Engineering Commons^™

Thermal Efficiency Analysis On Lean Burn Spark Ignition Engine, Joshua Patrick Jayaseelan

Electronic Theses and Dissertations

Advanced spark ignition (SI) engines can operate under lean conditions in order to improve the efficiency and reduce the emissions. Under extensive lean conditions, the ignition and complete combustion of the charge mixture is a challenge, because of the reduced cylinder charge reactivity, leading to combustion instabilities, thus making the empirical investigations in the vicinity of and beyond the lean limit of current engines, unviable. With further improvements to the ignition and combustion control, the lean operation limit may be extended in future engines. To circumvent this limitation to an extent, in this work, the potential of extremely lean mixtures …

A Data-Driven Approach Using Long-Short Term Memory For Fault Prognosis And Remaining Useful Life Estimation Of Satellite Reaction Wheel, Md Sirajul Islam

Electronic Theses and Dissertations

Artificial satellites are objects or a body that are stationed in the orbit of another object. The purpose of artificial satellites includes monitoring, information transfer, studying a different planet, space exploration, and fulfilling many other modern-day needs. For the increased demand, the number of artificial satellites revolving around the earth is also increasing. Due to cost efficiency, bulk manufacturing capability, and ease to launch in the orbits, small satellites are the topic of interest. Reaction wheels are widely used in the attitude control system of small satellites. Unfortunately, reaction wheels failure restricts the efficacy of a satellite, and it is …

Finite Element Analysis Of Surface Hardening Treatments Of Steels For Automotive Powertrain Applications, Filippo Jones

Electronic Theses and Dissertations

Surface hardening is a procedure that is usually performed on steel components, in order to impart in these the strength and surface hardness that are necessary for their correct operation, whilst maintaining a reasonable value of ductility in the overall component.

The latter is usually composed of a sequence of heat treatments: carburizing, quenching and tempering. Each of these have different effects that, if correctly combined, can lead to the desired final mechanical properties in the component.

Carburizing is a process that increases the amount of carbon concentration at the component surface. Quenching is a quick decrease in temperature that …

Quantification Of Velocity At The Sparkplug In A Lab Scale Combustion Chamber, Mayur Panduranga Kodikal

Electronic Theses and Dissertations

Lean burn has been considered an effective strategy to improve the thermal efficiency of spark-ignition engines. Under lean or diluted conditions, however, the combustion speed is reduced. Therefore, to speed up the combustion, in-cylinder turbulence is induced which may impede the spark initiation. This research aims to quantify the turbulence in a constant volume optical combustion chamber.

An Improved Delayed Detached Eddy Simulation (IDDES) study was done to understand the turbulence characteristics of the flow in the optical chamber. Spark anemometry was used to obtain a relationship between the spark plasma evolution and freestream velocity. Finally, this technique has been …

Reaction Wheels Fault Isolation Onboard 3-Axis Controlled Satellite Using Enhanced Random Forest With Multidomain Features, Mofiyinoluwa Oluwatobi Folami

Electronic Theses and Dissertations

With the increasing number of satellite launches throughout the years, it is only natural that an interest in the safety and monitoring of these systems would increase as well. However, as a system becomes more complex it becomes difficult to generate a high-fidelity model that accurately describes all the system components. With such constraints using data-driven approaches becomes a more feasible option. One of the most commonly used actuators in spacecraft is known as the reaction wheel. If these reaction wheels are not maintained or monitored, it could result in mission failure and unwarranted costs. That is why fault detection …

Development Of Superior Energy Absorbing Devices With Adaptive Capabilities Utilizing Hybrid Cutting/Clamping Deformation Modes, John Magliaro

Electronic Theses and Dissertations

The primary objective of this research was to investigate cutting deformation modes, employing higher-bladed cutters (i.e. 6 or more evenly space blades), with an emphasis on superior energy absorbing capabilities in comparison to axial crushing, the current state-of-the-art. A series of test cases involving AA6061 extrusions were identified utilizing analytical models of the steady-state cutting force and mean crushing force and selecting geometries where the ratio of the former force normalized with respect to the latter exceeded unity. Quasi-static testing confirmed that the total energy absorbing capacity could be exceeded while simultaneously reducing the peak force under quasi-static loading for …

Development Of Superior Energy Absorbing Devices With Adaptive Capabilities Utilizing Hybrid Cutting/Clamping Deformation Modes, John Magliaro

Electronic Theses and Dissertations

The primary objective of this research was to investigate cutting deformation modes, employing higher-bladed cutters (i.e. 6 or more evenly space blades), with an emphasis on superior energy absorbing capabilities in comparison to axial crushing, the current state-of-the-art. A series of test cases involving AA6061 extrusions were identified utilizing analytical models of the steady-state cutting force and mean crushing force and selecting geometries where the ratio of the former force normalized with respect to the latter exceeded unity. Quasi-static testing confirmed that the total energy absorbing capacity could be exceeded while simultaneously reducing the peak force under quasi-static loading for …

Development Of A Stochastic Reactor Model Network Towards Combustion Systems, Nupur Gupta

