Research On Water Beam Stabilization Technology Based On Water-jet Guided Laser

The water guide laser processing technology is a new processing technology which uses the water beam optical fiber formed by water jet to guide the laser to the surface of the workpiece.Because of its advantages of parallel groove cutting,large width diameter ratio,small heat affected area,no microcracks,less recast layer,it has been widely concerned at home and abroad.At present,the technology of water guide laser,represented by Swiss synova company,has been industrialized and applied in many aspects,but its equipment is expensive;the domestic water guide laser processing system is still in the preliminary stage of laboratory development,and the key technology has not been fully mastered.In this paper,based on the relevant research at home and abroad,the theory and Simulation of the water beam stability generation technology of the water guide laser are studied.According to the simulation calculation and analysis of the water beam fiber stability technology,a set of high-speed stable water guide fiber generation scheme with reasonable cost is developed.In this paper,the basic principle of micro water beam guided laser is analyzed.On this basis,the critical angle theory of laser beam completely bound to water beam,the energy dissipation theory of light conduction in the medium and the theory of constricted water fiber suitable for water-borne laser are analyzed.It is a theoretical preparation for the study of water beam stability of water beam guided laser system.In order to obtain the highly stable water beam in the nozzle,the transient laminar two-phase flow in the axisymmetric nozzle with different capillary lengths was analyzed by using CFD software,and the hydrodynamic equations were established.The effects of environmental factors(air disturbance,temperature),water beam parameters(water pressure,water jet velocity),nozzle structure(convergence angle,length,nozzle diameter)on water beam stability are analyzed.The simulation results show that the edge of the nozzle is sharpened with a right angle,the Reynolds number at the entrance is 18100,and the ratio of the length and diameter of the capillary section is less than 0.8,and the angle of the cone section is 15°,which is greater than the angle of the cone section reattachment 10°,the stable water beam is generated in the nozzle.Under the condition of reasonable parameters,the nozzle is developed.The laser beam enters the thin water layer and converges at the inlet of the nozzle.The state of fluid distribution in the thin water layer directly affects the effect of laser coupling to the water beam.Using FLUENT software to simulate the steady flow field and hydrodynamics of single inlet and double inlet coupled cavity,and theoretically simulate the conditions needed to generate stable water beam.The main objects of the simulation are the distribution of flow field structure and the diameter and thickness of the thin water layer in the chamber with different inlet pressures.The simulation results provide parameter guidance for the design of water chamber structure under different pressures,and complete the development of the chamber.Finally,the problem of continuous stability of liquid supply pressure is explored.Because of the different booster pumps,there will be different flow pulses and pressure shocks in the outlet pipeline of the liquid supply system under high pressure.By analyzing the operation characteristics of vane type,plunger type and hydraulic reciprocating pump,this paper designs three kinds of pressure operation liquid supply systems,which are0-10 mpa,0-50 mpa and above 50 MPa.The preliminary experiment is carried out under the condition of low pressure with the plunger pump as the power source.Under the condition of 0.2-0.3mpa,2MPa and 4MPa,the stable water beam can be generated.