Mechanical Engineering Commons^™

Modeling And Simulation Of A Supercritical Co2-Liquid Sodium Compact Heat Exchanger For Sodium Fast Reactors, Hailei Wang, Sean M. Kissick

Mechanical and Aerospace Engineering Faculty Publications

The study focuses on modeling and simulations of sodium-sCO2 intermediary compact heat exchangers for sodium-cooled fast reactors (SFR). A simplified 1-D analytical model was developed in companion with a 3-D CFD model. Using classic heat transfer correlations for Nusselt number, some simulation results using the 1-D model have achieved reasonable match with the CFD simulation results for longer channels (i.e., 40 cm and 80 cm). However, for short channel (10 cm) when axial conduction within the sodium fluid is significant, the 1-D model significantly over-predicted the heat transfer effectiveness. By incorporating the temperature-jump model, the 1-D model can extend its …

Theoretical Modeling Of Heat And Mass Transfer Processes In Phase Change And Electrochemical Energy Storage Systems, Mohammad Parhizi

Mechanical and Aerospace Engineering Dissertations - Archive

Theoretical understanding of heat and mass transfer processes in energy storage and conversion devices is of much interest for a wide variety of engineering applications. Two commonly used mechanisms for energy storage are electrochemical energy storage, such as in Li-ion cells, and phase change based energy storage, such as in phase change materials (PCM). Previous studies show that heat and mass transfer in both PCMs and Li-ion cells are critical processes affecting the performance and safety of these systems. This dissertation investigates several theoretical aspects of heat and mass transfer in these energy storage systems, with the goal of improving …

Finite Element Based Methodology To Predict Fatigue Compression Failure In Composite Based On Fiber Kinking Damage Model, Md Saddam Hossain

Mechanical and Aerospace Engineering Dissertations - Archive

Advanced polymer matrix composites are widely used in designing high-performance and lightweight spacecraft, rotorcraft, and automotive structures, due to its superior performance such as specific stiffness, specific strength, and toughness, which are appealing in reducing the weight of these structures. One critical factor that limits the efficient design of structures composed of fiber-reinforced composites (FRP) is the vulnerability of the material under compression loading since compressive strength of FRP material is typically a lot less compared to the tensile strength. Moreover, composite structure may undergo compression loading either by accidentally or by deliberately, large margins of safety are usually imposed …

A Scaling Investigation Of Feasibility And Hover Endurance For Electric Quasi Quadrotor Configurations, Budhyant Venepalli

Mechanical and Aerospace Engineering Dissertations - Archive

Motivated by recent developments in distributed propulsion electric vehicles, an effort is made in the present study to numerically investigate the upper bound of hover endurance achievable by electric quasi-quadrotors at various mass scales in the range of 0.1 kg to 10000 kg total vehicle mass. A feasible rotor propulsion pod design space is determined considering physics-based conceptual design constraints defined by blade tip Mach number and Reynolds number to ensure effective and energy-efficient generation of lift. A conceptual level scaling optimization for two-bladed rotor quasi-quadrotors was carried out at constant blade tip speed. A momentum theory model, a blade …

A Molecular Scale Study Of Cavitation Growth And Shock Response In Soft Materials, Khandakar Mahmud

Mechanical and Aerospace Engineering Dissertations - Archive

Cavitation is a mechanism through which small vapor-filled cavities are formed in a liquid medium due to rapid changes of pressure. In liquid, the cavitation bubble is created when surrounding pressure drops below the saturation vapor pressure. Here, cavitation formation due to shock wave is considered. The molecular level heterogeneous and homogenous cavitation mechanisms and bubble growth kinetics in soft gelatin hydrogel and water has been studied. Gelatin, which is derived from collagen, is frequently used as a brain simulant material. As such, the morphology of gelatin is very different from water. In the heterogeneous cavitation study, using molecular dynamics …

Experimental And Numerical Study Of Open Bath Immersion Cooling Of Microprocessors., Amirreza Niazmand