Electronic Theses and Dissertations

Due to their negative health implications, the reduction of emissions from combustion processes is imperative. In order to reduce emissions, predicting and understanding their thermo-chemical formation in different types of combustion systems are necessary. Modern combustion systems, such as internal combustion engines and gas turbine engines, require innovative numerical methodologies that aid in the understanding of underlying chemical kinetics and mixing time-scales, all while being computationally inexpensive. However, current inclusive methodologies for predicting emissions and ignition events rely on computationally expensive computational fluid dynamics. The main objective of this thesis is to present a newly developed stochastic reactor model network …

Numerical Studies On Liquid Water Transport In Pemfc Cathode With Biomimetic Flow Field Designs, Duy-Khang Dang

Electronic Theses and Dissertations

The performance and durability of proton exchange membrane fuel cells (PEMFCs) are greatly influenced by their water management capability. Therefore, novel flow field designs have been developing by researchers for the improvement of PEMFCs. Among those designs, novel biomimetic designs or so-called nature-inspired designs have captured special attention from researchers due to their capability of distributing fluids effectively with their prominent characteristics such as low pressure drops and efficient fluid distribution. This thesis presents a numerical investigation of the liquid water transport in PEMFC cathode with various biomimetic flow field designs. It includes a symmetrical biomimetic flow field design based …

Predictive Model Of Air Dam Deflection Under Aerodynamic Loads, Chang Kyun Kang

Electronic Theses and Dissertations

Plastic components are widely used on the exterior body of automotive vehicles. When the vehicle is moving, these components experience deformation caused by air flow. Simultaneously, the deformation affects the flow of air around the vehicle. This research is focused on developing virtual simulation techniques for determining the vehicle air dam behaviour under aerodynamic loads. The main objective of this research is to develop a fluid-structure interaction (FSI) methodology for predicting deflection of the air dam.

Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) codes are coupled so that fluid pressure and air dam displacement parameters are exchanged. The …

Optimization Of Chemical Compositions Of Al-Si-Cu-Ni-Sr Alloys With High Strengths And Electrical Conductivities, Yuxian Li

Electronic Theses and Dissertations

Mechanical strengths and electrical conductivity are the very important engineering properties of lightweight metallic materials used in the automotive industry, especially for battery-powered electric vehicles (BEV). However, the main issue is that high strength and high electrical conductivity are mutually exclusive due to physical nature of these properties. The aim of this study is to develop new cast aluminum alloys for the production of rotor bar in the rotor with high as-cast strength and electrical conductivity. A design of experiment (DOE) technique, Taguchi method, was used to develop high as-cast strength and electrical conductivity alloys with various element addition of …

The Impact Of High Voltage Electrode Diameter On Spark Discharge Process, Jiaming Zhang

Electronic Theses and Dissertations

The ever-growing demands to meet the exhaust emission regulations and fuel economy requirements, drive the development of modern spark ignition (SI) engines towards lean or diluted conditions at boosted intake pressure and with intensified charge motions. Boosted in-cylinder pressure conditions require additional energy to initiate the spark discharge, thereby challenging the ignition system. Additionally, the geometry of the spark plug has a profound influence on the spark discharge characteristics. The main objective of this research is to study the impact of high voltage electrode diameter on breakdown voltage and equivalent spark gap resistance at elevated background pressures (1-25 bar abs.). …

Pseudo-Zero Velocity Re-Detection Double Threshold Zero-Velocity Update Method For Inertial Sensor-Based Pedestrian, Tianyi Zhao

Electronic Theses and Dissertations

Zero-velocity update method is widely used in inertial measurement unit based pedestrian navigation systems for mitigating sensor drifting error. In the basic pedestrian dead reckoning system, especially in a foot-tie PDR system, zero-velocity update method and a Kalman filter are two core algorithms. In the basic PDR system, ZUPT usually uses a single threshold to judge the gait of pedestrians. A single threshold, however, makes ZUPT unable to accurately judge the gait of pedestrians in different road conditions. In this thesis paper, we propose a new, redesigned zero-velocity update method without using additional equipment and filter algorithms to further improve …

Development Of A Pneumatically Controllable Microdroplet Generator With Electrical Sensing, Gnanesh Nagesh

Electronic Theses and Dissertations

Microfluidic droplet generation is popular in lab-on-a-chip based biochemical analysis because it can provide precise and high throughput fluids in the form of small droplets. This thesis presents a T-junction microdroplet generator with pneumatic actuation for regulating droplet size and a capacitance-based sensor with real-time sensing capability for characterizing droplet composition and size. The multi-layer device developed in this thesis is compatible with rapid manufacturing using a desktop-based laser cutter to fabricate the fluidic and pneumatic layers. A finite element based numerical model was developed to predict the best operating and geometric parameters for droplet generation. It was revealed that …

Interfacial Heat Transfer In Squeeze Casting Of Cast Al Alloy A380 And Mg Alloy Az91 And Wrought Alloy Az31, Luyang Ren

