To reveal the rock breaking mechanism of straight-swirling integrated jet
the erosion experiments of straight jet
swirling jet and straight-swirling integrated jet were carried out
and the velocity fields of the three jets were obtained by 3DPIV. The damage characteristics of straight-swirling integrated jet were revealed via comparative analyses for distribution laws of hole depth and jet velocity along radial direction at the same target distance. The results show that the straight-swirling integrated jet eliminates the low velocity area and the hole center boss of swirling jet
and both the jet distribution width and hole diameter are bigger than those of straight jet. The jet structure can be divided into straight jet area
high swirl strength jet area
low swirl strength jet area and periphery jet area; the jet energy of straight jet area decides the capacity of rock breaking; high swirl strength jet area has high radial and tangential velocity
thus long depth hole near that by straight jet can be drilled by radial tension and circumferential shearing force under the condition of resultant velocity lower than straight jet; rocks in low swirl strength jet area are damaged by both straight and swirling jets
which decrease the rock strength
and the broken rocks can be transported effectively in this lower velocity area
where rock breaking of periphery jet area results from the wearing of returning jet with rock debris.
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