Research On Heat Transfer Of Cooling System For Compressor Blade Welding Repair Fixture

Compressor blades are often exposed to harsh working conditions,causing corrosion,wear and cracks,which are harmful to flight safety.Repairing them can reduce blade replacement costs.TC4 titanium alloy is commonly used as the rotor blade of compressor.The tip wear of the TC4 is often repaired by micro-plasma arc welding to restore its original performance.However,due to the poor thermal conductivity of TC4 titanium alloy,the heat is not easy to be lost,and it is easy to react with air at high temperatures,causing the weld to be doped with impurities,and it is difficult to achieve the inherent strength of the base material,the reliability and safety are also lowered.Therefore,the research on the cooling system of the blade welding repair fixture is of great significance.Firstly,the general welding(without cooling)repair process of micro-plasma arc is studied.The planar double-ellipse heat source model is used to establish the three-dimensional moving heat source welding finite element model by COMSOL software.The transient temperature field distribution of the "blade-clamp" system is obtained.The heat transfer mechanism between the blade and the fixture is obtained,and the thermal cycle curve of the characteristic points of the blade surface is obtained.The cooling time is calculated,and the correctness of the heat source is verified by experiments.Secondly,the simulation study on the forced cooling process of argon cross-blown fixture surface is carried out.The thermal-flow field coupling model is established to analyze the heat transfer process of the cooling system.The cooling time is compared with the normal welding conditions.The results show that the argon blowing fixture surface can take away a certain amount of heat,but the cooling effect is small for the entire welding thermal cycle,and the cooling effect of different argon flow rates is not much different.Furthermore,the argon vertical impinging cooling method is proposed.The influence of different model parameters on the cooling performance under vertical impingement cooling mode is studied,and the subsequent simulation parameters are determined.Finally,the water-cooling runner model of the fixture was established,and the cooling time under water cooling is compared with ordinary welding.The cooling effect of different cooling water flow rates was analyzed.According to the analysis results,combined with the impingement model parameters determined in the previous chapter,the suitable cold-heat source spacing and cooling water flow rate are selected,and the water-gas composite cooling combined simulation model is established.The calculation results show that the water-gas composite cooling method can achieve a good cooling effect and compared the cooling time under different cooling methods.According to the simulation results,the MPAW welding experimental platform was built,and the morphology of the surfacing layer of the post-weld test piece under the approximate composite cooling method and the ordinary welding condition was compared.The experimental results show that the composite cooling method can reduce the impurity inhalation of the molten pool and improve the welding quality.