One of the most important tasks of gas turbine secondary air system is to seal stator-rotor cavities in order to prevent hot gas ingestion into disk spaces. Minimizing this sealing flow by an effective rim sealing design reduces secondary air consumption and contributes to machine efficiency and power. Understanding the flow behavior in rim seal area, in interaction with main flow, is vital for improving the design. In this paper, numerical and experimental investigation of rim cavity sealing performance in a turbine stator well in MAPNA heavy-duty gas turbine MGT-70 is presented. Numerical investigations are performed using 1D models and 3D CFD simulations. Using an in-house flow network simulation tool, a 1D model of the secondary air system is set up. This lumped model is used for simulating the overall flow behavior and distribution. Details of the flow are investigated using high fidelity 3D CFD. Rim cavity sealing path, together with mainstream flow, including upstream and downstream vanes and blades, are modeled considering all geometrical details. The interaction of main and secondary flows in rim area is processed and an approach is proposed to evaluate the sealing effectiveness using CFD simulations. Furthermore, some tests are conducted in one of MGT-70 upgraded units. Pressure and temperature sensors are installed in secondary air system and main flow path, with particular attention to rim cavity area. The test results are adequately utilized to experimentally investigate the overall rim cavity sealing performance, monitor hot gas ingestion, and also validate and tune the numerical simulations.

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