The quest for more efficient machines is always ongoing in the engineering world. This project is no different. ABB are investigating a new type of propeller that seems to offer increased efficiency compared to normal screw propellers. That is a so called foil wheel propeller. The foil move in a circular pattern with the fluid stream moving in the radial direction of the propeller instead of the axial as in a screw propeller. If the propeller is placed and modeled correctly it can also be used as a thrust vectoring device. This report focuses on the fluid physics of the foil wheel propeller, or as it is called in this report radial flow propeller. First of all the movements and interactions of the blades must be understood. Both to keep the efficiency high to compete with screw propellers, but also to foresee any problems that may occur with such a new device. A scaled down version of the propeller have been commissioned by ABB and will be tested in some time after the work within this report is completed. The effects associated to this will also be analyzed. The tool to compute the flow physics of the radial flow propeller will be computational fluid dynamics. Computational fluid dynamics uses a numerical method to compute the entire fluid field in space and time. The flow around the propeller is highly complex so a detailed analysis is needed if a well functioning control system is to be constructed for instance. The differences between the downscale and the full-scale are great, even when the non dimensional coefficients are considered. The down-scale case will be less efficient, it will be difficulties predicting the performance of the full-scale since the downscale flow is much less powerful than the full-scale case. The interaction between the blades has a large effect. There is a strong relation between angle of attack and the number of blades. The forces that are large change by about 30\% so it must definitely be considered if a model is to be used for a control system.

The wheelchair tennis evidence base has developed considerably in recent years. For those with a spinal cord injury (SCI), or severe physical impairment, tennis participation represents an opportunity for skill and motor development, and potential for disease risk reduction (Abel et al., 2008). However, as a complex series of technical, tactical and physical elements are implicated, participation for novice, developmental or low-skill players can be challenging. Hence, extension of the evidence base to consider the responses of such groups during play is of considerable value. Initial experimental studies in this thesis investigated the validity, reliability and applicability of instrumentation for the assessment of wheelchair tennis court-movement. Comparisons were made between a global positioning system (GPS) and the data logger (DL) device (Study 1). GPS underestimated criterion distance in tennis-specific drills and reported lower match-play values than the DL. In contrast, DL placed on the outside wheel offered an accurate representation of distance. However, underestimations for DL were revealed at speeds > 2.50 m·s-1 during treadmill testing. Consequently, Study 2 extended this work with consideration of DL applicability for wheelchair tennis match-play. Examination of speed profiles revealed that time spent below the threshold for accuracy was trivial, confirming DL applicability for court-movement assessment. Further between-group comparisons for rank [highly-ranked (HIGH), low-ranked (LOW)], sex (male, female) and format (singles, doubles) revealed that LOW were stationary for longer than HIGH and spent more time at low propulsion speeds. Time in higher speed zones was greatest for HIGH and doubles players. Between-group differences (rank) were further scrutinised in Study 3 with attention paid to describing the physiological response of competitive match-play aligned to court-movement. Set outcome (result) was also examined. Independent of result, HIGH covered greater overall, forwards, reverse and forwards-to-reverse distances than LOW. Interestingly, HIGH winners covered greater distances than HIGH losers and had a higher mean average and minimum heart rate (HR) than LOW winners. In contrast, LOW losers had a higher mean average and mean minimum HR than LOW winners. Collectively, these outcomes suggest an enhanced ability for HIGH to respond to ball movement and the physiological and skill challenges of match-play. While this thesis confirmed that the activity duration and playing intensity is sufficient to confer health-related effects (Study 3), differences identified for rank suggested that strategies to 4 enable performance improvements in LOW were merited. The International Tennis Federation (ITF) has suggested that all starter players should be able to serve, rally and score from their first lesson (ITF, 2007). The reality however, is that chair propulsion whilst holding a racket is complex, and therefore, tennis play is challenging for novice and developmental players. Hence, the remainder of experimental work focused on interventions to enable increased court-movement and development of wheelchair tennis-specific court-mobility for LOW. The ITF have endorsed the use of a low-compression ball (LCB) for novices. An LCB bounces lower and moves more slowly through the air than a standard-compression ball (SCB). Novel findings from Study 4 revealed that greater total and forwards distances, greater average speeds and less time stationary result from use of the LCB. Increased movement activity occurred without associated increases in physiological cost, but was considered advantageous, with players adopting stronger positions for shot-play. Further examination of the linkage between movement and physiological variables were explored in the final experimental investigation (Study 5). A short period of organised practice enabled higher overall and forwards distances, and peak and average speeds to be achieved during match-play, without associated increases in physiological cost. Changes were desirable and represented enhanced court-mobility and mechanical efficiency (ME). Wheelchair tennis players were also more self-confident in tennis-specific chair-mobility, post-practice. The racket was a constraint, with lower distances and speeds, and a lower peak physiological response, achieved during tennis practice completed with a racket. This thesis advocates the use of an LCB and a short period of pre-match court-mobility practice for the novice wheelchair tennis player. Collectively, these interventions are likely to prompt greater court-movement enabling better court-positioning, develop confidence in court-mobility and shot-play, develop competence in racket handling whilst pushing, and enhancing ME. These characteristics are likely to enable participation with the likely inference being that greater competence, skill and self-confidence promotes greater enjoyment and therefore enhances longer-term compliance. This is of considerable practical significance given that tennis typically attracts new players to the game, but is less successful at retaining them (ITF, 2007).

