Due to many advantages, swash plate pumps are wide spread in hydraulic systems. The main advantages are the through drive capability, the adjustability and most of all, the high power density. Their application range is limited, historically, to 450bar including medium and higher volume sizes. In higher pressure range, constant pumps such as wobbling disks or radial piston pumps are normally used. This is because the higher stressed parts can be dimensioned much bigger. Pumps with lower power such as constant displacement gear pumps are generally used in low price applications. In order to enlarge the application range of swash plate pumps, their advantages have to be further improved and strengthened. This paper shows by example how the pressure of the basic series A4VSO was increased up to a nominal pressure of 630bar and the historical pressure mark of 450bar could be exceeded. This increase in pressure level enables for example steel treatment manufacturers to reduce their component sizes without the need of a pressure transducer. Furthermore the power density of the redesigned HA4VSO was increased by 36%, compared to the standard A4VSO, by significantly increasing the self-priming speed. On the other side of the application range, in lower power mobile applications such as small tractors, forklift and skid steer loader, there is an increasing demand for less exhaust emissions and better fuel economy. The energy saving potential by changing from a hydraulic system with constant hydraulic pumps to variable hydraulic pumps is already proven on high power applications. By developing the variable axial piston pump A1VO to the requirements of lower horse power application, it is now also possible to realize such savings in lower horse power applications. Furthermore efficiency of the pump itself can be improved. An example of this is shown by way of the new A4 series 33.

Ce travail de thèse est une étude multi-échelles de temps de la morphodynamique d'une île barrière soumise à des conditions de forçages paroxysmaux de mousson, de tempêtes tropicales et de typhons. Cette étude se concentre dans un premier temps, sur un large travail de terrain effectué dans le cadre du projet KUN-SHEN. Sept mois de mesures (de novembre 2011 à janvier 2012 et de mai à septembre 2012) ont permis l'acquisition d'un jeu de données inédit dans la littérature, exhaustif et de haute résolution temporelle et spatiale. Des mesures hydrodynamiques du large jusqu’à la zone de jet de rive ont été acquises en parallèle d'un suivi topographique de la plage émergée. Les mesures de vagues ont été acquises à partir d'une bouée au large, de deux houlographes-courantomètres en avant-côte (mesures en continu à 2 Hz) ainsi que de pressiomètres enfouis dans la plage sub-aérienne (mesures en continu à 5 Hz). Les levés topo-bathymétriques ont été réalisés au D-GPS (résolution centimétrique) une fois par semaine pendant la saison de mousson et juste après et avant chaque événements de tempêtes extrêmes pendant la saison des typhons. Le travail d'analyse cible ensuite la morphodynamique de la zone de jet de rive et de la plage émergée sur un panel d’échelles spatio-temporelles allant de l'instantanée à annuelle. A l’échelle instantanée, ce sont