<p dir="ltr">Boiling processes have long had an important role in power generation and air conditioning applications. The efficient and reliable heat dissipation afforded through the phase change process in the boiling has led to their generation of a substantial body of work in this field over several decades. Despite decades of efforts, the heat transfer performance prediction in boiling has been highly empirical with models working only for a narrow range of surface/fluids or other operating conditions. The limitation in these models is a result of a lack of mechanistic understanding of the underlying heat and mass transfer process. Surface dryout or boiling crisis is a process wherein there is a spontaneous formation of vapor film on top of the surface causing a catastrophic increase in surface temperature. The heat flux at which this formation of vapor film occurs is called critical heat flux (CHF). The CHF demarcates the upper limit to the regime of stable nucleating bubbles called nucleate boiling. The mechanism causing dryout is under debate for over half a century and several conflicting theories that cause dryout have been suggested since the 1950s including hydrodynamic, irreversible dryspot expansion, macrolayer dryout/liftoff, critical bubble distributions, vapor-recoil based theories and more. The lack of consensus is due to limitation in the information collected on the dynamic multiscale and chaotic bubble interactions. Recent advances in high-fidelity spatiotemporal phase, temperature, and heat flux measurements now enable diagnostic tools that can be leveraged to understand the complex heat transfer processes emerging from bubble-surface interaction on the boiling surface. In this work, we develop such techniques to understand various transport mechanisms underlying boiling and its crisis.</p><p dir="ltr">In this work, an experimental technique for collecting synchronized through-substrate visual and infrared (IR) measurements of a boiling surface is developed. An IR and visually transparent sapphire substrate with an IR-opaque indium-tin-oxide (ITO) heater layer is used to measure the phase (liquid and vapor areas) and temperature of the ITO layer. The visual camera collects the light reflected off the substrate from a red LED and the images collected show a contrast between liquid and vapor areas that is used to generate binarized phase maps. The temperature from the IR camera is used as boundary condition to solve a conduction problem for heat fluxes going into the fluid. Four distinct heat flux signatures corresponding to liquid, contact line, vapor and rewetting regions are observed. A post-processing methodology utilizing synchronous phase measurements to identify and partition these regions is introduced. The high-fidelity phase measurements allow for detection of fine features that are not discernable using heat flux maps alone. Analysis of the heat flux and temperature maps of partitioned regions for HFE-7100 fluid on the ITO surface show qualitative agreement with the trends in mechanisms underlying those areas. The experiment and post-processing methodology introduced in this work is the first to provide partitioning of underlying heat transfer mechanisms for multi-bubbles throughout the entire range of the boiling curve during both steady and transient scenarios.</p><p dir="ltr">The technique developed is used to probe the mechanisms underlying the boiling crisis. Theories suggested in the literature for boiling crisis are carefully evaluated and evidence against hydrodynamic instability, macrolayer dryout, vapor recoil, irreversible expansion of dryspots, macrolayer liftoff model, and bifurcations from critical distributions is observed. The signature in the peak of the spatially averaged fluid heat flux is observed to precede any other signs of dryout. Beyond the peak heat flux an increase in superheat leads to reduced heat dissipated by boiling and further increases the temperature causing a thermal runaway in the substrate that eventually leads to dryout. Hence, the boiling crisis is found to be a consequence of a peak in the nucleate boiling curve. The cause for the peak in the boiling heat flux for the surface-fluid combination tested was due to degradation of heat transfer caused by the replacement of high-heat-transfer contact line region with lower-heat-transfer vapor covered regions, among the multiple competing mechanisms. Hence, we propose that mechanistically modeling the boiling crisis rests on prediction of the peak in the upper portion of the nucleate boiling curve by considering all underlying heat transfer mechanisms. A modeling framework based on heat flux partitioning, where the overall heat transferred during boiling is calculated as the sum of the heat transferred by individual mechanisms is demonstrated as potential pathway to predict the upper portion of the nucleate boiling curve and thereby critical heat flux. Based on the terms involved in summation for individual mechanisms, we propose that the boiling curve for any given surface be interpreted as a path on a multidimensional surface (boiling manifold). Estimation of such a boiling manifold allows for prediction of the boiling curve for any surface, given development of the relations between these parameters and surface-fluid properties, and can further be used to backtrack relevant thermophysical or nucleation properties for enhanced boiling performance.</p><p dir="ltr">Enhancement of pool boiling heat transfer performance using surface modifications is of major interest to applications and this work further delves into characterizing the boiling performance using traditional surface averaged measurements of microstructured surfaces using HFE-7100. We find that microlayer evaporation from the imbibed liquid layer underneath the growing vapor bubbles is the key mechanism of boiling heat transfer enhancement in microstructures. Further, this implies that characterization of microstructured surfaces for evaporative performance can serve as an important proxy to enable heat transfer coefficient enhancement prediction during pool boiling. Hence, we also developed an easily calculated Figure of Merit (FOM) that characterizes the efficacy of evaporation from microstructured surfaces.