Mechanical and Aerospace Engineering Dissertations - Archive

The increase on demand of communication and networking has resulted to increase for more powerful servers and bigger data centers. With increase the power of electronics, thermal management and cooling of the equipment become a gigantic challenge due to lower surface, they have higher power density and traditional methods of cooling become ineffective. Generally, air cooling method is the first option for cooling of the electronics due to cheaper price. To increase the efficiency and capacity of cooling liquid immersion cooling is used due to higher thermal properties like heat capacity and thermal conductivity compare to air. Two methods of …

Hypoid Gear Noise And Vibration Control In Automotive Rear Axle Systems, Chia-Ching Lin

Mechanical and Aerospace Engineering Dissertations - Archive

Gear whine is a key issue for the vehicle powertrain system, and the design of a quiet, reliable driveline system is highly desirable for the automotive industry. From past studies, the main source of excitation for gear vibration and noise is the transmission error (TE), which generates the dynamic mesh force between the gear teeth. Then the vibration transmits through the flexible axle components and radiates off from the surface of the axle housing structure. The dynamic responses of the hypoid geared rotor system in the rear axle have a significant effect on the performance of noise, vibration, and harshness …

A Multiscale Study Of Cavitation Mechanism And Damage In Soft Materials, Fuad Hasan

Mechanical and Aerospace Engineering Dissertations - Archive

Cavitation is defined as the formation and growth of the gaseous bubble in bulk liquid due to the tensile pressure followed by the violent collapse. The collapse of the bubble is particularly significant due to its potential to cause damage to relatively stronger materials by either creating pressure waves (symmetric collapse) or liquid jet (asymmetric collapse). The study of cavitation in soft materials (e.g., tissue, brain, gelatin gel, etc.) has, therefore, gained a fair share of attention in the scientific communities. Recent studies have indicated that cavitation could be one of the leading causes of the mild Traumatic Brain Injury …

Molecular Level Mechanical Properties Of Ultra High Temperature Ceramics And Their Nanocomposites, Md Riaz Kayser

Mechanical and Aerospace Engineering Dissertations - Archive

Ultra High-Temperature Ceramics (UHTC) have been of great interest in the spacecraft, aerospace, and aeronautic industry due to their high melting point and their potential application as a protective material for the stagnation areas of leading edges. In this work, the effect of nanoparticle reinforcement for achieving tailored mechanical properties of UHTC’s has been studied. Two different material systems have been considered, namely the ZrB2-based and the HfO2-based nanocomposites. In the first study, the grain boundary driven mechanical behavior of polycrystalline ZrB2 and ZrC-ZrB2 nanocomposites using large-scale molecular dynamics simulations have been performed. The atomistic models of polycrystalline ZrB2 and …

Reliability Enhancement Of Heterogeneous 3d Integrated Circuit And Characterization Of Thermal Interface Material, A S M Raufur Chowdhury

Mechanical and Aerospace Engineering Dissertations - Archive

Electronic products require high functional integration in small footprints with lower cost. At the same time, it is required to maintain effective communication between the IC’s and the electronic systems. Various challenges are arising due to these factors such as signal processing time, heat dissipation, structural integrity, chip package interaction which need to be dealt effectively during electronic packaging. 3D stacking of the processors and the components accomplishes these goals and in high computing application it reduces the delay. Through-silicon via (TSV) is the heart of 3D integration, and the stacking of chips is emerging now as a powerful tool …

Experimental Investigation Of Effect Of Support Structure Geometry On The Microstructure And Metallurgical Properties Of In718 Parts Fabricated By Selective Laser Melting, Sourabh Hemant Thakare

Mechanical and Aerospace Engineering Theses - Archive

Additive Manufacturing is a modern manufacturing technique that provides extreme design freedom and the ability to manufacture multiple parts with high complexities at the same time. Various fabrication techniques have been developed, and this study focuses on selective laser melting (SLM) due to its ability to provide near-perfect parts at low cost while being able to work with a wide range of materials. In SLM, the part is manufactured, layer-by-layer, by melting and solidification of powder material under controlled inert conditions. The fabrication of complex geometries is not possible without proper allocation of support structures for the part, which keeps …

Experimental Investigation Of Laser Scan Strategy On The Microstructure, Mechanical Properties And Residual Stress Of Inconel 718 Parts Fabricated By Selective Laser Melting, Kiriti Mamidi

