Papers by Keyword: RNG k-ε Model

Abstract: The gas sensor is significant for coalmine production safety. In order to carry out optimal gas sensor placement in heading face, the software named Fluent was used to simulate underground gas distribution. Geometry model was established and divided by grids. Gas distribution in heading face was simulated using RNG k-ε model by Fluent according to conversation equation in turbulent state, turbulent kinetic energy equation and turbulent dissipation rate equation. The results show that gas is likely to accumulate in the upper corner, when wind passes through the corner after washing heading face, wind velocity is unstable, the performance of sensor placed in inner side of turning is different from that placed in outer side of turning. Distance of gas sensor to heading face should be no more than 10m which accords with the mine safety regulations well. The result shows that gas can be monitored effectively by applying this method which has an important value and instructive significance.

Abstract: RNG (Renormalization Group) k-ε turbulent model was applied to the numerical simulation of turbulent mixing processes in the RQL gas turbine combustor, and SIMPLE algorithm was used to solve the finite difference equations. The calculated conclusions were used to analyze temperature distribution of the mixed flow field and near-wall region of the flow field, and then discuss the NO_x emissions. The results show that the effect of the injector zone geometry and the jet to crossflow momentum flux ratios on the NO_x emissions is obvious. The reasonable control of jet is beneficial to reduce the local high temperature area and is able to improve the distribution of the exit temperature. And then achieve the goal of reducing the environmental pollution.

Abstract: The gas sensor is very important for coalmine production safety. The Fluent software was used to simulate underground gas distribution. Geometry model was established and divided by grids. Gas distribution in fully mechanized coal face was simulated using RNG k-ε model according to conversation equation in turbulent state, turbulent kinetic energy equation and turbulent dissipation rate equation. The results show that gas is likely to accumulate in the upper corner, when wind passes through the corner after washing fully mechanized coal face, wind velocity is unstable, performance of sensor placed in inner side of turning is different from that placed in outer side of turning. The result shows that gas can be monitored effectively with this method which has an important value and instructive significance.

Abstract: With the help of Fluent 6.2 and supporting software, 3D numerical simulation of fluid flow and heat transfer enhancement of plastic spiral tubes were performed on computer, and the velocity, turbulence intensity and improvement of convective heat transfer coefficient distribution in plastic spiral tubes were analyzed and compared with those in smooth tubes, and characteristics of fluid flow and heat transfer were obtained. The results showed that there were obvious axial, tangential and radial velocities in spiral space, and they were bigger than those in smooth tubes. The turbulence intensity was also increased greatly because of the existence of spiral channels. The dirt production was prevented and the tube's convection heat transfer was effectively strengthened. Its surface average heat transfer coefficient had been enhanced by about 20% compared with the smooth tubes; The pressure drop caused by plastic spiral flange was in the permissible range of engineering application. It was suitable for the heat exchanger at a flow velocity lower than 0.8m/s.