Aerospace Engineering Commons^™

Computational Study Of Air-Cooled Servers With Improved Ducting And Chassis Re-Design, Himanshu Girishchandra Modi

Mechanical and Aerospace Engineering Theses - Archive

In recent years there has been a phenomenal increase in cloud computing, net-working, virtualization, and storage which has led to an increase in demand for data centers. To meet this demand, there is a need for the latest computing nodes which causes an increase in power consumption. The cooling system occupy almost 40% portion of total energy consumption. Per ASHRAE TC 9.9, IT equipment needs to operate within recommended and allowable temperatures and humidity zone based on the circumstances. As the inlet air temperature increases, fan power consumption increases too and the Central Processing Units (CPUs) and high heat-generating components …

Experimental Study Of Dynamic Cooling Of Racks Using Flow Control Devices, Fnu Akash

Mechanical and Aerospace Engineering Theses - Archive

A data center is a cluster of multiple servers that a company uses to store and process large amounts of data. Due to never-ending demands, the processor densities are increasing every day. A higher processor density would result in the servers heating up more than it would normally creating a need for an efficient cooling system. On an average a water-cooled system would consume up to 40% of the total power required by a data center. Studies are being conducted on improving the overall efficiency of the system by either improving the thermal properties of the system or by improving …

Modeling, Fabrication, And Characterization Of Porous Inconel 718 Structures Using Selective Laser Melting Process, Srihari Srivathsan

Mechanical and Aerospace Engineering Theses - Archive

Bio-inspired cellular structures are of great interest these days for many applications, from engineering research to industries. Honeycomb, Body-Centered Cubic with/without Z-struts (BCC-Z/ BCC), Face Centered Cubic with/without Z-struts (FCC-Z/ FCC), and Triply Periodic Minimal Surface (TPMS) such as Gyroid, Diamond, and Schwartz lattices are the most common bio-inspired lattice structures. These structures can be tailored based on their structural organization resulting in superior materials with lightweight properties, adequate strength, and low stiffness. Thankfully, additive manufacturing (AM) has made the fabrication of these complex cellular materials realistic. However, the use of AM could lead to several defects, such as damaged …

Cfd Analysis On Liquid Cooled Cold Plate Using Copper Nanoparticles, Sarthak Agarwal

Mechanical and Aerospace Engineering Theses - Archive

In today’s world, most data centres have multiple racks with numerous servers in each of them. The high amount of heat dissipation has become the largest server-level cooling problem for the data centres. The higher dissipation required, the higher is the total energy required to run the data centre. Although still the most widely used cooling methodology, air cooling has reached its cooling capabilities especially for High-Performance Computing data centres. Liquid-cooled servers have several advantages over their air-cooled counterparts, primarily of which are high thermal mass, lower maintenance and eventually lower costs by maintenance by labour. Nano-fluids have been used …

Prediction And Validation Of Continuous Fiber Stiffened Plates Manufactured With Continuous Fiber Fabrication, Nabeel Ahmed Khan

Mechanical and Aerospace Engineering Theses - Archive

The purpose of this thesis was to develop an analytical method for predicting the structural properties of continuous fiber stiffened plates, which was then validated both experimentally and via finite element analysis. The MarkForged Mark Two 3D printer enables parts to be printed with continuous carbon fibers embedded within them. A manufacturing process was developed for printing stiffened grids with our without skins, with continuous fiber reinforcement on the top and bottom of the stiffening ribs, which allows bending stiffness can be maximized. An orthotropic grid was printed using Continues Filament Fabrication (CFF), an additive manufacturing process that embeds reinforcing …

Impact Of Viscoelastic Properties Of Low Loss Printed Circuit Boards (Pcbs) On Reliability Of Wcsp Packages Under Drop Test, Akshay Boovanahally Lakshminarayana

Mechanical and Aerospace Engineering Theses - Archive

Reliability of electronic packages is a major concern as different failure modes are induced due to factors such as temperature loads, mechanical stresses, humidity, corrosion and so on. Finite element analysis (FEA) is often performed to assess reliability under different loading conditions such as thermal cycling, drop testing, power cycling and vibrational loads. Having accurate material property data is one of the key requirements to perform successful FEA study, and a significant amount of time and money is spent to perform accurate material characterizations. Lump modeling approach, where components are represented by a block and assigned effective properties, is commonly …

Measurement Of Change In Cte Of Pcbs Due To Single Phase Immersion Cooling And Impact Of Changed Properties Of Pcbs On Solder Joint Reliability Of Bga Package, Sameer Hemant Dhandarphale

