The most probable cause of the erosion is the too high speed of the fluid with the entrained metal particles.
The NPSHr in table is valid only far fluid without entrained air.
According to the injection principle, because of the entrainment of high-speed fluid, the waste gas and the rock powder returning to the circular spacing between the drill bit and the hole wall is entrained from the re-absorption spacing to the drill bit accepting cavity, and is mixed with the high-speed air flow from the spline housing injection spray nozzle in the drill bit mixing spray nozzle, to form the mixed jet fluid.
It has shown from the experimental results that the vorticity near the jet boundary region is high in magnitude due to the interaction between the jet fluid and the entrained ambient fluid.
This will lend themselves to better understanding the underlying physical mechanisms of fluid loading on plates and shells. (5) The coupling effects on two concentric cylindrical shells with periodic annular plates as well as entrainedfluid are investigated theoretically.