Mechanical Engineering Commons^™

Assessment Of Noise Metrics For Application To Rotorcraft, Andrew L. Mcmullen

Open Access Theses

It is anticipated that the use of rotorcraft passenger vehicles for shorter journeys will increase because their use can reduce the time between boarding and take-off. The characteristics of rotorcraft noise are very different to that of fixed wing aircraft. There can be strong tonal components, fluctuations that can also make the noise sound impulsive, and future rotorcraft may produce proportionally more low frequency noise content. Most metrics that are used today to predict noise impact on communities around airports (e.g., L_dn) are just functions of A-weighted sound pressure level. To build a better noise annoyance model that …

Experimental Characterization Of The Pt Asymmetry With Balanced Inflow And Outflow At Different Reynolds Numbers, Zijie Qu

Open Access Theses

This research focused on characterizing the PT asymmetry with balanced inflow and outflow conditions at different Reynolds number using experimental method. The characterization process utilized PIV data to explore the relationship between PT asymmetry and Reynolds number in two different experiments. In the first experiment, balanced inflow and outflow are used to generate the flow field in a cuboid test section with different Reynolds number, the inflow and outflow are located at the central of left side and right side of the test section. In the second experiment, a main flow is introduced to the first experiment by adding another …

Impinging Jet Spray Formation Using Non-Newtonian Liquids, Neil S. Rodrigues

Open Access Theses

Over the past two decades there has been a heightened interest in implementing gelled propellants for rocket propulsion, especially for hypergolic bi-propellants such as monomethylhydrazine (MMH) and nitrogen tetroxide oxidizer (NTO). Due to the very high level of toxicity of hypergolic liquid rocket propellants, increasing safety is an important area of need for continued space exploration and defense operations. Gelled propellants provide an attractive solution to meeting the requirements for safety, while also potentially improving performance. ^ A gelling agent can be added to liquid propellants exhibiting Newtonian behavior to transform the liquid into a non-Newtonian fluid with some solid-like …

Design Of A High Performance Actuation System Enabled By Energy Coupling Actuation, Daniel Richard Skelton

Open Access Theses

The main goal of the research was to design, manufacture, and test a new linear actuation system. Research was conducted on several types of actuation methods applied to hydraulic valves. A literature review showed that most existing actuator systems have the actuator and control mass coupled together. There is a need for high speed actuation. The proposed idea is to have the actuation mass always moving while accelerating and decelerating the control mass. The decoupling of these two will allow for the actuation and control mechanism to be independent and only move the control mechanism when needed. Initial modeling, as …

Development, Numerical Demonstration And Experimental Verification Of A Method For Model Updating Of Boundary Conditions, Christian Eduardo Silva Salazar

Open Access Theses

The study of vibrations in beams has been largely addressed by authors and researchers. However, relatively few researchers have considered the case of unknown boundary conditions, as usually it is reasonable to assume the classical cases such as simply supported, clamped or free. Indeed, there are a wide variety of boundary-condition configurations, each one representing a whole different problem with its own modal characteristics. ^ A method for updating experimental beam models to specifically address the issue of unknown boundary conditions is proposed. This methodology takes advantage of vector comparison techniques such as the modal assurance criterion and the dot …

The Prediction Of Airborne And Structure-Borne Noise Potential For A Tire, Nicholas Sakamoto

Open Access Theses

Tire/pavement interaction noise is a major component of both exterior pass-by noise and vehicle interior noise. The current testing methods for ranking tires from loud to quiet require expensive equipment, multiple tires, and/or long experimental set-up and run times. If a laboratory based off-vehicle test could be used to identify the airborne and structure-borne potential of a tire from its dynamic characteristics, a relative ranking of a large group of tires could be performed at relatively modest expense. This would provide a smaller sample set of tires for follow-up testing and thus save expense for automobile OEMs. The focus of …

Design And Development Of A Novel Test Method To Measure The Slipper / Swashplate Interface Fluid Film In A Positive Displacement Machine, Natalie A. Spencer

Open Access Theses

Although robust models of fluid film behavior between the slipper / swashplate lubricating interface in positive displacement machines have been developed, measuring this same fluid film thickness to a highly accurate degree inside a relatively unaltered axial piston unit has never been accomplished until now. A test method was created to close this gap in available data by measuring fluid film thickness between the slipper and swashplate in a 130cc axial piston pump. Precise knowledge of the gap height between the slipper and swashplate at various shaft angle locations during operation provides critical insight into machine behavior. The design, validation, …

