Study On The Influence Of Thrust Takeoff On The Separation Interval Of Aeroengine

Civil engine is one of the most important aircraft parts,its operational reliability and performance are concerned by the airlines.Factors which affect aircraft engine overhaul interval guarantee the flight safety of aircraft and reduce the airlines operating costs effectively.In this paper,the factor of thrust reduction and thrust level is selected as required that affect the overhaul interval of aeroengine,mainly from two aspects of the engine take-off EGT margin and the turbine blade life.Two methods of the thrust reduction take-off are studied: flexible thrust take-off method and(Derated thrust take-off).CFM56-7B is used to study the application of thrust level in engineering practice.Based on the aeroengine design theories and computer simulation of throttle characteristics of ground platform,the performance parameters of turbine engine with different thrust reduction were analyzed by adopting regression analysis method.The amount of changes of turbine exhaust temperature and T3 temperature at different take-off thrusts were obtained.Analyzed several methods of the exhaust gas temperature margin(EGTM)?The exhaust temperature data obtained under thrust reduction take-off condition need to be compensated to the stand sea level and full thrust state,and take-off EGTMs under different thrust levels are calculated.The EGTM decay rate model was established and calculated,the number of remaining cycles of the engine is obtained by taking the EGTM and EGTM decay rates.Quantitative relationship between the take-off EGTM and overhaul interval is established under thrust reduction condition.Turbine T3 temperature is improved under thrust Reduction conditions,thereby prolongs the turbine blade life.Since high-pressure turbine rotor blades are subject to heavy loads,damages can also cause the engine to be released.According to the turbine T3 temperature and speed obtained under different thrusts,the finite element software is used to model the high pressure turbine blades,and the temperature load is applied to the turbine blades to obtain the stress.The life expectancy of the high-pressure turbine rotor blades was calculatedby using the [L-M] durable life formula.The creep life of the high-pressure turbine rotor blades was calculated when full thrust was taken and 10% thrust was taken off.Quantitative relationship between the tire lift and the life span of the turbine blades is obtained.