The steam turbine is a principal prime mover, that drives the electricity, in the thermal, nuclear and geothermal power generation systems. Thus, the efficiency of a steam turbine is critical for the performance of power plants. One of the well-known degrade factors of the performance is a wet loss which is mainly caused by the coarse droplet generated during the steam passing through the turbine. Thus, reducing wet loss is a technical challenge but a good solution is not yet provided. A coarse droplet trapped by nozzles becomes a liquid film and the film is atomized by high-speed gas flows. The atomized fluid might be reorganized into huge droplets resulting in the significant wet loss. In order to control these processes, quantitative prediction of the liquid film profile and its atomization against such as a spray angle, diameter and distribution should be useful. In this study, first, we perform the numerical simulation of three-dimensional airflow around low-pressure turbine blades and compare the result with the experimental data. Then, on the basis of the airflow data, we calculate the motion of droplet particles in a one-way coupling manner. The patterns of the droplet motion against the turbine blade are summarized into a regime diagram. Through these numerical experiments, we propose a prediction model of the trajectories of the droplet by non-dimensional numbers, i.e. Stokes number and Reynolds number. The accuracy and limitation of the proposed model will be discussed with a validation test. We found that Stokes number can control the trapping ratio of the droplet impact on a blade even at high Reynolds number.


Numerical Simulation of a Particle in Air Flow Around a Turbine Blade

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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