Electronic Theses and Dissertations

The weight reduction of vehicles and airplanes in the automotive and aerospace industries is urgently needed due to the government regulation and market demand. To satisfy engineering performance of lightweight auto and aero components, high strength light alloys such as aluminum (Al) or magnesium (Mg) alloys are usually adopted. This study was intended to explore a solution for casting high strength cast and wrought Al and Mg alloys. Before light alloys can be utilized for mass production, critical processing parameters need to be accurately determined. The interfacial heat transfer coefficient is one of the most important factors in casting processes. …

Heat And Fluid Flow Downstream Of A Row Of Finite-Height Circular Cylinders, Saarah Akhand

Major Papers

Induced turbulence created by a row of finite height cylinders is applicable in different engineering applications, e.g., for promoting convective cooling of solar panel. In this study, flow past a row of 13 side-by-side finite-height circular cylinders having a height-diameter (h/d) ratio of 2 (20mm/10mm) and center to center distance between adjacent cylinders (g) of 2d was scrutinized at a Reynolds number based on cylinder height of 4700 inside a wind tunnel over a flat plate. The flow at 5h and 10h downstream of the cylinder array was characterized using a 2-d hot wire anemometer. To understand the convective heat …

Exergy Analysis Of A Small-Scale Trigenerative Compressed Air Energy Storage System, Raghuveera Sai Sarath Dittakavi

Major Papers

Trigenerative compressed air energy storage (T-CAES) capitalizes on the heat of the compression process, something that is often wasted in more conventional CAES approaches. A T-CAES system with a 4-kW compressor and 2-kW turbine is thermodynamically analyzed in this study. Exergy analyses performed on each component in the system identify specific areas for improvement. It is found that, under actual conditions, more than half of the total exergy destruction is caused by the accumulator and about a quarter of the destruction is caused by the pressure regulator and turbine. Further, the pressure regulator, accumulator and turbine offer 66%, 27% and …

Advanced Exergy Analysis Of A Whispergen Stirling Engine System, Akash Mathew

Major Papers

With the increasing demand for energy, it has become imperative to look for better and more efficient systems. Combined heat and power systems can provide the required power output while also utilizing the waste heat to increase the overall efficiency of the system. This study analyzed a 1 kW WhisperGen Combined Heat and Power system powered by a Stirling engine. A thermodynamic analysis of the engine was performed to understand the losses occurring within it. In addition, the WhisperGen engine was analyzed in terms of its exergy losses through an advanced exergy analysis on the different components of the engine. …

Enhancing Flat Plate Heat Convection Using A Pair Of Winglets – The Effect Of Transverse Spacing, Siddharth Koushik Mohanakrishnan

Major Papers

We can manipulate the prevailing atmospheric wind to enhance the convective cooling of a solar photovoltaic panel and thus its energy conversion efficiency. The transverse spacing (D) of a delta winglet pair was examined for its role in convective heat transfer enhancement. A pair of winglets with an inclination angle of 90° and chord/height (c/h) ratio of 2 was positioned at an attack angle of 30° with respect to incoming wind at a Reynolds number, based on the winglet height, of 6300. The transverse distance, D, was varied from 0 to 3h in 1 …

Comparative Investigations From Tribological And Corrosion Properties Of Alumina And Nickel-Alumina Coatings On Cast Iron, Jiayi Sun

Electronic Theses and Dissertations

Plasma Electrolytic Aluminating (PEA) Alumina coating on cast iron has a high wear/ corrosion resistance, but porous structure could cause pitting corrosion. Nickel is a widely used anti-corrosion material, but the wear resistance of nickel could still be developed. To explore advantages and disadvantages of combination of these two materials, electroless Nickel plating was applied on PEA Alumina coating. Electroless plated Ni grew from the interface of the alumina coating and cast iron and then sealed the micropores of the alumina coating in a nickel acetate bath, which could protect cast iron substrate from the pitting corrosion. In addition, some …

Design Of High Stability Superhydrophobic Surfaces, Shuo Wang

Major Papers

In the recent two decades, superhydrophobic surfaces' properties and their potential applications have attracted much attention. With the main advantages of self-cleaning, anti-icing, and drag-reduction, the superhydrophobic surfaces can be applied to many industry fields. But the traditional fabrication methods developed in the last twenty years for the superhydrophobic surfaces were focusing on mimicking nature. Specifically, most of the fabrication methods were based on the micro, and nano-scale structure of plants and animals, which came with the problems that such weeny structure on the surfaces would be damaged easily in the practical application without the self-healing capability like the creatures …

Development And Testing The Properties Of Hybrid Composite Using Aluminium 6061 With Tic And Graphene, Nishanth Pasupathy

Major Papers

Aluminum is more widely employed metal in industries due to its advantageous characteristics. But there are some limitations in the usage of aluminum which can be resolved by developing composites with reinforcement. So, AMMC is gaining more recognition in the industrial sector with regards to its mechanical behavior and possess good thermal conductance. Aluminum based MMC reinforced with TiC and graphene particles were developed successfully by two step stir casting. Two step stir casting was incorporated to overcome the disadvantages of the traditional stir casting technique that results in increased porosity and agglomeration which results in the non-homogeneous distribution of …