| Turbine is a critical component of the aircraft engine, and there are two trends of the development of the turbine technology. One is increasing the turbine inlet temperature, and the other is enhancing the turbine load and decreasing the number of the turbine blade row. In view of the above, adopting high-load turbine could increase the load of the turbine efficiently, and using counter-rotating turbine could enhance the thrust-weight ratio significantly and improve the performances of the aircraft engine.Since the high-load transonic turbine is both important and advanced for the research and development of the aircraft engine in the future, and the counter-rotating turbine has become the development direction of the turbine technology, we designed and analyzed a novel counter-rotating turbine integrating a high-load turbine with a counter-rotating turbine in this thesis.The low-pressure stage of a vaneless counter-rotating turbine (VCRT) with high-load high-pressure stage was designed and studied. The design objective of the low-pressure stage was set up through the characteristic analysis of the high-load turbine, and then the low-pressure stage of the VCRT was designed in detail. Both the flow characteristics of the VCRT in design and off-design conditions were researched. The results show that the design objective of the low-pressure stage has been achieved.In addition, the influences of the blade tip clearance on the VCRT were analyzed. The results of the numerical analysis indicate that the tip clearance leakage flow has remarkable effects on whole blade outlet flow field, especially on the region near the blade tip. When the blade tip clearance size gets bigger, the work output and efficiency of the high-pressure stage and low-pressure stage will decline, the Expansion Ratio of the high-pressure stage will increase, while the Expansion Ratio of the low-pressure stage will decrease. Finally, the influences of the axial spacing on the VCRT were analyzed. The results indicate that increasing the axial gap between the high-pressure stage and the low-pressure stage appropriately could weaken the interstage interference, and thus the performances of the VCRT could get improved. |
