Experimental study of coupled cavitation-erosion jets with viscoelastic surfactant solution
In order to study the jet mechanism of the Helmholtz cavitation nozzle,based on the cavitation jet theory,a low viscosity viscoelastic surfactant(VES)solution was used as the medium,and the Schnerr-Sauer cavitation model and DPM model were used to simulate the flow field of the Helmholtz self-excited oscillation cavitation nozzle.The flow field characteristics near the wall of the VES cavitation-erosion coupled jet with added particles and the motion characteristics of particles impacting the wall were numerically simulated,and cavitation-erosion coupled jet experiments were conducted through the submerged jet test bench to explore the impact characteristics of VES solution cavitation-erosion coupled jet on the target material.The results show that compared with clean water,VES jet can provide a higher erosion rate,which is 1.37 times that of clean water,reaching 3.29×10-3 kg/kg.Under the same conditions,the erosion rate of the cavitation nozzle is 7.47×10-4 kg/kg,which is slightly lower than that of the streamlined nozzle.However,the diameter of the cavitation nozzle for the erosion pit on the target is 10.5 mm,which is larger than 7.5 mm of the streamlined nozzle.Moreover,the impact morphology of the cavitation nozzle on the target is V-shaped,which is more conducive to rock drilling and breaking than W-shape of the streamlined nozzle.By analyzing the difference of cavitation and fluid properties on the erosion characteristics of target material,the coupled jet mechanism of VES solution was expounded.The research findings provide new insights for applying VES-based cavitation-erosion coupled jets in assisting drilling and improving downhole rock-breaking efficiency.
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