To reduce vibration and noise and increase transmission efficiency, a three segment method for modifying the pinion profile was proposed. Cutter surface equations were deduced by changing the shape of the cutter-edge,...To reduce vibration and noise and increase transmission efficiency, a three segment method for modifying the pinion profile was proposed. Cutter surface equations were deduced by changing the shape of the cutter-edge, substituting three segment parabolas for the line. The influence of longitudinal tooth modifications on tooth surface load distributions was discussed. Transmission error minimization and uniformity of tooth surface load distribution were chosen as optimization goals and the modified parameters were obtained by applying the complex method. Finally, an experiment comparing the loaded transmission error, vibration, and noise both before and after modifications was carried out. The results indicate that the modified design is reliable.展开更多
This paper describes the redesign of a high pressure rotor (with exit Mach number around 1.5) for the vaneless counter-rotating turbine by choosing adequate exit-to-throat width ratio. Based on the previous design ana...This paper describes the redesign of a high pressure rotor (with exit Mach number around 1.5) for the vaneless counter-rotating turbine by choosing adequate exit-to-throat width ratio. Based on the previous design analysis and test results, effects of the exit-to-throat width ratio on the performance of the transonic turbine cascade were proposed. In order to investigate the influence of the exit-to-throat width ratio on the performance of the turbine cascade, a flow model of the convergent-divergent turbine cascade was constructed by using the theory of Laval nozzle. Then a method on how to choose the adequate exit-to-throat width ratio for the turbine cascade was proposed. To validate the method, it was used to calculate the adequate exit-to-throat width ratio for the high pressure rotor of the vaneless counter-rotating turbine. The high pressure turbine rotor was redesigned with the new exit-to-throat width ratio. Numerical simulation results show that the isentropic efficiency of the redesigned vaneless counter-rotating turbine under the design condition has increased by 0.9% and the efficiencies under the off-design conditions are also improved significantly. On the original design, a group of compressional waves are created from the suction surface after about 60% axial chord in the high pressure turbine rotor. While on the new design the compressional waves are eliminated. Furthermore, on the original design, the inner-extending waves first impinge on the next high pressure turbine rotor suction surface. Its reflection is strong enough and cannot be neglected. However on the new design the inner-extending waves are weakened or even eliminated. Another main progress is that the redesigned high pressure turbine rotor is of practical significance. In the original rotor, a part of the blade (from 60% axial chord to the trailing edge) is thin leading to the intensity problem and difficult arrangement of the cooling system. In the new design, however, the thickness distribution of the rotor airfoil along the chord is relatively reasonable. The intensity of the rotor is enhanced. It is possible to arrange the cooling system reasonably.展开更多
基金Supported by the National Natural Science Foundation under Grant No. 50875211
文摘To reduce vibration and noise and increase transmission efficiency, a three segment method for modifying the pinion profile was proposed. Cutter surface equations were deduced by changing the shape of the cutter-edge, substituting three segment parabolas for the line. The influence of longitudinal tooth modifications on tooth surface load distributions was discussed. Transmission error minimization and uniformity of tooth surface load distribution were chosen as optimization goals and the modified parameters were obtained by applying the complex method. Finally, an experiment comparing the loaded transmission error, vibration, and noise both before and after modifications was carried out. The results indicate that the modified design is reliable.
基金supported by the National Natural Science Foundation of China (Grant No. 90718025)the National Basic Research Program of China ("973" Program) (Grant No. 2010CB227302)
文摘This paper describes the redesign of a high pressure rotor (with exit Mach number around 1.5) for the vaneless counter-rotating turbine by choosing adequate exit-to-throat width ratio. Based on the previous design analysis and test results, effects of the exit-to-throat width ratio on the performance of the transonic turbine cascade were proposed. In order to investigate the influence of the exit-to-throat width ratio on the performance of the turbine cascade, a flow model of the convergent-divergent turbine cascade was constructed by using the theory of Laval nozzle. Then a method on how to choose the adequate exit-to-throat width ratio for the turbine cascade was proposed. To validate the method, it was used to calculate the adequate exit-to-throat width ratio for the high pressure rotor of the vaneless counter-rotating turbine. The high pressure turbine rotor was redesigned with the new exit-to-throat width ratio. Numerical simulation results show that the isentropic efficiency of the redesigned vaneless counter-rotating turbine under the design condition has increased by 0.9% and the efficiencies under the off-design conditions are also improved significantly. On the original design, a group of compressional waves are created from the suction surface after about 60% axial chord in the high pressure turbine rotor. While on the new design the compressional waves are eliminated. Furthermore, on the original design, the inner-extending waves first impinge on the next high pressure turbine rotor suction surface. Its reflection is strong enough and cannot be neglected. However on the new design the inner-extending waves are weakened or even eliminated. Another main progress is that the redesigned high pressure turbine rotor is of practical significance. In the original rotor, a part of the blade (from 60% axial chord to the trailing edge) is thin leading to the intensity problem and difficult arrangement of the cooling system. In the new design, however, the thickness distribution of the rotor airfoil along the chord is relatively reasonable. The intensity of the rotor is enhanced. It is possible to arrange the cooling system reasonably.
