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Bunjevac, Joseph AntunPIV Analysis of Wake Structure of Real Elephant Seal Whiskers
Master of Science in Mechanical Engineering, Cleveland State University, 2017, Washkewicz College of Engineering
Seals are able to accurately detect minute disturbances in the ambient flow environment using their whiskers, which is attributed to the exceptional capability of their whiskers to suppress vortex-induced vibrations in the wake. To explore potential applications for designing smart flow devices, such as high-sensitivity underwater flow sensors and drag reduction components, researchers have studied how the role of some key parameters of whisker-like morphology affect the wake structure. Due to the naturally presented variation in size and curvature along the length of whiskers, it is not well understood how a real whisker changes the surrounding flow and the vortex shedding behavior. This study aims to detail the flow statistics around a real Elephant Seal whisker at low Reynolds numbers (i.e. one hundred) using particle image velocimetry in a water channel. Wake flow structures are inspected and compared between two Elephant Seal whiskers (undulating) and a California Sea Lion whisker (smooth), along with idealized whisker-like models. Undulating whiskers significantly change the mean flow properties and suppress turbulence intensities in the wake region as compared to the smooth whisker at the tested Re. The undulating whiskers are able to create a low turbulence intensity area directly behind the whiskers trailing, vproviding these whiskers with their Vortex Induced Vibration reduction properties.

Committee:

Wei Zhang, Ph.D. (Advisor); Mounir Ibrahim, Ph.D. (Committee Member); Thijs Heus, Ph.D. (Committee Member)

Subjects:

Biomechanics; Fluid Dynamics

Keywords:

Undulating whiskers, vortex dynamics, seal whiskers, elephant seal, harbor seal, PIV, water channel, flow, vortex induced vibration, VIV, turbulence, vortex supression, undulations

Garafolo, Nicholas GordonA Compressible Advection Approach in Permeation of Elastomer Space Seals
Doctor of Philosophy, University of Akron, 2010, Mechanical Engineering
The preservation of air in manned spacecraft is of grave importance. It is imperative that a comprehensive understanding in the fundamental mechanics of compressible permeation be applied to research and development of elastomeric space seals. Current state of the art space seal designs have relied heavily on past experimental experience, where design iterations are accomplished through costly experimental evaluations alone. To this end, a compressible advection model of permeation in elastomeric space seals was accomplished through a porous media approach. The model allows for compressibility effects on permeation, enables gas dilation, and lumps both diffusion and the incompressible permeability constants. A one-dimensional analysis resulted in a Generalized Emden-Fowler Equation, to which exact, analytical solutions exist. The analysis yielded two permeation parameters which are dependent of the material-fluid and independent of geometry: (1) the incompressible permeability coefficient, k and (2) the Klinkenberg coefficient, b. A series of experiments, coupled with analytical analysis, resulted in material characterization of dry air in the silicone elastomer S0383-70, a candidate space seal material. The material characterization revealed that the permeation coefficients are temperature dependent, supporting conclusions of previous space seal research. An experimental investigation of a subscale candidate space seal established a baseline leak rate for the computational prediction at +23°C and +50°C. A detailed uncertainty analysis was performed on the leak rate methodology, resulting in uncertainties within 7.0%. A second order, computational analysis of the developed model was performed on a domain representative of the candidate, space seal profile and with test conditions similar to that of the experimental baseline evaluations. The predicted leak rate showed exceptional correlation with the experimental investigation, as the predictions were within the uncertainty bounds of the experimental results. This in-detail study of dry air permeation through a candidate space seal material and geometry provides researchers and designers with an accurate and proven methodology for the prediction the mass leak rate for future space seals.