Mechanical and Aerospace Engineering Theses - Archive

Inconel 718 (IN718) is a nickel-based superalloy which exhibits excellent tensile and impact resistant properties along with good corrosion resistance at high temperatures. However, due to the high toughness and work hardening, the machinability of this superalloy is low. Therefore, the selective laser melting (SLM) process has been adopted as an efficient technique to fabricate IN718 parts as it overcomes the problems associated with conventional manufacturing of superalloys. SLM is a widely used additive manufacturing technique which offers the possibility to induce multi-functionality into a single component, and thus reduce the number of components that are needed. In the SLM …

Numerical Analysis Of Immersion Cooling On A Server Using Al2o3/Mineral Oil Nanofluid, Prajwal Srinivas Murthy

Mechanical and Aerospace Engineering Theses - Archive

In the current world, technology has developed significantly, with a massive processing and storage of data, resulting in the high increase in Power Density and Heat Generation of servers, computers and its components in data centers. This calls for an engineering solution, for efficient heat dissipation of these servers to ensure their reliability and prolonged working. Air cooling is a prominent method of data center cooling. However, due to its low heat carrying capacity, it is not an efficient method for cooling high heat generating servers. There are two methods to remove this heat, increasing the area of heat transfer …

Optimum Design Of Shimmed Foil Bearing Considering Rotordynamic Stability, Venkata Sai Jyothish Atluri

Mechanical and Aerospace Engineering Theses - Archive

Air foil bearing technology has made substantial development in the past years and has found its applications in high speed turbomachinery. Yet the rotordynamic instability has still been a persisting issue in the single pad air foil bearings. The single pad bearing can resolve this issue by using large clearance with the shaft but the large clearance requires large impeller tip clearance which is not ideal. Multi pad air foil bearings with non-uniform clearance distribution can be used to improve the rotodynamic stability, but the three pad bearings have inferior load capacities due to the less angular length of each …

Attraction, Transport And Release Of Water Fleas’ Ephippia For Migration, Xiang Wang

Mechanical and Aerospace Engineering Dissertations - Archive

Planktonic crustaceans of the genus Daphnia live in aquatic environments. Although they are lack of walking and flying capabilities, they have developed adaptations that facilitate the dispersal of their dormant forms, ephippia to cross terrestrial barriers and reach neighborhood waterbodies. It increases the survival rate of their species. A possible way for this spread to occur is the transport of their ephippia through waterfowls’ legs. Yet, little is known about the key role of the legs in the dispersal and the main mechanisms. The ephippia first get attached to the waterfowls’ legs. The waterfowls may then carry these ephippia to …

Investigation Of The Impact Of Material Models On Reliability Assessment Of Electronic Packages, Abel Misrak

Mechanical and Aerospace Engineering Dissertations - Archive

Drop testing, thermal cycling, power cycling, etc. are some of the tests used to assess the reliability of new electronic products. However, performing experimental study of every new design is costly and time consuming. Computational tools are often employed to perform the required reliability analysis in a shorter time period and save valuable resources. Extensive set of material characterization work needs to be done before an accurate material model can be developed and used in computational analysis. Structural components such as printed circuit boards (PCBs) are critical in the thermomechanical reliability assessment of electronic packages. The bulk material properties of …

Sub-Modelling Approach For Computationally Efficient Thermal Simulations Of Large Li-Ion Battery Packs, Vishnu V. Ganesan

Mechanical and Aerospace Engineering Theses - Archive

Accurate and rapid prediction of temperature distribution in a large Li-ion battery pack comprising thousands of cells is critical for ensuring safety and performance of battery packs for electric vehicles (EVs). Due to the multiscale geometry and the large number of individual cells in an EV battery pack, full-scale thermal simulations typically take a long time to complete. Approaches for rapidly computing the temperature field in a large battery pack without significant loss of accuracy is, therefore, a key technological need. This paper presents thermal simulations of a large, air-cooled Li-ion battery pack containing thousands of individual cells using the …

Correlation And Effect Of Process Parameters On The Properties Of Inconel 718 Parts Fabricated By Selective Laser Melting Using Response Surface Method, Bharath Bhushan Ravichander

