report presents an air-cooling device for a lower-limb prosthesis. This device’s purpose is to maintain a constant skin-prosthesis interface temperature. A compact heat sink and small fan were used to transfer the bio-heat to the ambient surroundings. By changing the power of the fan, the thermal resistance of the whole system can be adjusted to match various thermal loads and environmental temperatures. Heat pads were used to mimic the heat generation of a residual limb, and cooling …

2015 Afrl University Design Challenge, Daniel Slattery, Andrew P. Killmeyer, Brandon Null, Brendan Jones, Casey Hale, Jake Stein, Jeff Quartermaine, Kevin Rolik, Nick Tsangeos, Sam Moats, Marisa Seeley

Williams Honors College, Honors Research Projects

The University of Akron’s Air Force Research Laboratory’s Design Challenge Team has engineered a Heat Stress Prevention Kit that includes a facial mask in which the soldier will cool down from the inside out by breathing in the cool air circulating throughout the mask. This cool air is produced from a thermoelectric chip, which has a specific temperature difference on either side, one hot and one cold. Each of the sides is isolated from one another and with the combination of heat sinks, fans, and the simple process of breathing, a system is created by inhaling cool air. The entire …

Design Of The University Of Akron's 2015 Fsae Electric Vehicle Braking System, Nicholas D. Galbincea

Williams Honors College, Honors Research Projects

The following report encompasses the design of the 2015 University of Akron’s FSAE formula electric braking system. The system is one based on hydraulic braking and designed for a one man performance racing vehicle. The objective of the system is to convert the kinetic energy of the vehicle into thermal energy, allowing the vehicle to decelerate optimally and safely. The design includes three major categories: calculation and evaluation of the hydraulic system in order to select calipers and master cylinders, the design of the pedal box, and the design of the rotors.

The results and findings of the proceeding report …

Designing A Heat Sink For Lithium-Ion Battery Packs In Electric Vehicles, Dylan Irvine, Evan Foreman, Christopher B. Remington, Aaron Jackson, Sam Endrizzi

Williams Honors College, Honors Research Projects

This report addresses the concepts and implementation of fluid cooled heat sink designs for an electric or hybrid vehicle battery. To determine the battery’s temperature and heat flux profile, testing was performed by measuring these values at multiple locations on a lithium-ion pouch battery using heat flux sensors and thermocouples during the charge and discharge cycles of the battery. Once the data was collected and analyzed, trendlines were fit to the heat flux data then used to create equations for the heat flux profile during the discharging stage. Each equation represented a specific region on the battery geometry. Four heat …

2015 Afrl University And Service Academy Design Challenge, Andrew P. Killmeyer, Jacob Stein, Casey Hale, Jeff Quartermaine, Kevin Rolik, Brandon Null, Nick Tsangeos, Marissa Seeley, Sam Moats, Nicholas Garafolo Phd, Daniel Slattery

Williams Honors College, Honors Research Projects

The University of Akron’s Air Force Research Laboratory’s Design Challenge Team has engineered a Heat Stress Prevention Kit that includes a facial mask in which the soldier will cool down from the inside out by breathing in the cool air circulating throughout the mask. This cool air is produced from a thermoelectric chip, which has a specific temperature difference on either side, one hot and one cold. Each of the sides are isolated from one another and with the combination of heatsinks, fans, and the simple process of breathing, a system is created by inhaling cool air. The entire system …

Design Of An Sae Baja Racing Off-Road Vehicle Powertrain, Eric T. Payne

Williams Honors College, Honors Research Projects

No abstract provided.

Evaporative Techniques For Stormwater Runoff Alleviation, Allison M. Arnold

Graduate Theses, Dissertations, and Problem Reports (ETD)

Current climate changes have led to a projected steady increase in rainfall over the next several decades, notably in the Greater Pittsburgh Area. Even without this predicted increase the urbanization of many regions has altered local natural environments, which in the past stored, shed and evaporated this runoff water effectively, maintaining balance within the water table. These added rainfall forecasts, combined with America’s growing trend to develop and expand the urbanization of our natural earth, has resulted in a growing surplus of stormwater runoff water affecting these cities and their suburbs, leaving many sanitation departments unable to meet the heightened …

Computational Fluid Dynamics Modeling Of The Effects Of Water Injection In A Diesel Engine, Rabun Z. Wallace

College of Graduate Studies: Theses & Dissertations

Water injection has been used in internal combustion engines for many years. It has been used to cool combustion temperatures, reduce emissions, and in some instances clean carbon buildup from the cylinder. Research has shown that the water to fuel mass ratio is most effective between 20-30%, so the upper and lower limit were used for simulations in Converge CFD. To validate the CFD model, a case without water injection was compared to experimental data from Sandia National Laboratory. The predicted in-cylinder pressure and heat release rate showed good agreement with the experimental data. Cases were run with the injection …