Committee:

Dr. Scott D. Sawyer (Advisor); Minel J. Bruan, Ph.D. (Committee Member); Alex Povitsky, Ph.D. (Committee Member); S. Graham Kelly, III., Ph.D. (Committee Member); Subramaniya I. Hariharan, Ph.D. (Committee Member); Gerald W. Young, Ph.D. (Committee Member); Christopher C. Daniels, Ph.D. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

permeation; leakage; leak rate; silicone elastomer; permeability; permeation; advection; compressible advection; compressibility; porosity; diffusion; seal; space seal; face seal; main docking interface; Klinkenberg coefficient

Spirig, John VincentA new generation of high temperature oxygen sensors
Doctor of Philosophy, The Ohio State University, 2007, Chemistry
Potentiometric internal reference oxygen sensors were created by embedding a metal/metal oxide mixture within an yttria-stabilized zirconia oxygen-conducting ceramic superstructure. A static internal reference oxygen pressure was produced inside the reference chamber of the sensor at the target application temperature. The metal/metal oxide-containing reference chamber was sealed within the stabilized zirconia ceramic superstructure by a high pressure (3-6 MPa) and high temperature (1200-1300 °>C) bonding method that initiated grain boundary sliding between the ceramic components. The bonding method created ceramic joints that were pore-free and indistinguishable from the bulk ceramic. The oxygen sensor presented in this study is capable of long-term operation and is resistant to the strains of thermal cycling. The temperature ceiling of this device was limited to 800 °C by the glass used to seal the sensor package where the lead wire breached the inner-to-outer environment. Were it possible to create a gas-tight joint between an electron carrier and stabilized zirconia, additional sealing agents would not be necessary during sensor construction. In order to enable this enhancement it is necessary to make a gas-tight joint between two dissimilar materials: a ceramic electrolyte and an efficient ceramic electron carrier. A conducting perovskite, LaxSr1-xAlyMn1-yO3, was joined to YTZP at 1250 °C and 1350 °C. X-ray diffraction was used to gain structural information on the perovskite. Room temperature resistivity measurements were performed on joined and unjoined samples to determine the extent to which joining altered electron conduction within the LSAM. Electron microscopy confirmed that intergranular penetration occurred at the joining plane leading to effective bonding between the two dissimilar ceramics. Raman spectral maps of the joined samples demonstrated that joining temperature determines the extent to which interlayers begin to form in the joining plane. X-ray microdiffraction of the joining planes confirmed a threshold temperature for operation of a device created from these materials at 1350 °C. A new material with diminished reactivity and high conductivity is presented to serve as a replacement for metal electrodes. In this manner, the model for a new generation of high-temperature oxygen sensors with internal references and ceramic wires is elucidated.

Committee:

Prabir Dutta (Advisor)

Keywords:

oxygen sensor; perovskite; joining; seal; plastic deformation; LSAM; LSM; combustion sensor; ceramic bonding; grain boundary sliding

Rinehart, Aidan WalkerA Characterization of Seal Whisker Morphology and the Effects of Angle of Incidence on Wake Structure
Master of Science in Mechanical Engineering, Cleveland State University, 2016, Washkewicz College of Engineering
Seal whiskers have been found to produce unique wake flow structures that minimize self-induced vibration and reduce drag. The cause of these wake features are due to the peculiar three-dimensional morphology of the whisker surface. The whisker morphology can be described as an elliptical cross section with variation of diameter in the major and minor axis along the length and, angle of incidence, rotation of the elliptical plane with respect to the whisker axis, α at the peak and β at the trough. This research provided a more complete morphology characterization accomplished through CT scanning and analysis of 27 harbor and elephant seal whisker samples. The results of this study confirmed previously reported values and added a characterization of the angle of incidence finding that the majority of angles observed fall within ±5° and exhibit a random variation in magnitude and direction along the whisker length. While the wake effects of several parameters of the whisker morphology have been studied, the effect of the angle of incidence has not been well understood. This research examined the influence of the angle of incidence on the wake flow structure through series of water channel studies. Four models of whisker-like geometries based on the morphology study were tested which isolate the angle of incidence as the only variation between models. The model variations in angle of incidence selected provided a baseline case (α = β = 0°), captured the range of angles observed in nature (α = β = -5°, and α = β = -15°), and investigated the influence of direction of angle of incidence (α = -5°, β = -5°). The wake structure for each seal whisker model was measured through particle image velocimetry (PIV). Angle of incidence was found to influence the wake structure through reorganization of velocity field patterns, reduction of recovery length and modification of magnitude of Tu. The results of this research helped provide a more complete understanding of the seal whisker morphology relationship to wake structure and can provide insight into design practices for application of whisker-like geometry to various engineering problems.

