Dust Separation in a Gas Turbine Pre-Swirl Cooling Air System: A Parameter Variation

Abstract

With the increase of cooling air passing through the internal air system of modern gas turbines, a greater amount of air borne particles is transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blockage. A test rig has been designed to give information about the quantity of separated particles at various critical areas of the internal air system. With this test rig, the behavior of particles in the internal cooling air system could be studied at realistic flow conditions compared to a modern, heavy duty gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. Numerical studies to characterize the flow behavior of the disperse phase in a continuous fluid using Lagrange Tracking were performed. The main influencing parameters, which are the mass flow through the system, the rotor speed and the nozzle angle of the pre-swirl generator, were varied. Furthermore to validate the theoretical studies, based on the presented variations a special point of operation was selected to get a comparable measurement, which is presented in the paper. Comparison between simulation and measurement shows additional influences of the particle shape, which were discussed. The resulting enhanced model and the comparison to the measurement is presented in the paper.