Numerical investigation on flow field characteristics of Helmholtz oscillator

Abstract

Self-excietd oscillation pulsed(SOP) jet, is capable of great destruction. As a typical kind of SOP nozzle, Helmhotlz oscillator has its special application. Previous researches mainly focus on optimization of the structure parameters, erosion ability of jets and so on. In this paper, the flow field of Helmhotlz oscillator was numerically simulated. 20 nozzles with different structures were manufactured according to simulation results; their performances were tested on different driving pressure and confining pressure under the condition of submerging. Conclusions can be drawn as follows: Compared with traditional conical nozzle, the flow characteristics of Helmholtz nozzle are obviously different. Change of structural parameters has obvious influence on the amplitude of pressure fluctuation. If the structure parameters are reasonably adjusted, energy dissipation will be reduced and working ability will be optimized. A large scale vortex structure is formed by the flow turbulence of SOP jet. In some cases that require suction and mixture, SOP nozzle has unique advantages. Since the theory of the SOP nozzle is still evolving, it is necessary to further study the pulse mechanism to realize artificial modulation.