Committee:

Wei Zhang, PhD (Advisor); Ibrahim Mounir, PhD (Committee Member); Shyam Vikram, PhD (Committee Member)

Subjects:

Aerospace Engineering; Aquatic Sciences; Engineering; Fluid Dynamics; Mechanical Engineering

Keywords:

seal; whisker; PIV; biomimicry; fluid dynamics; particle image velocimetry; bio-engineering; engineering; mechanical engineering; aerospace engineering; experimental fluid dynamics;

Conrad, Mason ChristianAn Experimental Investigation of Silicone-to-Metal Bond Strength in Composite Space Docking System Seals
Master of Sciences (Engineering), Case Western Reserve University, 2009, EMC - Mechanical Engineering
The National Aeronautics and Space Administration (NASA) is currently developing a new universal docking mechanism for future space exploration missions calledthe Low Impact Docking System (LIDS). In order to successfully mate two pressurized vehicles or structures in space, advanced seals are required at the interface to prevent the loss of breathable air to vacuum. The leading candidate LIDS main interface seal design is a composite assembly of silicone elastomer seal bulbs permanently molded into grooves in an electroless nickel-plated aluminum retainer. A composite seal of the style being developed has not been proven in a docking role in the history of manned spaceflight. High adhesive loads on the seal bulbs during undocking could potentially overcome the strength of the molded bond between the elastomer and the metal retainer. Bond failure would jeopardize the operation of the seal and docking port, and orbital debris could be liberated. The strength of the silicone-to-metal bond is a critical consideration for the new system, especially due to the presence of small areas of disbond created by the molding process. In the work presented herein, silicone- to-metal bonds of subscale seal specimens with different sizes of intentional disbond are destructively tensile tested. Tension is applied either uniformly on the entire seal circumference or locally in a single circumferential location. Bond failure due to uniform tension produces a wide scatter of observable failure modes and measured load-displacement behaviors. Although the ideal failure mode for the silicone-to- metal bond is 100% cohesive failure of the material, the highest observed cohesion amount is 20% of bond area for the uniform loading condition. Localized tension produces failure either as immediate tearing of the elastomer material outside the bond region or as complete peel-out of the seal bulb in one piece. In intentionally flawed specimens, neither load case considered shows a correlation between disbond size and bond strength.

Committee:

Joseph Prahl, PhD (Committee Chair); Iwan Alexander, PhD (Committee Member); Roger Quinn, PhD (Committee Member)

Subjects:

Aerospace Materials; Engineering; Mechanical Engineering; Polymers

Keywords:

silicone; bond strength; seal; Orion;

Smith, Russell LynnOxygen Plasma Surface Activation of Polynorbornene for Bonding to Glass with Applications to Microfluidic Systems
Master of Sciences (Engineering), Case Western Reserve University, 2011, EECS - Electrical Engineering
This work investigates the surface activation in oxygen plasma of the polymer material polynorbornene (PNB) for bonding to glass. Like the material PDMS which is frequently utilized in microfluidic systems, PNB may be rendered hydrophilic for bonding by treatment in oxygen plasma. For rapid prototyping of microfluidic devices, PNB has the advantage over conventionally-processed PDMS of being directly photodefinable. An investigation of PNB contact angle following oxygen plasma treatment was conducted to determine the optimal plasma power, pressure, and duration for surface activation. Development of a contact angle goniometer is discussed. Hydrophobic recovery of oxygen-plasma treated PNB is also investigated and compared to PDMS. Bonding of PNB to piranha-cleaned glass is demonstrated and bond strength is evaluated by blister test.