</p><p dir="ltr">To summarize, in this work we developed an experimental technique using synchronous through-substrate high-speed visual and IR imaging methods. New post-processing techniques for partitioning of different heat transfer mechanisms are proposed and used to analyze boiling on an ITO-coated sapphire substrate with HFE-7100 as the working fluid. We reveal thermal runaway in the substrate caused due to a negative-sloping boiling curve as the mechanism of dryout. Mechanistic modeling of the critical heat flux thus involves calculating the peak in the nucleate boiling curve. A framework to predict the nucleate boiling curve and subsequently critical heat flux is proposed based on the partitioning analysis. The experimental method developed lays the groundwork for measuring heat flux and superheats associated with various mechanisms, and hence, enables validation of future partitioning-based boiling heat transfer models that intrinsically enable prediction of the peak.</p>

<p>  </p> <p>Cavitation is one of the most common causes of failures in axial piston machines. Due to the detrimental effects that cavitation has on unit performance, it is of important consideration both in the design of new units and in defining the operational limits of existing market products. The work in this thesis aimed to contribute to the current knowledge in both areas, with a focus on design considerations with respect to cavitation scalability, and on operating conditions by measuring cavitation severity under separate and combined inciting parameters. Though the application of unit scaling is common in industry for the design of pump families, there have been no comprehensive attempts to quantify whether cavitation in fluid power units may be adequately accounted for in published scaling laws. In this thesis, the scalability of cavitation phenomena was examined through a CFD scaling study performed using a modified version of the Full Cavitation Model.  Results indicate that linear scaling is consistent in maintaining volumetric efficiency performance within 1% across scaled units up to eight times larger or smaller than the baseline. However, the gas and vapor volume distributions vary significantly between scaled units, due largely to the linear non-scalability of fluid inertia and turbulent factors. Physical exchange between phases within a working fluid was shown to be time-dependent, such that the scaled-down unit exhibits bubble collapse rates up to 30% and 150% greater than the baseline and scaled-up units, respectfully. Considering these effects, the presented work demonstrates a potential for increased cavitation damage area when downscaling a unit and reduced risk in upscaling, despite the scaling law being a reliable indicator for volumetric efficiency. </p> <p>To define a more complete study of cavitation under a variety of operating conditions and inciting parameters, this a new experimental procedure and testing circuit was proposed with focus on repeatability by controlled pressure drops and preliminary quantification of inlet fluid quality. By measuring cavitation conditions under pressure starvation, incomplete filling, and combinations thereof, the direct effect of different inception methods on unit performance was shown to be readily identifiable. Through visualization of the inlet flow, reduction in inlet pressure levels was correlated to fluid cloudiness levels and bubble size, with transparency loss at 0.0 bar_g and transition from bubbly to plug flow at -0.4 bar_g. Incomplete filling-induced cavitation was also shown to be detectable by inlet flow conditions, with a distinct change in bubble coalescence rate when operating under shaft speeds greater than or equal to fill speed for a given inlet pressure. </p>

<p>The present study investigates the capability of computational fluid dynamics (CFD) extensively to predict hydrodynamics and heat transfer characteristics of FC-72 flow boiling in a 2.5-mm ´ 5.0-mm rectangular channel and experimentally explores system instabilities: <em>density wave oscillation</em> (DWO), <em>pressure drop oscillation</em> (PDO) and <em>parallel channel instability</em> (PCI) in a micro-channel heat sink containing 38 parallel channels having a hydraulic diameter of 316-μm. </p> <p>The computational method performs transient analysis to model the entire flow field and bubble behavior for subcooled flow boiling in a rectangular channel heated on two opposite walls at high heat flux conditions of about 40% – 80% of <em>critical heat flux</em> (CHF).  The 3D CFD solver is constructed in ANSYS Fluent in which the <em>volume of fluid</em> (VOF) model is combined with a <em>shear stress transport</em> (SST) <em>k</em>-<em>ω</em> turbulent model, a surface tension model, and interfacial phase change model, along with a model for effects of shear-lift and bubble collision dispersion to overcome a fundamental weakness in modeling multiphase flows.  Detailed information about bubble distribution in the vicinity of the heated surface, thermal conduction inside the heating wall, local heat fluxes passing through the solid-fluid interface, and velocity and temperature profiles, which are not easily observed or measured by experiments, is carefully evaluated.  The simulation results are compared to experimental data to validate the solver’s ability to predict the flow configuration with single/double-side heating.  