Large-eddy simulation of unsteady turbine rim sealing flows

•Significant improvement of turbine rim sealing flow prediction by LES.•Mechanisms of inherent unsteady flow structures in rim sealing flows.•Clockwise vortex of mean flow within the rim gap, which is in contrast with the flow field observed in the classic rotor-stator cavity model.•Establish and validate analysis strategy to investigate unsteady flow structure characteristics.•Possible evidence of Taylor–Couette instabilities in rim seal flows.