Numerical study of swirling turbulent flow through an abrupt expansion

Abstract

This thesis deals with the numerical study of swirling turbulent flow through an abrupt expansion, which has many practical applications. The computer program used for this analysis utilizes the k-€ model. The governing equations are discretized over the appropriate control volumes using the hybrid differencing scheme and nonuniform staggered grid. The capability of the model in predicting such complex flows having swirl and recirculation is tested by comparing with available experimental data. It is shown that the model can predict complex flows like swirling turbulent jet with sudden expansion with reasonable accuracy. The effect of inlet condition, type of swirl generation, swirl intensity, Reynolds number and expansion ratio on the flow field are also examined. It is observed that, change in inlet velocity profiles and method of swirl generation at inlet has significant effect on the distribution of fluid flow properties after expansion. Due to moderate swirl on-axis recirculation is produced and due to high swirl off-axis recirculation is produced in addition to the corner recirculation produced by the sudden expansion geometry. By proper nondimensionalization, we can plot profiles from which the required flow variables can be interpreted at different swirl levels and Reynolds number.