A high cycle fatigue reliability analysis approach to helicopter rotor hub is proposed under working load spectrum.Automatic calculation for the approach is implemented through writing the calculating programs.In the ...A high cycle fatigue reliability analysis approach to helicopter rotor hub is proposed under working load spectrum.Automatic calculation for the approach is implemented through writing the calculating programs.In the system,the modification of geometric model of rotor hub is controlled by several parameters,and finite element method and S-N curve method are then employed to solve the fatigue life by automatically assigned parameters.A database between assigned parameters and fatigue life is obtained via Latin Hypercube Sampling(LHS) on tolerance zone of rotor hub.Different data-fitting technologies are used and compared to determine a highest-precision approximation for this database.The parameters are assumed to be independent of each other and follow normal distributions.Fatigue reliability is then computed by the Monte Carlo(MO method and the mean-value first order second moment(MFOSM) method.Results show that the approach has high efficiency and precision,and is suitable for engineering application.展开更多
Currently, domestic and abroad scholars put more attention on contra-rotating dual-rotor axial fan. But there is less scholars study on asymmetric dual-rotor small axial fan, which is one of the contra-rotating dual-r...Currently, domestic and abroad scholars put more attention on contra-rotating dual-rotor axial fan. But there is less scholars study on asymmetric dual-rotor small axial fan, which is one of the contra-rotating dual-rotor axial fans. Like axial fan, many factors have influence on the performance of the asymmetric dual-rotor small axial flow fan, such as the wheel hub ratio, blade shape, blade number, stagger angle and the tip clearance. Because wheel hub ratio has great impact on the performance of the fan, we choose the size of wheel hub ratio as a variable factor to study the model change. There is a different wheel hub ratio between front stage impeller and rear stage of asymmetric dual-rotor small axial fan, so it is very beneficial to select the greater wind area that the fan area of external diameter minuses the area occupied by the blades and the hub as front stage impeller. In this paper, the hub-ratio of front stage impeller is 0.72, and that of rear stage is 0.72, 0.67 and 0.62 respectively along with the front stage impeller. Three kinds of models with different hub ratio of rear stage are simulated using the CFD software and the static characteristics are obtained. Based on the experimental test results, the internal flow field of the asymmetric dual-rotor small axial fan is analyzed in detail, the impact trends of different hub-ratio on the performance of asymmetric dual-rotor small axial fan are obtained and the argument of structure optimization for dual-rotor small axial fan is provided.展开更多
文摘A high cycle fatigue reliability analysis approach to helicopter rotor hub is proposed under working load spectrum.Automatic calculation for the approach is implemented through writing the calculating programs.In the system,the modification of geometric model of rotor hub is controlled by several parameters,and finite element method and S-N curve method are then employed to solve the fatigue life by automatically assigned parameters.A database between assigned parameters and fatigue life is obtained via Latin Hypercube Sampling(LHS) on tolerance zone of rotor hub.Different data-fitting technologies are used and compared to determine a highest-precision approximation for this database.The parameters are assumed to be independent of each other and follow normal distributions.Fatigue reliability is then computed by the Monte Carlo(MO method and the mean-value first order second moment(MFOSM) method.Results show that the approach has high efficiency and precision,and is suitable for engineering application.
文摘Currently, domestic and abroad scholars put more attention on contra-rotating dual-rotor axial fan. But there is less scholars study on asymmetric dual-rotor small axial fan, which is one of the contra-rotating dual-rotor axial fans. Like axial fan, many factors have influence on the performance of the asymmetric dual-rotor small axial flow fan, such as the wheel hub ratio, blade shape, blade number, stagger angle and the tip clearance. Because wheel hub ratio has great impact on the performance of the fan, we choose the size of wheel hub ratio as a variable factor to study the model change. There is a different wheel hub ratio between front stage impeller and rear stage of asymmetric dual-rotor small axial fan, so it is very beneficial to select the greater wind area that the fan area of external diameter minuses the area occupied by the blades and the hub as front stage impeller. In this paper, the hub-ratio of front stage impeller is 0.72, and that of rear stage is 0.72, 0.67 and 0.62 respectively along with the front stage impeller. Three kinds of models with different hub ratio of rear stage are simulated using the CFD software and the static characteristics are obtained. Based on the experimental test results, the internal flow field of the asymmetric dual-rotor small axial fan is analyzed in detail, the impact trends of different hub-ratio on the performance of asymmetric dual-rotor small axial fan are obtained and the argument of structure optimization for dual-rotor small axial fan is provided.
基金This work was supported by the Active Control Rotor Technology Project(No.FKFB20231108055)the National Natural Science Foundation of China(No.11972181)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX21_0228).
