Prediction of fluid flow through U-bend channels using linear and nonlinear models of turbulence

In the present study, performance of nonlinear low Reynolds number k-ε model of turbulence has been investigated in order to predict turbulent flow field through three dimensional U bend channel of intercooling passage of gas turbine blade. Finite volume method is used to solve governing equations of mean fluid flow. In this study, linear low Reynold number model of turbulence and Zonal Eddy Viscosity model k-ε/1-eq. and cubic nonlinear low Reynolds number model has been used to model the turbulence field. Results of Computations show that the zonal model predicts the profiles of velocity and turbulent stress as same as linear model and overestimate the turbulent stresses in separated zones but results of nonlinear model shows improvement in prediction of velocity and turbulent stresses in separated zones. Also, linear, nonlinear and zonal models have similar prediction about separation point of flow but nonlinear model has been predicted the level of Reynolds stresses and its changes from inner side toward outer side and maximum level of Reynolds stresses more accurate in comparison with zonal and linear models specially on near-wall plane.