The possible benefits of thermal remediation of NAPL-contaminated subsurface were analyzed at pore-scale. Force balance analysis was performed to provide the insight and information on the critical conditions for the blob mobilization. First, the critical blob radius for blob mobilization was calculated in terms of blob radius, temperature, and water velocity. Temperature increase enhanced the blob mobilization along with the decrease of interfacial tension. Water velocity increase also enhanced the blob mobilization. Critical water velocity provided the critical condition for the initiation of blob mobilization to distinguish singlet and doublet in blob size. Second, the terminal (or steady state) blob velocity at the steady state blob motion was determined. Increases of temperature and water velocity raised the terminal blob velocity. When the observation of blob mobilization moved from REV scale (macroscale) to pore-scale, terminal blob velocity showed the different phenomena according to the change of oil saturation. At macro-scale, the terminal blob velocity was smaller than water velocity by an order or two. However, the terminal blob velocity reached to water velocity at pore-scale. This investigation would provide the better understanding on the pore-scale analysis of residual NAPL blob mobilization by thermal remediation. Additionally, the pore-scale analysis developed in this study would be incorporated into a general conservation equation in terms of the accumulation of multiple blobs. It would derive continuumaveraged equations that accurately represent pore-level physics. In conclusion, the study on the critical conditions for the initiation of blob mobilization as a single discrete blob would have some contribution to the transport and fate of NAPL contaminant and the desired subsurface remediation.

Eddy current separation aims to recover non-ferrous metals from non-metals utilizing electromagnetic interactions. In order to describe the separation process, a representative model is needed that can accurately calculate the induced forces. Such a model can be used to optimize the efficiency of current equipment as well as designing ones that can offer new capabilities. Models proposed so far for the separation process, using traditional approaches to calculate forces, had limited success due to complex nature of electromagnetic interactions. In this dissertation, a novel method for calculating the magnetic force acting on non-ferrous metal particles was developed. By this method, force calculations can be carried out accurately using intrinsic parameters of particles such as size and shape, as well as its orientation within the field. The method also takes into account the operating parameters of the equipment such as the rotational speed of the magnetic element and the speed of the belt. In order to verify this method and collect empirical data, a novel data acquisition and interpretation approach was developed. A computer simulator was also developed that can calculate trajectories of particles based on operating parameters of the eddy current separator and characteristics of the material being processed. The accuracy of the simulator was verified using empirical data obtained by the novel data acquisition method. This contribution provides a viable option for reducing the cost of analyzing; optimizing and designing eddy current separators. / PHD

Approved for public release, distribution is unlimited / The geometric characteristics of flapping-wing propulsion are studied experimentally through the use of a force balance and a Micro Air Vehicle (MAV) system. The system used is built to duplicate the propulsion system currently on the flying model of the Naval Postgraduate School (NPS) MAV model. Experiments are carried out in a low speed wind tunnel to determine the effects of mean separation and plunge amplitude on the flapping wing propulsion system. Additionally, the effects of flapping-wing shape, flapping frequency, and MAV angle of attack (AOA) are also investigated. Some flow visualization is also performed. The intent is to optimize the system so that payload and controllability improvements can be made to the NPS MAV. / Ensign, United States Naval Reserve