les variations d’élévation de la surface libre de l'eau et du lit sableux (quelques secondes) qui sont observées au cours de chacune des phases (montant, apex, tombant) de la tempête tropicale Talim (juin 2012, Hs = 10.34 m et Ts = 14.6 s). Pour le même événement de tempête, la réponse morphologique de toute la plage émergée est ensuite décrite et quantifiée dans le détail à l’échelle événementielle (quelques jours). Les bilans sédimentaires de chacune des saisons sont ensuite quantifiés dans le but de caractériser la dynamique saisonnière (quelques mois) à annuelle d'une barrière sableuse soumise à deux types de forçages extrêmes différents (mousson/typhons). L'impact sur le front de plage, des groupes de tempêtes faibles à modérées pendant l'hiver est ainsi comparé à l'impact des tempêtes extrêmes pendant l'été. On souligne finalement 1) l'importance d'un jeu de mesures in-situ de bonne qualité dans un travail d'analyse morphodynamique, 2) l'essentialité de l’emboîtement des échelles spatio-temporelle ainsi que 3) le rôle du profil morphologique héritée dans la réponse morphologique d'une plage émergée lorsqu'elle est soumise à des conditions de forçages de vent et de vague extrêmes. / This work focuses on a multi-scale analysis of a sand barrier morphodynamics exposed to paroxysmal forcings of monsoon, tropical storms, and typhoons. The study provided a large dataset of in-situ measures acquired in the framework of the KUNSHEN project. Seven months of field work (from November 2011 to January 2012 and from May to September 2012) provided a new, exhaustive and hight resolution measures. Measures of hydrodynamic conditions from offshore to the swash zone are acquired as well as high frequency topographic surveys of the emerged beach. Waves monitoring are from an offshore buoy, two current profilers in the shoreface (continuous measures at 2 Hz) and pressure sensors buried in the sub-aerial beach (continuous measures at 5 Hz). The topo-bathymetric surveys were acquired using D-GPS (centimetric resolution) one time a week during winter season of monsoon and just before and after each extreme storm during summer season of typhoons.Then, analysis focus in the morphodynamics of the swash zone and the emerged beach on a range of scales from instantaneous to one year. At the instantaneous scale, we analyze variations of the water surface fluctuation and sand bed elevation (seconds) during each phases (rising, apex and falling) of the Talim tropical storm (June 2012, Hs = 10.34 m and Ts = 14.6 s). Concerning the same storm, we characterize the morphologic changes of the whole emerged beach at the evenemential scale (days). Sand balances of each seasons are quantified in order to characterize the dynamics from seasonal scale (months) to annual scale of a sand barrier driven by two types of extreme forcings (monsoon/typhoons). On the beach-front, impact of groups of winter weak storms is compared to the impact of extremes tropical storms and typhoons. To conclude, we highlight 1) importance of in-situ measures in morphodynamic studies, 2) the major role of scales stacking and 3) the role of herited beach profile in the morphologic responses of the emerged beach driven by extremes forcings of wind and wave.

