Master of Sciences, Case Western Reserve University, 2018, Physics

Boundary Labs, LLC is an early-stage company composed of three students at Case Western Reserve University which aimed to evaluate the feasibility of commercialization of a novel dielectric barrier discharge (DBD) plasma actuator as an active flow control (AFC) method in wind turbines. The hypothesized benefits of DBD plasma actuators for AFC include improved energy capture from wind, low cost, and ease of implementation. This thesis is a two-part case study. The first part emulates a Small Business Innovation Research (SBIR) Phase I Proposal for the technology and includes discussions arguing that a strong commercial potential for the proposed technology exists in the United States and that technical development is feasible. The second part includes miscellaneous sections outside the scope of an SBIR proposal, leading to a discussion of the Boundary Labs team decision to discontinue development of this technology.

Committee: Edward Caner (Committee Chair); Robert Brown (Committee Member); Michael Martens (Committee Member) Subjects: Alternative Energy; Energy; Entrepreneurship; Physics

Master of Science, The Ohio State University, 2015, Aero/Astro Engineering

Dynamic stall is a performance-limiting phenomenon experienced by rotorcraft in directional and maneuvering flight. Dynamic stall occurs on the retreating blade due to the high angles of attack that are experienced by the blades. Increasing the angle of attack is required to overcome the asymmetry of lift across the rotor disk that is a result from the velocity disparities between the advancing and retreating blade. This works sets out to study and improve the performance of a dynamically pitching NACA 0015 airfoil. The airfoil is subjected to both an incompressible and compressible flow field to simulate the dynamics of a rotor blade with cyclic pitching. In this experimental investigation of dynamic stall flow control, the effectiveness of nanosecond dielectric barrier discharge (NS-DBD) plasma actuation will be evaluated as a means to exert control authority. The NS-DBD plasma actuation is generated by a high-voltage magnetic compression pulsed power supply that was designed and built at The Ohio State University. To measure the influence of plasma actuation on the flow, surface pressures on the airfoil were measured through discrete pressure taps located on both the suction and pressure surfaces. The surface pressures are used to calculate the lift and moment during the dynamic pitching cycle. To visualize the compressibility effects in the outer flow, shadowgraph imagery was used to capture features in the flow around the leading edge of the test article. Tests were conducted at static and oscillating angles of attack at both Mach 0.2 and 0.4, and Reynolds numbers of 1.2 million and 2.2 million respectively. Pitch oscillations were conducted at reduced frequencies of k = 0.05. Actuation frequencies varied from non-dimensional frequencies (F + ) of 0.78 to 6.09. Surface pressures acquired at Mach 0.2 without actuation applied agreed with historical data at static angles of attack, validating that the application of the ac (open full item for complete abstract)

Committee: James Gregory PhD (Advisor); Jeffrey Bons PhD (Committee Member); Mo Samimy PhD (Committee Member) Subjects: Aerospace Engineering

Doctor of Philosophy, The Ohio State University, 2014, Chemistry

Heat release studies of plasma assisted combustion have been performed in fuel-air mixtures excited by nanosecond dielectric barrier discharges initially at room temperature and maintained at low pressure (~40 – 50 torr). The following topics have been extensively investigated: (i) the applicability of pure O2 broadband Rotational Coherent Anti-Stokes Raman Scattering spectroscopy at very low O2 pressures of ~8 torr or less to obtain rotational temperature, (ii) validation of a proposed low temperature fuel-oxidation kinetics mechanism fully decoupled from NOx chemistry, (iii) characterization of nanosecond pulse discharges in a dielectric barrier discharge cell and a pin-to-pin discharge geometry, and (iv) effect of fuel addition on heat release in a pin-to-pin discharge geometry at low pressure. For the first topic, the applicability of pure O2 broadband Rotational Coherent Anti-Stokes Raman Scattering (RCARS) Spectroscopy at very low O2 partial pressure of ~ 8 torr or less to obtain rotational temperature has been demonstrated. Very good experimental precisions of ~ ± 1 to 2 K has been demonstrated for diffuse and volumetric plasmas excited by a repetitively pulsed nanosecond discharge. It is shown that the electron-multiplication feature of an EMCCD camera increases the signal to noise ratio significantly. For the second topic, the pure O2 RCARS system was applied to the dielectric barrier discharge cell to obtain time-resolved temperature measurements in nanosecond pulse discharges in 20% O2-Ar, H2-O2-Ar and C2-H2-O2-Ar mixtures, initially at room temperature, operated at a high pulse repetition rate of 40 kHz, in plane-to-plane double dielectric barrier geometry at a pressure of 40 Torr. Nitrogen was deliberately excluded from the system so as to decouple NOx chemistry from the plasma fuel-oxidation processes. It was found that a 0-D model predictions for temperature are in very good agreement in the baseline mixture without fuel and the hydrogen (open full item for complete abstract)

