Structure Design Method For Turbine Rotor Of Small Turbofan Engine Based On Strength Analysis

Due to its high thrust-to-weight ratio, low SFC, compact structure and good start-up performance, small gas turbine is widely used in energy, power generation, aviation, ship, vehicle and military, and it must play an important role in our national economy and national security. Hence, developing small gas turbine could not only acquire economic benefits but also have important strategic significance. Turbine components is one of the key components of a turbofan engine. The performance of whole engine is determined by the performance of turbine, because of its cruel high temperature operating circumstance. What’s more, because of the high revolution speed of turbine rotor, structure design is always the emphases and the difficulty of turbine design. So it is of vital importance to establish a feasible and effective design method for turbine rotor in the process of developing small gas turbine.According to the above analysis, based on the structure design of a small turbofan engine, this dissertation focused on the turbine rotor structure design method of the turbofan engine. First of all, structure project design was regarded as a starting point, both domestic and foreign successful turbine components’ structure design cases of similar type and thrust level turbofan engines were analyzed. After absorbing engineering experience of structure design and advanced structure design concept of these cases, the turbine rotor structure design project of the investigated small turbofan engine was brought forward. Several problems including temperature estimate method and rationality of rotor material choosing were discussed based on the project. Then blade structure design (tenon connection design included) and disk structure design were done on this project. Processes of both blade design based on strength check and parametric optimization and disk design were established, several important problems of the processes were investigated in detail. To be specific, the issues below were discussed in chapters:1) The structure characteristics of the small turbofan engine turbine rotor, for example, contact stress calculation of tenon and mortice for complex three dimensional blade. Finite element analysis method was applied to find the method to calculate strength of definite structure and definite load, which ensured the reliability of the strength check results.2) Research on multi-dimensional and multi-arrangement transformation method on cold and hot blade for turbine blade. One dimensional linear cold and hot blade transformation, three dimensional cold and hot blade transformation and heat-structure coupling cold and hot blade transformation were compared for certain blade.3) Design characteristics of parameters for fir-tree tenon and mortise teeth. Two dimensional teeth shape optimization design was regarded as starting point, and the influence of tenon skew angle on mortise contact stress was researched.4) The study on rigidity for support structure of low pressure rotor system."T" shape disk structure was introduced into low pressure turbine skillfully, rigidity adjust for the low pressure rotor system was achieved by adjusting the flange structure arrangement of the "T" shape disk, and reliable connection for disk in hot operating condition, turbine tip clearance control and guarantee of component efficiency ere also solved. The achievements acquired in this dissertation are not only been applied on structure project for the small turbofan engine, some achievements have passed core engine test. It is very important to deepen the understanding of turbine component structure design through test data analysis, it is also the author’s next step research plan.