The SUPERTANK dataset is analyzed to examine the upper limit of beach change in response to elevated water level induced by wave runup. Thirty SUPERTANK runs are investigated, including both erosional and accretionary wave conditions under random and monochromatic waves. Two experiments, one under a spilling and one under a plunging breaker-type, from the Large-Scale Sediment Transport Facility (LSTF) are also analyzed. The upper limit of beach change approximately equals the maximum vertical excursion of swash runup. Exceptions to this direct relationship are those with beach or dune scarps when gravity-driven changes, i.e., avalanching, become significant. The vertical extent of wave runup, Rmax, above mean water level on a beach without a scarp is found to approximately equal the significant breaking wave height, Hbs. Therefore, a simple formula Rmax = Hbs is proposed. The linear relationship between maximum runup and breaking wave height is supported by a conceptual derivation. This predictive formula reproduced the measured runup from a large-scale 3-dimensional movable bed physical model. Beach and dune scarps substantially limit the uprush of swash motion, resulting in a much reduced maximum runup. Predictions of wave runup are not improved by including a slope-dependent surf-similarity parameter. The limit of wave runup is substantially less for monochromatic waves than for random waves, attributed to absence of low-frequency motion for monochromatic waves.

Les processus dynamiques présents en zone de swash ont un impact significatif sur l'évolution des zones côtières. Une part importante du transport sédimentaire cross-shore se produit dans cette zone, plus particulièrement dans cette zone où se produisent le run-up et le run-down. La zone située au-delà de la ligne de rivage au repos est le plus souvent décrite par des modèles intégrés sur la verticale. La décroissance des vagues est bien reproduite, cependant l'étude du transport sédimentaire impose une paramétrisation du frottement sur le fond. Nous présentons les résultats de simulations RANS de la propagation d'un mascaret (obtenu par un "lâcher de barrage") sur une plage en pente et le run-up et le run-down ainsi générés. Les résultats numériques sont comparés aux résultats expérimentaux de Yeh et al. (1989). Les simulations ont été réalisées avec le code Navier-Stokes diphasique AQUILON. Deux méthodes de suivi d'interface VOF (VOF TVD ET VOF PLIC) sont implémentées. La viscosité turbulente est calculée par un modèle V2-F (Durbin, 1991). Une estimation des grandeurs turbulentes k et epsilon basée sur la théorie des ondes longues pour la propagation d'un ressaut hydraulique est présentée. Une modélisation VOF-PLIC & V2-F est appliquée pour reproduire les caractéristiques macroscopiques du lâcher de barrage, qui comme on pouvait s'y attendre dépendent peu de la turbulence. Nous étudions aussi l'impact des conditions initiales sur k et epsilon sur l'établissement de l'écoulement turbulent. Après ces validations vis-à-vis de la turbulence, des simulations du cas décrit par Yeh et al. (1989) sont menées pour optimiser le choix des paramètres de calcul. La théorie de Whitham (1958), prédit un effondrement du mascaret au niveau de la ligne de rivage au repos. La théorie de Shen and Meyer (1963) est toujours à l'heure actuelle le modèle de référence. Les résultats expérimentaux de Yeh et al. (1989) montrent clairement un phénomène différent. L'utilisation conjointe de la technique VOF-TVD et du modèle de turbulence V2-F semble apporter les meilleurs résultats par rapport aux expériences de Yeh et al. (1989). Une étude de la transition mascaret/lame de swash est proposée. Nos résultats montrent que la théorie de Whitham décrit de façon assez précise le mécanisme de d'effondrement du mascaret. Les résultats de nos simulations sont utilisés pour décrire la transition entre l'effondrement du mascaret et l'écoulement du run-up. L'analyse des processus de frottement dans le jet de rive met en évidence une forte dissymétrie entre le run-up et le run-down avec cisaillement plus faible lors du run-down

<p>The advantages of high efficiency, reliability, flexibility and high power to weight ratio make axial piston pumps popular for use in a wide variety of applications like construction and agricultural machinery, off road vehicles and aerospace applications. However, a major drawback which limits their extensive use in other commercial applications is noise. One of the important components in axial piston machines is the valve plate, which influences the transition of the suction and delivery flows into and out of the displacement chamber. Appropriate design of the valve plate can play a significant role in influencing the rate of compression and expansion in the displacement chamber, and hence contribute towards the abatement of noise in axial piston machines. Furthermore, the relief grooves in valve plates makes them relatively less sensitive to operating conditions for the operation of the pump. The high sensitivity of the valve plate design towards the pressure build up in the displacement chamber and towards the noise sources are big motivation factors towards rigorously exploring the design space to find suitable designs to meet the objective of noise reduction. This motivates the development of an advanced computational tool, colloquially called 'MiNoS', where a powerful optimization algorithm has been combined together with a novel parametrization scheme for valve plate design and a 1D simulation model of swash plate type axial piston machines to find optimized designs which can contribute towards noise reduction in swash plate type axial piston machines. Furthermore, incorporation of the appropriate constraint also helps in avoiding designs susceptible to the onset of cavitation in the displacement chamber. A case study performed using the developed computational tool has been shown later in this work.</p>

