Heat Transfer, Combustion Commons^™

Experimental Study Of Wall Bounded Harbor Seal Whisker Inspired Pin Geometries, Anish Prasad, Mark Ricklick

Publications

Conventional cylindrical/elliptical pins are one of the most widely used geometries in convection cooling systems and are used in the internal cooling of gas turbine blades and other applications, as they promote better heat transfer at the expense of large pressure losses and unsteadiness in the flow. The need to reduce pressure drop and maintain the heat transfer rates are a pressing requirement for a variety of industries to improve their cooling efficiency. One such prominent field of research is conducted in optimizing the design of pin geometries. In this study, a harbor seal whisker inspired geometry is being studied …

Cfd And Heat Transfer Analysis Of Rocket Cooling Techniques On An Aerospike Nozzle, Geoffrey Sullivan

College of Graduate Studies: Theses & Dissertations

In recent years the development of rocket engines has been mainly focused on improving the engine cycle and creating new fuels. Rocket nozzle design has not been changed since the late 1960s. Recent needs for reliable and reusable rockets, as well as advancements in additive manufacturing, have brought new interest into the aerospike nozzle concept. This nozzle is a type of altitude adjusting nozzle that is up to 90% more efficient than bell nozzles at low altitudes and spends up to 30% less fuel. Since the nozzle body is submerged in the hot exhaust gasses it is difficult to keep …

Calorimetric Measurements Of Lunar Regolith Simulant And Water. An Experimental Study Correlating Weight Percent Water And Temperature Change Through Periods Of Phase Change., George B. Johnson

Dissertations, Master's Theses and Master's Reports

Permanently Shaded Regions (PSRs) are cold traps located around the lunar south pole that have been confirmed to contain possible interesting quantities or volatiles such as H2O, CO2, SO2, CH4, and others. [1] The identification of these volatiles on the lunar surface was a critical step in the development of NASA’s strategic goals for scientific discoveries, sustained space travel and exploration, and re-establishing a human presence on the moon. These volatiles are vital to the future of operating in and exploring space. The LCROSS impact revealed the existence of these resources in PSRs but more information is needed about the …

Numerical Investigation On The Effect Of Spectral Radiative Heat Transfer Within An Ablative Material, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

The spectral radiative heat flux could impact the material response. In order to evaluate it, a coupling scheme between KATS - MR and P1 approximation model of radiation transfer equation (RTE) is constructed and used. A Band model is developed that divides the spectral domain into small bands of unequal widths. Two verification studies are conducted: one by comparing the simulation computed by the Band model with pure conduction results and the other by comparing with similar models of RTE. The comparative results from the verification studies indicate that the Band model is computationally efficient and can be used to …

State-Of-The-Art Of Thermal Control Solutions To Establish A Modular, Multi-Orbit Capable Spacecraft Thermal Management System Design Methodology, Robert C. Consolo Jr

Doctoral Dissertations and Master's Theses

Today, the exploration and exploitation of space continues to become a more common occurrence. All types of spacecraft (S/C) utilize various types of thermal management solutions to mitigate the effects of thermal loading from the unforgiving vacuum of space. Without an appropriately designed thermal system, components on-board the S/C can experience failure or malfunction due to fluctuations in temperatures either beyond the designed operational parameters or unstable oscillating temperatures. The purpose of this study is to perform a comprehensive review of technologies available today that are being used for thermal management onboard S/C in addition to investigating the means to …

Numerical Simulation Of A Cryogenic Spray, Neel Kishorkumar Shah

Doctoral Dissertations and Master's Theses

Cryogenic sprays have many applications in modern engineering. Cooling of electronic equipment subject to high heat flows, surgical ablation of gastrointestinal mucosae or orbital maneuvering are a few examples of their versatility. However, the atomization of a cryogenic liquid is a complex process. During such an event, aerodynamic effects associated with secondary atomization are further affected by thermodynamic flashing. A better understanding of the characteristics of cryogenic sprays is then necessary to allow for improved design and optimization in applications. The overarching objective of this study is to document such characteristics. The numerical simulation was performed over cryogenic nitrogen spray …

