Research On Flow Field And Resonance Characteristics Of Double-cavity Self-excited Oscillation Fire Nozzle

Traditional fire nozzles are generally straight-line or diversion nozzles,with small jet velocity,short range,and easy divergence of the jet,which cannot meet the requirements of long range and precise fire extinguishing,and has certain limitations for long-distance fire extinguishing.Self-excited oscillation nozzle is a nozzle that can convert continuous jet into pulsed cavitation jet without external force.It has the advantages of simple structure,high work efficiency and low cost.A chamber is added to the nozzle to make the jet flow one more operation and release process,which can produce a better jet effect.In this paper,the dual-cavity self-excited oscillation nozzle is taken as the research object,and the flow field characteristics and resonance mechanism of the nozzle are studied.The main work of this paper is as follows:A simulation model of a dual-cavity self-oscillating nozzle.According to the flow field characteristics of the non-submerged pulsed cavitation jet,large eddy simulation,Realizable k-ε turbulence model,Mixture multiphase flow model,and Schnerr and Saue cavitation model were selected to establish the simulation of the internal and external flow field characteristics of the dual-cavity self-oscillating nozzle Model.Simulation analysis of flow field of dual-chamber self-oscillating nozzle.The change of the vortex ring in the internal flow field of the dual-cavity self-excited oscillating nozzle is analyzed,the influence of the change of the vortex ring in the chamber on the velocity of the pulsed jet is discussed under different structures and working pressures,and the jet bunching effect in the external flow field of different working parameters is compared.Resonant frequency analysis of dual-cavity self-oscillating nozzle.With the help of fluid network theory,a parametric model of the dual-cavity self-oscillating nozzle is established,the relationship between the jet frequency and pulse amplitude of the dualcavity nozzle and its own structural parameters and materials is derived,and the amplitudefrequency characteristic curves of different nozzle working conditions and working pressures are compared.Experimental research on dual-cavity self-excited oscillating nozzle.The jet pressure and acceleration curves are obtained by the pressure and acceleration sensors,and compared with the frequency test data of the large eddy simulation and the Realizable k-ε turbulence model,the correctness of the numerical simulation model is verified.