Engineering Commons^™

Wind And Thermal Effects On Ground Mounted Photovoltaic (Pv) Panels, Chowdhury Mohammad Jubayer

Electronic Thesis and Dissertation Repository

A combination of Computational Fluid Dynamics (CFD) simulations and wind tunnel experiments are carried out to investigate the effects of wind on the aerodynamic loading and heat transfer of a ground mounted stand-alone photovoltaic (PV) panel with tilt angle of 25^o in open country atmospheric boundary layer. Several azimuthal wind directions are considered: Southern 0^o, Southwest 45^o, Northwest 135^o and Northern 180^o. Three dimensional Reynolds-Averaged Navier-Stokes (RANS) approaches with an unsteady solver using Shear Stress Transport (SST) k-ω turbulence closure are employed for the CFD simulations, whereas Particle Image Velocimetry (PIV) and …

On The Application Of Mechanical Vibration In Robotics-Assisted Soft Tissue Intervention, Iman Khalaji

Electronic Thesis and Dissertation Repository

Mechanical vibration as a way of transmitting energy has been an interesting subject to study. While cyclic oscillation is usually associated with fatigue effect, and hence a detrimental factor in failure of structures and machineries, by controlled transmission of vibration, energy can be transferred from the source to the target. In this thesis, the application of such mechanical vibration in a few surgical procedures is demonstrated.

Three challenges associated with lung cancer diagnosis and treatment are chosen for this purpose, namely, Motion Compensation, tumor targeting in lung Needle Insertion and Soft Tissue Dissection:

1. A robotic solution is proposed …

Design Of A Haptic Interface For Medical Applications Using Magneto-Rheological Fluid Based Actuators, Nima Najmaei

Electronic Thesis and Dissertation Repository

This thesis reports on the design, construction, and evaluation of a prototype two degrees-of-freedom (DOF) haptic interface, which takes advantage of Magneto-Rheological Fluid (MRF) based clutches for actuation. Haptic information provides important cues in teleoperated systems and enables the user to feel the interaction with a remote or virtual environment during teleoperation. The two main objectives in designing a haptic interface are stability and transparency. Indeed, deficiencies in these factors in haptics-enabled telerobotic systems has the introduction of haptics in medical environments where safety and reliability are prime considerations. An actuator with poor dynamics, high inertia, large size, and heavy …

Numerical Modeling Of Deformation, Oscillation, Spreading And Collision Characteristics Of Droplets In An Electric Field, Osameh Ghazian

Electronic Thesis and Dissertation Repository

Electric field induced flows, or electrohydrodynamics (EHD), have been promising in many fast-growing technologies, where droplet movement and deformation can be controlled to enhance heat transfer and mass transport. Several complex EHD problems existing in many applications were investigated in this thesis.

Firstly, this thesis presents the results of numerical simulations of the deformation, oscillation and breakup of a weakly conducting droplet suspended in an ambient medium with higher conductivity. It is the first time that the deformation of such a droplet was investigated numerically in a 3D configuration. We have determined three types of behavior for the droplets, which …

Studies In Small Scale Thermal Convection, Daniel F. Stranges

Electronic Thesis and Dissertation Repository

The effect of non-Fourier heat transfer and partial-slip boundary conditions in Rayleigh-Bénard are analyzed theoretically. Non-Fourier fluids possess a relaxation time that reflects the delay in the response of the heat flux to a change in the temperature gradient while the partial slip boundary condition assumes that the fluid velocity and temperature are not equal to that of the wall. Both non-Fourier and partial-slip effects become important when small-scale heat transfer applications are investigated such as convection around micro- and nano-devices as suggested by the extended heat transport equations from kinetic theory. Other applications are also known to exhibit one …

Digital Generation And Radiation In Spherical-Void-Phase Porous Media, Nolan J. Dyck

Electronic Thesis and Dissertation Repository

This thesis documents a novel method for method to generate digital samples of spherical void phase foams to predict effective hydraulic, thermal and radiative properties with the intention of assessing the viability of carbon foam as a volumetric solar receiver. The method employs discrete element modeling software to simulate the compression of spherical bubbles into a fully periodic, cubic domain. These domains were subsequently used to determine a variety of effective transport properties to be used in porous media design problems. The predicted properties agreed well with those obtained through experimental and other numerical methods, notably predicting more accurate properties …