Injection Studies On A Small-Scale Rotating Detonation Engine With Improved Flow Control, Jonathan J. Wyatt

Theses and Dissertations

The Rotating Detonation Engine (RDE) has gained increasing attention in recent years for its potential advantages over typical deflagration combustion. A Micro-RDE design with an outer diameter of 28mm operating on Nitrous Oxide and Ethylene was recently developed, which stretched the limits of small-scale detonation engines. The testing on this rig has shown a stable one wave mode detonation with frequencies reaching 16.8 kHz. Key parameters that influence the detonation wave mode are cell size, fill height, and wave speed, which are heavily influence d by injection schemes. Previous testing utilized a partially premixed jets in crossflow (JIC) injection scheme, …

Investigations Of The Negative Temperature Coefficient Region Of Sustainable Aviation Fuels For Mitigation Of Global Warming, Richard C. Smith Iii

Honors College Theses

An investigation was led to determine the correlations between the durations of Ignition Delay (ID), Combustion Delay (CD), Derived Cetane Number (DCN), Negative Temperature Coefficient (NTC), Low-Temperature Heat Release (LTHR) regions, ringing intensity, and precent mass burn, and the effect of blending the Fischer-Tropsch (F-T) synthetic aerospace fuel (SAF), iso-paraffinic kerosene (IPK), with petroleum derived Jet-A aerospace fuel on these regions. Neat blends of Jet-A and IPK and three by mass blends of the fuels will be researched. These blends include mass percentages of 75%Jet-A and 25%IPK (75Jet-A25IPK), 50%Jet-A 50%IPK (50Jet-A50IPK), and 25%Jet-A 75%IPK (25Jet-A75IPK). The study will utilize a …

Fully Coupled Internal Radiative Heat Transfer For The 3d Material Response Of Heat Shield, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

The radiative transfer equation (RTE) is strongly coupled to the material response code KATS. A P-1 approximation model of RTE is used to account for radiation heat transfer within the material. First, the verification of the RTE model is performed by comparing the numerical and analytical solutions. Next, the coupling scheme is validated by comparing the temperature profiles of pure conduction and conduction coupled with radiative emission. The validation study is conducted on Marschall et al. cases (radiant heating, arc-jet heating, and space shuttle entry), 3D Block, 2D IsoQ sample, and Stardust Return Capsule. The validation results agree well for …

Review: Factors Affecting Composite Laminates Against Lightning Strikes, Aaryan Manoj Nair

Publications and Research

Lightning strike protection (LSP) have recently been a newly developing field particularly with the emergence of graphene thin film integration into carbon fiber composite structures. This technology has a widespread application in airplanes, wind turbines, and other instruments which are susceptible to frequent lightning strikes. Electrical discharge of the instrument in a safe manner is vital for the safety of the passengers (in the case of flights) as well as the integrity of the aircraft structures because of their specific mechanical and structural properties, which are essential for their functioning. The purpose of the study is to fabricate graphene thin …

Numerical Reconstruction Of Spalled Particle Trajectories In An Arc-Jet Environment, Raghava S. C. Davuluri, Sean C. C. Bailey, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

To evaluate the effects of spallation on ablative material, it is necessary to evaluate the mass loss. To do so, a Lagrangian particle trajectory code is used to reconstruct trajectories that match the experimental data for all kinematic parameters. The results from spallation experiments conducted at the NASA HYMETS facility over a wedge sample were used. A data-driven adaptive methodology was used to adapts the ejection parameters until the numerical trajectory matches the experimental data. The preliminary reconstruction results show that the size of the particles seemed to be correlated with the location of the ejection event. The size of …

Modeling Thin Layers In Material Response Solvers, Christen Setters

Theses and Dissertations--Mechanical and Aerospace 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 …

Investigations Of Air-Water Multiphase Flow In Tubes: Computational Fluid Dynamics, Wei Hong Goo