Committee: Walter Lempert PhD (Advisor); Anne McCoy PhD (Committee Member); Terry Gustafson PhD (Committee Member) Subjects: Chemistry; Engineering; Physical Chemistry

Doctor of Philosophy (PhD), Wright State University, 2011, Engineering PhD

Low Reynolds number boundary layer separation causes reduced aerodynamic performance in a variety of applications such as MAVs, UAVs, and turbomachinery. The inclusion of a boundary layer separation control system offers a way to improve efficiency in conditions that would otherwise result in poor performance. Many effective passive and active boundary layer control methods exist. Active methods offer the ability to turn on, off, or adjust parameters of the flow control system with either an open loop or closed loop control strategy using sensors. This research investigates the use of a unique sensor called Surface Stress Sensitive Film (S3F) in a closed loop, low Reynolds number separation control system. S3F is an elastic film that responds to flow pressure gradients and shear stress along its wetted surface, allowing optical measurement of wall pressure and skin friction. A new method for installing the S3F sensor to assure a smooth interface between the wall and wetted S3F surface was investigated using Particle Image Velocimetry techniques (PIV). A Dielectric Barrier Discharge (DBD) plasma actuator is used to control laminar boundary layer separation on an Eppler 387 airfoil over a range of low Reynolds numbers. Several different DBD plasma actuator electrode configurations were fabricated and characterized in an open loop configuration to verify separation control of the Eppler 387 boundary layer. The open loop study led to the choice of a spanwise array of steady linear vertical jets generated by DBD plasma as the control system flow effecter. Operation of the plasma actuator resulted in a 33% reduction in section drag coefficient and reattachment of an otherwise separated boundary layer. The dissertation culminates with an experimental demonstration of S3F technology integrated with a control system and flow effecter for closed loop, low Reynolds number separation control. A simple On/Off controller and Proportional Integral (PI) controller were used to clos (open full item for complete abstract)

Committee: Mitch Wolff PhD (Advisor); Rolf Sondergaard PhD (Committee Member); James Menart PhD (Committee Member); Mark Reeder PhD (Committee Member); Joseph Shang PhD (Committee Member) Subjects: Aerospace Engineering; Engineering; Fluid Dynamics; Mechanical Engineering

Doctor of Philosophy (PhD), Wright State University, 2009, Engineering PhD

The use of aerodynamic actuators, such as leading edge slats, trailing edge flaps, roughing strips and ailerons interact with the air during flight, providing maneuverability for air vehicles. These mechanical devices have many inherent, detrimental attributes, such as space requirements on the wing, added wing weight, second response times, increased drag, and increased airframe vibration, resulting in the production of noise. The potential to eliminate or improve upon these detrimental attributes may be realizable by replacing the current mechanical actuators with plasma actuators. Specifically, the surface-discharge-mode, dielectric barrier discharge (SDBD), plasma actuator has a response time on the order of microseconds to milliseconds, does not increase vibration by mounting flush to the wing surface, does not increase drag, and adds negligible weight to the wing. Unfortunately, these devices are not yet powerful enough to perform many of the tasks required for aerodynamic applications; however, they have demonstrated the potential to do so, providing motivation for the current study. Currently, the approach of the research community has focused on coordinating studies designed to determine the physics of the device and parametric studies to determine optimal configurations required for immediate application. In this work, an experimentally based study utilizing optical emission spectroscopy, current-voltage measurements, and a force balance have been successfully applied, contributing new, specific detail to the morphology and characterization of the SDBD. The results of this study were tailored to aid the development of the appropriate, essential physics required for computational modeling of the SDBD. Initially, force measurements of the induced thrust were obtained to demonstrate how week the induced thrust is, justifying the need for a fundamental study. These results are also important in understanding an apparent discrepancy in the reported dependence o (open full item for complete abstract)

Committee: James Menart PhD (Advisor); William Bailey PhD (Committee Member); Jerry Clark PhD (Committee Member); Roger Kimmel PhD (Committee Member); Joseph Shang PhD (Committee Member); Henry Young PhD (Committee Member) Subjects: Electrical Engineering; Fluid Dynamics; Mechanical Engineering; Physics