| Ultra-high speed,ultra-high altitude,ultra-long endurance,ultra-long range and high thrust-weight ratio are the main directions of the performance development of modern aero-engines.Therefore,the structural design of aero-engines is becoming more and more complex,and the requirements for the performance and accuracy of their components are constantly improving.Turbine guide is one of the main structural components of aeroengine.The power turbine secondary guide assembly of a helicopter aeroengine is composed of an outer ring,an inner ring,solid blades and upper and lower flanges,and its structure is complex.The guide is manufactured by investment casting process.Its main casting defects are miss-run at the exhaust side of the blade and coarse columnar crystals.In this paper,the casting simulation software Pro CAST and material performance calculation software JMat Pro were used to simulate the casting system and calculate the material performance respectively.Through the analysis of Pro CAST software,under cast defects and vertical columnar crystals are caused by the nonuniformity temperature field during solidification.It can be solved by adding insulation layer to the exhaust edge of turbine guide.At the same time,it can solve the problem of under casting too.By centrifugal casting,dendrite growth during solidification can be significantly destroyed,and hindering grain growth.It makes grains can only appear in the state of equiaxed grains.Finally,through the guide after centrifugal casting.It not only completes the casting mold filling,but also formed fine equiaxed crystal.Centrifugal casting expected to eliminate the columnar defects. |
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