Mechanical and Aerospace Engineering Theses - Archive

Oil immersion cooling in high-density data centers is emerging as an alternative for traditional air cooling because of the less power consumption, capacity to handle high power density and less space requirement. To adopt this technique extensively, effect of immersion on reliability of server components in dielectric coolant needs to be evaluated. One of the major reliability concerns in BGA package is 2nd level solder joint failure. The primary reason of solder joint failure is CTE mismatch between the PCB and the package. Also, difference in stiffness of the PCB and the package affects the solder joint reliability. As properties …

Aerodynamic Interactions Of Synchronized Propellers, Nathan Welker, Samuel Johnson

Utah Space Grant Consortium

Emerging advances in electric-propulsion technology are enabling aircraft to use distributed electric propulsion (DEP) to increase efficiency and maneuverability. Distributed electric propulsion can also provide unique take-off and landing abilities which are not commonly found on traditional aircraft. The implementation of DEP effectively decreases the spacing between propellers, introducing complex aerodynamic interactions that are not well understood. This study aims to obtain experimental measurements of the flow fields of synchronized propellers at close-proximity in a side-by-side configuration using particle image velocimetry (PIV) in a wind tunnel. The results of this work will be focused on identifying the impact closely-spaced propellers …

Monte-Carlo Methods And The Step-Back Kalman Filter For Orbital State Estimation, Louis Tonc

Utah Space Grant Consortium

This research assesses the performance of filtering schemes for tracking uncooperative satellites through space-based optical measurements, and identifies a simple and numerically stable methodology that ameliorates the poor performance of standard filtering schemes at a substantially reduced cost in comparison to nonlinear particle filter-based remedies. Traditional filtering schemes, such as the extended Kalman filter (EKF) and unscented Kalman filter (UKF), both diverge when tracking a resident space object (RSO) in geosynchronous orbit (GEO) when there is a long time duration between measurements. This divergence is identified as a consequence of nonlinearity in the dynamics and nonlinearity in the optical measurements, …

Post-Impact Flexural Behavior Of Carbon-Aramid/Epoxy Hybrid Composites, A. Wagih, T. A. Sebaey, A. Yudhanto, G. Lubineau

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Hybrid polymeric composites are currently used in aerospace structures due to their specific strength and stiffness as well as larger design space. This paper presents an experimental study on residual flexural strength of impacted Carbon-aramid/Epoxy hybrid composite laminates. Specimens are designed in a sandwich form in which plies of aramid/epoxy represent the core and carbon/epoxy plies play the role of face sheets. This design is expected to take advantage of the high energy absorption capabilities of aramid/epoxy composites. We pre-damage such composites by performing low-velocity impact at different energy levels. Three-point bending tests then are used to measure the residual …

On The Advantages Of The Disabled In Space., Samantha R. Timmers

College of Arts & Sciences Senior Theses

Since the start of the astronaut program in the 1960s, candidates have had to prove to be in prime physical shape before being granted clearance to fly, whereas those with physical disabilities such as blindness or deafness are automatically disqualified. The stigma that disabled persons are less qualified to succeed in a physically alien environment has persisted, though little research exists in revisiting the difficulties posed by allowing this group into the space program. This paper aims to reconsider the advantages and disadvantages of a disability-friendly space program, to include cost considerations, potential challenges, and the unique benefits posed by …

Design Optimization Of An Elastically Supported Multi-Beam Rotordynamic System To Minimize Flexural Response With Considerations For Robustness, Bret R. Hauser

Mechanical and Aerospace Engineering Dissertations - Archive

Modern rotating machines are often required to operate with a small physical footprint and/or overall weight; necessitating that they utilize wide-ranging shaft speed to accomplish needed power levels. It is not uncommon that these designs also be required to support operation through a speed range encompassing multiple Critical Speeds while also limiting flexural vibrations to acceptable levels. Design optimization of this class of problem can be particularly difficult in that responses can be highly multi-modal and, when coupled with Finite Element (FE) solvers meet the conditions of a High Dimensional, Computationally Expensive Black Box (HEB) system. Because of this, some …

Towards Gross-Pitaevskiian Description Of Solar System & Galaxies, Florentin Smarandache, Victor Christianto, Yunita Umniyati

Branch Mathematics and Statistics Faculty and Staff Publications

In this paper, we argue that Gross-Pitaevskii model can be a more complete description of both solar system and spiral galaxies, especially taking into account the nature of chirality and vortices in galaxies. We also hope to bring out some correspondence among existing models, e.g., the topological vortex approach, Burgers equation in the light of KAM theory, and the Cantorian Navier-Stokes approach. We hope further investigation can be done around this line of approach.

