Influence of inlet conditions on the flowfield in a model gas turbine combustor

The flowfields in gas turbine combustors have not been well understood in either experiments or numerical simulations. To increase the accuracy of flow prediction, numerical errors, which come from turbulence model, mesh size, iteration number, and inlet conditions, should be reduced with the assistance of measurements. However, so far very few experimental data have been obtained to evaluate the numerical models and the predicted results. The purpose of the present study is to obtain the inlet conditions for a combustor in an isothermal model of the gas turbine combustor that was made to demonstrate the fundamental flow structure of swirling flow and jet flow interactions, in order to compare predicted results with measured results and demonstrate the influence of inlet conditions on the flowfield. A very small fiber laser-Doppler velocimeter was used to measure radial velocity in order to understand the recirculating flow and flow interactions. The momentum ratio of the swirl mass flow rate to the jet mass flow rate was taken to be 1.78–7.01, which would cover all loading conditions. The results indicated that the radial velocity at the swirler exit should be given; otherwise the radial velocity should be half the axial velocity, and the swirl velocity at the jet exit also should be considered, so we propose a way to determine swirl velocity at the jet exits. The predicted flow patterns and turbulent kinetic energy profiles show the major flow structure that can be seen in the experiments. The errors due to the influence of inlet conditions on the flowfield could be reduced and the accuracy of prediction increased if the proposed modification is used.