Student Works (2020-2029)

Mixing is a very crucial process in many industries, such as food processing industry, minerals processing industry, petrochemicals and refining industry, pulp and paper industry, polymer industry, pharmaceuticals industry and many more. There are different types of mixing, such as liquid-gas mixing, liquid-liquid mixing, solid-liquid mixing and many more. The definition of multiphase flow is the simultaneous flow of materials with multiple thermodynamic phases. A lot of process industries require multiphase flows during operation. Bubbly flow is defined as the flow of liquids that contains dispersed gas bubbles. One of the main applications of multiphases flows and bubbly flows is …

Development And Application Of Elliptic Blending Lag K-Omega Sst Standard And Wall-Distance-Free Turbulence Model, Wenjie Shang

McKelvey School of Engineering Graduate Student Theses & Dissertations

In recent decades, Computational Fluid Dynamics (CFD) has become the most widely used technology to understand the fundamental complex fluid dynamics of turbulent flows as well as for modeling of turbulent flows in industrial applications. In industrial applications, the widely used methodology is to solve Reynolds-Average Navier-Stokes Equations (RANS) equations in conjunction with a turbulence model since it strikes a balance between accuracy and computational cost compared to other high fidelity approaches namely the Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS), There are a large number of turbulence models proposed in past five decades, majority of them are …

Thermal Modeling Of Additive Manufacturing Using Graph Theory: Validation With Directed Energy Deposition, Jordan Severson

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Metal additive manufacturing (AM/3D printing) offers unparalleled advantages over conventional manufacturing, including greater design freedom and a lower lead time. However, the use of AM parts in safety-critical industries, such as aerospace and biomedical, is limited by the tendency of the process to create flaws that can lead to sudden failure during use. The root cause of flaw formation in metal AM parts, such as porosity and deformation, is linked to the temperature inside the part during the process, called the thermal history. The thermal history is a function of the process parameters and part design.

Consequently, the first step …

Quantifying Wicking In Functionlized Surfaces, Maureen Winter, Ryan Regan, Alfred Tsubaki, Craig Zuhlke, Dennis Alexander, George Gogos

UCARE: Research Products

Wicking remains the enigmatic key factor in many research areas. From boiling in power plants, to anti-icing on plane wings, to medical instruments, to heat pipes, efficiency and safety depend on how quickly a surface becomes wet. Yet wicking remains difficult to quantify and define as a property of the surface. This experiment strives to measure the wicking property by examining the rate that a liquid can be pulled out of a container. A superhydrophilic surface is placed in contact with the liquid at the bottom of a tube so that the volume flow rate across the surface can be …

Detonation Confinement In A Radial Rotating Detonation Engine, Kavi Muraleetharan

Theses and Dissertations

Radial Rotating Detonation Engines (RRDE) have provided an opportunity for use of a pressure-gain combustor in a more compact form compared to an axial RDE. A successfully tested RRDE has operated over a wide range of test conditions and produced detonation modes with one, two, and three waves. The presence of multiple waves located the detonation waves to the outer radius, while one wave modes operated closer to the inner radius. Locating the detonation wave closer to the inner diameter resulted in less time for combustion prior to the radial turbine. Subsequently, this tended to decrease efficiency. To attempt to …

Design And Analysis Of A Compact Combustor For Integration With A Jetcat P90 Rxi, Daniel Holobeny

Theses and Dissertations

Ultra Compact Combustors are a novel approach to modern gas turbine combustor designs that look to reduce the overall combustor length and weight. A previous study integrated an Ultra Compact Combustor into a JetCat P90 RXi turbine engine and achieved self-sustained operation with a length savings of 33% relative to the stock combustor. However, that combustor could not operate across the full stock engine performance range due to flameout at increased mass ow rates as reactions were pushed out of the primary zone. To ensure reactions stayed in the primary zone, a new design with a larger combustor volume was …

