Effect of jets in crossflow in deposition mitigation on full 3D NGV with endwall features

Particle ingestion is a major concern for the operation of gas turbines. In the case of an aircraft, particle dispersed in the air ingested by the engine can threaten flight safety. Swallowed particles can erode or stick to aerodynamic surfaces. Both the occurrences translate in a reduction of performance due to variation in shape and in roughness of the aerodynamic surfaces. This work is devoted to the analysis of fouling, i.e. the deposition of particles over time. By observing that the deposition pattern is strongly influenced by the flow field in the nearby of the walls, the central idea of this work is to employ Active Flow Control (AFC) to mitigate fouling when emergency conditions are met by the aircraft. The proposed system will inject air bled from compressor discharge in front of the critical locations where fouling is supposed to occur. The present work aspires to lay the foundations for the development of such an AFC device, by focusing on the modified aerodynamics consequent to the introduction of the transverse jet. The potential of this device is evaluated quantitatively using CFD simulations. An energy-based sticking model, coupled with a mesh-morphing solver, is used to track the airfoil deposition thickness evolution in time. The work is two-fold: first, the dynamics of the interaction between flow structures and particle transport is addressed. Second, the attention is posed on correlating fouling pattern variation to the modified aerodynamics of the vane consequent to the introduction of the device. Three design concepts are investigated on the 3D test case geometry of an HPT NGV cascade. The counter-rotating vortex pair (CVP) is detected as the main responsible for jet-particle interaction. Finally, the jet impact on aerodynamic performance is also assessed.