Parameter optimization of anti crystallization flocking drainage pipe based on flow field distribution characteristics

The crystal plugging of tunnel drainage pipe seriously affects the safe and normal use of the tunnel. In order to obtain the mechanism of flocking drainage pipe anti crystal plugging based on the characteristics of flow field distribution, numerical simulation was used to optimize the parameters of flocking drainage pipe. The results show that: with the existence of fluff, the velocity in the lower part of the drainage pipe decreases by about 50%, and the velocity in the upper part increases by about 25~50%. With the increase of the length of fluff, the velocity funnel between fluffs gradually increases, the velocity distribution at the bottom of the funnel is basically unchanged, and the velocity in the upper part gradually increases. The velocity in the upper part of the flocked drainage pipe fluctuates above the fluff to a certain extent. The flow velocity in the lower part of the drainage pipe forms a flow velocity ladder in the longitudinal direction of the villus, and the width of the ladder is about 2/3 of the longitudinal spacing of the villus. The optimized parameters of 3-D flow field of flocked drainage pipe are helpful to the further improvement of indoor test, and provide theoretical basis for the mechanism of preventing crystal blockage of flocked drainage pipe.