A Numerical Procedure To Design The Optimal Axial Balance In External Gear Machines And Its Potential In Formulating Novel Efficient Design Solutions, Divya Thiagarajan

Open Access Theses

A novel numerical procedure to design the optimal axial balance in external gear machines (EGMs) has been formulated and developed in the present study. Lateral lubricating interfaces exist between the lateral bushes and the rotating gears in pressure compensated designs of EGMs and play a significant role in minimizing power losses arising from fluid shear stress and leakages from the gap. Moreover, lateral bushes in pressure compensated designs of EGMs perform significant functions of sealing the tooth space volumes while they transfer fluid from the inlet to the outlet port. ^ The losses from the lateral gap from these two …

A Web-Based Online Collaboration Platform For Formulating Engineering Design Projects, Sainath Varikuti

Open Access Theses

Effective communication and collaboration among students, faculty and industrial sponsors play a vital role while formulating and solving engineering design projects. With the advent in the web technology, online platforms and systems have been proposed to facilitate interactions and collaboration among different stakeholders in the context of senior design projects. However, there are noticeable gaps in the literature with respect to understanding the effects of online collaboration platforms for formulating engineering design projects. Most of the existing literature is focused on exploring the utility of online platforms on activities after the problem is defined and teams are formed. Also, there …

Optical Direct-Write Nanolithography Based On Self-Assembled Resist, Meghana Akella

Open Access Theses

Holographic display is being developed for next generation mobile phones. However, manufacturing of miniature gratings for the holographic projectors cost a few thousand dollars today, not making the concept practical for commercial purposes. In this thesis, we discuss the feasibility of self-assembled nanoparticles to manufacture holographic gratings cost-effectively and at the nanoscale. Using our approach, the gratings can be manufactured at the scale of 20nm and the cost per chip is expected to cost a few dollars.^ In this thesis, a hydrophobic SAM was used to modify the surface of silicon. Direct-write UV laser lithography was used for photothermal patterning …

Transverse Compression Of High-Performance Ballistic Fibers, Zherui Guo

Open Access Theses

High performance ballistic fibers have been in use for decades, specifically in protective applications against ballistic impact such as bulletproof vest layers and aircraft turbine engine fragmentation barriers. These high performance fibers have extremely high strength-to-weight ratios and high moduli of elasticity in the axial direction, making them extremely suitable for high impact situations. In particular, para-phenyleneterephthalamide (PPTA for short) fibers such as Kevlar^® and ultra-high-molecular-weight polyethylene fibers such as Dyneema^® are amongst the more popular high performance fibers in today's world. While the longitudinal mechanical response of these fibers have been extensively researched, their transverse mechanical response …

Cylinder Block / Valve Plate Interface Performance Investigation Through The Introduction Of Micro-Surface Shaping, Rene Chacon Portillo

Open Access Theses

Swash plate type axial piston machines are widely used positive displacement machines in different fields of industry ranging from aerospace, agriculture, automotive, heavy machinery, etc. Lubricating gaps are the main source of energy dissipation in axial piston machines. This type of machines have three lubricating interfaces: slipper/swash plate interface, piston cylinder and the cylinder block/valve plate interface. The cylinder block/valve plate interface being one of the most critical design elements of the machine. Extensive research has been done at Maha Fluid Power Research Center in Purdue University both to model this interface and to study the effects of micro-surface shaping …

Design, Development And Testing Of A Balance Board With Variable Torsional Stiffness And Time Delay, Denise Renee Cruise

Open Access Theses

The ability to balance and maintain upright posture can decline for a variety of reasons, such as aging and neuromuscular impairment. As the ability to balance declines, the risk of falling increases. Falls are a major cause of injury, and often lead to a dramatic decline in quality of life. Currently, to alleviate balance deficiencies, people participate in balance training, which most commonly refers to standing on an unstable balance board; the most common boards used are either passive wobble boards, or more advanced commercial systems such as the Biodex System SD ® or the Neurocom SMART Balance Master® . …

Laboratory Apparatus For Gas Turbine Combustion Development, Dustin Lee Cruise

Open Access Theses

The next generation of combustor technology will be required to meet the demands of a world more focused on greenhouse gases and global warming. Due to this new focus on emission control, combustors must produce less NO x , while operating in a higher pressure environment that is more prone to combustion instabilities.

