Aerodynamic performance investigation of turbine in the event of one blade primary fracture failure

One of major safety requirements from current airworthiness regulations is that the probability of hazardous engine effects should not occur exceed 10⁻⁷ per engine flight hour even in the event of component failure. Service experience of aero-engines indicates that turbine blade fracture is a common fault whose probability is far more than 10⁻⁷ per engine flight hour. It is obvious that overall engine system will be affected by blade failure. So, aerodynamic performance investigation in the event of one blade fracture failure has been assessed in the current study. With ANSYS-CFX, numerical model of GE-E3 (Energy Efficient Engine) high pressure turbine was established according to literature data. By comparing surface Mach number distribution at mid-span of vane in the first stage obtained numerically and experimentally, the most efficient turbulence model, i.e., the SST k-ω model, was identified. Based on the model, the 3-dimensional flow simulations under two configurations, full wheel geometry GE-E3 high pressure turbine without and with one blade fracture failure have been achieved. The following conclusions were drawn from 3-dimensional simulations: firstly, as for GE-E3 high pressure turbine,the effect of single turbine blade failure on turbine characteristics is slight; secondly, with blade loading coefficient as a criterion which is used for judging whether blade is affected, five blades which are significantly affected can be identified, and the surface pressure distributions of these five affected blades alter to varying degrees, accordingly,these film outflow static pressure characteristics alter as well; thirdly, after turbine blade fails, airflow accelerates violently along the suction side of downstream blade closest to failed blade and separates, however, air flow can not expand efficiently along the pressure side of upstream blade nearest to failed blade.