Keresés
Keresési eredmények
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Evaluating the Efficiency of Polyhedral Mesh Elements in Solving the Problem of the Flow around Ship’s Rudder
241-256Megtekintések száma:205Meshing is one of the crucial key features to the success of CFD based simulations, this study is evaluating the efficiency of polyhedral elements in solving the problem of the flow around ship rudder, using a Reynolds-averaged Navier-Stokes turbulence model (SST k-ω), and compares it to a tetrahedral based mesh, considering that polyhedral elements were neglected in the past due to difficulties in implementing them, this was solved by introducing a tool by ANSYS that converges tetrahedral elements to polyhedral element, and integrating it into FLUENT software, the model was validated by comparing it with previously validated model which used the full version of ANSYS, this study was concluded using the academic version, but still it was able to produce satisfying results in predicting the lift and the drag coefficient, the pressure around the rudder surface, the velocity and the turbulent kinetic energy, finally the mesh quality was evaluated using the orthogonal quality criteria, the results showed the supremacy of the polyhedral elements in saving time and computational resources and improving mesh quality, and keeping high level of accuracy in predicting the results.
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Vitorlás kishajóra ható ellenállás erő visgálata hajtáslánc csere okozta merülésváltozás esetén numerikus áramlástani szimulációk használatával
30-35Megtekintések száma:217Kedvtelési célú vízijárművek esetén a környezetvédelmi okokból egyre szigorodó szabályok miatt a motoros hajtások megoldásaiba való beavatkozás napjainkban gyakori munkafolyamat. Belsőégésű motorról elektromos motorra való átváltáskor a merülésváltozás hajónként eltérő, azonban közösen elmondható minden esetben, hogy a tömeg változásával a merülés is változik. Emiatt a hajóra ható ellenállási erő nagysága is változik. Jelen cikkben egy konkrét példán keresztül vizsgáljuk, milyen hozadékai vannak a tömegnövekedés okozta merülésváltozásnak különféle haladási sebességeknél.
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Numerical Model Analysis of Natural Gas Combustion Burners
67-71Megtekintések száma:131Traditional power plants still the dominating power source for all the major industries and powerdemanding facilities, the most crucial facility for the whole plant operations is the industrial boiler which generatessteam, heating energy or electrical power. Boilers generate energy by combustion. The improvement of combustion efficiency could greatly influence the energy consumption and will make the boiler more efficient and cleaner (less emissions), that’s why it is important to understand the combustion and thermal flow behaviours inside the boiler. Beside experimental testing, computational work nowadays becoming more and more important due to lower cost and acceptable accuracy with minimum error. With numerical calculations method, the computational model created by a Computational Fluid Dynamics (CFD) software could reduce a lot of trial and error on experimental work. In this paper utilizing the ANSYS FLUENT 19.1 software to make crate the combustion model. The ratio of air to fuel mixture, the equivalency factor, mass flow rate of the mixture, velocity, mass fractions of the mixture components (fuel and air) and their temperatures will serve as the input parameter while the exhaust gase component mass fraction, temperature, mass flow and velocity will be monitored.
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Numerical Model Analysis of Myring–Savonius wind turbines
180-185Megtekintések száma:172Nowadays the importance of renewable energy is growing, and the utilization of the low wind energy potential is getting crucial. There are turbines with low and high tip speed ratio. Turbines with low tip speed ratio such as the Savonius wind turbine can generate adequate amount of torque at low wind velocities. These types of turbines are also called drag machines. The geometry of the blade can greatly influence the efficiency of the device. With Computational Fluid Dynamics (CFD) method, several optimizations can be done before the production. In our paper the Savonius wind turbine blade geometry was based on the so-called Myring equation. The primary objective of this paper was to increase the power coefficient by modelling the effect of the wind on the turbine blade. For the sake of simplicity, a 2D cross-sectional area was investigated in the simulation with ANSYS CFX 19.1.
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Introduction to Design and Analysis of Torsional Vibration Dampers in Vehicle Industry
310-324Megtekintések száma:319The crankshaft of today’s internal combustion engines with high performance output are exposed to harmful torsional oscillations originated from the unbalanced gas and inertial forces. To avoid the fatigue damage of engine components, caused by the undesired vibrations, torsional vibration dampers can be applied. Viscodampers are one type of the torsional vibration dampers, which operational fluid is silicone oil. For cost-effective R&D activities and production, finite element and finite volume numerical discretization methods based calculation techniques must be involved into the engineering work supported by the modern computer technology. The aim of this paper is to provide an insight into the multidisciplinary design and development process of visco-dampers in vehicle industry applications. Four different examples as structural, fatigue, CFD analyses and structural optimization have been introduced in the present work. It turned out from the static structural and fatigue analyses, that the investigated damper has safety factor over the limit for both static structural and fatigue analyses, so it is suitable for the given load conditions. In the structural optimization process 34.36% mass reduction has been achieved. According to the coupled fluid dynamic and heat transfer simulations a rather stagnating air zone evolved between the engine and the damper during the operation, which can cause efficiency reduction of cooling fins mounted onto the housing. In light of the numerical results, the suitable damper position has been determined for the highest heat transfer.