Thermal Performance Of Sierpinski Carpet Fractal Fins At Various Angles Of Inclination In A Natural Convection Environment, Haidar Jamil Khalil

College of Graduate Studies: Theses & Dissertations

As technology advances, higher performance cooling systems are desired to meet numerous thermal management challenges. Extended surfaces, also known as heat sinks or fins, are commonly used to passively dissipate unwanted heat from mechanical and electrical systems. Fractal fins in accordance with the first four iterations (including a base iteration) of the Sierpinski carpet, manufactured from AL-5052, were studied along seven different inclinations from 0° (orientated perpendicular to the direction of gravity) to 90° (orientated parallel to the direction of gravity), in iterations of 15°. The purpose of study was to investigate the thermal performance of the first four fractal …

Generation Of Premix Laminar Flame Speed Library, Sai Prashanth Kumar

Dissertations, Master's Theses and Master's Reports

The Laminar flame speed is an essential parameter in measuring turbulent premixed combustion applied in Spark ignition engines. Instead of using power-law correlations, which is valid only for particular ranges, the procedure for generating a premixed laminar flame speed library is defined using MTU – Master mechanism for a wide range of charge mixture conditions inside an engine combustion chamber: Temperature (300 – 700 K), Pressure (1 – 70 bar) and reactant mixture composition of equivalence ratio (0.4 – 2.0) Laminar flame speed library is generated for methane. The mechanism's performance was improved by adjusting the pre-exponential factor of the …

Development Of Universal Solver For High Enthalpy Flows Through Ablative Materials, Umran Duzel

Theses and Dissertations--Mechanical and Aerospace 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 …

Rocket Motor Nozzle, Corey Hillegass

Williams Honors College, Honors Research Projects

For this honors research and senior design project, the authors will research, analyze, and manufacture a rocket motor nozzle for the Akronauts rocket design team. This research and design project will improve how the rocket design team will decide and manufacture nozzles going forward. The impact of this improvement allows the rocket design team to take steps toward being self-sustaining by manufacturing student designed parts as opposed to commercially bought parts. This will not only be successful in increasing student impact on future designs, but also provides a technical challenge for the authors and will present as an impressive feat …

Characterizing Premixed Syngas Combustion In Micro-Channels, Sunita Pokharel

Graduate Theses, Dissertations, and Problem Reports (ETD)

Increasing demands in the next-generation portable power-generation devices such as unmanned aerial vehicles (UAV), microsatellite thrusters, micro-chemical reactors and sensors calls for fuels with high specific energy and low emissions to meet the current demand of green energy. Fuel-lean synthesis gas (syngas) meets both these requirements exhibiting a promising route to a clean and green environment. Thus, it is of critical importance to characterize syngas combustion and understand its properties in the micro-combustion industry. In addition to complicated flame dynamics in microscale systems, varying the syngas-fuel mixture composition as well as the boundary conditions and geometry of a combustor significantly …

The Investigation Of Noise, Vibrations And Emissions Of Aero-Gas Turbine Combustion With Synthetic Kerosene Fuels, Margaret Kilpatrick

Honors College Theses

Climatic changes from aviation emissions are complex and include effects of greenhouse gases such as: CO2, NOx, and aerosols. For that reason, the objectives of this study were to investigate the noise, vibrations and emissions characteristics of synthetic kerosene combustion in an aerospace gas turbine to reduce the engine’s environmental impact. Sustainably produced synthetic kerosene is known for having low soot emissions due to little to no aromatics (compounds that create particle pollutants), and for being a sustainable alternative fuel source to imported oil. The noise and sound levels were collected using Bruel & Kjaer microphones to measure various mid …

Flow Behavior In Radial Rotating Detonation Engines, Scott A. Boller

Theses and Dissertations

Recent progress has been made in demonstrating Radial Rotating Detonation Engine (RRDE) technology for use in a compact Auxiliary Power Unit with a rapid response time. Investigation of RRDEs also suggests an increase in stable operating range, which is hypothesized to be due to the additional degree of freedom in the radial direction which the detonation wave can propagate. This investigation seeks to determine if the detonation wave is in fact changing its radial location. High speed photography was used to capture chemiluminescence of the detonation wave within the channel to examine its radial location, which was found to vary …