Committee:

Christian Zorman, PhD (Committee Chair); Philip Feng, PhD (Committee Member); Francis Merat, PhD (Committee Member)

Subjects:

Electrical Engineering

Keywords:

polynorbornene; PNB; Avatrel; contact angle; hydrophilic; bond; seal; oxygen plasma; microfluidic; MEMS; goniometer

May, Nicholas AAerodynamic Consequences of a Pneumotachograph Mask Leak
Master of Science (MS), Bowling Green State University, 2016, Communication Disorders
Studies in airflow during speech production typically use a pneumotachographic mask system placed upon the face to measure the expired airflows. Accurate measures of airflow require mask calibration and a complete seal of the mask rim to the face. Literature frequently cites mask rim leaks as causing flow measure inaccuracies, but quantitative studies of inaccuracies are needed. The purpose of this study was to determine the degree of inaccuracy of flow measurement using a Glottal Enterprises aerodynamic system for a variety of leak sizes. The primary hypothesis was that the greater the air leak cross sectional area at the rim of the mask, the greater the reduction in measured flows through the mask (and therefore the greater the error in measuring the upstream airflow). A range of airflows was both pushed and pulled through the Glottal Enterprises mask system with leaks being simulated by metal tubes of various cross-sectional areas. Two leak locations (bridge-of-nose and corner-of-mouth), single vs. multiple leaks, and two different leak geometries (rectangular and elliptical) were studied. Results suggest the following conclusions: (1) As leak area increases, the amount of leak flow increases; (2) the amount of flow leak is not independent of location; (3) given equivalent leak area, multiple leak locations provide more airflow resistance and less leak flow; (4) elliptical tubes were found to be more resistive to airflow than rectangular tubes. A general equation was obtained that relates the amount of flow reduction (the leak flow) to the rim leak cross sectional area and the upstream flow: Leak(cc/s) = 0.4125*Area(cm2)*Flow(cc/s), for airway flow in the range of ±2000 cc/s. This equation may provide researchers and clinicians in the field with a tool for generalizing airflow leak effects.

Committee:

Ronald Scherer, PhD (Advisor); Alexander Goberman, PhD (Committee Member); Jason Whitfield, PhD (Committee Member)

Subjects:

Fluid Dynamics; Speech Therapy

Keywords:

mask leak; mask seal; pneumotachograph; aerodynamic measurement; voice and speech; measurement error; speech language pathology; voice science; clinical measurement

Main, JoelUsing Travertine-Cemented Fault Breccias to Understand the Architecture and History of the Gunnison Fault Zone, eastern Basin and Range, Utah
Master of Science, The Ohio State University, 2015, Geological Sciences
In the easternmost Basin and Range Province (BRP) in central Utah, the east-west trending Dry Canyon Graben formed perpendicular to the Gunnison Fault, which bounds the San Pitch Mountains horst block. A detailed investigation of the Rock Canyon fault zone, bordering the northern side of the Dry Canyon Graben, using field mapping, structural kinematic analysis, textural analysis of fault rocks, and radiogenic dating, has helped reveal the linkages between the graben and regional Basin and Range structure. Discovery of both dip-slip and oblique-slip lineations on faults in both the Rock Canyon fault zone and the south Dry Canyon fault zone indicate at least two phases of displacement occurred along boundary faults of the Dry Canyon Graben. Rock Canyon fault zone is likely connected to the Gunnison Fault, and Dry Canyon Graben may be part of a complex accommodation zone between three overlapping segments of the Gunnison Fault. A precise U-series date of 346.95 + 0.000098 Ka documents late Pleistocene fault activity. This suggests that the Dry Canyon Graben is a Basin and Range structure that formed concurrent with the Gunnison fault up until at least 347 Ka before present. Rock Canyon Fault zone is associated with multiple phases of fault rupture and sealing, indicated by polyphase cement-rich chaotic breccias, juxtaposed layers of slickenfibers, and composite zones of alternating breccias and veins along faults. The main faulting process is dilational faulting and collapse of subsurface fault voids as indicated by the dominance of cement-rich clast-supported chaotic breccias. Repeated rupture in the same zone is indicative of a fault weakening system. The crystal textures, travertine forms and layered carbonate deposits in the fault zone point to a near-surface environment for the deformation processes, where low lithostatic pressures permit open space to form and remain open. CO2-rich fluids ascended through fracture conduits along the Gunnison and Rock Canyon zone faults, likely derived from the Navajo Sandstone reservoir in the subsurface Sanpete-Sevier Valley anticline. Tufa deposits along the Gunnison Fault trace at Birch Canyon are reinterpreted as cascade deposits draping over and depositing in-situ over a pre-existing escarpment on a segment of the Gunnison Fault. If the Birch Canyon escarpment marks a fault scarp related to the Gunnison Fault, then the last displacement on that fault strand must be older than ~3200 years, the oldest dated tufa deposited in the linked upper and lower alluvial fans.