The added momentum by shear-lift is shown to govern primarily the dynamic behavior of tiny bubbles stuck on the heated bottom wall and therefore has a more significant impact on both heat transfer and heated wall temperature.  By including bubble collision dispersion force, coalescence of densely packed bubbles in the bulk region is significantly inhibited, with more giant bubbles even incurring additional breakup into smaller bubbles and culminating in far less vapor accumulation along the top wall.  Including these momentums is shown to yield better agreement with local interfacial behavior along the channel, overall flow pattern, and heat transfer parameters (wall temperature and heat transfer coefficient) observed and measured in experiments.  The computational approach is also shown to be highly effective at predicting local phenomena (velocity and temperature profiles) not easily determined through experiments.  Different flow regimes predicted along the heated length exhibit a number of dominant mechanisms, including bubble nucleation, bubble growth, coalescence, vapor blankets, interfacial waviness, and residual liquid sub-layer, all of which agree well with the experiment.  Vapor velocity is shown to increase appreciably along the heated length because of increased void fraction, while liquid velocity experiences large fluctuations.  Non-equilibrium effects are accentuated with increasing mass velocity, contributing minor deviations of fluid temperature from simulations compared to those predicted by the analytical method.  Predicted wall temperature is reasonably uniform in the middle of the heated length but increases in the entrance region due to sensible heat transfer in the subcooled liquid and decreases toward the exit, primarily because of flow acceleration resulting from increased void fraction.  When it comes to analyzing heat transfer mechanisms at extremely high heat flux via CFD, predicted flow pattern, bubble behavior, and heat transfer parameters (such as wall temperature excursion and thermal energy concentration) clearly represent phenomena of premature CHF, which take place slightly earlier than actual operating conditions.  But, despite these slight differences, the present computational work does demonstrate the ability to effectively predict the severe degradation in heat transfer performance commonly encountered at heat fluxes nearing CHF.  </p> <p>Much of the published literature addressing flow instabilities in thermal management systems employing micro-channel modules are focused on instability characteristics of the module alone, and far fewer studies have aimed at understanding the relationship between these characteristics and compressive volume in the flow loop external to the module.  From a practical point of view, developers of micro-channel thermal management systems for many modern applications are in pursuit of practical remedies that would significantly mitigate instabilities and their impact on cooling performance.  Experiments are executed using FC-72 as a working fluid with a wide range of mass velocities and a reasonably constant inlet subcooling of ~15°C.  The flow instabilities are reflected in pressure fluctuations detected mainly in the heat sink’s upstream plenum.  Both inlet pressure and pressure drop signals are analyzed in pursuit of amplitude and frequency characteristics for different mass velocities and over a range of heat fluxes.  The current experimental study also examines the effects of compressible volume location in a closed pump-driven flow loop designed to deliver FC-72 to a micro-channel test module having 38 channels with 315-μm hydraulic diameter.  Three accumulator locations are investigated: upstream of the test module, downstream of the test module, and between the condenser and pump.  Both high-frequency temporal parameter data and high-speed video records are analyzed for ranges of mass velocity and heat flux, with inlet subcooling held constant at ~15°C.  PDO is shown to dominate when the accumulator is situated upstream, whereas PCI is dominant for the other two locations.  Appreciable confinement of bubbles in individual channels is shown to promote rapid axial bubble growth.  The study shows significant variations in the amount of vapor generated and dominant flow patterns among channels, a clear manifestation of PCI, especially for low mass velocities and high heat fluxes.  It is also shown effects of the heat sink’s instabilities are felt in other components of the flow loop.  The parametric trends for PCI are investigated with the aid of three different types of stability maps which show different abilities at demarcating stable and unstable operations.  PDO shows severe pressure oscillations across the micro-channel heat sink, with rapid bubble growth and confinement, elongated bubble expansion in both directions, flow stagnation, and flow reversal (including vapor backflow to the inlet plenum) constituting the principal sequence of events characterizing the instability.  Spectral analysis of pressure signals is performed using Fast Fourier Transform, which shows PDO extending the inlet pressure fluctuations with the same dominant frequency to other upstream flow loop components, with higher amplitudes closer to the pump exit.  From a practical system operation point of view, throttling the flow upstream of the heat sink eliminates PDO but renders PCI dominant, and placing the accumulator in the liquid flow segment of the loop between the condenser and pump ensures the most stable operation.</p>