Video monitoring of beaches is becoming the preferred method for observing changes to nearshore morphology. Consequently this work investigates a new technique for predicting the probability of inundation that is based on measuring runup variation using video. Runup is defined as the water-level elevation maxima on the foreshore relative to the still water level and the waterline is defined as the position where the MWL intersects the beach face. Tairua, and Pauanui Beaches, on the north east coast of the North Island of New Zealand, were used as the field site in this study and represent two very different beaches with the same incoming wave and meteorological conditions. Tairua is most frequently in an intermediate beach state, whereas Pauanui is usually flatter in nature. In order to rectify runup observations, an estimate of the runup elevation was needed (Z). This was estimated by measuring the variation of the waterline over a tidal cycle from time-averaged video images during a storm event and provided beach morphology statistics (i.e. beach slope (α) and beach intercept (b)) used in the rectification process where Z=aX+b. The maximum swash excursions were digitized from time-stacks, and rectified to provide run-up timeseries with duration 20 minutes. Field calibrations revealed a videoed waterline that was seaward of the surveyed waterline. Quantification of this error gave a vertical offset of 0.33m at Tairua and 0.25m at Pauanui. At Tairua, incident wave energy was dominant in the swash zone, and the runup distributions followed a Rayleigh distribution. At Pauanui, the flatter beach, the runup distributions were approximately bimodal due to the dominance of infragravity energy in the swash signal. The slope of the beach was a major control on the runup elevation; runup at Pauanui was directly affected by the deepwater wave height and the tide, while at Tairua there was no correlation. Overall, the results of the study indicate realistic runup measurements, over a wide range of time scales and, importantly, during storm events. However, comparisons of videoed runup and empirical runup formulae revealed larger deviations as the beach steepness increased. Furthur tests need to be carried out to see if this is a limitation of this technique, used to measure runup. The runup statistics are consistently higher at Tairua and suggests that swash runs up higher on steeper beaches. However, because of the characteristics of flatter beaches (such as high water tables and low drainage efficiencies) the impact of extreme runup elevations on such beaches are more critical in regards to erosion and/ or inundation. The coastal environment is of great importance to Māori. Damage to the coast and coastal waahi tapu (places of spiritual importance) caused by erosion and inundation, adversely affects the spiritual and cultural well-being of Māori. For this reason, a chapter was dedicated to investigating the practices used by Māori to protect and preserve the coasts in accordance with tikanga Māori (Māori protocols). Mimicking nature was and still is a practice used by Māori to restore the beaches after erosive events, and includes replanting native dune plants and using natural materials on the beaches to stabilize the dunes. Tapu and rahui (the power and influence of the gods) were imposed on communities to prohibit and prevent people from free access to either food resources or to a particular place, in order to protect people and/ or resources. Interpretations of Māori oral histories provide insights into past local hazards and inform about the safety and viability of certain activities within an area. Environmental indicators were used to identify and forecast extreme weather conditions locally. Māori knowledge of past hazards, and the coastal environment as a whole, is a valuable resource and provides a unique source of expertise that can contribute to current coastal hazards management plans in New Zealand and provide insights about the areas that may again be impacted by natural hazards.

The displacement of the variable displacement pumps can be adjusted by changing the swivel angle of the swash plate. In fact, the swivel angle oscillates because of the oscillating torque on the swash plate, which caused by the pressure fluctuation of the piston chamber. The swivel angle is most often considered as a constant value in previous studies. However, the oscillation of the swash plate leads to an additional movement of the piston, which has an impact on the pressure fluctuation and the flow ripple. In this study, an improved model of a self-supplied variable displacement pump is established. The swash plate oscillation under different operating conditions is presented. In order to investigate the effect of the swash plate oscillation on the pressure ripple, a comparison between the case of the fixed swash plate and the oscillated swash plate is conducted. Results show the pressure ripple with an oscillated swash plate shows a smaller pressure ripple. It also shows that the nine pistons and the control mechanism both affect the pressure ripple and flow fluctuation.

No description available.

Cette thèse propose une modélisation numérique 2D des écoulements en zone de jet de rive avec un code Volume-Of-Fluid. Dans un premier temps, le détail de la structure interne de l’écoulement de jet de rive généré par l’effondrement d’un front d’onde turbulent sur une plage imperméable lisse est étudié. Le modèle numérique est ensuite étendu à la simulation des écoulements en milieu poreux internes à la plage. L’utilisation d’une unique équation de quantité de mouvement (VARANS) et de la méthode 1-fluide, permet de résoudre simultanément les écoulements de l’eau et de l’air à la surface et dans une plage perméable. Ce modèle a été confronté à une série de cas tests analytiques et à de récentes mesures expérimentales. Les résultats numériques montrent l’aptitude du modèle VOF-VARANS à reproduire les écoulements en zone de jet de rive sur une plage imperméable fixe. / A 2D numerical modeling of flows in the swash zone is proposed using a Volume-Of- Fluid code. The detailed flow structure of a bore-driven swash event over an impermeable beach is first studied. The numerical model is then developed to account for porous media flow within the beach. The unique VARANS momentum equation and 1-fluid method used allow to solve simultaneously both surface and subsurface flows of air and water phases in the swash zone. This model is validated against a series of analytical tests cases and confronted to recent experimental measurements. The numerical results highlight the ability of the VOF-VARANS model to reproduce swash flows over and within a permeable beach.

No description available.