Investigation of Water Film Formation on Blade Surfaces of a Wet Compression Transonic Compressor Rotor

As is known, when water injected at the inlet of the compressor, the water droplets will move onto the blade where water film could form on the blade surface. In this paper, the movement and formation of the water film on a transonic rotor, NASA Rotor 37, are simulated and analyzed by using unsteady numerical methods under different water injecting conditions. The motions of water droplets and flows in the blade passage are presented in detail. Tearing process of water film on the blade surface is also a key point of this research. The preliminary results indicate that the movement of water droplets is tending to deviate from the suction surface and pile on the pressure surface due to the effect of inertia force, and water film could be formed on the pressure surface. Continuity and scope of the water film on the blade surface will develop with the increasing of droplet sizes and water injection rate. Based on the simulation, it is found that more discrete water films are formed on the pressure side of blade when the droplets move onto the pressure surface, tearing phenomenon may occur where the area is of lower water film thickness. Smaller enough sprayed droplet size can not only ensure the compressor performance of wet compression, but also avoid the erosion caused by water film accumulation.