En framtida alternativ framdrivningsmetod av fartyg skulle kunna vara en ångjetstråle som expanderas via en ejektor. Syftet med studien var att utföra ett experiment med två olika typer av utloppsmunstycken på ejektorns diffusor, för att därigenom ta reda på vilken design som lämpar sig för denna framdrivningsmetod samt vilken tryckkraft som är möjlig att uppnå. Studiens resultat är tänkt att användas som underlag för fortsatta studier om fartygsframdrift med ångjetstråle via en ejektor, för att eventuellt kunna öka energieffektiviteten i jämförelse med dagens framdrivningsmetoder. Resultatet visar att en cirkulär strålbild ger högst tryckkraft trots ett lägre inloppstryck vid en vattentemperatur på 70 °C i jämförelse med en platt strålbild vid ett högre inloppstryck och samma temperatur. Experimentet gav ingen mätbar tryckkraft vid expansion av fuktig ånga med ett tryck på 3 MPa och en temperatur på 150 °C. / A future alternative propulsion method of ships could be a steam jet that is expanded via an ejector. The purpose of the study was to conduct an experiment on two different types of outlet nozzles on the diffuser of the ejector. This was carried out to find which design that is suitable for this propulsion method and what propulsion force that was possible to achieve. The result of the study was then thought to be used as a basis for further studies of steam jet propulsion through an ejector, to possibly increase the energy efficiency in comparison with today's propulsion methods. The result shows that a circular jet provides maximum propulsion force despite a lower inlet pressure and a water temperature at 70 °C in comparison with a flat jet at higher inlet pressures and equal temperature. The experiment gave no measurable propulsion force when expanding wet steam at a pressure of 3 MPa and a temperature at 150 °C.