La croissance et le détachement des bulles formées sur une paroi par injection ou ébullition sont présents dans de nombreuses situationsindustrielles (les contacteurs gaz/liquide, les évaporateurs ou des dispositifs d’impression à jet d’encre). Dans la plupart des applications, les bulles grossissent dans un écoulement cisaillé ou au repos et la plupart des études visent à prévoir le rayon de détachement par une analyse de l’équilibre des forces. Ainsi, une bonne modélisation des forces capillaires et hydrodynamiques est nécessaire pour prédire correctement le rayonau détachement. Dans un premier temps, la croissance quasi-statique d’une bulle d’air formée sur la paroi d’une cuve et d’un canal rectangulaire est étudiée. Trois substrats différents sont utilisés pour observer l’influence des conditions de mouillage. La dynamique de la croissance de la bulle et le détachement sont alors enregistrés différentes configurations : canal horizontal, canal incliné, avec et sans écoulement liquide. Ensuite,le comportement des bulles de vapeurs en croissance sur une paroi en ébullition en vase et convective est étudié. Les expériences sonteffectuées en gravité terrestre et en microgravité dans un liquide sous-refroidi (HFE 7000) à basse pression (1-2bars). Des bulles de vapeurssont nuclées sur la paroi par l’intermédiaire d’un générateur de bulles. Ce dernier chauffe le liquide environnant au-dessus de sa température de saturation. Les bulles croient sur le site de nucléation dans un écoulement cisaillé et se détachent soit directement soit en glissant le long de la paroi. Une copie de la cellule d’essai appelée RUBI développée par l’ESA est implémentée dans le dispositif expérimental pour effectuer lespremières expériences en microgravité avant son lancement dans la station spatiale ISS. Toutes les acquisitions sont filmées à l’aide d’une caméra rapide et l’extraction du contour de la bulle est réalisée par traitement d’images. Différentes forces agissant sur une bulle sont calculées à partir des paramètres géométriques de la bulle. Un modèle prédictif de détachement de bulles est proposé. Enfin, un bilan thermique diphasique est effectué. / The growth and departure of bubbles nucleated on a wall are of particular interest in industrial situations such as gas/liquid contactors in chemicalprocessing, vapor nucleation in evaporators or inkjet printing devices. In most of these industrial applications, the bubbles grow in a shear flow and most studies aim topredict the radius at detachment by a force balance analysis. Thus a good modeling of both the hydrodynamic and capillary forces is needed to predict correctly this radius. First, the quasi-static growth of an air bubble nucleated on the wall of a tank and a rectangular channel is investigated. Three different substrates are used to observe the wettability effect. The dynamics of the bubble growth and detachment is then recorded for different configurations : horizontal channel, inclined channel, with and without a shear flow. Then, behavior of vapor bubbles growing at a wall in pool boiling and flow boiling is investigated. Experiments are performed in normal and microgravity environments with a subcooled test liquid HFE-7000 at low pressure (1-2 bars). Vapor bubbles are nucleated on the wall by a bubble generator that heats the liquid above its saturation temperature. This bubble generator was designed to provide nucleation on an isolated site. These bubbles grow on this nucleation site under an imposed shear flow and depart downstream either along the wall or perpendicularly. A copy of the test cell called RUBI developed by ESA is included in our experiment to perform the first experiments in microgravity before its launch to the ISS. Geometric and kinematic features of the air bubbles and vapor bubblesare measured by processing images obtained by high-speed video recordings. Different forces acting on the bubbles are calculated from these measurements, using a point force approach. The validity of this mechanistic approach to the bubble dynamics is discussed. At last, heat transfer balance is estimated on the bubble.

Tato práce se zabývá měřením aerodynamických charakteristik modelu závodního vozu Formula SAE v aerodynamickém tunelu, v měřítku 1:4. V první části je představen projekt Formula SAE a popsána role aerodynamiky v rámci této soutěže. Následuje přehled teoretického pozadí, které je relevantní k provedenému experimentu. Ve druhé části práce je popsán samotný experiment a prezentovány jeho výsledky. Součástí je návrh, výroba a kalibrace šestikomponentní tenzometrické váhy pro měření aerodynamického zatížení. Testy v aerodynamickém tunelu byly provedeny ve čtyřech konfiguracích, aby bylo možné určit vliv přítlačných křídel a podlahy s difuzorem na výsledné aerodynamické charakteristiky vozu.

