Research on Turbine Tip Clearance Modeling Considering Active Tip Clearance Control

In order to reflect effects of static and dynamic performance with the changes of turbine tip clearance,a real-time engine component level model with the function of turbine tip clearance calculation and active clearance control system were studied. A method to estimate the related temperature and calculate dynamic tip clearance more accurately was presented which is a combination of semi-infinite transient heat conduction equations and polynomial fitting. Through the relationship between the change of turbine tip clearance and performance parameters,current turbine performance map were corrected to improve the calculation accuracy of conventional engine component level model. A 0.25 mm reduction in turbine tip clearance can lead to an increase in turbine efficiency up to 1% and a reduction in sfc by 1%. Compared with the active tip control systems of air-cooled,a mechanical active tip clearance control system with clearance change in the closed-loop was demonstrated to make the dynamic process tip clearance always in the required position. The simulation results during the transition process of ground acceleration and cruise deceleration verified the effectiveness of the new real-time engine model and active clearance control system.