Dynamic Regulation Process of the Variable-Geometry Power Turbine

Abstract

In this paper, the dynamic regulating process of a variable-geometry power turbine is investigated through wind-tunnel experiments. Particle image velocimetry is used to obtain the dynamic evolution of the flowfield in the cascade passage, including two adjustment processes of increasing and decreasing the throat area. During the test, snapshots of the clockwise/counterclockwise rotation of a blade in the range of [Formula: see text] to [Formula: see text] are processed with a piecewise time-averaged method. The results indicate that the macroscopic change in the flowfield structure mainly appears in the wake region and the high-velocity region. In this process, the velocity and flow angle change monotonously with the blade rotation. The change rate of velocity is determined by both the blade position and the dimensionless outlet location [Formula: see text]. The overall change rate of velocity when the blade approaches the design position is higher than that at other positions, and the airflow near the suction surface is more sensitive to the adjustment of the cascade geometry compared with that near the pressure surface. As for the flow angle, the specific value is mainly determined by the blade position, and the variation law is related to the blade rotation speed.