La nageoire caudale des animaux aquatiques peut être modélisée par un foil oscillant qui produit de la poussée. Le sillage moyen d'un tel foil oscillant est un jet de quantité de mouvement nette positive. Il a été proposé que les caractéristiques de stabilité de ces sillages moyens sont liées à l'efficacité de la propulsion des animaux aquatiques. Dans cet étude, nous reprenons cette question en tenant compte à la fois de la poussée et de la traînée exercée sur un corps auto-propulsé lorsqu'il nage. Nous étudions la stabilité d'une famille de sillages ayant une quantité de mouvement nulle, construit comme l'approximation d'Oseen d'un doublet de force se déplaçant à vitesse constante. En effectuant une analyse de stabilité locale, nous montrons d'abord que ces sillages subissent une transition convectif-absolu. En utilisant une approche "time-stepper" et intégrant le système de Navier-Stokes linéarisé, nous étudions la stabilité globale et mettons en évidence des effets non-parallèles de l'écoulement principal, ainsi que le rôle de la région absolument instable dans l'écoulement. Pour compléter le scénario d'instabilité globale, nous abordons l'évolution non linéaire d'une perturbation injectée dans le sillage. Ces résultats sont ensuite discutés dans le contexte de la nage d'un animal aquatique. Selon les résultats de stabilité, les sillages de quantité de mouvement nulle produit par les animaux aquatiques sont généralement stables, tandis que le sillage qui correspondrait à la poussée seule est instable. Il est essentiel de considérer toutes les forces exercées sur un animal auto-propulsé lors de l'examen de la stabilité de son sillage et l'efficacité de sa propulsion. / The caudal fin of swimming animals can be modelled as a thrust-producing flapping foil. When considered alone, such a foil produces on average a jet wake with a positive net momentum. It has been argued that the instability characteristics of these averaged wakes are linked to the propulsion efficiency of swimming animals. Here, we reconsider this question by taking into account both the thrust and the drag exerted on a self-propelled swimming body. To do so, we study the stability of a family of momentumless wakes, constructed as the Oseen approximation of a force doublet moving at constant velocity. By performing a local stability analysis, we first show that these wakes undergo a transition from absolute to convective instability. Then, using the time-stepper approach by integrating the linearised Navier-Stokes system, we investigate the global stability and reveal the influence of a non-parallel base flow as well as the role of the locally absolutely unstable upstream region in the wake. Finally, to complete the global scenario, we address the nonlinear evolution of the wake disturbance. These results are then discussed in the context of aquatic locomotion. According to the present stability results, the momentumless wake of aquatic animals is generally stable, whereas the corresponding thrust part is unstable. It is therefore essential to consider all forces exerted on a self-propelled animal when discussing its wake stability and its propulsion efficiency.

The remarkable efficacy with which normal surface mass transpiration (blowing and suction) alters a given base flow to achieve a desired predefined objective has motivated several investigations on drag reduction, self-propulsion and suppression of separation and wake unsteadiness in bluff body flows. However, the energetic efficiency, a critical parameter that determines the true efficacy and in particular practical feasibility of this control strategy, has received significantly less attention. In this work, we determine the optimal zero net mass transpiration blowing and suction profiles that minimize net power consumption while reducing drag or enabling self-propulsion in typical bluff body flows. We establish the influence of prescribed blowing and suction profiles on the hydrodynamic loads and net power consumption for a representative bluff body flow involving flow past a stationary two-dimensional circular cylinder. Using analysis based on Oseen’s equations, we find that all the symmetric modes, except the first one, lead to an increase in the net power consumption without affecting hydrodynamic drag. The optimal blowing and suction profile that yields minimum power consumption is such that the normal stress acting on the cylinder surface vanishes identically. Furthermore, we show that a self-propelling state corresponding to zero net drag force is attained when the first mode of blowing and suction profile is such that the flow field be-comes irrigational. Based on these findings we employ direct numerical simulation tools to decipher the Reynolds number dependence of the optimal profiles and the associated power consumption for both drag reduction and self-propulsion. For a typical Reynolds number, the time-averaged drag coefficient first decreases due to vortex shedding suppression, then increases and eventually decreases again after attaining a local maximum as the strength of the first mode is increased. The net power consumption continues to decrease with an increase in the strength of the first mode before reaching a minima after which it rises continuously. For a Reynolds number of 1000 over fifteen fold reduction in drag is achieved for an optimal blowing and suction profile with a maximum radial surface velocity that is nearly 1.97 times the free stream velocity. Next, to establish whether or not higher modes play a role in decreasing net power consumption at finite Reynolds number, we perform theoretical analysis of a configuration similar to the one described above for a spherical body. At zero Reynolds number, as a result of mode independence, we show that surface blow-ing and suction of any form that involves second or higher order axisymmetric or non-axisymmetric modes does not contribute to drag and only leads to an increase in total power consumption. However, at finite Reynolds number, using analysis based on Oseen’s equations, we find that the second and higher modes contribute substantially to the optimal profiles. Finally to understand the effects of a change in shape we consider generalization of the above analysis to axisymmetric prolate and oblate spheroidal bodies. We find that for a general axisymmetric body with non-constant curvature, the optimal drag reducing and self-propelling blowing and suction profiles for minimum power consumption contain second and higher-order modes along with the first mode even when the Reynolds number is zero. The net decrease in power consumption with the use of second and higher order modes exceeds 33% for a disk-like low aspect ratio self-propelling oblate spheroid. Moreover, we perform comparisons between blowing and suction and tangential surface velocity based boundary deformation propulsion mechanisms. Below an aspect ratio of 0.56 we find blowing and suction mechanism to be more efficient for self-propulsion of an oblate spheroid. In contrast, for a self-propelling pro-late spherical micro-swimmer, we show that the tangential surface tread milling consumes less power irrespective of the aspect ratio.