<p dir="ltr">As aircraft engine manufacturers continue to embark on their pursuit of higher-efficiency, lower-emissions gas turbines, a prevailing theme in the industry has been the increase of the engine bypass ratio. As the optimization space for engine bypass ratios trends towards smaller and smaller engine core sizes, the feasibility of centrifugal compressors as the final stage in an axial-centrifugal compressor becomes apparent due to their performance advantages at smaller scales.</p><p dir="ltr">This study performed an investigation into the aerodynamics of a stationary diffusion system intended for use with a final stage aeroengine centrifugal compressor using experimental and numerical techniques. Experimental work was performed at the Purdue Compressor Research Lab at Purdue University’s Maurice J. Zucrow Laboratories. Data were collected from several iterations of rapidly prototyped, additively manufactured diffuser and deswirl parts with internal instrumentation features. Furthermore, computational work on the stage was conducted using the Ansys Turbosystem.</p><p dir="ltr">The goal of this research is to identify trends in stationary diffusion system designs and the geometric features that cause them. Furthermore, the ability of steady computational fluid dynamics methods to predict these changes was evaluated using two turbulence models to produce a simulation of the compressor flow field. When used in conjunction with one another, the efficient use of computational methods to identify an optimal design and rapid prototyping to validate it leads to the determination of the best diffusion system design at a lower cost and time requirement than what is otherwise currently possible.</p><p dir="ltr">The different geometries which were tested identified the negative effects of spanwise vane contouring on the diffuser performance and the ability of endwall divergence to augment the pressure recovery performance of a design at the expense of increased losses. A full understanding of the effect of each design parameter is enabled by iterative inclusion or exclusion of certain design parameters. Furthermore, the use of computational fluid dynamics showed that the BSLEARSM turbulence model performs reasonably well in predicting the build-to-build performance trends. However, neither the BSLEARSM nor the SST turbulence model were able to accurately identify performance trends for the deswirl. For this reason, additional work is warranted to identify an optimal set of parameters to characterize the high axial and meridional turning present in this component.</p>

<p dir="ltr">Generation IV high-temperature gas-cooled reactors (HTGR) are designed to exhibit passive safety under all off-normal circumstances. One such scenario, known as depressurized loss of forced circulation (DLOFC), occurs after a break in the coaxial inlet/outlet header. As the headers are traditionally located at the base of the reactor vessel, the low-density helium coolant is preserved in the core following the initial rupture accident. Upon depressurization, however, air from the surrounding reactor environment slowly enters the coolant channel through molecular diffusion. As the incoming fluid continues to deplete the helium concentration, the onset of natural circulation (ONC) can occur causing bulk air ingress leading to the oxidation and degradation of core components. Therefore, investigating methods to improve the time to ONC is critical in impeding reactor core component damage brought about by DLOFC in an HTGR.</p><p dir="ltr">The Transformational Challenge Reactor (TCR) has similar features to those of an HTGR, but the primary difference is the use of a more complex, additively manufactured (AM) fuel geometry. The more compact, AM, ceramic fuel elements can be conveniently produced with optimally configured channels that suppress the air ingress progress and improve thermofluidic performance. DLOFC and air ingress are experimentally studied in a scaled HTGR flow test setup. Distributed temperature measurements and time to ONC data are collected for the experiments conducted. Multiple geometries are analyzed throughout the investigation. The thermal transient and time to ONC data gathered for the different test geometries and temperatures are compared. The results show that the AM and pebble bed elements deter ONC significantly longer than the baseline geometry representative of a prismatic fuel coolant channel. The AM part delayed ONC as compared to the pebble bed test piece at higher temperatures. The distributed temperature sensor shows intra-leg circulation at higher temperature tests.</p><p dir="ltr">Thermophysical properties of the 316 stainless steel AM component are compared to those of a standard 316 stainless steel round bar. The properties ascertained include the density, emissivity, specific heat, and thermal conductivity. The density of the AM part is 1.5% greater than the density of the standard bar. The emissivity of the AM part is determined to be over three times greater than the emissivity of the polished standard stainless steel round. The specific heat of the AM element is 16% greater than that of the standard 316 stainless steel specific heat. The thermal conductivity of the AM component is measured to be within 1.5% of the standard 316 stainless steel round bar thermal conductivity.</p>

The purpose of this study was to investigate the relationship between mobility and the standardized testing environment. The project focused on nine students who had a pronounced need for movement while learning and/or being tested. The study was conducted to determine whether the achievement scores of these nine students would be influenced by the denial or availability of movement while they were administered a standardized reading test. Twenty-one second grade students were the subjects. Two forms of Level B of the Gates-MacGinitie Reading Test were used. All subjects were tested in a traditional environment with no movement allowed. The same subjects were then tested at a later time in a mobile environment with movement and change of location permitted. The Wilcoxon Matched-Pairs Signed-Rank Test was used as the statistical base. Results showed a .05 significance. Of the nine mobile students, six scored equally as well or better when placed in a mobile testing environment.

