Research On Accumulation Model Of HVOF Spraying Coatings For Surface Reconstructing Of Turbine Components

Hydraulic turbine is a kind of power machinery which converts water flow energy into mechanical energy.Its components contact with water for a long time and are impacted by water flow,which will cause material damage on the surface of components.For this reason,the Institute of Mechanical Design of the Ministry of Water Resources has developed a kind of material for surface spraying of turbine components.The surface of new and old turbine components can be increased and repaired by supersonic flame spraying(HVOF).Because there are many parts of hydraulic turbine and the sprayed surface is complex,it will cause some special spraying parts,especially the interface and angle position of spraying difficulties and uneven coating.Therefore,based on the study of the surface characteristics of hydraulic turbine components and the stability and diffusion angle of HVOF jet flow field,the spraying path is planned according to the curvature of surface.The accumulation model of coating.The main work is as follows:(1)Classify the surface of common water turbine components which need to be augmented,and implement topological triangular mesh for its three-dimensional CAD model.With the effective radius of HVOF spraying spot circle as the boundary,the spraying surface is divided into two categories according to the curvature.The spraying interval division and the spraying trajectory optimization related to the control of spraying gun trajectory are studied,and a better accumulation model is obtained to solve the spraying difficulties and uneven problems of special parts.(2)The influence of HVOF coal oxygen content on jet temperature field,velocity field and particle flow spatial distribution is studied and analyzed,and the simulation results are given.To verify the experimental results,a spraying jet temperature measuring device is invented,which can measure the jet temperature and diffusion angle of HVOF in situ.According to the fluctuation of jet temperature and diffusion angle in the injection period,the spraying jet temperature and diffusion angle can be measured in situ.The stabilization degree of the jet was judged.The control parameters of the jet were kerosene 24m3/h and oxygen 850L/min.Based on this,a coating accumulation model related to spraying speed and spraying distance was established.(3)Optimum design of spraying trajectory for large and small curvature surfaces respectively.For spraying objects with small curvature and large surface,the spraying area is divided first,and then the spraying trajectory is planned in the area.Taking the coincidence distance between trajectories as the optimization objective,under the above stable jet conditions,the optimal coincidence distance is 7.8mm by theoretical analysis and experimental verification.According to the different spraying speed,the distance between the edge spraying trajectory and the boundary of the spraying area was optimized,and the optimal trajectory control model was obtained.The optimization simulation was carried out with the movable guide vane as an example.For the spraying object with large curvature and small angle,the optimization design of spraying trajectory based on the characteristics of spraying gun inclination angle is given,and the optimization model of the trajectory parameters of spraying gun with large curvature and small angle is established,which is related to the spraying gun inclination angle,and the preliminary verification is carried out.