Master of Science in Aerospace Systems Engineering (MSASE), Wright State University, 2021, Mechanical Engineering

The dual-plane airfoil has been adopted in the design of aircraft wings, wind turbine blades, and propellers. The purpose of this research is to investigate the most important design parameters of a dual-plane airfoil model for the best aerodynamic performance, such as gap, stagger, and decalage. The dual-plane airfoil model was designed using the S826 profile. A mechanical mechanism with electrical actuator control is particularly designed to alter the gap and stagger smoothly, as well as the angle of attack (AOA) for each airfoil. It results in a gap range of 1.38c to 2.17c, a stagger range of -0.75c to 1.75c (c is the chord length), an AOA range of -10 to 20 degrees. The decalage angles of 0, 1, and 2 degrees are adopted in the tests for AOA=12 degrees. A low-speed open-circuit wind tunnel at Wright State University is used for the experiment at two Reynolds numbers, 𝑅𝑒=60000, and 𝑅𝑒=100000, respectively. Both airfoils are equipped with 21 pressure tap holes around the airfoil in the middle section. Pressure distribution data around the airfoil is sampled at a rate of 400 Hertz using the DSA 3217 Pressure Scanner. The collected data is processed to calculate the pressure coefficient on the surface of both airfoils. The pressure distribution profiles are generated and compared at various gaps, staggers, and decalages. Lift and drag coefficients are calculated by integrating the pressure distribution over the airfoil. It has been found that both stagger and gap have a significant effect on the pressure distribution at AOA of 12 degrees for the bottom airfoil. A gap ranges from 1.38c to 1.57c can suppress the separation and increase the lift coefficient of the top airfoil at various staggers and decalages. A stagger of 1.75c and negative staggers at a gap of 1.38c can suppress the separation and increase the lift coefficient of the bottom airfoil. Due to boundary layer separation, negative staggers are not effective for 𝑅𝑒=60000. The decalage effect is distinct at (open full item for complete abstract)

Committee: Zifeng Yang Ph.D. (Advisor); Jim Menart Ph.D. (Committee Member); Junghsen Lieh Ph.D. (Committee Member) Subjects: Aerospace Engineering; Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2016, Biomedical Engineering

Volume overload (VO) induced heart failure results from an increase in blood volume (preload) to the heart. The heart responds to increases in hemodynamic load through compensative remodeling. VO has a distinct pattern of remodeling compared to pressure overload induced heart failure, which results in fibrosis. VO results in a net decrease in extracellular matrix (ECM). This loss of ECM contributes to the progression of the disease due to the loss of structural integrity. Since cardiac fibroblasts (CFs) are the main cells responsible for maintaining ECM in the heart, we characterized the in vitro phenotype of CFs isolated from a rat VO model, aortocaval fistula (ACF). Compared to sham operated animals, ACF fibroblasts displayed a phenotype that we described as “hypofibrotic”. ACF CFs secreted relatively less collagen and profibrotic molecules, such as a-smooth muscle actin (aSMA) and connective tissue growth factor (CTGF). Interestingly, ACFs produce approximately twice as much transforming growth factor-ß1 (TGF-ß), a key profibrotic stimulus, as their sham counterparts. However, there were no changes in the canonical TGF-ß pathway that could account for the hypofibrotic phenotype observed in ACF fibroblasts. Since others have shown that the cytoskeleton and the Rho/ROCK pathway play a role in fibroblast phenotype, we characterized the actin cytoskeleton in sham and ACF fibroblasts. We found that ACF CFs have significantly less F-actin than sham CFs. We were able to show that it is possible the actin cytoskeleton might account for phenotypic differences in CFs by chemically altering the amounts of F-actin and G-actin. When the cells were treated with a ROCK inhibitor, which allows F-actin to depolymerize into G-actin, CFs displayed a more hypofibrotic phenotype. Conversely, enhancement of F-actin with jasplakinolide treatment forced the CFs to have a profibrotic phenotype. Numerous studies have linked substrate modulus with effects on the cytoskeleton. S (open full item for complete abstract)

Committee: Keith Gooch PhD (Advisor); Jun Liu PhD (Committee Member); Pamela Lucchesi PhD (Committee Member); Aaron Trask PhD (Committee Member) Subjects: Biomedical Engineering

Master of Science, The Ohio State University, 2011, Mechanical Engineering

A new diesel engine control strategy has been developed. In order to successfully validate and implement this control strategy experimental design techniques were used which optimize the data collection process. This included the setup of cylinder pressure measurements as well as the creation of an automating testing program. This program automates engine testing, interfacing with key components such as the dynamometer and engine controller (ECU). Both steady state and transient testing algorithms were developed. Several advanced analysis techniques have been developed for the project. A combustion noise algorithm was created which uses cylinder pressure signals. An in depth study on pegging cylinder pressure was completed, utilizing GT Power©. GT Power© was also used to analyze an experimental design to simulate altitude at sea level in the test cell.

Committee: Giorgio Rizzoni PhD (Advisor); Shawn Midlam-Mohler PhD (Committee Member); Yann Guezennec PhD (Committee Member) Subjects: Automotive Engineering; Engineering; Mechanical Engineering