The shipping industry is reliant on port authorities for the facilitation of safe entry and departure of ships at the ports. This role can not be fulfilled without the assistance of harbour tugs which are run by the marine operations section of the Transnet National Ports Authority. The tugs have to be safe and efficient in the process of pulling and pushing ships around the harbour. Harbour tugs are expensive to acquire and to maintain. The marine operations business has to make appropriate choices of tug propulsion design in order to realise the benefits of the tugs acquired by the ports authority. This can be achieved by analysing the current tugs that the operations are using, which will then serve as valuable information when the time for asset replacement is due. The researcher chose to use the two tug propulsion designs currently used by the Port Elizabeth harbour tugs as a basis for this analysis. The analysis links the three factors of maintenance management, equipment efficiency and equipment safety, to the minimisation of operational costs as perceived by the tug personnel, the pilots and the marine managers. This study seeks to verify the link between these factors and the perceived minimisation of operational costs. Available literature was reviewed and data was collected using a suitably designed questionnaire for this research. This research paper has led to recommendations that should inform the tug acquisition decisions and raise the awareness of the marine employees to relate the factors set out above to minimise operational costs.

The subject of the thesis is to identify and assess the current status of electromobility in the Czech Republic and proposal of partly strategiy and recommendations for company Mercedes-Benz Czech Republic s.r.o. in this area. The theoretical part deals with the definition of the theory of strategic management process, especially the analysis of the external and internal area and methodologies of creation strategy. The practical part describes the characteristics of the Mercedes-Benz Czech Republic s.r.o., direct analysis of the electromobility and internal analysis of the company. Finally, there is a summary SWOT analysis and strategy formulation and recommendations in the area of electromobility for the company.

L'objectif de ce travail est d'étudier l'effet thermoélectrique à l'échelle nanométrique des nanostructures chauffées. Dans un premier temps, nous étudions les mécanismes d'autopropulsion thermo-électrophorétique de particules Janus chauffées par laser. Ce mécanisme d'autopropulsion est principalement induit par l'effet Seebeck ou l'effet thermoélectrique. Cet effet provient de la séparation des charges survenues lorsqu'un gradient de température est présent dans la solution d'électrolyte: Une forte absorption du laser par la partie métallisée de la particule génère un gradient de température qui en retour agit sur les espèces ioniques (positive et négative) et les conduits vers les zones chaudes ou les zones froides. Ce mouvement d'ions entraine la création d'un champ électrique dipolaire qui, à proximité de la particule, dépend fortement des propriétés de surface. Ce changement de comportement de ce champ électrique sur une surface isolant ou conductrice n'affecte pas la vitesse de la particule. Dans un second temps, nous étudions les effets d'interactions hydrodynamiques et de la condensation des contre-ions sur la thermophorèse des polymères d'ADN. Comme résultat principal, la mobilité thermophorétique montre, en fonction de la longueur de la chaîne, un comportement non-monotone et se compose de deux contributions induites par les forces conductrices dominantes que sont l'effet Seebeck et le gradient de permittivité. À la fin, nous comparons notre résultat théorique avec une récente expérience sur l'ADN / The aim of this work is to study the nanoscale Seebeck effect at hot nanostructures. At first, we study the thermo-electrophoresis self-propulsion mechanism for a heated metal capped Janus colloid. The self-propulsion mechanism is mainly induced by the electrolyte Seebeck effect or thermoelectric effect. This effect takes its origin from the separation of charges occurring while a temperature gradient is present in a electrolyte solution: A strong absorption of laser light by the metal side of the particle creates a temperature gradient which in turn acts on ion-species (positive and negative) and drives them to the hot or the cold region. This motion of ion results in a dipolar electric field which, close to the particle, depends strongly on the surface properties. The change of behavior of the electric field at the insulating or conducting surface does not affect the velocity of the particle. At second, we study the effect of hydrodynamic interactions and counterion condensation in thermophoresis for DNA polymer. As the main result, the thermophoretic mobility shows, in function of the chain length, a non-monotonuous behavior and consists of two contributions induced by the dominant driving forces which are the thermally induced permittivity-gradient and the electrolyte Seebeck effect. At the end, we compare our theoretical result with recent experiment on single-stranded DNA.