<p>Particle suspensions in viscoelastic fluids (e.g., polymeric fluids, liquid crystalline solutions, gels) are ubiquitous in industrial processes and in biology. In such fluids, particles often acquire lift forces that push them to preferential streamlines in the flow domain. This lift force depends greatly on the fluid’s rheology, and plays a vital role in many applications such as particle separations in microfluidic devices, particle rinsing on silicon wafers, and particle resuspension in enhanced oil recovery. Previous studies have provided understanding on how fluid rheology affects the motion of spherical particles in simple viscoelastic fluid flows such as shear flows. However, the combined effect of more complex flow profiles and particle shape is still under-explored. The main contribution of this thesis is to: (a) provide understanding on the migration and rotation dynamics of an arbitrary-shaped particle in complex flows of a viscoelastic fluid, and (b) develop guidelines for designing such suspensions for general applications.</p> <p><br></p> <p>In the first part of the thesis, we develop theories based on the second-order fluid (SOF) constitutive model to provide solutions for the polymeric force and torque on an arbitrary-shaped solid particle under a general quadratic flow field. When the first and second normal stress coefficients satisfy  <strong>Ψ</strong>₁  = −2 <strong>Ψ</strong> ₂ (corotational limit), the fluid viscoelasticity modifies only the fluid pressure and we provide exact solutions to the polymer force and torque on the particle. For a general SOF with  <strong>Ψ</strong> ₁ ≠  −2 <strong>Ψ</strong> ₂, fluid viscoelasticity modifies the shear stresses, and we provide a procedure for numerical solutions. General scaling laws are also identified to quantify the polymeric lift based on different particle shapes and orientation. We find that the particle migration speed is directly proportional to the length the particle spans in the shear gradient direction (L_sg), and that polymeric torques lead to unique orientation behavior under flow.</p> <p><br></p> <p>Secondly, we investigate the migration and rotational behavior of prolate and oblate spheroids in various viscoelastic, pressure-driven flows. In a 2-D slit flow, fluid viscoelasticity causes prolate particles to transition to a log-rolling motion where the particles orient perpendicular to the flow-flow gradient plane. This behavior leads to a slower overall migration speed (i.e., lift) of prolate particles towards the flow centerline compared to spherical particles of the same volume. In a circular tube flow, prolate particles align their long axis along the flow direction due to the extra polymer torque generated by the velocity curvature in all radial directions. Again, this effect causes prolate particles to migrate slower to the flow centerline than spheres of the same volume. For oblate particles, we quantify their long-time orientation and find that they migrate slower than spheres of the same volume, but exhibit larger migration speeds than prolate particles. Lastly, we examine the effect of normal stress ratio ? <strong>α</strong>  = <strong>Ψ</strong> ₂ /<strong>Ψ</strong>₁on the particle motion and find that this parameter only quantitatively impacts the particle migration velocity but has negligible effect on the rotational dynamics. We therefore can utilize the exact solution derived under the corotational limit (?<strong>α</strong> = −1/2) for a quick and reasonable prediction on the particle dynamics.</p> <p><br></p> <p>We next experimentally investigate the migration behavior of spheroidal particles in microfluidic systems and draw comparisons to our theoretical predictions. A dilute suspension of prolate/oblate microparticles in a density-matched 8% aqueous polyvinylpyrrolidone (PVP) solution is used as the model suspension system. Using brightfield microscopy, we qualitatively confirm our theoretical predictions for flow Deborah numbers 0 < De < 0.1 – i.e., that spherical particles show faster migration speed than prolate and oblate particles of the same volume in tube flows.