Engineering Mechanics Commons^™

Emission Reduction In Small Displacement Diesel Engines Using Cooled Exhaust Gas Recirculation, Chris Simoson

All Theses

A reduced-order dynamic model is presented and experimentally validated to demonstrate the use of cooled exhaust gas recirculation to alleviate the tradeoff between nitric oxide reduction and performance preservation in a small displacement diesel engine. Exhaust gas recirculation (EGR) is an effective method for internal combustion engine oxides of nitrogen (NOx) reduction, but its thermal throttling diminishes power efficiency. The capacity to cool exhaust gases prior to merging with intake air may achieve the desired pollutant effect while minimizing engine performance losses.
Simulation and experimental results revealed significant NOx reductions throughout all testing scenarios using EGR, but also experienced a …

Modeling Of The Transient Behavior Of Heat Pipes With Room-Temperature Working Fluids, Pascal Brocheny

All Dissertations

The heat pipe is a capillary-driven and two-phase flow device, capable of transporting and converting large amounts of energy with minimal losses. As a means of thermal management, uses of heat pipe technology not only include thermal control of satellites and spacecrafts in aerospace applications, but also the cooling of electronic components for ground applications. Recently, there has been a flourishing interest in exploring the use of heat pipe technology in the automotive field. However, in many thermal control applications, heat pipes using room-temperature working fluids, such as water or ammonia, with operating temperatures between 200 K (-73ºC) and 550 …

Simulation And Characterization Of Tire Nonuniformity-Induced Steering Nibble Vibrations Through Integrated Subsystems Modeling, Derek Mangun

All Theses

Periodic force variations produced by nonuniform tire/wheel assemblies are known root causes of torsional steering wheel vibrations known as 'nibble'. Previous studies have sought to investigate this issue through modeling or experimentation involving the entire vehicle or specific subsystems, however a direct link between objectively measured tire force variations and the vibration levels perceived by vehicle occupants has yet to be established. Analytical models of a nonuniform tire, double-wishbone suspension system, and rack and pinion steering system are sourced from literature and integrated into a single subsystem-level model validated against experimental data obtained as part of a collaborative effort. The …

A Robust Conjugate Heat Transfer Methodology With Novel Turbulence Modeling Applied To Internally-Cooled Gas Turbine Airfoils, William York

All Dissertations

Computational fluid dynamics and heat transfer (CFD) has become a viable, physics-based analysis tool for complex flow and/or heat transfer problems in recent years due, in large part, to rapid advances in computing power. CFD based on the Reynolds-averaged Navier-Stokes (RANS) equations is starting to enter the mainstream design environment in certain industries where rapid and reliable predictive capability is necessary. One such application is the gas turbine industry, where thermal management of airfoils at extremely high temperatures is one of the most critical components in engine design for reliability. The problem is complicated by the need for advanced airfoil …

Investigation Of The Effects Of Subgrid-Scale Turbulence On Resolvable-Scale Statistics, Qinglin Chen

All Dissertations

The effects of the subgrid-scale (SGS) turbulence on the resolvable-scale statistics and the effects of SGS models on large-eddy simulation (LES) are studied. It is shown that the SGS turbulence evolves the resolvable-scale joint probability density function (JPDF) through the conditional means of the SGS stress, the SGS scalar flux, and their production rate, which must be reproduced by the SGS model for LES to predict correctly the one-point resolvable-scale statistics, a primary goal of LES. This necessary condition is used as the basis for studying SGS physics and for testing SGS models. Theoretical predictions, measurements data obtained in a …

Modeling And Simulation Of Friction-Limited Continuously Variable Transmissions, Nilabh Srivastava

All Dissertations

Over the last few decades, a lot of research effort has increasingly been directed towards developing vehicle transmissions that accomplish the government imperatives of increased vehicle efficiency and lower exhaust (greenhouse gaseous) emissions. These exhaust emissions can be regulated or lowered by increasing the fuel economy of a vehicle, and CVTs (continuously variable transmissions), indubitably, play a crucial role in this plan to improve the fuel economy. A continuously variable transmission is an emerging automotive transmission technology that offers a continuum of gear ratios between desired limits. A CVT offers numerous advantages over the conventional multi-step gear transmissions such as …

The Effects Of Viscoelastic Behavior On The Operation Of A Delayed Resonator Vibration Absorber, John Cowans

All Theses

Delayed resonators have proven to be effective vibration absorbers (VAs) for tracking and canceling the effects of harmonic excitations on a structure. The Delayed Resonator (DR) is selfcontained, as no information from outside of its substructure is required for proper operation. It adjusts for variations in frequency using time-delay and gain as control parameters.
This thesis examines the relationship between viscoelastic (VE) loss mechanisms in systems with DR and the choice of modeling method used to calculate control parameters and determine system stability. It is hypothesized that a VE loss mechanism approximated by a single viscous dashpot may lead to …

