Abstract
For the cooling method in surfacing repairing, most of the research focuses on the method based on the fixture structure. However, due to the low thermal conductivity and ultrathin alloy blade, the heat transfer speed from the molten pool to fixture is slow. When the heat is transferred to the fixture, most of the molten pool has solidified and absorbed or segregated out some impurities. Therefore, how to cool the welding area directly is more critical. For this reason, the thermal cycle characteristics of typical points of the blade and the heat transfer process of the key area of the fixture are analyzed, the original cooling time is calculated, and two innovative cooling methods based on lateral forced convection cooling and vertical jet impact forced convection cooling are proposed. For lateral forced cooling, with “AF-field” lateral convection cooling modeling, the cooling effects of characteristic points and sections under different flow velocities are calculated. For vertical jet impact cooling, the pressure, flow rate, and convective heat flux distribution on the wall under different impact heights and nozzle diameter are calculated. The influence of different inlet flow rates on cooling performance is influenced, based on the analysis results of impact modeling, the moving heat sink model is established, and the cooling effect under different heat sink-source distances is calculated. The heat transfer rules of two methods are analyzed in detail through modeling and simulations. The results show that both methods can improve the cooling effect and the vertical jet impact cooling method has an effect that is more obvious. When the nozzle radius is 2 mm, the impact height is 4d, the inlet flow velocity is 35 m/s, and the distance is 7 mm, and the cooling time under the vertical jet impact method is shortened by 12.5%, which can achieve better cooling effect. The experiment further validates the effectiveness of the modeling and simulations.
Highlights
Compressor blades work in high temperature and high pressure for long time and often suffer from abrasion and defect, which affect flight safety
Titanium alloy have poor thermal conductivity and slow heat dissipation after welding. e use of inert gas protection cannot completely isolate the air, and the weld zone reacts with C, H, and O in the air to form impurities when the temperature is above 250°C. ese impurities have poor mechanical properties and are difficult to eliminate in postweld heat treatment, which is an important factor affecting welding quality
Karimzadeh et al [5] established a sequential coupled thermomechanical model based on the large displacement theory to study the welding of titanium alloy and found out the influence of heat input on the welding effect
Summary
Compressor blades work in high temperature and high pressure for long time and often suffer from abrasion and defect, which affect flight safety. Karimzadeh et al [5] established a sequential coupled thermomechanical model based on the large displacement theory to study the welding of titanium alloy and found out the influence of heat input on the welding effect. Chunhua et al [10] proposed a new method of local cooling auxiliary laser tailor welding for laser tailor welding and realized the local cooling of the heat-affected zone by adding a built-in runner auxiliary mechanism to the copper fixture. E new engine compressor blades use ultrathin alloys with the partial tip thickness less than 1.5 mm; the two main repair methods currently used are microplasma arc welding (MPAW) surfacing and laser cladding [15,16,17]. Based on the analysis of thermal cycle law and heat dissipation characteristics of the fixture for MPAW welding blade repair, this work proposes two new cooling methods. One is the argon lateral-forced convection cooling method and the other is the argon vertical jet impact forced convection cooling method. en, calculate the cooling effect of the two cooling methods by modeling and simulation and verify the effectiveness by experiments. e research results are of great significance for the improvement of the welding repair process of ultrathin compressor blades
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
