Research On The Precise Shape-controlling Method Of The Turbine Blade Film-cooling Hole Based On Ultrafast Laser

Film cooling can effectively improve the high-temperature creep ability of the aerial engine hot end parts by designing a large number of linearly arranged gas film holes on the turbine blade surface to form a thin layer of cold air to isolate high-temperature gas,whose cooling efficiency related closely to the accuracy and quality of the film holes.In this paper,the problems of low precision and unstable quality of gas film holes processed with ultrafast laser are discussed.The design parameters of the film holes are modified.The process model of drilling micro holes with ultrafast laser is established.The spatio-temporal evolution of drilling micro holes is analyzed.The main contents are described as follows:1.Based on the directional solidification process of turbine blades,the numerical simulation of blade casting process is carried out.The casting model of blade is obtained-Combined with the measurement of blade casting model,the displacement field model of blade casting is established.2.The deformation model of the torsion,bending and shrinkage of the blade is established by using the deformation error compensation method.A correction method of the film hole position parameters is proposed,which is based on the camber line of the blade sections.3.The micro hole drilling experiments on the 304 stainless steel,5052 aluminum alloy and DD6 nickel base alloy with femtosecond laser using the five-axis ultrafast laser blade micro hole machining machine are completed.The effects of laser repetition rate,average output power,laser rotation speed and overlapping rate to the drilling process of micro holes are analyzed.The orthogonal experiments of laser energy parameters are carried out.The mapping model of energy parameters and micro hole drilling process is established.4.Combined with the double-temperature equation which can describe ultrafast laser ablation on metal surface,the temperature curves of electrons and lattices in the laser ablation process are solved.The process of laser helical processing is analyzed.The spatio-temporal evolution of drilling micro holes is established.