Internal Combustion Engine Cooling Strategies: Theory And Test, John Chastain

All Theses

Advanced internal combustion engine thermal management systems can enhance overall engine performance through the use of computer controlled cooling system actuators. Existing ground vehicle cooling systems generally have performance limitations due to the fixed behavior of the wax-based thermostat valve and crankshaft dependent operation of the coolant pump and radiator fan. Upgrading the traditional thermostat valve, water pump, and radiator fan with actuators permit real time computer control for improved temperature tracking and reduced power consumption. In this paper, the benefits associated with advanced automotive cooling systems are experimentally investigated. A 4.6L engine with a real-time data acquisition and control …

Statistical Interpretation Of Mohr-Coulomb Theory As Applied To Fracture In Brittle Materials Containing Cracks, Mudit J. Monsi

Mechanical & Aerospace Engineering Theses & Dissertations

Fracture in brittle materials containing pre-existing cracks was studied. The probability of of crack growth under both shear and tensile stresses was determined for an arbitrary distribution of crack sizes. Two different crack orientation distributions, random and uniform, as well as friction were also taken into account. The material's reliability was assumed to depend on the number of active cracks at a particular stress level, and this was expressed as an arbitrary 2-parameter Weibull distribution. Two new and efficient methods for calculating crack growth probabilities based on spherical triangles and spherical caps were developed. They utilized normalized stress coordinates and …

Socio-Economic Impacts Of Computer Viruses In Tanzania, M Victor

Tanzania Journal of Engineering and Technology (TJET)

This paper reports on a research project conducted with an objective of identifying and assessing various approaches used by different computer users (Management, System Administrators and end users) in Tanzania to combat computer viruses (CVs), and to assess users' awareness level on CVs. Specifically, the study aimed at assessing the awareness level on CVs to the Tanzanian business community; analyze the socio -economic impact caused by CVs in Tanzania and; assess existing methods, capacity and limitations on controlling CVs in Tanzania. Data was collected using both questionnaires and interview from financial institutions such as NBC and BOT, and telecommunications sector …

Experimental And Finite Element Analysis Of Preloaded Bolted Joints Under Impact Loading, Brendan O'Toole, Kumarswamy Karpanan, Masoud Feghhi

Mechanical Engineering Faculty Research

One of the primary parameters in analyzing bolted joints is preload in the bolt. We have considered several possible preload modeling techniques to analyze the effect of preload on the dynamic response of the bolted joints. Five different methods of applying preload in the nonlinear finite element analysis are evaluated. These methods are “force on bolt and nut”, “force on bolt shank”, “interference fit”, “thermal gradient” and “initial stress method”. Explicit and implicit analyses are used for transient response and preload generation in bolt respectively. Time history and shock response spectrum are used to compare experimental and simulation results. Simulation …

Energy Efficient Process Heating: Managing Air Flow, Kevin Carpenter, J. Kelly Kissock

Mechanical and Aerospace Engineering Faculty Publications

Much energy is lost through excess air flow in and out of process heating equipment. Energy saving opportunities from managing air flow include minimizing combustion air, preheating combustion air, minimizing ventilation air, and reconfiguring openings to reduce leakage.

This paper identifies these opportunities and presents methods to quantify potential energy savings from implementing these energy-savings measures. Case study examples are used to demonstrate the methods and the potential energy savings.The method for calculating savings from minimizing combustion air accounts for improvement in efficiency from increased combustion temperature and decreased combustion gas mass flow rate.

The method for calculating savings from …

Me-Em 2006 Annual Report, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering Annual Reports

Table of Contents

• Overview, Mission, and Vision
• Comments on the Strategic Plan
• Enrollment, Degrees, and Expenditure Data
• External Advisory Board
• Faculty and Staff
• Students
• Alumni
• Resources
• Graduates
• Publications

Response To "Comment On Variational Approach To The Volume Viscosity Of Fluids" [Phys. Fluids 18, 109101 (2006)], Allen J. Zuckerwar, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

We respond to the Comment of Markus Scholle and therewith revise our material entropy constraint to account for the production of entropy. (c) 2006 American Institute of Physics.

Variational Approach To The Volume Viscosity Of Fluids, Allan J. Zuckerwar, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

The variational principle of Hamilton is applied to develop an analytical formulation to describe the volume viscosity in fluids. The procedure described here differs from those used in the past in that a dissipative process is represented by the chemical affinity and progress variable (sometimes called "order parameter") of a reacting species. These state variables appear in the variational integral in two places: first, in the expression for the internal energy, and second, in a subsidiary condition accounting for the conservation of the reacting species. As a result of the variational procedure, two dissipative terms appear in the Navier-Stokes equation. …