This work focuses on the development of a lab and combustor that will be used for the next generation combustor development. The lab development includes layout and organization, facilities, measurement and instrumentation, automation of the testing process, and an imaging tool for diagnostics.

A Lean Direction Injection …

Design Of Optical Access For The Application Of Laser Doppler Velocimetry In A Low Specific Speed Centrifugal Compressor, Bryce Ashton Heckaman

Open Access Theses

The objective of this research has been to design optical access for the application of laser Doppler velocimetry (LDV) in a low specific speed centrifugal compressor. The ability to acquire non-intrusive flow measurements will provide valuable insight into tip leakage flow, secondary flow, and impeller/diffuser interactions within the centrifugal compressor. The current research facility houses a new low specific speed centrifugal compressor which design is based off a compressor that would be installed as the last stage of a high-pressure compressor.

The LDV optical access has been designed and includes two fused silica windows that are housed in stainless steel …

Optimal Control Of Unknown Nonlinear System From Inputoutput Data, Xin Jin

Open Access Theses

Optimal control designers usually require a plant model to design a controller. The problem is the controller's performance heavily depends on the accuracy of the plant model. However, in many situations, it is very time-consuming to implement the system identification procedure and an accurate structure of a plant model is very difficult to obtain. On the other hand, neuro-fuzzy models with product inference engine, singleton fuzzifier, center average defuzzifier, and Gaussian membership functions can be easily trained by many well-established learning algorithms based on given input-output data pairs. Therefore, this kind of model is used in the current optimal controller …

High Temperature Flooded Expansion For Solar Thermal Power Generation, Nelson Alexander James

Open Access Theses

Even though solar power usage has seen rapid growth over the past decade, fossil fuel generation sources are still generally a less expensive means of producing power. The Liquid-Flooded Ericsson Cycle (LFEC) was investigated as a high efficiency power cycle for reducing the cost of concentrated solar power (CSP) plants and helping to address this cost disparity. High temperature flooded expansion was identified as one of the main challenges in regards to utilizing the LFEC as a power cycle. Thermodynamic models were developed to help assess the performance of the LFEC and a load stand was constructed to test a …

Integration And Implementation Of High-Voltage Energy Storage Sub-System For A Parallel-Through-The-Road Plug-In Hybrid Electric Vehicle, Bilwa A. Jadhav

Open Access Theses

With research showing an alarming rate of increase in global warming and thus causing dangerous instabilities in the weather, a strong push has been initiated to reduce greenhouse gas emissions. Transportation being one of the top offenders in greenhouse gas emissions, has led the drive for improving the efficiency of the modern automobile. One of the current strategies for reducing the emissions produced by the transportation sector is hybrid vehicles powered from both a fuel such as gasoline, diesel, or hydrogen; and electricity. This merger has proven to be effective at decreasing harmful emissions including, carbon dioxide (CO 2 ) …

Fundamental Design Principles Of Novel Mems Based "Landau" Switches, Sensors, And Actuators : Role Of Electrode Geometry And Operation Regime, Ankit Jain

Open Access Dissertations

Microelectromechanical systems (MEMS) are considered as potential candidates for "More-Moore" and "More-than-Moore" applications due to their versatile use as sensors, switches, and actuators. Examples include accelerometers for sensing, RF-MEMS capacitive switches in communication, suspended-gate (SG) FETs in computation, and deformable mirrors in optics. In spite of the wide range of applications of MEMS in diverse fields, one of the major challenges for MEMS is their instability. Instability divides the operation into stable and unstable regimes and poses fundamental challenges for several applications. For example: Tuning range of deformable mirrors is fundamentally limited by pull-in instability, RF-MEMS capacitive switches suffer from …

High Fidelity Simulations Of Electrokinetic Phenomena In Microfluidic Devices, Qian Li

Open Access Dissertations

Electroosmotic flow with electrokinetic effects is the primary method of fluid handling in micro-total analysis systems. Under external applied electric fields, electrokinetic micro-devices allow for innovative functionality in a wide range of microfluidic applications including sample injection, separation, rapid micromixing, and miniaturized chemical and biochemical analysis and detection. This dissertation focuses on simulations of two electrokinetic phenomena, isotachophoresis (ITP) and electrokinetic instability (EKI). A set of coupled governing equations including the incompressible Naiver-Stokes equations, Nernst-Planck transport equations and a charge conservation equation are solved in the simulation. A multiblock in-house solver based on high-order finite difference schemes is developed to …