</p> <p><br></p> <p>We finally design a holographic imaging method to capture the 3-D position and orientation of dynamic microparticles in microfluidic flow. We adopt in-line holography setup and propose a straightforward hologram reconstruction method to extract the 3-D position and orientation of a non-spherical particle. The method utilizes image moment to locate the particle and localize the detection region. We detect the particle position in the depth direction by quantifying the image sharpness at different depth position, and uses principal component analysis (PCA) to detect the orientation of the particle. For a semi-transparent particle that produces complex diffraction patterns, a mask based on the image moment information can be utilized during the image sharpness process to better resolve the particle position.</p> <p><br></p> <p>In the last part of this thesis, we conclude our work and discuss the future research perspectives. We also comment on the possible application of current work to various fields of research and industrial processes.</p> <p><br></p>

In der vorliegenden Arbeit wird eine Methodik zur Entwicklung mechanischer Simulationen der Interaktion Sportler-Sportgerät-Umwelt zur Untersuchung der Funktionalität von Sportgeräten konzipiert und vorgestellt. Die mechanische Simulation ist die gegenständliche Nachbildung spezieller Teilaspekte des Sportlers, z.B. der Körperform, der Trägheitseigenschaften, der Masse, der Interaktionskräfte zur Umwelt oder charakteristischer Bewegungsabläufe zum Zweck der Durchführung gezielter Experimente zur Untersuchung des dynamischen Systemverhaltens Sportler-Sportgerät-Umwelt. Dazu werden drei Fallbeispiele aus der Forschungstätigkeit der Arbeitsgruppe HLST an der Technischen Universität Chemnitz mit Methoden zur Verifikation von Simulationsmodellen – dem strukturierten Durchgehen, der Validierung im Dialog und dem Schreibtischtest – analysiert. Die Analyseergebnisse werden in eine Grobstruktur eingebettet, die aus relevanten Vorarbeiten zur Anwendung der Allgemeinen Modelltheorie abgeleitet ist. Die in den jeweiligen Fallbeispielen verwendeten Prozessschritte, Methoden und Werkzeuge werden dargestellt und die Entwicklungsergebnisse erörtert. Im Abschluss jedes Fallbeispiels wird der Entwicklungsprozess anhand von einheitlichen Kriterien bewertet. In einem abschließenden Schritt erfolgt die Zusammenführung der im Stand der Technik dargelegten Grundlagen und der in den drei Fallbeispielen gewonnenen Informationen zu einer strukturieren und kommentierten Methodik.:1 Einleitung 8 1.1 Definitionen 8 1.2 Einsatzgebiete der mechanischen Simulation 11 1.2.1 Überblick 11 1.2.2 Sicherheit gegen Versagen 12 1.2.3 Konformität 14 1.2.4 Funktionalität 15 1.3 Motivation und Zielsetzung 16 1.4 Aufbau der Arbeit 16 2 Theoretische Grundlagen 18 2.1 Experimentelle Methoden der Sportgeräteentwicklung 18 2.1.1 Einordnung nach Odenwald (2006) 18 2.1.2 Einordnung nach Witte (2013) 19 2.1.3 Einordnung nach Senner (2001) 20 2.1.4 Eigene Systematisierung 23 2.2 Allgemeine Modelltheorie 26 2.3 Existierende Ansätze für die Applikation der Allgemeinen Modelltheorie 29 2.3.1 Anwendung der AMT in der Chemie 29 2.3.2 Anwendung der AMT in der Biomechanik 30 2.3.3 Anwendung der AMT in Logistik und Produktion 32 2.3.4 Fazit 37 3 Präzisierung der Problemstellung 38 4 Methodik 39 5 Fallbeispiel Schwimmanzug – Strömungswiderstand 41 5.1 Vorbemerkungen 41 5.2 Aufgabenanalyse 42 5.2.1 Definition der zu untersuchenden Funktionalität des Sportgeräts 42 5.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 42 5.2.3 Analyse der Simulationswürdigkeit 43 5.2.4 Identifikation des Originals 47 5.3 Modellformulierung 48 5.3.1 Modellansatz 48 5.3.2 Modellsynthese 50 5.4 Modellimplementierung 53 5.4.1 Herstellung des Strömungskörpers 53 5.4.2 Simulation der Fortbewegung im Wasser 54 5.5 Modellanwendung 57 5.6 Modellüberprüfung 60 5.6.1 Abgleich zwischen den experimentellen Ergebnissen und dem theoretischen Modell 60 5.6.2 Vergleich mit dem Original 62 5.7 Fazit 67 6 Fallbeispiel Laufschuh – Stoßabsorption 69 6.1 Vorbemerkungen 69 6.2 Aufgabenanalyse 69 6.2.1 Definition der zu untersuchenden Funktionalität 69 6.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 71 6.2.3 Analyse der Simulationswürdigkeit 71 6.2.4 Definition des Originals 72 6.3 Modellformulierung 72 6.3.1 Modellansatz 72 6.3.2 Systemanalyse 72 6.3.3 Modellsynthese 77 6.4 Modellimplementierung 78 6.4.1 Krafterzeugung 78 6.4.2 Kraftübertragung 79 6.5 Modellanwendung 81 6.6 Modellüberprüfung 82 6.6.1 Soll-Istwert-Vergleich 82 6.6.2 Reliabilität 83 6.6.3 Korrelation zu Stoßbelastungsvariablen 85 6.6.4 Ereignisvaliditätstest: Sohlentemperatur 86 6.6.5 Ereignisvaliditätstest: Sohlendeformation 88 6.7 Fazit 91 7 Fallbeispiel Fußballschuh – Traktionseigenschaften 94 7.1 Vorbemerkungen 94 7.2 Aufgabenanalyse 94 7.2.1 Definition der zu untersuchenden Funktionalität 94 7.