Aerospace Engineering Commons^™

Transient Analysis Of A Pulsed Detonation Combustor Using The Numerical Propulsion System Simulation, Anthony Scott Hasler

Mechanical and Aerospace Engineering Theses - Archive

The performance of a hybrid mixed flow turbofan (with detonation tubes installed in the bypass duct) is investigated in this study and compared with a baseline model of a mixed flow turbofan with a standard combustion chamber as a duct burner. Previous studies have shown that pulsed detonation combustors have the potential to be more efficient than standard combustors, but they also present new challenges that must be overcome before they can be utilized. The Numerical Propulsion System Simulation (NPSS) will be used to perform the analysis with a pulsed detonation combustor model based on a numerical simulation done by …

Analytical Method For Analyzing C-Channel Stiffener Made Of Laminate Composite, Tattchapong Kumton

Mechanical and Aerospace Engineering Theses - Archive

Composite materials play the important role in the aviation industry. Conventional materials such as aluminum were replaced by composite material on the main structures. The objective of this study focuses on development of analytical method to analyze the laminated composite structure with C-channel cross-section. A lamination theory base closed-form solution was developed to analysis ply stresses on the C-channel cross-section. The developed method contains the effects of coupling due to unsymmetrical of both laminate and structural configuration levels. The present method also included the expression of the sectional properties such as centroid, axial and bending stiffnesses of cross-section. The results …

Particle Advection Using The Lattice-Boltzmann Method, Matthew Carroll

Mechanical and Aerospace Engineering Theses - Archive

Lattice-Boltzmann Method (LBM) CFD analysis can be helpful in analysing fluid flow through porous media and complex geometries that may be difficult to simulate using traditional CFD methods. In this thesis, the technical details of lattice Botlzmann particle advection are presented. The lattice Botlzmann equations are explained as well as a method for introducing a particle in a fluid flow and advecting the particle using viscous, pressure, and gravitational forces. A method is developed to advect a particle through a computational lattice mesh using pressure forces, gravitational forces, as well as LBM-specific viscous force equations. The capability of the particle …

Stress Concentrations Around A Square Cutout In A Composite Plate, Colin Cannon

Mechanical and Aerospace Engineering Theses - Archive

Composite structure in the aircraft industry has been in development for well over half a century and yet the understanding of the effects of a square cutout is generally limited to quasi-isotropic laminates. Currently, the closed-form solution to calculate the stresses around a cutout is limited to symmetric anisotropic laminates with limitations on the cutout shapes. Finite Element Analysis, using MSC PATRAN and NASTRAN, was performed on 2D composite laminates containing square cutouts with rounded corners. The laminate stacking sequence was varied from symmetrical and balanced to unsymmetrical and unbalanced and the square cutouts each had different radii at the …

Cfd Based Aerodynamic Modeling To Study Flight Dynamics Of A Flapping Wing Micro Air Vehicle, Alok Ashok Rege

Mechanical and Aerospace Engineering Theses - Archive

The demand for small unmanned air vehicles, commonly termed micro air vehicles or MAV's, is rapidly increasing. Driven by applications ranging from civil search-and-rescue missions to military surveillance missions, there is a rising level of interest and investment in better vehicle designs, and miniaturized components are enabling many rapid advances. The need to better understand fundamental aspects of flight for small vehicles has spawned a surge in high quality research in the area of micro air vehicles. These aircraft have a set of constraints which are, in many ways, considerably different from that of traditional aircraft and are often best …

Impact Of Louver Orientation On Air Flow Distribution And Thermal Management Of Data Centers, Kushal A. Aurangabadkar

Mechanical and Aerospace Engineering Theses - Archive

Nowadays with the increasing use of technology, Traditional data centers are being replaced by the highly efficient Containerized or Modular Data centers. The cooling systems and constructional cost employed for Traditional Data centers is more and inefficient. The research intricate, about 23% of the power is consumed by HVAC cooling units and which in turn leads to increase in operational costs. Hence in order to reduce the operational costs, free cooling with Air side economizer is incorporated, compared to other cooling systems. Airflow Distribution plays an important role in the Thermal management, if the airflow is less in quantity it …

Assessment Of The Mechanical Integrity Of Cu/Low-K Dielectric In A Flip Chip Package, Thiagarajan Raman

