An experimental study on leakage flow in different geometrical disk seals

This paper presents an experimental study on the leakage flow in rotor-stator system. The experimental set-up of the rotor-stator system is a simplification of a Francis turbine runner with focus on the seals. It consists of a motor, a bearing, a shaft, a fixed rotor made of steel, a pump and a plastic ring fixed on the steel rotor, which can be replaced with different geometrical pads to test various seals. A small radial clearance (0.2mm) between the rotational disk and stator is settled. Leakage loss, pressure variation under the rotational disk and pressure difference between above and below the disk for various geometrical seals is measured at different rotational speeds. The results indicate that the rotational disk can reduce the leakage loss as the speed increases and the performance of disk without pads is better than the disk with straight pads under the same supply flow.