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In this study, the thickness of water film, which is frequently formed on compressor blade surface, was investigated. Simultaneously, its movement and extra torque demand were provided by a simulation model of the code. Having taken into account the transformation in blade's profile and the thickness feature of the films, the working medium characteristic transformation in compressor stage was analyzed. In addition, formation, development and movement of the water film on a compressor stage were simulated by using unsteady numerical methods in various water injected conditions. Movement characteristics of water droplets in cascade were investigated to understand the flow mechanisms responsible for water film formation process. The forming and the tearing process of water films, which formed on the blade surface, were analyzed at different injection conditions. In consideration of the "Scoop effect" in actual situation, the maximum quantity of injected water can reach 12 %. Results indicated that continuity and region of the film would be developed with the increment of droplet size and injection rate. It was also found that water film's tearing process brought about flow losses near blade surface due to the increment of surface roughness. [ABSTRACT FROM AUTHOR]

The part-load performance of gas turbine is of great importance due to the consideration of running time spent at part power, and Variable Geometry Turbine (VGT) is an important way to meet the requirements. Effect of variable geometry guide-vane with cylindrical endwalls on part-load turbine stage performance is quantified by detailed analysis of aerodynamic characteristics. The turbine stage characteristics of corrected mass flow, corrected output power and efficiency are presented to investigate the VGT performance under the condition of four off-design rotating angles. In addition, the flow field, the loss distribution and the leakage flow are analyzed for different rotating angles. Results show that both the corrected mass flow and the corrected output power increase as the vane throat area is increased, the total leakage area and the shroud area are increased with the increase of rotating angle, whereas the hub leakage area is decreased, and the total pressure loss and the entropy change of variable geometry vane are both increased with the decrease of vane throat area. [ABSTRACT FROM AUTHOR]

The variable geometry turbine (VGT) has been widely used in different fields due to its higher efficiency and lower fuel consumption at part-load. However, the flow field in a VGT is characterized by the leakage flow through the radial clearance of rotational vane compared with a general fixed vane turbine. Numerical simulations are conducted on a linear turbine cascade to reduce the leakage flow based on passive control method. The aerodynamic performances and flow fields are compared for four kinds of tip configuration firstly. Then, the effect of variable geometry on the linear turbine cascade aerodynamic performance is investigated for five installation angles ranging from –5 to 5 deg. In addition, the development patterns and trends of the tip leakage vortex and the passage vortex are analyzed. The results show that the squealer tip and the rotating axis have a significant impact on suppressing leakage flow. The leakage flow rate has a tendency to decrease, and the total pressure coefficient is gradually increased when installation angle ranges from –5 to 5 deg. The interactions between tip leakage vortex and passage vortex leads to the different trends on leakage flow at various installation angles and axial sections. [ABSTRACT FROM AUTHOR]