Experimental Study on Turbine Rim Seal Characteristics under Pulsed Detonation Inflow Conditions

Pulse detonation turbine engines exhibit higher cycle thermal efficiency than traditional gas turbine engines. However, the strong periodic pulsation characteristics of the pulse detonation combustor pose severe challenges to the sealing design of the downstream turbine rim cavity. To date, studies on rim seal behavior under pulsed detonation inflow remain scarce. To address this gap, a 1/8-scale stationary rim seal test rig was designed, constructed, and installed downstream of a single-tube reverse-flow pulse detonation combustor. Experimental investigations into rim seal performance were subsequently conducted over a range of operating frequencies from 10Hz to 30Hz. The propagation characteristics of the detonation wave in the main flow path, along with the pressure fluctuation, temperature evolution, and hot gas ingestion in the rim cavities at various frequencies, were systematically analyzed. Experimental results indicate that under pulsed detonation inflow, the high-temperature mainstream gas periodically ingresses through the rim clearance into the front cavity AⅡ and the rear cavity B, whereas front cavity AI remains free from ingestion due to the effective pressure barrier formed by the sealing air. The pressure fluctuation intensity in cavity AⅡ reaches as high as 74.2%, significantly exceeding that in cavity B (≤36.5%). The amplitude of pressure disturbance in the rim cavities is primarily governed by the peak pressure of the mainstream shock wave and the pressure difference of the sealing air. As the operating frequency increases, both the mainstream gas temperature and the frequency of hot gas ingestion rise, leading to a monotonic increase in temperature rise in cavities AⅡ and B. Under thermal equilibrium conditions at 30 Hz, the maximum temperature rise in cavity AⅡ is approximately 40°C, while that in cavity B exceeds 100°C. These findings provide theoretical and experimental support for the design of the air system in pulse detonation turbine engines.