<p>Solar-powered Unmanned Aerial Vehicles (UAVs) solve the problem of loiter time as aircrafts can fly as long as sufficient illumination and reserve battery power is available. However, Solar-powered UAVs still face the problem of excessive wingspan to increase solar capture area, which detracts from maneuverability and portability. As a result, a feature of merit for solar UAVs has emerged that strives to reduce the wingspan of such UAVs. The purpose of this project is to improve energy use efficiency by applying a distributed propulsion system to reduce the wingspan of solar-powered UAVs and increase payload. The research focuses on optimizing a new design analysis method applied to the distributed propulsion system and further employs the novel application of solar arrays on both top and bottom of the wings. The design methodology will result in a 2.1-meter wingspan, which is the shortest at 2020, for a 24-hour duration solar-powered UAV.</p><br>

Transportation is a primary pollution source contributing to 14 percent of global greenhouse gas emissions, and 12 percent of transportation emissions came from maritime activities. Emissions from the ferry industry, which carries roughly 2.1 billion passengers and 250 million vehicles annually, is a major concern for the general public due to their near-shore operations. Compared to the rapidly advancing clean automotive propulsion, fuel efficiency and emissions improvements for marine vessels are more urgent and beneficial due to the significantly higher petroleum fuel consumption and heavy pollutants and the relatively slow adoption of clean propulsion technology by the marine industry. Hybrid electric propulsion, proven to be effective for ground vehicles, presents a promising solution for more efficient clean marine transportation. Due to the diversified hull/propulsor design and operation cycle, the development of a hybrid electric marine propulsion system demands model-based design and control optimization for each unique and small batch production vessel. The integrated design and control optimization further require accurate and computation efficient hull resistance and propulsor thrust calculation methods that can be used to predict needed propulsion power and gauge vessel performance, energy efficiency, and emissions. This research focuses on improving the low-order empirical hull resistance and propulsor thrust models in the longitudinal direction by extracting model parameters from one-pass computational fluid dynamics (CFD) simulation and testing the acquired models in integrated design optimization of the marine propulsion system. The model is implemented in MATLAB/Simulink and ANSYS Aqwa and validated using operation data from BC Ferries’ ship Tachek. The modified low-order model (M-LOM) is then used in the integrated optimizations of propulsion system component sizes and operation control strategies for another BC Ferries’ ship, Skeena Queen. The performance, energy efficiency, and emissions of various propulsion options, including nature gas-mechanical and natural gas-electric benchmarks, and hybrid electric alternatives of series hybrid, parallel hybrid, and battery/pure electric are compared to demonstrate the benefits of the new method in completing these complex tasks and hybrid electric marine propulsion. The research forms the foundation for further studies to achieve more accurate propulsion demand prediction and a more comprehensive lifecycle cost assessment of clean marine propulsion solutions. / Graduate