Committee:

Terry Wilson (Advisor); Matt Saltzman (Committee Member); Berry Lyons (Committee Member)

Subjects:

Earth; Geological; Geology

Keywords:

travertine; tufa, basin and range; fault; Gunnison; rock canyon; relay ramp; polyphase; u-series; dilational faulting; birch canyon; rupture; seal; san pitch mountains; accommodation zone; Sevier-Sanpete Valley; navajo sanstone; Utah; Dry Canyon Graben

Parihar, Shailendra S.High Temperature Seals for Solid Oxide Fuel Cells
PhD, University of Cincinnati, 2007, Engineering : Materials Science
Solid Oxide Fuel cells (SOFCs) represent a clean and efficient alternative to existing methods of energy production. But, they need hermetic seals to prevent fuel-oxidant mixing within the stack. Glasses are attractive options for fabrication of these high temperature seals but suffer from their inherent brittleness and tend to crack during thermal cycling. In this study, an innovative concept of self-healing glass seals is developed to solve the problem of cracking of glasses in a SOFC seal. Rationale behind this concept is that a glass of suitable viscosity characteristics can flow and heal cracks at SOFC operating temperatures and thus can provide seals which can self-repair. A novel method, based on in-situ video imaging of cracks on the glass surface during high temperature treatment is developed and used to select and evaluate the suitability of different glasses for making self-healing seals. Promising glasses are studied experimentally to determine kinetics of healing of Vickers indented cracks at various temperatures. In addition, the effect of crystallization of glass on its healing kinetics is studied. A model is developed for crack healing behavior and is used to validate the experimental data. Studies on Cracks healing and crystallization of glasses showed that glasses with no crystallization tendency show fast crack healing response, whereas glasses which crystallize display sluggish healing. A glass displaying fast healing kinetics and good stability against crystallization is used to fabricate self healing glass seals for SOFCs. Seals fabricated using this glass not only remained hermetic but also maintained their self healing ability for as long as 3000 hours at 8000C and 300 thermal cycles between room temperature and 8000C. These results clearly indicated that self-healing glasses are promising candidates for SOFC seals.

Committee:

Dr. Raj Singh (Advisor)

Subjects:

Engineering, Materials Science

Keywords:

Solid Oxide Fuel Cells; Glass Seals; Self-Healing Glasses; Seal Leak Testing

Steinetz, Bruce MichaelEvaluation of an innovative high-temperature ceramic wafer seal for hypersonic engine applications
Doctor of Philosophy, Case Western Reserve University, 1991, Mechanical Engineering
A critical mechanical system in advanced hypersonic engines is the panel-edge seal system that seals gaps between the articulating engine panels and the adjacent engine splitter walls. Significant advancements in seal technology are required to meet the extreme demands placed on the seals, including the simultaneous requirements of low leakage, conformable, high temperature, high pressure, sliding operation. In this investigation, the design, development, analytical and experimental evaluation of a new ceramic wafer seal that shows promise of meeting these demands will be addressed. A high temperature seal test fixture was designed and fabricated to measure static seal leakage performance under engine simulated conditions. Ceramic wafer seal leakage rates are presented for engine-simulated air pressure differentials (up to 100 psi), and temperatures (up to 1350°F), sealing both flat and distorted wall conditions, where distortions can be as large as 0.15 in. in only an 18 in. span. Seal leakage rates are low, meeting an industry-established tentative leakage limit for all combinations of temperature, pressure and wall conditions considered. A seal leakage model developed from externally-pressurized gas film bearing theory is also presented. Predicte d leakage rates agree favorably with the measured data for nearly all combinations of temperature and pressure. Discrepancies noted at high engine pressure and temperature are attributed to thermally-induced, non-uniform changes in the size and shape of the leakage gap condition. The challenging thermal environment the seal must operate in places considerable demands on the seal concept and material selection. Of the many high temperature materials considered in the design, ceramics were the only materials that met the many challenging seal material design requirements. Of the aluminum oxide, silicon carbide, and silicon nitride ceramics considered in the material ranking scheme developed herein, the silicon nitride class of ceramics ranked the highest because of their high temperature strength; resistance to the intense heating rates; resistance to hydrogen damage; and good structural properties. Baseline seal feasibility has been established through the research conducted in this investigation. Recommendations for future work are also discussed.