Thermal Convection Of Non-Fourier Fluids, Rahim Mohammadhasani Khorasany

Electronic Thesis and Dissertation Repository

The natural convection of non-Fourier fluids of the dual-phase-lagging (DPL) type is examined. These fluids possess a relaxation time and a retardation time, reflecting the delay in the response of the heat flux and the temperature gradient with respect to one another. DPL fluids span a wide range of applications, including low-temperature liquids, fluids subjected to fast heat transfer processes, and nanofluids (NFs), for which both the relaxation and retardation times are expressed in terms of nanoparticle concentration and solution properties. Both stationary and oscillatory convection become equally probable as the relaxation time increases. A nonlinear spectral approach is also …

Structural Response Analyses Of Piezoelectric Composites Using Nurbs, Vijairaj Raj

Electronic Thesis and Dissertation Repository

Variational method deduced on the basis of the minimum potential energy is an efficient method to find solutions for complex engineering problems. In structural mechanics, the potential energy comprises strain energy, kinetic energy and the work done by external actions. To obtain these, the displacement are required as a priori. This research is concerned with the development of a numerical method based on variational principles to analyze piezoelectric composite plates and solids. A Non-Uniform Rational B-Spline (NURBS) function is used for describing both the geometry and electromechanical displacement fields. Two dimensional plate models are formulated according to the first order …

Surface Modification Of Aluminum Alloys By Plasma Electrolytic Oxidation, Vahid Dehnavi

Electronic Thesis and Dissertation Repository

Plasma Electrolytic Oxidation (PEO) is a surface treatment for the production of ceramic oxide coatings with great properties, such as high wear and corrosion resistance, on metal substrates, particularly aluminum and magnesium alloys. Formation of PEO coatings involves complex processes and mechanisms that are difficult to study. Currently, the PEO process is in a transition phase from research to commercial application, with a primary focus on the corrosion and wear protection of light alloys, and has recently generated interest as a promising surface treatment for biomedical applications.

To justify the industrial application of PEO, a more systematic and in-depth study …

Experimental Study Of Two-Phase Flow In A Liquid Cross-Flow And An Effervescent Atomizer, Mona Hassanzadeh Jobehdar

Electronic Thesis and Dissertation Repository

Effervescent atomization uses the internal gas-liquid mixture to produce spray. The behavior of two-phase flow inside the atomizer influences the spray characteristics and is dependent on the atomizer internal geometry and operating conditions. The present study is conducted in two parts; study of the bubble formation from a novel submerged nozzle in a liquid cross-flow and investigation of the internal and external two-phase flows in an effervescent atomizer.

The present study investigated the performance of a novel nozzle developed by Gadallah and Siddiqui (2013) in the liquid cross-flow. The impact of the nozzle shape, its configurations and orientations was experimentally …

The Effects Of Oar-Shaft Stiffness And Length On Rowing Biomechanics, Brock Laschowski

Electronic Thesis and Dissertation Repository

This work investigates the effects of oar-shaft stiffness and length on rowing biomechanics. The mechanical properties of the oar-shafts were examined using an end-loaded cantilever system, and theoretical relations were proposed between the mechanics of the oar-shafts and rowing performance. On-water experiments were subsequently conducted and rowing biomechanics measured via the PowerLine Rowing Instrumentation System. The PowerLine system measures force and oar angle on the oarlock, as well as proper boat acceleration. The convergent validity and test-retest reliability of the PowerLine force measurements were determined prior to the on-water experiments. Thereafter, rowers were tested over a set distance using oar-shafts …

Uncertainty Quantification For A Class Of Mems-Based Vibratory Angular Rate Sensors, Nujhat Abedin

Electronic Thesis and Dissertation Repository

Numerical schemes that are suitable for predicting response statistics of mass-spring and ring gyroscopes are developed when this class of vibratory gyroscopes are subjected to certain system parameters as well as environment uncertainties. The emphasis is placed on the steady-state part of the response since it is more critical to the operation of a gyroscope. A peak-picking approach which simulates the demodulation process which is used in practice is employed first before applying the Monte Carlo simulation method to predict the response statistics. A number of simulation trials to predict response statistics have been performed for mass-spring and ring-type gyroscopes …

