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In the past, testing of lifeboat design has been carried out solely by experimental means.However, due to the large number of factors which influence the loads on the lifeboat. structure and its occupants, optimization studies by experimental means have become both time-consuming and expensive. In addition, many eects cannot be studied at laboratory scale due to the inability to match all similarity requirements. Recent advances in computational fluid dynamics (CFD) have made it possible to analyze the lifeboats performance under realistic conditions. By not being dependent on a physical...
Though wind turbines and windmills have been used for centuries, the application of aerodynamics technology to improve reliability and reduce costs of wind-generated energy has only been pursued in earnest for the past 40 years. Today, wind energy is mainly used to generate electricity. Wind is a renewable energy source. Power production from wind turbines is affected by certain conditions: wind speed, turbine speed, turbulence and the changes of wind direction. These conditions are not always optimal and have negative effects on most turbines. The present turbine is supposed to be less...
Several experiments have already reported the existence of flow oscillations in a tight lattice bare rod-bundle. This in-turn results in temperature oscillations, when heat transfer is also involved. Consequently, assessment of flow oscillations plays an important role in the design of future innovative reactor systems as proposed by the Generation IV International Forum. Literature review reveals that such flow oscillations have recently numerically been analyzed using Unsteady Reynolds Averaged Navier-Stokes (URANS) and Large Eddy Simulation (LES) techniques. The objective is to assess...
Distributions in the concentration of reactant species in a PEMFC can cause distributions in local current density, temperature, and water content over the area of a PEMFC. These distributions can lead to effects such as flooding and MEA dehydration thus causing stresses in different regions of the fuel cell. Changing flow-field configurations and channel characteristics have been shown to also affect the cell performance and uniformity indistributions. This work investigates how performance and distributions in a baseline laboratory cell prepared by a precise machining method compared with...
Cavitation is a significant problem for the shipping industry as it can lead to ship vibration and erosion, both resulting in increased maintenance costs. Therefore, a better understanding of cavitation and an accurate prediction capability are important. Lloyd's Register has performed cavitation observations and measurements at ship scale and, from that, has developed a better understanding of cavitation and its effects, which are discussed in this paper. These observations showed that details of the cavitating flow are paramount for the erosive potential of the flow. Furthermore,...
Numerical investigations of turbulent natural convection between concentric, cylinders has been carried out. Large Eddy Simulations (LES) have been performed on three different geometries. The first two consider a single inner cylinder at gap-based Rayleigh numbers of 1.18×109 and 2.38×1010 and an aspect ratios Ro/Ri=4.87 and 3.37, respectively. The last LES run considers three internal cylinders. It reveals that the flow patterns in the decay heat pen are more complex than the one internal concentric cylinder cases. The two-equations RANS models predictions for this test case are less...
This study is related to mixed convection heat transfer of air flowing through an ascending vertical annular passage with significant radiation heat transfer. This configuration leads to a maximum level of heat transfer impairment similar to the one obtained in pipe flows. Five turbulence model predictions are compared with the experimental data obtained by the Promethée facility. Both k–w models (Wilcox and SST) tend to overestimate heat transfer in mixed convection while the standard low-Re number k-e underestimates it. The AKN low-Re model performs poorly in all cases. Finally, only the v²...

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