Mechanical and Aerospace Engineering Theses - Archive

Miniaturization and more recently convergence have been driving the industry since the invention of the transistor and integrated circuit (IC). Though the gate delay has decreased with transistor scaling, the increase in the resistive capacitive (RC) interconnect delay due to shrinking interconnect dimensions has become a serious concern for the development of future-generation electronics. To reduce the delay due to resistance R, a major technology change was the replacement of Aluminum (Al) with Copper (Cu) interconnect layers in the BEoL (Back-end-of-line). Recently, some investigators have suggested using low-k dielectric (having dielectric constant less than 4) instead of SiO2 (k= 3.9) …

Numerical Study Of Sidewall Filling For Gas-Fed Pulse Detonation Engines, Wunnarat Rongrat

Mechanical and Aerospace Engineering Theses - Archive

Pulse detonation engines for aerospace propulsion are required to operate at 50-100 Hz meaning that each pulse is 10-20 ms long. Filling of the engine and the related purging process become dominant due to their long duration compared to ignition and detonation wave propagation. This study uses ANSYS FLUENT to investigate the filling of a 1 m long tube with an internal diameter of 100 mm. Six different configurations were investigated with an endwall port and various sidewall arrangements, including stagger and inclination. A stoichiometric mixture of gaseous octane and air at STP was used to ll the tube at …

Thermal Analysis Of High End Servers Based On Development Of Detail Model And Experiments, Shreyas Sampath

Mechanical and Aerospace Engineering Theses - Archive

Thermal management of an efficient data center can be primarily dictated by efficient servers. Continued increase in power density and power dissipation of high end processors, thermal analysis and management has made it strategically important in the challenge of advanced thermal solutions. Present day CFD software provides powerful tools to create very accurate fluid and heat transfer solutions. Validation of a detailed model of a server in CFD corresponds to accurate flow and temperature models and these detailed server models are the foundational blocks for accurate data center thermal management solutions. In this research, an experimental study of the thermal …

Structural Analysis Of Microsatellites, Yezad H. Anklesaria

Masters Theses

"Satellite design, development, fabrication, testing and entry into service is a complex process. Each step of this process involves intricate steps to achieve the desired objective. This thesis summarizes a study relating to the area of development and testing of microsatellites to support qualification and eventually preparing a spacecraft for spaceflight. Students in the Space Systems Engineering laboratory (SSE Lab) in the Aerospace Engineering Program are in the process of developing a pair of microsatellites for a technology demonstration in space.

After the initial design of the spacecraft is completed in the design phase a significant amount of time is …

New Detonation Concepts For Propulsion And Power Generation, Eric Braun

Mechanical and Aerospace Engineering Dissertations - Archive

A series of related analytical and experimental studies are focused on utilizing detonations for emerging propulsion and power generation devices. An understanding of the physical and thermodynamic processes for this unsteady thermodynamic cycle has taken over 100 years to develop. An overview of the thermodynamic processes and development history is provided.Thermodynamic cycle analysis of detonation-based systems has often been studied using surrogate models. A real gas model is used for a thermal efficiency prediction of a detonation wave based on the work and heat specified by process path diagrams and a control volume analysis. A combined first and second law …

Hygrothermally Stable Laminated Composites For Optimal Extension Twist Coupling In Closed Cell Configuration, Sean Muder

Mechanical and Aerospace Engineering Theses - Archive

An optimization routine utilizing the sequential quadratic programming method is used to develop laminates that are hygrothermally stable in flat-strip configuration and are optimal for extension twist coupling in closed cell configuration. The performance of the laminates obtained from the optimization in terms of the level of extension twist coupling and hygrothermal stability are evaluated and compared to laminates from a previous routine. A parametric study is conducted to illustrate the relationships between the geometric dimensions of a representative closed cell section and the level of extension twist coupling. Results from the parametric study suggested a more practical optimization approach …

Design, Calibration And Testing Of A Force Balance For A Hypersonic Shock Tunnel, Pravin Vadassery

Mechanical and Aerospace Engineering Theses - Archive

The forces acting on a flight vehicle are critical for determining its performance. Of particular interest is the hypersonic regime. Force measurements are much more complex in hypersonic flows, where those speeds are simulated in shock tunnels. A force balance for such facilities contains sensitive gages that measure stress waves and ultimately determine the different components of force acting on the model. An external force balance was designed and fabricated for the UTA Hypersonic shock tunnel to measure drag at Mach 10. Static and dynamic calibrations were performed to find the transfer function of the system. Forces were recovered using …

Guidance And Control Of Unmanned Airships For Waypoint Navigation In The Presence Of Wind, Ghassan M. Atmeh