Numerical Analysis Of Two Phase Flow And Heat Transfer In Condensers, Pooya Mirzabeygi

Electronic Thesis and Dissertation Repository

Steam surface condensers are commonly used in the power generation industry and their performance significantly affects the efficiency of the power plant. Therefore, it is vital to acquire a better understanding of the complex phenomena occurring inside condensers. A general three-dimensional numerical model is developed in this study to simulate the two-phase flow and heat transfer inside full-scale industrial condensers with irregular tube bundle shapes. The Eulerian-Eulerian two-phase model is selected to simulate gas and liquid flows and the interaction between them. A porous media approach is adopted to model the presence of large number of tubes in the condenser. …

Influence Of Approach Flow Conditions On Urban Street Canyon Flow, Karin Blackman

Electronic Thesis and Dissertation Repository

The turbulent flow within a street canyon and the approaching boundary layer has been studied using idealized wind tunnel models and a semi-idealized field experiment conducted in Nantes, France. The effect of upstream roughness on street canyon flow (lateral length/height, L/h = 30) using either 3D (cube) or 2D (rectangular block) upstream roughness, of the same height as the canyon, has been studied for two streamwise canyon width to height aspect ratios (AR) of 1 and 3 using Particle Image Velocimetry. A further wind tunnel model of equivalent geometry to the field experiment was used to compare with flow data …

A Cfd Assisted Control System Design For Supercritical Water Cooled Reactor, Rohit V. Maitri

Electronic Thesis and Dissertation Repository

In this study, the methodology to construct a control system based on computational fluid dynamics (CFD) simulations is developed for supercritical water cooled reactor (SCWR). The CFD model using Reynolds Stress Model (RSM) and k-w SST model is validated with the experimental cases of steady state and vertically up flowing supercritical water in circular tubes for normal heat transfer and deteriorated heat transfer (DHT) cases. This model is extended to simulate the transient thermal-hydraulic behaviour of supercritical fluid flow and heat transfer, and the results are also compared with the 1-D numerical model, THRUST. The DHT phenomenon is investigated using …

Mechanistic Failure Criterion For Unidirectional And Random Fibre Polymer Composites, Jamaloddin Jamali

Electronic Thesis and Dissertation Repository

Polymer composite design in energy absorbing components requires a failure criterion that can predict the energy involved in its fracture under different modes of loading. Present mixed mode criteria are mainly empirical or semi-empirical, and are only suitable for a small range of composite types.

The purpose of this study was to develop a mechanistic failure criterion that is applicable to a wide range of polymer composites. An energy based mechanistic failure criterion is proposed to characterize the toughness of unidirectional (UD) and randomly oriented short fibre composites (random fibre composites).

In UD and random composites, the criterion predicts the …

Numerical Simulation On Dilute Phase Pneumatic Transport, Ethan T. Doan

Electronic Thesis and Dissertation Repository

Pneumatic conveying is a technique that is widely used in many industrial mechanical and chemical applications. In the case of cement manufacturing pneumatic conveying is a large scale operation moving several kilograms of material per second which consumes electrical energy (operation of fans) and money (replacement of filters to remove particles from the air). At St Mary’s Cement the pneumatic conveying line was studied with a CFD model. The treatment of the secondary solid phase was done with the DPM formulation in ANSYS Fluent and turbulence was modelled with k-ω SST. It was found that simple geometric alterations to the …

Effects Of Surface Topographies On Heat And Fluid Flows, Hadi Vafadar Moradi

Electronic Thesis and Dissertation Repository

Responses of annular and planar flows to the introduction of grooves on the bounding surfaces have been analyzed. The required spectral algorithms based on the Fourier and Chebyshev expansions have been developed. The difficulties associated with the irregularities of the physical domain have been overcome using either the immersed boundary conditions (IBC) concept or the domain transformation method (DT).

Steady flows in annuli bounded by walls with longitudinal grooves have been studied. Analysis of pressure losses showed that the groove-induced changes can be represented as a superposition of a pressure drop due to a change in the average position of …