Want to improve your presenting skills? Want to show-off your research to your friends and class-mates? Sign up to give a talk at the Fall 2015 Student Lecture Series. Don’t have anything ready to present… not a problem come listen to your classmates discuss their work over pizza and learn by example.

The Student Lecture Series is a student run forum for graduate and BS/MS students from the MAE Department to present their work. The series is designed to provide opportunities for students to develop their technical presentation skills, promote the research of the department, and encourage faculty and student discussions of research. The low stress and informal atmosphere fosters a positive learning environment in which faculty and students of all levels can interact and learn from each other.

If you are interested in presenting at the Student Lecture Series this semester, please submit a title and the desired date and time to the SLS Chairs Mike P. (papageorge.3@osu.edu) or Mike A. (adams.1169@osu.edu). All slots will be filled on a first come first serve basis. Further details, including the format and schedule can be found in the overview and schedule tabs.

Micro-Gas Turbine Thrust Enhancement via Flow Angularity Corrections

By: Nathan Kidder

Noon – 12:30pm E525

Abstract: Low cost micro-gas turbine engines are widely available due to demand from enthusiasts within the model aircraft community. The low cost and ready availability of such engines makes them an attractive choice as power plants for small unmanned aircraft. However, being designed with the hobbyist community in mind, there is substantial room for improvements to be made in overall engine efficiency. This project performed performance enhancements to a commercial micro-gas turbine engine by converting circumferential exhaust momentum to axial through a modified nozzle design. Significant thrust improvements were made and validated via experimentally measured exhaust profiles netting a 55 percent reduction in flow angularity and a 3.8 percent thrust gain on the tested engine.

Biography: Nathan Kidder holds a B.S. in Aerospace Engineering from Ohio State and is currently continuing towards an M.S. under Dr. Jim Gregory in the Aerodynamic Flow Control and Advanced Diagnostics Group working in experimental aerodynamics.

Multiscale Simulation of the Failure Response of Adhesive-Bonded Structural Joints

By: Bowen Liang

11:30 – Noon E525

Abstract: Adhesive bonding enables the joining of thin and dissimilar materials, which is one of the main requirements for manufacturing lightweight structures in the automotive and aerospace industries. However, due to the small thickness and complex microstructure of the adhesive layer, which is often reinforced with embedded heterogeneities to improve its mechanical behavior, simulating the damage evolution in this layer can be challenging. This work implements a computational cohesive model to investigate the effects of microstructural features such as particles volume fraction, pre-existing flaws, and surface roughness of adherends on the failure response of a heterogeneous adhesive with embedded glass particles. The hierarchical interface-enriched finite element method (HIFEM) is implemented as the main computational engine for simulating the initiation and propagation of damage in the adhesive layer. A new virtual prototyping algorithm is also introduced and integrated with the HIFEM to enable the automated construction of realistic models of the adhesive microstructure based on digital data.

Biography: Bowen Liang received his BSE in Mechanical Engineering from Shanghai Jiaotong University. He is currently working towards his Ph.D. in Mechanical Engineering under Dr. Soheil Soghrati in the Automated Computational Mechanics Laboratory; his work focuses on the automated modeling and analysis of microstructural effects on the heterogeneous adhesives.

Probing the effects of interstitial flow and genetic changes on stroma activation in vitro

By: Alex Avendano

12:10 – 12:40pm E525

Abstract: Tumor stroma that surrounds cancer cells and composed of noncancerous cancer cell-types has emerged as a crucial mediator of tumor progression. Essential to the tumor-promoting properties of the stroma is the activation of its cellular constituents through genetic reprogramming. In addition to genetic alterations, tumors are characterized by elevated levels of interstitial flow (IFF). Mechanical stimulation by IFF is a known activator of stromal fibroblasts, which causes these fibroblasts to adapt a contractile phenotype characterized by expression of α-smooth muscle actin (α-SMA) and remodeling and alignment of ECM collagen fibers. Our expertise in the areas of microscale engineering and microfluidics has been employed to design a microphysiological system that allows compartmentalization of fibroblast seeded collagen hydrogels as well as controlled application of varying levels of IFF. Compartmentalization is achieved by utilizing surface tension and capillary effects to trap the cell seeded collagen hydrogel in the middle channel. Application of controlled IFF is achieved by creating a pressure gradient between the lateral flow channels using a syringe pump with adjustable flow rates. The design was fabricated using SU-8 photolithography and soft lithography techniques for Polydimethylsiloxane (PDMS). Reflectance microscopy has also been used along with the CT-FIRE algorithm to visualize and quantify the alignment of individual collagen fibers within fibroblast seeded hydrogels under static conditions.

Biography: Alex Avendano is a second year Ph.D student working in the Microsystems for Mechanobiology and Medicine Laboratory at Ohio State. His research focuses on the use of microfluidics to study how genetic reprogramming and elevated fluid flow within the tumor microenvironment contribute to the progression of cancer. He obtained his undergraduate degree from Iowa State University and is originally from Carolina, Puerto Rico.