Mechanical and Aerospace Engineering Theses - Archive

Airships are a specific class of Lighter-Than-Air (LTA) vehicles. These vehicles achieve lift mainly through buoyancy; the usually ellipsoidal shaped hull contains a lifting gas such as helium, which produces the required lift though air displacement. Due to this method of operation an airship has the ability to conduct low-power hover, which makes it ideal for applications requiring hovering over long periods of time such as surveillance, terrain mapping, meteorology and GPS. In such applications the conventional fixed wing unmanned aircraft is less suitable. The work presented in this thesis deals with designing a controller that is capable of navigating …

Heat Transfer Enhancement In A Rectangular Channel Using Vortex Generator In A Laminar Flow, Ninad C. Maniar

Mechanical and Aerospace Engineering Theses - Archive

Enhancement of heat transfer through various means has been an intense area of research for many years. There are numerous applications where high performance heat exchange is desired. The cooling of electronics, such as microprocessors, is one example. The recent rise in the studies of heat exchange enhancement techniques has also lead to efficient and compact heat exchangers. This research involves the numerical analysis of heat exchange enhancement in a rectangular channel using different types of longitudinal vortex generators (LVG) for a laminar flow. A computational fluid dynamics software package was used to compute the 3-D steady viscous flows with …

Cfd Analysis Of Direct Evaporative Cooling Zone Of Air-Side Economizer For Containerized Data Center, Niket Shah

Mechanical and Aerospace Engineering Theses - Archive

Conventional data centers are extremely large buildings that have complex power distribution and cooling systems. These traditional brick and mortar data centers employ relatively expensive cooling systems and are inefficient. It has in turn led to an increase in construction and operational costs. Jonathan Koomey, Ph.D. of Lawrence Berkeley National Laboratory estimated that worldwide data center power consumption was 152.5 Billion kWh in 2005. In 2007, the US EPA estimated that servers and data centers, “consumed about 61 billion kilowatt-hours (kWh) in 2006 (1.5 percent of total U.S. electricity consumption) for a total electricity cost of about $4.5 billion. These …

Surface Measurements And Predictions Of Full-Coverage Film Cooling, Gregory Natsui

Electronic Theses and Dissertations

Full-coverage film cooling is investigated both experimentally and numerically. First, surface measurements local of adiabatic film cooling effectiveness and heat transfer augmentation for four different arrays are described. Reported next is a comparison between two very common turbulence models, Realizable k-ε and SST k-ω, and their ability to predict local film cooling effectiveness throughout a full-coverage array. The objective of the experimental study is the quantification of local heat transfer augmentation and adiabatic film cooling effectiveness for four surfaces cooled by large, both in hole count and in non-dimensional spacing, arrays of film cooling holes. The four arrays are of …

Agglomeration, Evaporation And Morphological Changes In Droplets With Nanosilica And Nanoalumina Suspensions In An Acoustic Field, Erick Tijerino

Electronic Theses and Dissertations

Acoustic levitation permits the study of droplet dynamics without the effects of surface interactions present in other techniques such as pendant droplet methods. Despite the complexities of the interactions of the acoustic field with the suspended droplet, acoustic levitation provides distinct advantages of controlling morphology of droplets with nanosuspensions post precipitation. Droplet morphology is controlled by vaporization, deformation and agglomeration of nanoparticles, and therefore their respective timescales are important to control the final shape. The balance of forces acting on the droplet, such as the acoustic pressure and surface tension, determine the geometry of the levitated droplet. Thus, the morphology …

Investigation Of Instabilities Affecting Detonations: Improving The Resolution Using Block-Structured Adaptive Mesh Refinement, Prashaanth Ravindran

Mechanical and Aerospace Engineering Dissertations - Archive

The unstable nature of detonation waves is a result of the critical relationship between the hydrodynamic shock and the chemical reactions sustaining the shock. A perturbative analysis of the critical point is quite challenging due to the multiple spatio-temporal scales involved along with the non-linear nature of the shock-reaction mechanism. The author's research attempts to provide detailed resolution of the instabilities at the shock front. Another key aspect of the present research is to develop an understanding of the causality between the non-linear dynamics of the front and the eventual breakdown of the sub-structures. An accurate numerical simulation of detonation …

Energy Recovery In Passenger Cars, Alberto A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The turbocharged direct injection stoichiometric spark ignition gasoline engine has less than diesel full load brake engine thermal efficiencies and much larger than diesel penalties in brake engine thermal efficiencies reducing the load. This engine has, however, a much better power density, and therefore may operate at much higher brake mean effective pressure (BMEP) values over driving cycles thus reducing the fuel economy penalty of the vehicle. This engine also has the advantage of the very well developed three-way catalytic (TWC) converter after treatment to meet future emission regulations. Replacement of fossil gasoline with renewable gasoline-like fuels has major advantages. …