Investigation On Flow And Heat Transfer Characteristics In Low Pressure Turbine Of Aeroengine

Low Pressure Turbine (LPT) is an important component of aeroengine. The performance of LPT greatly influences the thrust-weight ratio and specific fuel consumption of aeroengine. It is of imperative to investigate the flow and heat transfer characteristics in LPT for improving the aeroengine performance and advanced technology research.The performance of LPT, including the aerodynamic flow features, the flow and cooling characteristics under the condition of altitude low Reynolds number(ALRN), and the flow and heat transfer in rotor-stator cavity are investigated by advanced computional fluid dynamics(CFD) in the thesis. The redesign and improvement work of the short duration turbine rig has also been carried out for further experimental investigation. The main contents of the thesis are listed as follows:1. The aerodynamic characteristics of an aeroengine turbine under various working conditions are investigated in detail. The component optimization is, moreover, carried out on the basis of the flow features and flowfield structures of the turbine. The efficiency of the optimized turbine is0.8%higher than the original one. Furthermore, the mass flow is improved by2.7%and the power of the LPT is increased by10.4%. It is concluded that the optimization work can increase the performance of the turbine remarkably.2. Flow and cooling characteristics of an aeroengine LPT under ALRN are investigated by conjugate heat transfer methodology, meanwhile the effects of Reynolds number on the LPT efficiency and characteristics of flow and cooling are discussed in detail. With the increasing of Reynolds number (<2x105), the efficiency of the LPT is increasing monotonically because of the decrease of boundary layer separation loss. The heat transfer coefficient is decreasing with the decreasing of Reynolds number.3. The research of tip injection of the LPT rotor indicates that the tip injection improves the efficiency apparently, and the turbine efficiency can be best with optimal jet intensity πj. The tip leakage mass flow is decreased and the tip leakage vortex is enhanced by the tip injection, meanwhile the tip injection accelerates the injection flow and main flow to mix together.4. Based on the previous experimental results in literatures, the flow and heat transfer characteristics in a pre-swirl rotor-stator cavity are further investigated. The result indicates that the flow features and flowfield structures are mainly influenced by centrifugal force and apparent force with different turbulent flow parameter λr, pre-swirl ratio βρ, and rotational Reynolds number Re. The nusselt number on the rotor surface increases with Re? increasing. Furthermore, the Nusselt number is progressively increasing along with the radial direction when the jet intensity of the rotor-stator cavity is low, however the nusselt number is degressive along with the radial direction when the jet intensity is high.5. The development and improvement of IET short duration experiment rig for further experiment study of flow and cooling characteristics is presented. The test results indicate that experiment facilities are well prepared for further experimental study.