En vindtunnel används för att simulera luftflödet som verkar på till exempel en nerskalad modell av en verklig flygplansvinge eller ett fordon. Detta hjälper att förstå och ta fram de komponenter som påverkar interaktionen samt krafter och moment.  Mittuniversitetets laboratorium är i behov av en ny kraftsensors-rigg, detta är en rigg som mäter krafter som påverkar på en vinge profil inuti en vindtunnel. En vidareutveckling av den befintliga kraftsensors-riggen skulle innebära en alltför lång arbetsprocess, därför bestämdes det att utvecklas en ny design av sensor-riggen som löser några felkällor som den tidigare sensor- riggen har; vilka är inexakta mätvärde samt att den befintliga riggen mäter enbart lyftkraften. Genom framtagning av en ny kraftsensors-rigg som går att tillverka i Mittuniversitetets lokaler minskar tiden för att utföra vindtunnel tester samt ökar mätvärdenas noggrannhet. Syftet med detta arbete har varit att ta fram konstruktion av en ny kraftsensors-rigg som kan mäta krafter i x- och y-axeln det vill säga lyft och dragkraft. Kraftsensors-riggen kommer att installeras i vindtunneln som finns i Mittuniversitets laboratorium.  I detta projekt följs det designprocessens arbetsgång som är uppdelat i fyra faser. Den första fasen, förstudiefasen, definierades produktens kravspecifikation och funktionsanalys. Den andra fasen, kreativa fasen, inleddes med brainstorming för att generera konceptlösnings idéer. Sedan används Pugh-matrisen i konceptutvärdering- och framtagningsfasen för att utvärdera och välja konceptet utifrån en kvantitativ-metod. Sedan modellerades en tredimensionell modell för det färdiga konceptet med hjälp av CAD. Slutligen i konstruktion-utvecklingsfasen framställdes konstruktionen med hjälp av CAD:s modeller. därefter skrevs de komplexa delarna ut med en 3D-utskrivare samtidigt som de mindre komplexa delar framställdes av trä med en laser skärare för att spara på material samt kostnader, till slut byggdes och testades riggen i Mittuniversitets verkstad.  Projektet resulterade i en kraftsensors-rigg som kan mäta både luftmotstånd-och lyftkraften i en låg hastighet vindtunnel med noggrannare mätvärde än den tidigare riggen. / A wind tunnel is used to simulate the air flow that acts on, for example, a scaled-down model of a real aircraft wing or a vehicle. Which allows a better understanding of the components that affect the interactions between the air and the object of study, that is to say the forces and torque affecting the object. In order to fully utilize the wind tunnel in the laboratory at Mid Sweden, it has proved necessary to design a new wind tunnel force balance, which is a structure that measures forces affecting objects inside the wind tunnel. The reason being is that the current force balance sensor has some issues concerning accuracy of measurement and the lack of measuring other forces than lifting forces. A further development of the existing force balance would involve too long a work process, so it was decided to develop a new design of a wind tunnel force balance that solves some sources of error that the previous design of the force balance has and introduce an air resistance measurement component. By developing a new force balance that can be manufactured in Mid Sweden University's premises, the time for performing wind tunnel testing is reduced and the accuracy of the measured values is increased. The purpose of this project has been to develop a construction of a new force balance that can measure forces in the x- and y-axis, meaning lifting and air resistance. The force balance will be installed in the wind tunnel located in Mid Sweden University's laboratory.  In this project, the workflow of the design process is followed, which is divided into four phases. The first phase, the research phase, defined the product's requirements specification and functional analysis. The second phase, concept development and control art, began with brainstorming to generate concept solution ideas. The Pugh matrix was then used in the prototyping and validation phase to evaluate and select the concept based on a quantitative method. Then a three-dimensional model for the finalized concept was modelled using CAD. Finally, in the testing and refining phase, the design was produced using the CAD models. Then the complex components were printed with a 3D-printer while the less complex component were made of wood using a laser cutter to save on materials and costs, finally the rig was built and tested in Mid Sweden University's workshop.  The project resulted in a force balance that can measure both air resistance and lifting force in a low-speed wind tunnel with a more accurate measurements than the previous force balance.