Active Drag Reduction Of Ground Vehicles Using Air-Jet Wheel Deflectors, Kaloki Nabutola

Doctoral Dissertations and Master's Theses

Seven turbulence models were used to simulate the flow within the wheelhouse of a simplified vehicle body. The performance of each model was evaluated by comparing the aerodynamic coefficients obtained using computational fluid dynamics (CFD) to data collected from wind tunnel experiments. The performance of large eddy simulation (LES) and detached eddy simulation (DES) was largely dependent on the time step and grid size to accurately resolve turbulent eddies. The standard k-e, realizable k-e, k-w, DES, and LES all trended towards a drag coefficient which was 20% lower than the experimental value. In all numerical cases, the lift coefficient was …

Analysis Of Local Convection Heat Transfer Rates Of Supercritical Carbon Dioxide In Tubes, Yang Chao

Doctoral Dissertations and Master's Theses

Numerical investigation on thermodynamic characteristics of pure supercritical carbon dioxide (𝑆𝐶𝑂2) and mixtures of Helium and 𝑆𝐶𝑂2 in horizontal straight tubes with diameter of 6mm under cooling and heating conditions is carried out by using SST 𝑘 − 𝜔 turbulence model. The computations are conducted at operating pressure of 8MPa with various operating conditions. Simulations are conducted by using the latest poly-hexcore mesh method in ANSYS FLUENT 19.2 and tetrahedral mesh method in CFX 19.2, results and solving time are compared. The effect of heat flux, mass flux, inlet temperature and buoyancy on heat transfer performance are studied, pressure drop …

Dmd And Pod Modal Analysis For Store Separation, Nicholas Peters

Doctoral Dissertations and Master's Theses

Store separation from aircraft and spacecraft has historically been a critical and in some cases fatal issue for the aerospace industry. Given the severity of the issue much effort has been spent on the development of processes to identify failure flight conditions for store separation. The processes currently used for identifying potential failure conditions however are both resource intensive and iterative processes. A potential remedy to reducing resource use and improve turn around time in this process is the implementation of a mode based reduced order model (ROM) for modeling store separation. The objective of this study was to first …

Unsteady Internal Ballistics Of A Hybrid Rocket, Naveen Sri Uddanti

Doctoral Dissertations and Master's Theses

With the recent progress made in the field of space tourism, hybrid rocket engines have gained a renewed interest due to their simplicity, low cost, operational flexibility, and safety. The flow in the ports of a hybrid rocket motor involves several coupled unsteady phenomena like moving walls, combustion in a boundary layer flow and mass addition along the port, through the regression of the solid fuel wall. The flow in the combustion chamber of a hybrid rocket is inherently unsteady because the geometry of the port varies as a function of space and time. In the current research, we develop …

Viscoplastic Study Of 3d Printed Carbon Fiber Composites, Alexander M. Seifans

Doctoral Dissertations and Master's Theses

The research presented here involves an attempt to model the viscoplastic response of 3D printed carbon fiber composites made using the Mark Two 3D printer by Markforged. The ability to manufacture composites through the use of 3D printers is relatively new and contains gaps in the various mechanical properties of the material, of interest is the viscoplastic response.

Due to the fabrication method, the properties of the composites cannot be assumed to be similar to that of conventionally made composites as the fused deposition in printing alters the material properties. In order to understand the effects of the printed fiber …

Shape Optimization Of Microfiber Composite Energy Harvesters, Suyash Lahoti

Doctoral Dissertations and Master's Theses

A model of energy harvesting beam with a piezoelectric material, microfiber composite (MFC), in a unimorph configuration was setup in Matlab using the governing equations of motions of a coupled electromechanical system. The equations of motion were derived using Hamilton’s variational principles and constitutive relations of a piezoelectric material. The mathematical model developed in Matlab was validated with an experiment and frequency response functions. The validated model was used to perform shape optimization so as to obtain the shape of the beam and the patch that harvests the largest voltage. The shape variables were length of the beam (LB), length …

Discrete Vortex Modeling Of Aerodynamic Flutter Of A Flat Plate With Damped Oscillations, Emma Chao

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aerodynamic flutter is the unstable oscillation of a body caused by the interaction of aerodynamic forces, structural elasticity, and inertial effects induced by vortex shedding. Current models of this phenomenon require finite element analysis and extensive computational power and processing time. The purpose of this study was to develop and validate a program that is faster and more efficient than existing approaches by using the discrete vortex method (DVM). By reducing the complexities of flutter to the shedding of vortices in an inviscid model of a two-dimensional flat plate with a torsional spring constant at its center, this phenomenon can …