Abstract:

The effect of rigidity of buffering spring on the flowing character of the liquid in the controlling passages of fluidic element and the backward impact velocity of the piston is studied by means of CFD dynamic analysis and is validated by experiments. The results show that exerting spring force axially on the piston has no effect on the switch of the main jet in the fluidic element, and buffering spring with proper rigidity can make the backward impact velocity decrease greatly, the backward impact velocity of the piston will reduce 52.88% when rigidity of spring enhances five times, which is helpful for reducing impact loads and keeping the parts made of tungsten carbide in the fluidic elements from breaking when the liquid-jet hammer works in well drilling.

Key words: piston, backward impact buffering, main jet switch, CFD dynamic analysis