Modeling Deposition in Gas Turbines with Conjugate Mesh-Morphing and Temperature Sensitivity

A versatile procedure is presented for simulating the growth and thermal impact of deposition in representative gas turbine cooling circuits. The methodology comprises the following sequence: (1) employ CFD to obtain a steady flow solution, (2) predict particle impacts and deposits with the Ohio State University (OSU) deposition model, and (3) implement conjugate mesh-morphing of both the fluid and solid domains to simulate the evolution of deposit structures. Impinging jet experiments are conducted at 990K with aerosolized Arizona Road Dust (ARD 0-10μm) impacting an unheated target. The simulations accurately model deposit cone evolution. A ‘regridding’ step is further employed in the mesh-morphing routine to significantly improve stability during adaptation of the mesh. Subsequent tests are conducted in an effusion cooling deposition facility, where an effusion plate is heated to 1144K with cooling air supplied at varying temperatures (811-978K) at a constant backflow margin of 3%. ARD (0-10 μm) is injected and the reduction in cooling air mass flow monitored. The results illustrate that higher cooling air temperatures lead to a quicker reduction in cooling air mass flow and variations in the deposit structure within the effusion holes. The enhanced mesh-morphing routine is integrated with the temperature sensitive OSU deposition model to simulate these tests. The simulations capture the increasing blockage rate with temperature and display similarities in the deposit structures. The ‘regridding’ step is determined to play a critical role in ensuring stability of the mesh-morphing routine in an effusion geometry.