Mechanical and Aerospace Engineering Theses - Archive

Inconel 718 (i.e., IN718) is a nickel-based superalloy that exhibits outstanding tensile and impact-resistant properties, along with good high-temperature corrosion resistance. However, the machinability is poor due to the high stiffness of IN718. Therefore, additive manufacturing provides an effective solution to overcome the work hardening. Selective laser melting (SLM) is the most common powder-bed additive manufacturing technique designed to use a high power-density laser to melt and fuse the metallic powder to fabricate functional parts with high accuracy. However, the accuracy and the functional properties of the fabricated parts are greatly dependent on the process parameters. Thus, depending on the …

Mechanism Of Compaction With Wrinkle Formation During Automatic Stitching Of Dry Fabrics And The Size Effect Of Compression Molded Discontinuous Fiber-Reinforced Composites, Anibal Benjamin Beltran Laredo

Mechanical & Aerospace Engineering Theses & Dissertations

With an ever-increasing demand for composites, more ways of manufacturing them are becoming popular and widely used. Stitching of dry fabrics is an efficient method for improving delamination resistance. Discontinuous fiber reinforced composites can be used as a lightweight alternative material for metals through a process of compression molding, which allows for complex shape manufacturing while offering structural grade mechanical properties.

This study demonstrates how the stitching of dry fabrics can be adapted to more complex surfaces. The consequences of stitching of curvilinear surfaces can result in defect formation. Therefore, to understand the physical formation of possible defects, experimental characterization …

Analysis Of Body And Tail Of A Flapping Drone, Yuan Chai

Student Works (2020-2029)

The Micro Aerial Vehicle (MAV) is a kind of unmanned aerial vehicle with a small size, which has a unique performance that larger aircrafts do not have. MAV can fly in confined spaces and perform hover, forward flight, etc. The flapping wing micro aerial vehicle is one type of flight imitates the insects (birds), which can fly based on the flapping wing. Compared with fixed-wing aircraft, the flapping wing micro aerial vehicle (FWMAV) has a smaller volume, lighter weight, and higher flight efficiency. FWMAV can be largely used in military and civil applications. In this project, the flapping drone is …

Fluid Flow Analysis Of Low-Altitute Agricultural Uav Pesticide Spraying Device, Dan Han

Student Works (2020-2029)

The nozzle is an important part of the drone pesticide spraying device. The quality of the nozzle directly affects the atomization performance. Fan nozzles are widely used in the field of plant protection in agriculture, forestry, pest control, and weed removal. When using drones to spray pesticides, the spraying velocity, the spraying range of the pesticides, and the atomized particle size are all key factors that directly affect the efficiency of pesticide use. This paper uses SOLIDWORKS and ANSYS software to design and simulate. The boundary conditions are kept the same, and the influence of the nozzle's grooving angle (α), …

Analysis Of One Way Valve Mechanism For Wings Of A Flapping Drone, Xinchen Deng

Student Works (2020-2029)

The flapping drone is one type of MAVs which is defined as a miniature unmanned aerial vehicle that is inspired by flying birds and insects. Flapping wings can make a perfect combination of thrust and lift by flapping up and down with full usage of unsteady air. The flapping drone has the advantages of high maneuverability and a special lift generation mechanism. Compared with rotary-wing or fixed-wing MAV, it is smaller, lighter, and has higher flight performance. It can quickly change the flight direction and flight speed by control the flapping frequency and it is the only flight mode that …

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 …

Low-Cost Reaction Wheel Design For Cubesat Applications, Nicholas J. Bonafede Jr.

Master's Theses

As science instruments on CubeSats become more sensitive to the attitude of the spacecraft, better methods must be employed to provide the accuracy needed to complete the planned mission. While systems that provide the accuracy required are available commercially, these solutions are not cost-effective, do not allow the design to be tailored to a specific mission, and most importantly, do not give students hand-on experience with attitude control actuators. This thesis documents the design, modeling, and simulation of a low-cost, student-fabricated, reaction wheel system for use in 3U CubeSat satellites. The entire design process for the development of this reaction …

Dynamic Effects Of Inertial Particles On The Wake Recovery Of A Model Wind Turbine, Sarah E. Smith