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 95 7.2.3 Analyse der Simulationswürdigkeit 96 7.2.4 Definition des Originals 97 7.3 Modellformulierung 98 7.3.1 Modellansatz 98 7.3.2 Systemanalyse 98 7.3.3 Modellsynthese 106 7.4 Modellimplementierung 107 7.5 Modellanwendung 110 7.6 Modellüberprüfung 114 7.6.1 Reliabilität 114 7.6.2 Sensitivitätsanalyse: Normalkraft 114 7.6.3 Sensitivitätsanalyse: Kraftanstieg horizontal 116 7.6.4 Vergleich mit der Realität 116 7.7 Fazit 117 8 Methodik zur Entwicklung mechanischer Simulationen der Interaktion Sportler-Sportgerät-Umwelt 119 8.1 Schematische Darstellung 119 8.2 Erläuterung der Vorgehensempfehlung 120 8.2.1 Klärung der Problemstellung 120 8.2.2 Modellbildung 122 8.2.3 Modellanwendung 124 9 Schlussbetrachtung 126 Literaturverzeichnis 128 Tabellenverzeichnis 133 Abbildungsverzeichnis 135 Danksagung 138 Selbstständigkeitserklärung 139 Lebenslauf 140 / In this dissertation a methodology is conceived that aims to structure the development process of test arrangements that mechanically simulate the interaction of athlete, sports equipment and environment. Mechanical simulation in this context is defined as the physical replication of specific properties of the athlete (e.g. the shape of the human body, body weight, joint kinematics, inertia, external forces in specific movements) in order to conduct experiments to investigate the dynamic behavior of the system athlete-equipment-environment. Therefore, three case studies of mechanical simulation models that have been developed at Technische Universität Chemnitz are analyzed by applying the validation and verification methods “structured walkthrough”, “face validity” and “desk checking”. The results of that analysis are embedded into a framework that is derived by literature review on applied model theory. For each of the three development processes the procedure model is identified and main tools and methods are discussed. Every case study is finally assessed by using standardized evaluation criterions. Finally, the main findings of the analysis of the case studies as well as knowledge obtained by reviewing the state of the art in model theory and simulation methods are used to build up a structured and commentated guideline.:1 Einleitung 8 1.1 Definitionen 8 1.2 Einsatzgebiete der mechanischen Simulation 11 1.2.1 Überblick 11 1.2.2 Sicherheit gegen Versagen 12 1.2.3 Konformität 14 1.2.4 Funktionalität 15 1.3 Motivation und Zielsetzung 16 1.4 Aufbau der Arbeit 16 2 Theoretische Grundlagen 18 2.1 Experimentelle Methoden der Sportgeräteentwicklung 18 2.1.1 Einordnung nach Odenwald (2006) 18 2.1.2 Einordnung nach Witte (2013) 19 2.1.3 Einordnung nach Senner (2001) 20 2.1.4 Eigene Systematisierung 23 2.2 Allgemeine Modelltheorie 26 2.3 Existierende Ansätze für die Applikation der Allgemeinen Modelltheorie 29 2.3.1 Anwendung der AMT in der Chemie 29 2.3.2 Anwendung der AMT in der Biomechanik 30 2.3.3 Anwendung der AMT in Logistik und Produktion 32 2.3.4 Fazit 37 3 Präzisierung der Problemstellung 38 4 Methodik 39 5 Fallbeispiel Schwimmanzug – Strömungswiderstand 41 5.1 Vorbemerkungen 41 5.2 Aufgabenanalyse 42 5.2.1 Definition der zu untersuchenden Funktionalität des Sportgeräts 42 5.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 42 5.2.3 Analyse der Simulationswürdigkeit 43 5.2.4 Identifikation des Originals 47 5.3 Modellformulierung 48 5.3.1 Modellansatz 48 5.3.2 Modellsynthese 50 5.4 Modellimplementierung 53 5.4.1 Herstellung des Strömungskörpers 53 5.4.2 Simulation der Fortbewegung im Wasser 54 5.5 Modellanwendung 57 5.6 Modellüberprüfung 60 5.6.1 Abgleich zwischen den experimentellen Ergebnissen und dem theoretischen Modell 60 5.6.2 Vergleich mit dem Original 62 5.7 Fazit 67 6 Fallbeispiel Laufschuh – Stoßabsorption 69 6.1 Vorbemerkungen 69 6.2 Aufgabenanalyse 69 6.2.1 Definition der zu untersuchenden Funktionalität 69 6.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 71 6.2.3 Analyse der Simulationswürdigkeit 71 6.2.4 Definition des Originals 72 6.3 Modellformulierung 72 6.3.1 Modellansatz 72 6.3.2 Systemanalyse 72 6.3.3 Modellsynthese 77 6.4 Modellimplementierung 78 6.4.1 Krafterzeugung 78 6.4.2 Kraftübertragung 79 6.5 Modellanwendung 81 6.6 Modellüberprüfung 82 6.6.1 Soll-Istwert-Vergleich 82 6.6.2 Reliabilität 83 6.6.3 Korrelation zu Stoßbelastungsvariablen 85 6.6.4 Ereignisvaliditätstest: Sohlentemperatur 86 6.6.5 Ereignisvaliditätstest: Sohlendeformation 88 6.7 Fazit 91 7 Fallbeispiel Fußballschuh – Traktionseigenschaften 94 7.1 Vorbemerkungen 94 7.2 Aufgabenanalyse 94 7.2.1 Definition der zu untersuchenden Funktionalität 94 7.