Papers by Keyword: Computational Fluid Mechanics

Abstract: The two dimensional study of natural convection in vertical cylindrical annular enclosure filled with Cu-water nanofluid under magnetic fields is numerically analyzed. The vertical walls are maintained at different uniform hot and cold temperatures, T_H and T_C, respectively. The top and bottom walls of the enclosure are thermally insulated. The governing equations are solved numerically by using a finite volume method. The coupling between the continuity and momentum equations is effected using the SIMPLER algorithm. Numerical analysis has been carried out for a wide range of Rayleigh number (10³ ≤Ra≤10⁶), Hartmann number (1 ≤Ha≤100) and nanoparticles volume fraction (0 ≤φ≤0.08). The influence of theses physical parameters on the streamlines, isotherms and average Nusselt has been numerically investigated.

Abstract: in this paper, a finite analysis/grid method for high-dimensional PDF equation of fluid mechanics of two phase flow is proposed. The particle high-dimensional scalar PDF transport equation in position-velocity phase space is reduced to velocity phase space and position phase space. An analytical solution of the particle velocity PDF is obtained by Fokker-Planck techniques, the particle position PDF is solved by finite difference method, which determines the distribution of particles in two-phase flow. It is shown that the Finite Analytic/Grid method can simulate the two-phase flow very efficiently.

Abstract: The flow coefficient of the valve is an important index of measuring the valve circulation ability, a major process parameter of and a significant technical indicator of valves and regulating valves on an industrial basis. Numerical simulation was performed on the flow coefficient of the valve by using FLUENT, software of computational fluid mechanics and by the standard model. The flow and the resistance coeffients were obtained based on the numerical simulation of a new type of throttling /sealing valve under the same pressure differentials but with different opening conditions. The results demonstrate that the flow coefficient of the throttling/sealing valve is in close compliance with the typical curve of equal percent, and thus provides an important basis for its optimized control.

Abstract: To enhance heat exchange between the rotor and external environment, many ribs are arranged on the cover of the machine. The air cooling condition for 1.5MW wind rotor is evaluated by Computational fluid dynamics(CFD). It is found that the density of the air, the flow velocity and the arrangement of the ribs on the rotor cover is the main factors impacting the air cooling effect of the rotor. Under the same running power, the air cooling condition becomes worse with the decrease of air density and becomes better with the increase of wind speed. To improve the cooling condition of the wind rotor, the arrangement of the ribs on the cover is optimized. The results show that the width ratio of the ribs and channels plays an important role in the heat convection. In all our cases, 0.5 is the best. Considering the manufacture processing, the arrangement of 400 ribs is selected in our optimization.

Abstract: The water cooling system of 1.5MW rotor is evaluated using Computational Fluid Dynamics (CFD). 48 cooling holes are opened on the rotor stator to arrange the water cooling pipes, the temperature of inlet of the cooling water is 50 C with the velocity 1.2m/s. It is found that the air gap between the cooling pipes and holes on the stator hinders the heat exchange extensively. For this reason, the cooling system can't meet the design requirement. In order to solve this problem, the pourable silicone is filled in the gap between the cooling pipes and holes to enhance thermal conductivity. Based on this idea, ten kinds of piping arrangements are proposed, among which, nine kinds can achieve the cooling requirement.