The presence and accretion of airborne particulates, including ash, sand, dust, and other compounds, in gas turbine engines can adversely affect performance and life of components. Engine experience and experimental work have shown that the thickness of accreted layers of these particulates can become large relative to the engine components on which they form. Numerical simulation to date has largely ignored the effects of resultant changes in the passage geometry due to the build-up of deposited particles. This paper will focus on updating the boundaries of the flow volume geometry by integrating the deposited volume of particulates on the solid surface. The technique is implemented using a novel, coupled deposition-dynamic mesh morphing (DMM) approach to the simulation of particulate-laden flows using Reynolds-averaged Navier–Stokes modeling of the bulk fluid, and Lagrangian-based particulate tracking. On an iterative basis, the particle deposition distributions are used to modify the surface topology by altering the locations of surface nodes, which modifies the mesh. The continuous phase solution and particle tracking are then recalculated. The sensitivity to the modeling time steps employed is explored. An impingement geometry case is used to assess the validity of the technique, and a passage with film cooling holes is interrogated. Differences are seen for all sticking and solid phase motion models employed. At small solid particle sizes, considerable disparity is observed between the particle motion modeling approaches, while the position and level of accretion is altered through the use of a nonisotropic stick and bounce model.
A review of multiphase flow and deposition effects in film-cooled gas turbines
