Response of a tip gap flow submitted to an unsteady shock wave front

This study investigates tip leakage flows resulting from the gap at the tip of turbine's blades, focusing on the flow dynamics under pulsed conditions. Wall-resolved large-eddy simulations are performed using the in-house solver IC3 for two gap heights, h/c=0.94% and h/c=2.18%. After validating the upstream turbulent boundary layer, an in-depth analysis of the tip leakage flow is conducted during the initial regime, i.e., before the passage of the unsteady shock wave front. Classical vortices—tip leakage vortex (TLV), induced vortex (IV), and tip separation vortex (TSV)—are identified. Results align with the literature for subsonic flows, showing that TLV intensity and trajectory depend on h/c. Power spectral density and spectral proper orthogonal decomposition analyses confirm the lack of vortex coherence. Barycentric turbulence maps reveal strong turbulence anisotropy, particularly in the tip region. The originality of this paper lies in its second part. For the first time, LES of tip gap flows submitted to an unsteady shock wave front are conducted. Two shock intensities defined by their pressure jump Π=1.6 and Π=3.0 are considered. For Π=1.6, variations in h/c do not significantly affect lift, but vorticity generated in the tip gap amplifies TLV, IV, and TSV circulations. At Π=3.0, stronger shock–wave interactions may be source of high losses due to an attached trailing-edge shock, boundary layer separation, and intensified pitchwise and spanwise vortices motions. These findings highlight the complexity of tip leakage flows under unsteady shock interactions and provide new insights into their aerodynamics.