Study of particles deposition in gas turbine blades in presence of film cooling

Exhaust entering the gas turbine is usually fed with solid particles produced in the combustion of hydrocarbons (ashes, unburned char, etc.). Then, the interaction between the particles motion and the film cooling jets must be properly addressed. Here an integrated approach based on an Eulerian- Lagrangian scheme for particle-laden flow was applied to a real turbomachinery case. The code was preliminary assessed by simulating two simplified test cases: a) 3-D cooling jet in a channel; b) 2-D turbine cascade with film cooling. These cases were selected to separately validate the main effects here considered: a) interaction of particles trajectories and 3D cooling jets; b) effect of the cooling jets on surface temperature and particles trajectory and possibly on particle deposition, in comparison with the non-cooled case. Finally, 3D simulation of the particle-laden flow around a real E3 gas turbine vane with and without film cooling was performed. Flow features, particles trajectories and deposit on the blade are presented. The compressible flow field was simulated using the OpenFOAM code obtaining credible predictions of the velocity and temperature field. Then the P-Track code developed by the authors was applied for tracking the particles trajectories and determining the deposit on the solid surface. As the temperature are relatively high, the sticking probability method, that is strongly dependent on the temperature itself, was used here. The results showed that the presence of the cooling jets affect deeply the deposit following two main causes: The influence of the jets in removing the fluid from the close-to-the-wall region and the reduction of temperature along the blade. Copyright © 2014 by ASME.