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 95 7.2.3 Analyse der Simulationswürdigkeit 96 7.2.4 Definition des Originals 97 7.3 Modellformulierung 98 7.3.1 Modellansatz 98 7.3.2 Systemanalyse 98 7.3.3 Modellsynthese 106 7.4 Modellimplementierung 107 7.5 Modellanwendung 110 7.6 Modellüberprüfung 114 7.6.1 Reliabilität 114 7.6.2 Sensitivitätsanalyse: Normalkraft 114 7.6.3 Sensitivitätsanalyse: Kraftanstieg horizontal 116 7.6.4 Vergleich mit der Realität 116 7.7 Fazit 117 8 Methodik zur Entwicklung mechanischer Simulationen der Interaktion Sportler-Sportgerät-Umwelt 119 8.1 Schematische Darstellung 119 8.2 Erläuterung der Vorgehensempfehlung 120 8.2.1 Klärung der Problemstellung 120 8.2.2 Modellbildung 122 8.2.3 Modellanwendung 124 9 Schlussbetrachtung 126 Literaturverzeichnis 128 Tabellenverzeichnis 133 Abbildungsverzeichnis 135 Danksagung 138 Selbstständigkeitserklärung 139 Lebenslauf 140

<p>Two studies incorporated providing the groundwork for a blueprint to design sodium sulfur cells from electrode fabrication to choices in electrolyte such as DME, DEGDME, TEGDME and two different salts NaClO4 and NaPF6. First study describes role of the binder within the system comparing carboxymethyl cellulose and carboxymethyl cellulose with a styrene butadiene elastomer addition. The second study focuses on methods to prevent polysulfide shuttling within room temperature sodium sulfur system</p>

<p>Two-phase modeling and simulation capabilities are strongly dependent on the accuracy of flow regime identification methods. Flow regimes have traditionally been determined through visual observation, resulting in subjective classifications that are susceptible to inconsistencies and disagreements between researchers. Since the majority of two-phase flow studies have been concentrated around vertical and horizontal pipe orientations, flow patterns in inclined pipes are not well-understood. Moreover, they may not be adequately described by conventional flow regimes which were conceptualized for vertical and horizontal flows. Recent work has explored applying machine learning methods to vertical and horizontal flow regime identification to help remedy the subjectivity of classification. Such methods have not, however, been successfully applied to inclined flow orientations. In this study, two novel unsupervised machine learning methods are proposed: a modular configuration of multiple machine learning algorithms that is adaptable to different pipe orientations, and a second universal approach consisting of several layered algorithms which is capable of performing flow regime classification for data spanning multiple orientations. To support this endeavor, an experimental database is established using a dual-ring impedance meter. The signals obtained by the impedance meter are capable of conveying distinct features of the various flow patterns observed in vertical, horizontal, and inclined pipes. Inputs to the unsupervised learning algorithms consist of statistical measures computed from these signals. A novel conceptualization for flow pattern classification is developed, which maps three statistical parameters from the data to red, green, and blue primary color intensities. By combining the three components, a flow pattern map can be developed wherein similar colors are produced by flow conditions with like statistics, transforming the way flow regimes are represented on a flow regime map. The resulting dynamic RGB flow pattern map provides a physical representation of gradual changes in flow patterns as they transition from one regime to another. By replacing the static transition boundaries with physically informed, dynamic gradients between flow patterns, transitional flow patterns may be described with far greater accuracy. This study demonstrates the effectiveness of the proposed method in generating objective flow regime maps, providing a basis for further research on the characterization of two-phase flow patterns in inclined pipes. The three proposed methods are compared and evaluated against flow regime maps found in literature.</p>