| The cavitation process has important academic value and practical significance to study the effect of near-wall surface.In this paper,the near-wall cavitation bubble process was studied by experimental methods.A single cavitation bubble was generated in deionized water by two ways of low-voltage electric spark or pulsed laser.Aiming at the study of single bubble cavitation,two experiment systems of lowvoltage electric spark-generated method and laser-induced method were established,bubble interact respectively with aluminum foil and SAP elastic spheres.For the cavitation low-voltage generated bubbles,by analyzing the influence law of different wall distances on the depth of impact pits,the smaller the wall distance,the greater the collapse impact of aluminum foil.The influence of each stage of cavitation bubble on the near wall surface is discussed.The different wall distance makes the bubble itself show different characteristic changes during cavitation.In addition,the moment of collapse micro-jet was observed in the experiment,and bubble induced by shock wave on the back of aluminum foil during cavitation collapse were also observed in the experiment,which proved the existence of shock wave in cavitation.To make up for the shortcomings of low voltage electric spark-generated method,an laser-induced cavitation bubble experimental system was established.For the laserinduced cavitation bubble,the function characteristics of SAP elastic ball at the initial generation,development and collapse stage of bubbles during cavitation were analyzed,and the difference of cavitation bubble between elastic and rigid wall was compared.According to the development stage of the cavitation process,the change of SAP elastic ball deformation under different dimensionless parameters was discussed,and the influence of bubble on SAP elastic ball wall was quantified.The experiment proved that with the decrease of wall distance in the cavitation process,the greater the influence of bubble effect on the elastic ball was,the maximum extrusion pressure was up to 5000 Pa.In the bubble collapse stage,the elastic ball is pulled by the point of the bubble collapse.Relevant research results have a good promoting effect on exploring the beneficial applications of reducing cavitation damage in instruments and excavating cavitation. |