The inherent thermal resistance of ceramic membranes allows for treatment of industrial waters at elevated temperatures. Traditionally, the high temperature of wastewater has been an issue compromising the integrity of polymeric membrane systems or requiring the temperature to be lowered for further treatments. In ceramic membrane systems, a decrease in viscosity with increasing temperature, however, can be utilized, which increases the permeate flux. In this study, the fouling of ceramic ultrafiltration by feed solutions containing colloidal silica was evaluated at temperatures between 25 – 90 °C seen in various industries. Ceramic membranes were able to perform well at elevated temperatures up to 90 ºC with sustained mechanical and chemical integrity. Results showed net benefit of filtration at elevated temperatures on permeate flux in spite of increasing total fouling resistance with temperature. When the temperature increased from 25 to 90 °C, there was a 90% increase in steady-state permeate flux. The dominant resistance was physically removable fouling, and the increase in fouling with feed temperature was supported by force balance analyses. This study provides a foundation from which further studies can be developed including pilot-scale testing, use of real wastewater, and the effects of operating conditions.

EDF vise à développer une « Approche Prédictive Locale » de la crise d'ébullition, i.e. une approche permettant d'élaborer des prédicteurs (empiriques) de flux critique basés sur des paramètres locaux fournis par le code NEPTUNE_CFD (pour les seuls écoulements à bulle dans un premier temps). Dans ce cadre général, ce travail de thèse a consisté à évaluer la modélisation du code NEPTUNE_CFD, sélectionnée pour simuler les écoulements bouillants à bulles,puis à l'enrichir. Ce dernier objectif nous a conduits à nous intéresser à la modélisation mécaniste de l'ébullition nucléée sous-saturée en convection forcée. Après une analyse bibliographique critique, nous avons identifié des améliorations physiques, en particulier la prise en compte du glissement des bulles le long de la paroi chauffante. Cette voie a nécessité le développement d'une approche de type « bilan des forces » pour renseigner le diamètre de détachement des bulles de leur site actif de nucléation et le diamètre de décollage des bulles de la paroi. Un nouveau modèle d'ébullition nucléée a, pour finir, été proposé, en relation avec ces développements, et évalué de manière préliminaire. / EDF aims at developing a "Local Predictive Approach" of the boiling crisis for PWR core configurations, i.e. an approach resulting in (empirical) critical heat flux predictors based on local parameters provided by NEPTUNE_CFD code (for boiling bubbly flows, only in a first stage). Within this general framework, this PhD work consisted in assess one modelling of NEPTUNE_CFD code selected to simulate boiling bubble flows, then improve it. The latter objective led us to focus on the mechanistic modelling of subcooled nucleate boiling in forced convection. After a literature review, we identified physical improvements to be accounted for, especially with respect to bubble sliding phenomenon along the heated wall. Subsequently, we developed a force balance model in order to provide needed closure laws related to bubble detachment diameter from the nucleation site and lift-off bubble diameter from the wall. A new boiling model including such developments was eventually proposed, and preliminary assessed

The dynamics of hydrogen gas bubbles growing during electrolysis in H 2 SO 4 on a Pt microelectrode are studied in detail by electrochemical, shadowgraphy and PIV methods. The bubble evolution under potentiostatic conditions is presented in terms of electric current, images and radius of the growing bubble, and the velocity profiles. It allowed to resolve the carpet of microbubbles underneath the growing bubble, the transition to a new oscillatory growth regime and a Marangoni convection around the bubble foot. To substantiate the effect of coalescence and of the electrostatic effect on the bubble departure diameter, a salt (sodium sulfate) was added to regulate the pH and the ionic strength of the electrolyte.

Early in the ship design process, naval architects must often evaluate and compare multiple hull forms for a specific set of requirements. Analytical tools are useful for quick comparisons, but they usually specialize in a specific hull type and are therefore not adequate for comparing dissimilar hull types. Scale model hydrodynamic testing is the traditional evaluation method, and is applicable to most hull forms. Scale model tests are usually performed on the largest model possible in order to achieve the most accurate performance predictions. However, such testing is very resource intensive, and is therefore not a cost effective method of evaluating multiple hull forms. This thesis explores the testing of small scale models. It is hypothesized that although the data acquired by these tests will not be accurate enough for performance predictions, they will be accurate enough to rank the performance of the multiple hull forms being evaluated.