Numerical Simulation of Flow field and Temperature field in Combustion Chamber Widened Suddenly

The flowfield and temperature field are numerically Simulated by the mathematical model of the fluid flow and heat transfer in circular combustion chamber widened suddenly. The distributions and influence factors of the flow field and temperature field are studied in it. The results have the guiding significance for the design of combustion chamber. The mathematical models can serve as the quantitative analysis methods for design.     

Study on the Sedimentation Rule of the Particles in Debris Flow

In this paper, according to the study on a great number of experiments and data analyses, the sedimentation rule of solid particles in debris flow is set up. Three main factors that influence the particle sedimentation in debris flow were studied; the basic reasons to influence the particle sedimentation were analyzed. The particle sedimentation in debris flow could be divided into three stages,i, e. the starting stage, the quick sedimentation stage and the accumulation stage,and detailed analysis on the sedimentation process each stage was made. The liquid viscosity, particle quality and additional water pressure have an important role on the sedimentation rule of the particle in debris flow.     

Numerical simulation of backward flow of methane roof layer in an airway

We study methane backward flow in the laneways at various wind velocities and angles based on computational fluid dynamics theory; analyze the backward flow area length, the concentration distribution and the methane roof layer thickness. The results show that the methane roof layer would move against the airflow in a declensional ventilated airway if the downward air velocity is not large enough. The faster the airflow speed, the smaller the methane backward flow area becomes, and the methane roof layer becomes thicker and shorter. In a declensional ventilated airway, the methane/air mixing capacity increases with the increase of the inclination of the airway, and the thickness of methane roof layer decreases with the increase of the inclination of the airway.     

Numerical Analysis of Diffusion Characteristic in the Proton Exchange Membrane Fuel Cell

A two-dimension,steady-state,multi-component transport model is presented to investigate the cathode performance of a proton exchange membrane fuel cell with an interdigitated gas distributor.Darcy law is used to describe the flow in the porous media.Subsequently,the model is applied to predict the pressure,velocity and mass fraction distributions in the electrode and explore the effect of the change of differential pressure between the inlet and the outlet,electrode thickness and rib width on the performance of fuel cell.The results show that: current density creases with the higher differential pressure between the inlet and outlet,but the increment is diminishing;electrode thickness has an optimum value which depends on the electrode morphology and the gas distributor design parameters;using narrower electrode rib can improve the performance of fuel cell.     

Effect of attached particles on the mechanical propertiesof dipolar chains in magnetorheological fluids

There are some particles attached to the side of dipolar chains in magnetorheological fluids. The reorganization and rupture of these chains are simulated when a tension and shear movement are applied, respectively. And the micromechanical behavior of these chains is also analyzed. It is found that the attached particles move into the chains during the tension, which increases the strain when the chain ruptures. While in shear process, attached particles introduce localized weakness in chain, which makes the chain rupture more easily and decreases the strength of the chain.     

Numerical Simulation of the Separation Effect of a Rotational Flow Sedimentation Tank Based on Fluent

This paper introduced FLUENT CFD simulation software and based on this software, the numerical modeling of the rotational flow sedimentation tank is set up and calculated. The separation efficiency curve and accumulation efficiency curve have been obtained and the deposition character inside the rotational flow sedimentation tank is shown. The conclusions given in this paper are valuable to the further improvement of the rotational flow sedimentation tank design.     

Numerical Simulation on Confluence of the Two Rivers in Chongqing City

Flows of the confluence of Yangtze River and Jialing River in the city of Chongqing are numerically simulated by using Delft3D Model with staggered grids and ADI integral method. The water level, flow velocity and drogue trace are studied. Comparing the numerical results with observed data shows good agreement. Therefore the computational model and the simplified parameters are of good accuracy and have practical meaning. The results show that the contamination will linger near the Caiyuanba area and drift to Chaotianmen and the right bank of Yangtze River upstream. The results can be used to forecast flood, inspect contamination and management of riverway in the city.     

Influence of ladle shroud’s shapes on characteristics of fluid flow in tundish

The influence of trumpet-shaped ladle shroud and straight ladle shroud on characteristics of fluid flow in a single strand slab tundish under different liquid levels through physical simulation is studied. The results show that the peak value of RTD curves after using trumpet-shaped ladle shroud is relatively low, the curves become smooth, the flow field is relatively stable and there isn’t short circuit flow. Also, the respond residence time, the mean residence time and the plug residence time of the liquid in tundish are prolonged. Besides, when the trumpet-shaped ladle shroud is used, the dead volume fraction is smaller, the plug volume fraction becomes larger and the ratio of the plug volume fraction to the dead volume fraction is greater. Therefore, when the liquid level of tundish is going up, its flow pattern becomes more reasonable after using trumpet-shaped ladle shroud, which is in favor of improving the quality of molten steel in tundish.     

Numerical simulation on natural convection of water near the maximum density in horizontal annulus

In order to understand the basic characteristics of the heat transfer of natural convection of water near the maximum density in a horizontal annulus, two dimensional numerical simulation was conducted using the finite volume method. The outer wall temperature was maintained at 0 ℃, and the temperature of inner wall at 1 ℃ to 10 ℃. The results show that the heat transfer coefficient at the inner wall first decreases with increased annulus width, then increases, and then constantly decreases with the increased inner radius in the region of calculation. When the temperature difference is below 4 ℃, the heat transfer coefficient increases with increasing temperature difference. When the temperature difference exceeds 4 ℃, it decreases with the increase of the temperature difference. Finally, the formula of heat transfer at the inner wall was obtained by using stepwise linear regression.