Simulations On Optimization Of Liquid Spray Burners & Operating Parameters, Pallavi Gajjar, Vinayak Malhotra

International Journal of Aviation, Aeronautics, and Aerospace

Spray burners form an essential part of any liquid propulsion system as they are responsible for injecting, atomizing, mixing and combusting the liquid fuel. Spray combustion used in aerospace applications like the liquid rocket engines, gas turbines or any other controlled environment for that matter places a huge emphasis on safe and effective operations. These applications make use of relatively small amounts of propellant volumes to generate enormous amounts of energy through combustion for producing thrust. For such cases involving enormous energy interactions, combustion comes with its own set of challenges. The predominant challenge among them all is that of …

Improving The Delivered Specific Impulse Of Composite Rocket Propellant Through Alteration Of Chemical Composition: Methodology And Parameters For Characterization Of Propellant And Validation Of Simulation Software Common To The Amateur Rocketry Community, Isaac O'Brien, Austin Ryan

Williams Honors College, Honors Research Projects

In this study, two solid composite rocket propellants were designed utilizing ProPEP, a rocket propellant formulation software common in the amateur and hobby rocketry communities. The two propellants were designed to optimize specific impulse relative to a literature propellant designed by 1020 Research Labs. The literature propellant was also tested in order to validate the design of experiment as well as the mixing and testing procedures. All three propellants, which includes the literature propellant RCS-P, and the two novel propellants AKR-P1 and AKR-P2 were characterized with static tests. The results of the static tests provide data on propellant performance and …

Scaling Analysis And Experimental Investigation Of A Rotating Detonation Engine, David Thomas Billups

Graduate Theses, Dissertations, and Problem Reports (ETD)

Pressure gain combustion (PGC) technologies, specifically rotating detonation engines (RDEs), are poised to provide the next big leap in gas turbine engine advancement, significantly increasing the thermal. RDEs make use of thermodynamic advantages of isochoric as opposed to isobaric combustion. Theorized to increase thermal efficiency by up to 7% [1], the RDE would have significant impact on reducing anthropogenic carbon emissions. In addition to efficiency gains, the RDE also provides mechanical simplicity and reduced size advantages compared to it’s traditional counterparts and PGC competition.

The United States (U.S.) Department of Energy (DOE) National Energy Technology Laboratory (NETL) maintains and operates …

Effect Of Aerogel On The Thermal Performance Of Corrugated Composite Sandwich Structures, Jacob Dillon Chess

Master's Theses

Current insulation solutions across multiple industries, especially the commercial sector, can be bulky and ineffective when considering their volume. Aerogels are excellent insulators, exhibiting low thermal conductivities and low densities with a porosity of around 95%. Such characteristics make aerogels effective in decreasing conductive heat transfer within a solid. These requirements are crucial for aerospace and spaceflight applications, where sensitive components exist among extreme temperature environments. When implemented into insulation applications, aerogel can perform better than existing technology while using less material, which limits the amount of volume allocated for insulation. The application of these materials into composites can result …

Thermal Modelling And Validation Of Heat Profiles In An Rf Plasma Micro-Thruster, Alec Sean Henken

Master's Theses

The need and demand for propulsion devices on nanosatellites has grown over the last decade due to interest in expanding nanosatellite mission abilities, such as attitude control, station-keeping, and collision avoidance. One potential micro-propulsion device suitable for nanosatellites is an electrothermal plasma thruster called Pocket Rocket. Pocket Rocket is a low-power, low-cost propulsion platform specifically designed for use in nanosatellites such as CubeSats. Due to difficulties associated with integrating propulsion devices onto spacecraft such as volume constraints and heat dissipation limitations, a characterization of the heat generation and heat transfer properties of Pocket Rocket is necessary. Several heat-transfer models of …