Numerical Study of Film Cooling and Particle Depositions in Turbine Blade of High-Temperature Gas-Cooled Reactor

Abstract Direct-circulation helium gas turbines represent an important development for high-temperature gas-cooled reactors. During the operation of such a reactor, graphite dust is generated continuously in the core, so it is important to investigate the transport characteristics of graphite dust particles in the helium turbine and the mechanism whereby they interact with the cooling characteristics of the turbine blades. Proposed here is a slotted-hole film cooling scheme to effectively cool the helium turbine, and the motion of graphite particles is analyzed. The discrete phase model is used to calculate the particle trajectories, and user-defined functions are used to establish the deposition and rebound models for the particle-wall interactions. The mechanism whereby the slotted holes improve both the cooling performance and the distribution of film cooling effectiveness is studied, and the deposition rate of graphite dust is calculated for different particle sizes. The results indicate that (i) with increasing blowing ratio, the film cooling effectiveness increases and then decreases, (ii) the deposition rate of smaller particles is much higher than that of larger particles, and (iii) using an appropriate slot depth and blowing ratio increases the film cooling effectiveness and makes its distribution much more uniform, as well as reducing the deposition of graphite dust particles. The present findings are beneficial for designing direct-circulation helium turbines for high-temperature gas-cooled reactors.