Consideration on the Basic Design and Application of Counter-Rotating Turbines

According to the comprehensive basic analysis of counter rotating turbines given by the author ten years ago,some aero thermodynamic design problems, which have not yet attracted enough attention of turbine designers,are raised and discussed.The possibilities for application of various counter rotating elementary stages and their cascades are elaborated from the viewpoint of the required matchings of the loads,rotating speeds and pressure ratios between the high pressure and low pressure counter rotating shafts,and then the turboengine systems suitable for utilization of the counter rotating turbines are proposed.Finally the possibility and necessity for designing the ultra high turning angle cascades and the ultra high inlet and outlet angle (related to axial direction) low turning angle cascades are considered.Therefore the consideration on integration of the requirements for both the engine systems and turbomachinery gasdynamic designs will be beneficial to the development of the counter rotating turbines.