Committee:

Thomas Kicher (Advisor)

Keywords:

high-temperature; ceramic wafer seal; hypersonic engine

Thomas, Jed H.Evaluation of the flue gas desulfurization mine seal and sedimentation pond at Broken Aro Mine Reclamation Site located in Coshocton County, Ohio
Master of Science (MS), Ohio University, 2001, Chemical Engineering (Engineering)
Evaluation of the flue gas desulfurization mine seal and sedimentation pond at Broken Aro Mine Reclamation Site located in Coshocton County, Ohio

Committee:

Ben Stuart (Advisor)

Subjects:

Engineering, Chemical

Keywords:

Flue Gas Desulfurization; Mine Seal; Sedimentation Pond; Broken Aro Mine; Reclamation Site; Coshocton County; Ohio

Rusch, Otto W.Evaluation of User’s Ability to Adequately Seal Respirator Cartridges/Filters of Differing Size and Shape
MS, University of Cincinnati, 2008, Medicine : Industrial Hygiene (Environmental Health)
This study was conducted to evaluate effectiveness in obtaining an adequate seal on a respirator cartridge/filter as if it were being used during a negative pressure user seal check. The study determined what percent of subjects were able to use their hand to obtain an adequate seal on each of the cartridges/filters. An apparatus was constructed using a pump, rotameter and digital manometer, each cartridge/filter line was kept at a pressure of -2"H2O (±5%). There were 33 subjects involved in the study. To obtain an adequate seal during a negative pressure user seal check, a specific cartridge/filter intake area (i.e., ≤ 24cm2) was identified for 95% of the study population. The equipment used in this study could be modified by respirator manufacturers and certifying agencies to verify the probability that an adequate seal can be achieved during negative pressure user seal checks whenever a newly designed inlet opening is created.

Committee:

Roy McKay, PhD (Committee Chair); Tiina Reponen, PhD (Committee Member); Glenn Talaska, PhD (Committee Member)

Keywords:

user seal check; fit check; respirator; cartridge; filter

Levering, Dale FranklinAn autecological study of Polygonatum pubescens (Willd.) Pursh and Polygonatum biflorum (Walt.) Ell. : emphasizing inter-and intra-specific photosynthetic and respiratory rate variation /
Doctor of Philosophy, The Ohio State University, 1972, Graduate School

Committee:

Not Provided (Other)

Subjects:

Biology

Keywords:

Solomons seal

Liette, Jared V.Dynamic Characterization of the Rectangular Piston Seal in a Disc-Caliper Braking System Using Analytical and Experimental Methods
Master of Science, The Ohio State University, 2011, Mechanical Engineering
A dynamic model of a disc-caliper braking system is critical in the design of braking control systems, development of lighter and more fuel-efficient vehicle components, and reduction of brake-induced vibration by tuning the brake system dynamic properties. Along with the hydraulic pressure within the piston chamber, the rectangular seal around the pistons couples the mechanical and hydraulic components. This rectangular seal component and its effect on the brake system dynamics is the focus of this thesis. Through the use of a simplified, yet representative experiment of a floating disc-caliper, the physical sources of the stiffness and damping mechanisms associated with the seal during a dynamic braking event are identified under harmonic excitation (at 5 Hz). A tractable analytical model of the experiment that incorporates the identified dynamic properties of the seal is proposed. The linear time-invariant model describes the governing equations of both the hydraulic brake system components and the mechanical caliper components, and provides some insights into a seemingly nonlinear system. For a range of pressure amplitudes and brake configurations, excellent agreement between predictions and measurements is obtained for the peak-to-peak values of the piston/bore chamber pressure, the force transmitted by the pistons, and the caliper displacement.

Committee:

Rajendra Singh, Dr. (Advisor); Hayrani Oz, Dr. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

rectangular seal; dynamic characterization; linear time-invariant; floating disc-caliper braking system