Numerical Simulation For Inner Turbulence With Adverse And Favorable Pressure Gradient By DHR κ-ε Model

Fully developed incompressible turbulent flow with adverse and favorable pressure gradient in a conical diffuser and outlet pipe having a total divergence of 8°and an area ratio of 4:1 has been simulated by a DHR k—εturbulence model and it's wall function·BFC (Boundary -Fitted Coordinates) approach. The research has been done for pipe entry Reynolds numbers of 1.16×10~5 and 2.93×10~5. Based on the near wall denseness model radial fitted-body nonuniform grid system ,The mesh figures of physical plane have been plotted .Analyzing the effection of calculated results under different calculated conditions,such as different time step,relaxation coefficient,numerical methods and wall difference methods. The calculation results of the mean velocity and turbulence energy have been given,and they have been analysed and compared with the experimental results respectively. At the same time,The distribution of the main flow parameters in a conical diffuser and outlet pipe,such as the mean flow velocity,the mean pres-sure,turbulence energy,turbulence dissipation and eddy viscosity coefficient have been given. The effective degree of calculation efficiency and calculation accuracy has been studied under the different calculated conditions and draw corresponding conclusions,and they have offered reference for science research and engineering techniques actual application,possessing theoretical and actual meaning.