Numerical And Experimental Study On Spray Characteristics Of Atomizing Nozzles Of Helicopter Main Reducer

Oil mist lubrication is an advanced emergency lubrication method.After the compressed air is mixed with a small amount of oil,the oil mist is formed and sprayed onto the friction surface to lubricate the friction surface.It has the advantages of high lubrication efficiency and good lubricating effect.Therefore,exploring the atomization characteristics of the nozzle has an important influence on effectively improving the spray lubrication performance of the main reducer.In this paper,a pneumatic two-phase flow nozzle of helicopter main reducer was taken as the research object,and the atomization performance of the nozzles were studied by a combination of numerical simulation and experimental verification.The main research contents were as follows:(1)Based on the theory of fluid mechanics and spray,the discrete phase governing equation and atomization mathematical model based on the Euler-Lagrange method in numerical simulation were expounded.The CFD model of nozzle atomization was established by meshing through ICEM and verifying the grid independence,and a numerical simulation method based on continuous phase-discrete phase coupling was formed.(2)Fluent was used to simulate the gas-phase flow field and spray field of the nozzle,and the flow field pressure,velocity distribution and droplet size characteristics were obtained.The effects of nozzle structure,working condition parameters and physical properties of lubricating oil on droplet size distribution,Salter Mean Diameter(SMD)and penetration distance were studied,and the influence laws of different parameters on nozzle atomization performance were obtained,which provided a certain reference for the working condition setting and structure design of the emergency oil mist lubricated atomizing nozzle of the helicopter main reducer.(3)A two-phase flow nozzle atomization test rig was designed and built to carry out the atomization characteristics test of the nozzle under different under different working conditions.The spray photographs were taken by the camera.The particle size distribution and the average diameter SMD of the droplet were measured by the DP-02 laser particle size analyzer.The experimental and simulation results were analyzed and compared to verify the accuracy of the numerical simulation method of nozzle atomization.