Dissertations and Theses

Impacting particles such as rain, dust, and other debris can have devastating structural effects on wind turbines, but little is known about the interaction of such debris within turbine wakes. This study aims to characterize behavior of inertial particles within the turbulent wake of a wind turbine and relative effects on wake recovery. Here a model wind turbine is subjected to varied two-phase inflow conditions, with wind as the carrier fluid (Re_λ = 49 - 88) and polydisperse water droplets (26 to 45µm in diameter) at varied concentrations (Φ_v=0.24 x 10^-5 - 1.3 …

Droplet Ejections During Wet Lab Operations Aboard Spacecraft, Caleb Cushman Turner

Dissertations and Theses

The breakup and rupture of liquid bridges, thin films, bubbles, droplets, rivulets, and jets can produce satellite droplets that are subsequently ejected into their surrounding environment. For example, when any solid object is withdrawn from a liquid bath, the formation of an ever-thinning columnar liquid bridge eventually ruptures along the axis of the bridge. When rupture occurs under typical pipetting conditions the dynamics governing the rupture almost always produce at a minimum a satellite droplet. When these droplets occur they are often too small and too fast to be observed by the human eye. In a terrestrial environment they are …

Improving Thermal Conduction Across Cathode/Electrolyte Interfaces In Solid-State Lithium-Ion Batteries By Hierarchical Hydrogen-Bond Network, Jinlong He, Lin Zhang, Ling Liu

Mechanical and Aerospace Engineering Student Publications and Presentations

Effective thermal management is an important issue to ensure safety and performance of lithium-ion batteries. Fast heat removal is highly desired but has been obstructed by the high thermal resistance across cathode/electrolyte interface. In this study, self-assembled monolayers (SAMs) are used as the vibrational mediator to tune interfacial thermal conductance between an electrode, lithium cobalt oxide (LCO), and a solid state electrolyte, polyethylene oxide (PEO). Embedded at the LCO/PEO interface, SAMs are specially designed to form hierarchical hydrogen-bond (H-bond) network with PEO. Molecular dynamics simulations demonstrate that all SAM-decorated interfaces show enhanced thermal conductance and dominated by H-bonds types. The …

Distributed Adaptive State Estimation And Tracking Scheme For Nonlinear Systems Using Active Passive Sensor Networks, Akhilesh Raj, S. Jagannathan, Tansel Yucelen

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel adaptive neural network (NN) based distributed state estimation scheme for a heterogeneous sensor network (HSN), to estimate the state vector of an unknown nonlinear process/target by using sensed output when the target input remains unknown. The active nodes in the HSN can sense the target output based on the detection range. By using a connected graph, the active nodes will communicate their estimated state vector from their adaptive NN observer to other passive nodes in the neighborhood that cannot sense the target, so that they can estimate the target state vector. Next, a subset of …

Numerical Method For Rapid Aerostructural Design And Optimization, Jeffrey D. Taylor, Douglas F. Hunsaker

Mechanical and Aerospace Engineering Student Publications and Presentations

During early phases of wing design, analytic and low-fidelity methods are often used to identify promising design concepts. In many cases, solutions obtained using these methods provide intuition about the design space that is not easily obtained using higher-fidelity methods. This is especially true for aerostructural design. However, many analytic and low-fidelity aerostructural solutions are limited in application to wings with specific planforms and weight distributions. Here, a numerical method for minimizing induced drag with structural constraints is presented that uses approximations that apply to wings with arbitrary planforms and weight distributions. The method is applied to the NASA Ikhana …

Vibration Isolation System, Bradley Y. Kwan, Bailey Groh, Max Wu, Nicole Yen

Mechanical Engineering

The Vibration Isolation System Senior Project is a collaborative group project between its sponsor, Maxar Technologies, and a team of students from Cal Poly - SLO to effectively design, manufacture, and test a structural assembly for satellites, isolating vibrations during launch and orbit conditions. After initial sponsor contact, requirements and needs were set which dictated deliverables for the senior project group. The group performed analyses to validate all design decisions, including a modified concept and design direction, selection of a prototype viscoelastic damping material, preliminary testing to validate design specifications, and detailed design and analysis toward a finalized design. Instead …