Doctor of Philosophy, The Ohio State University, 2022, Mechanical Engineering

In electrification applications where lightweighting is a priority, geared drives as opposed to direct drives are preferred. Magnetic gearing, where torque and speed are transferred through magnetic interaction forces, is an alternative to mechanical gearing where the transfer is through physical contact forces. Magnetic gearing is attractive since it offers operation with reduced issues associated with lubrication, noise, and maintenance. The coaxial magnetic gear (CMG) topology currently exhibits the highest specific torque values and is studied in this work in several aspects, including modeling of its torque and efficiency using finite element (FE) and analytical tools in terms of several design parameters such as dimensions, geometric variables defining its configuration, and material properties. Since mechanical quantities are coupled through magnetic fields, the modeling and design of CMGs rely on accurate and efficient electromagnetic models. FE constructs as well as analytical models based on electromagnetic theory are proposed in this work, both in static and dynamic operating conditions. The Jiles- Atherton model is used to represent nonlinear magnetic properties of the flux modulator material. The torque capacity and end effects are investigated in 2-D and 3-D simulations by means of parametric sweeps. The end effects typically reduce the torque capacity of a CMG by 30% and the target in this task is to mitigate this torque loss by presenting the trends and limitations with changing material properties. An analytical study is proposed that predicts the spatial harmonics in the cogging torque profile of a CMG following a 1-D magnetic circuit formulation. The harmonics predicted by this effort will be compared against FE predictions. Two other analytical models based on the subdomain resolution of 2-D electromagnetic diffusion are proposed that will describe 2-D magnetostatic and magnetoquasistatic fields, torque, eddy currents, powe (open full item for complete abstract)

Committee: Marcelo Dapino (Advisor); Jen-Ping Chen (Committee Member); Kiran D'Souza (Committee Member); Ahmet Kahraman (Committee Member) Subjects: Electromagnetics; Mechanical Engineering

Master of Science in Mechanical Engineering, Cleveland State University, 2021, Washkewicz College of Engineering

Recent developments in aircraft propulsion electrification are motivated by economic and environmental factors such as lowering greenhouse gas emissions, reducing noise, and increasing fuel efficiency. This thesis focuses on a hybrid gas-electric propulsion concept combining a gas turbine jet engine with an electromechanical (EM) system. An optimal control system allows energy to be recovered from the gas turbine engine or injected into it from an electric storage unit. Energy extraction or injection can be obtained by selecting a performance weight in the optimization function that trades off fuel consumption with stored electrical energy utilization. The goal of this research is to validate the effectiveness and plausibility of the optimal controller during representative acceleration and deceleration maneuvers and at steady state. To accomplish this, the gas turbine engine dynamics are simulated using NASA's T-MATS package and used in a hardware co-simulation approach along with physical hardware representative of the EM system, namely motors, power converter, and an energy storage device. A time scaling methodology was used to reconcile the power levels of the physical EM system (in the order of a kilowatt) with those of the engine simulation (in the order of megawatts). Multiple steady state missions were represented within a full simulation environment and in the lab test environment that covered a wide range of fuel-electric optimization weights. In addition, a chop-burst study was conducted to ensure the readiness of the system to handle flight missions. Based upon captured data, specifically that of shaft torque, supercapacitor voltage, and fuel flow measurements, it was determined that the optimal control objective was met. An increase in fuel-electric optimization weight corresponded to a desired change in torque to the engine and voltage to the energy storage device.

Committee: Hanz Richter (Advisor); Jerzy Sawicki (Committee Member); Lili Dong (Committee Member) Subjects: Engineering; Mechanical Engineering