Wake Interaction Effects Using a Parallelized Free Vortex Wake Method

By: Kelsey Shaler

Noon – 12:30pm E525

Abstract: Turbine-wake interactions pose significant challenges in the development of optimal wind farm configurations. These interactions can lead to a marked reduction in wind farm power efficiency as well as an increase in structural loading which reduces their functional lifetime. This work aims to develop a moderate fidelity Free Vortex Wake (FVW) model to capture turbine-wake interactions between multiple turbines. Discussed in this talk is the potential usage of the FVW model in turbine-wake interaction studies with a focus on comparisons to the Dynamic Wake Meandering (DWM) wake model.

Biography: Kelsey Shaler received her BSE in mechanical engineering from the University of Maine. She is currently working towards her Ph. D. in mechanical engineering under Dr. Jack McNamara in the Multi-Physics Interaction Research Group; her work focuses on computational models for turbine-wake interactions.

Overcoming the effective medium limitations on thermoelectric composites

By: Michael Adams

Time: 11:30am – noon

Abstract: Composites of semiconductors are often considered as a way to yield high thermoelectric figures of merit. The most constraining limitation in this approach is given by the effective medium theory [1,2]. When one considers a composite made from two thermoelectric materials, A and B, in the absence of interactions between them the thermoelectric figure of merit of the composite cannot exceed that of the highest of the figures of merit of either A or B [1]. However, it is possible for thermoelectric power factor of the composite to exceed the highest of the power factors of either A or B [2]. Here we describe a mechanism that can lift this limitation by treating charge and heat flux differently. Silica beads coated with a conducting shell are inserted into a thermoelectric host. Phonons are scattered by the beads but electrons can pass through the conducting shells. In this talk, we will present the theory first, followed by experimental data demonstrating enhancement of ZT in p-type (Bi,Sb)₂Te₃ for room temperature operation.

Electric Field Vector Measurements in an AC Dielectric Barrier Discharge Overlapped with a Nanosecond Pulse Discharge

By Ben Goldberg

Time: 12:10 – 12:45pm

Time-resolved electric field measurements by picosecond CARS / 4-wave mixing are carried out in a double dielectric barrier discharge in H2 between two plane electrodes covered by quartz plates. The discharge is sustained by an AC voltage waveform, overlapped with nanosecond pulses (peak voltage 9 kV, pulse FWHM 100 ns), generated when the AC voltage is zero and operated at twice the frequency. Measurements taken in the AC discharge without nanosecond pulses show that electric field remains nearly constant during the majority AC discharge period. However, adding nanosecond pulses to the AC waveform results in large-volume breakdown generated every half-period, with a well-reproduced time delay after each pulse. Each of these “regular” AC breakdowns results in significant electric field reduction in the discharge volume. Basically, diffuse plasma produced by a nanosecond pulse neutralizes surface charge accumulated during the AC discharge and generates nearly uniform volume ionization, which results in subsequent large-volume breakdown when the AC voltage is applied. Thus, the results show that combining the AC waveform with nanosecond pulses transforms the AC discharge from a superposition of random, small scale micro-discharges to regular, large volume discharges.

Bio: Ben Goldberg received his B.S. in physics from Ohio State University as well as his M.S. in Mechanical Engineering. Currently, he is working for Dr. Adamovich in the Non-Equilibrium Thermodynamics Laboratory where he is researching electric field development in pulsed nanoseconds discharges with sub-nanoseconds precision.

Recent Advances in Laser Diagnostics Applied to Reacting and Non-Reacting Turbulent Jets

By: Michael Papageorge

Time: Noon – 12:40

Abstract: Laser diagnostics have played a pivotal roll in the experimental study of both reacting and non-reacting turbulent flows. Through the use of lasers measurements have moved away from intrusive physical probes to highly accurate non-obstructive techniques. With the advent of the high-power q-switched laser 2-D imaging of flows has become mainstream allowing for statistical study of a variety of flows and for single shot qualitative analysis. This work however, has lacked a time resolved component for gas-phase flows. With the design of High-Energy Pulse-Burst Laser Systems this hurdle has become overcome. Laser based imaging measurements are now possible with both high spatial and temporal resolution allowing for unprecedented flow dynamics analysis and qualitative observation. This talk will outline several of the measurements made in the Turbulence and Combustion Research Lab utilizing this diagnostic system to highlight the cutting edge of temporally and spatially resolved flow measurements.

Bio: Michael Papageorge received his BSE from Princeton University where he studied hypersonic boundary layers with Dr. Lex Smits.  He is currently working towards his Ph. D. in Mechanical Engineering under Dr. Jeffrey Sutton. His work at OSU has focused on the development and application of advanced laser diagnostic systems for the study of scalar mixing.

Want to improve your presenting skills? Want to show-off your research to your friends and class-mates? Sign up to give a talk at the Fall 2015 Student Lecture Series. Don’t have anything ready to present… not a problem come listen to your classmates discuss their work over pizza and learn by example.

The Student Lecture Series is a student run forum for graduate and BS/MS students from the MAE Department to present their work. The series is designed to provide opportunities for students to develop their technical presentation skills, promote the research of the department, and encourage faculty and student discussions of research. The low stress and informal atmosphere fosters a positive learning environment in which faculty and students of all levels can interact and learn from each other.

If you are interested in presenting at the Student Lecture Series this semester, please submit a title and the desired date and time to the SLS Chairs Mike P. (papageorge.3@osu.edu) or Mike A. (adams.1169@osu.edu). All slots will be filled on a first come first serve basis. Further details, including the format and schedule can be found in the overview and schedule tabs.