In order to predict electromechanical equipments' nonlinear and non-stationary condition effectively, max Lyapunov exponent is introduced to the fault trend prediction of large rotating mechanical equipments based on...In order to predict electromechanical equipments' nonlinear and non-stationary condition effectively, max Lyapunov exponent is introduced to the fault trend prediction of large rotating mechanical equipments based on chaos theory. The predict method of chaos time series and two methods of proposing f and F are dis- cussed. The arithmetic of max prediction time of chaos time series is provided. Aiming at the key part of large rotating mechanical equipments-bearing, used this prediction method the simulation experiment is carried out. The result shows that this method has excellent performance for condition trend prediction.展开更多
In order to satisfy the requirement of high precision measurement in a high dynamic environment, a kind of gyro aided multi-accelerometer inertial measurement unit (GAMA-IMU) with six accelerometers and two gyros (...In order to satisfy the requirement of high precision measurement in a high dynamic environment, a kind of gyro aided multi-accelerometer inertial measurement unit (GAMA-IMU) with six accelerometers and two gyros (6A2G) was proposed in this paper. The available configurations have the problem of low measurement precision In a high dynamic environment due to channel coupling. The three channels were decoupled when calculating the angular velocity in the proposed configuration. The yawing and pitching angular velocity were directly measured by gyros, while only the rolling angular velocity was obtained by the GAMA-IMU indirectly from the rolling angular acceleration and quadratic component of rolling angular velocity. Then a single channel rolling angular velocity calculation model was established and the extended Kalman filter (EKF) was used to do state esti- mation. Simulations were carried out and results indicated that the calculation precision of the proposed 6A2G configuration could meet the demand of high precision measurement for a high-speed rotating carrier.展开更多
For the purpose to improve a design quality of high-speed spindle units, we have developed mathematical models and software to simulate a rotation accuracy of spindles running on ball bearings. In order to better unde...For the purpose to improve a design quality of high-speed spindle units, we have developed mathematical models and software to simulate a rotation accuracy of spindles running on ball bearings. In order to better understand the mechanics of ball bearings, the dynamic interaction of ball bearings and spindle unit, and the influence of the bearing imperfections on the spindle rotation accuracy, we have carried out computer aided analysis and experimental studies. When doing this, we have found that the spindle rotation accuracy can vary drastically with rotational speed. The influence of bearing preload has a secondary importance. Comparison of the results of these studies has demonstrated adequacy of the models developed to the real spindle units.展开更多
Rotating packed bed has high efficiency of gas-liquid mass transfer.So it is significant to investigate fluid motion in rotating packed bed.Numerical simulations of the effects of packing feature size on liquid flow c...Rotating packed bed has high efficiency of gas-liquid mass transfer.So it is significant to investigate fluid motion in rotating packed bed.Numerical simulations of the effects of packing feature size on liquid flow characteristics in a rotating packed bed are reported in this paper.The particle image velocimetry is compared with the numerical simulations to validate the turbulent model.Results show that the liquid exists in the packing zone in the form of droplet and liquid line,and the cavity is droplet.When the radial thickness of the packing is less than 0.101 m,liquid line and droplets appear in the cavity.When rotational speed and radial thickness of the packing increase,the average diameter of the droplets becomes smaller,and the droplet size distribution becomes uniform.As the initial velocity of the liquid increases,the average droplet diameter increases and the uniformity of particle size distribution become worse.The droplet velocity increases with the radial thickness of the packing increasing,and gradually decreases when it reaches the cavity region.The effect of packing thickness is most substantial through linear fitting.The predicted and simulated values are within±15%.The cumulative volume distribution curves of the experimental and simulated droplets are consistent with the R-R distribution.展开更多
The simulation of the ground effect has always been a technical difficulty in wind tunnel tests of high-speed trains.In this paper,large eddy simulation and the curl acoustic integral equation were used to simulate th...The simulation of the ground effect has always been a technical difficulty in wind tunnel tests of high-speed trains.In this paper,large eddy simulation and the curl acoustic integral equation were used to simulate the flow-acoustic field results of high-speed trains under four ground simulation systems(GSSs):“moving ground+rotating wheel”,“stationary ground+rotating wheel”,“moving ground+stationary wheel”,and“stationary ground+stationary wheel”.By comparing the fluid-acoustic field results of the four GSSs,the influence laws of different GSSs on the flow field structure,aero-acoustic source,and far-field radiation noise characteristics were investigated,providing guidance for the acoustic wind tunnel testing of high-speed trains.The calculation results of the aerodynamic noise of a 350 km/h high-speed train show that the moving ground and rotating wheel affect mainly the aero-acoustic performance under the train bottom.The influence of the rotating wheel on the equivalent sound source power of the whole vehicle was not more than 5%,but that of the moving ground slip was more than 15%.The average influence of the rotating wheel on the sound pressure level radiated by the whole vehicle was 0.3 dBA,while that of the moving ground was 1.8 dBA.展开更多
旋转设备是现代工业的主要部件,是保证制造系统可靠性和稳定性的关键因素之一。因此,对旋转设备的健康状态监测和剩余寿命预测具有重要的研究意义和理论价值。基于郊狼优化算法,优化了粒子滤波权值退化的问题,提升了剩余寿命的预测精度...旋转设备是现代工业的主要部件,是保证制造系统可靠性和稳定性的关键因素之一。因此,对旋转设备的健康状态监测和剩余寿命预测具有重要的研究意义和理论价值。基于郊狼优化算法,优化了粒子滤波权值退化的问题,提升了剩余寿命的预测精度。首先,采用深度相关对齐(Deep CORrelation alignment, Deep CORAL)域适应方法进行训练集与测试集的特征分布对齐,并利用长短期时间序列网络进行健康指标构建,提高了健康指标构建的准确性;其次,利用基于郊狼优化算法的改进粒子滤波算法,提高了旋转设备剩余寿命预测的精度和可靠性;最后,以刀具为例,引入PHM2010刀具磨损数据集,实验结果验证了所提方法的有效性。展开更多
基金Sponsored by Key Funding Project for Science and Technology under the Beijing Municipal Education Commission(KZ200910772001)
文摘In order to predict electromechanical equipments' nonlinear and non-stationary condition effectively, max Lyapunov exponent is introduced to the fault trend prediction of large rotating mechanical equipments based on chaos theory. The predict method of chaos time series and two methods of proposing f and F are dis- cussed. The arithmetic of max prediction time of chaos time series is provided. Aiming at the key part of large rotating mechanical equipments-bearing, used this prediction method the simulation experiment is carried out. The result shows that this method has excellent performance for condition trend prediction.
文摘In order to satisfy the requirement of high precision measurement in a high dynamic environment, a kind of gyro aided multi-accelerometer inertial measurement unit (GAMA-IMU) with six accelerometers and two gyros (6A2G) was proposed in this paper. The available configurations have the problem of low measurement precision In a high dynamic environment due to channel coupling. The three channels were decoupled when calculating the angular velocity in the proposed configuration. The yawing and pitching angular velocity were directly measured by gyros, while only the rolling angular velocity was obtained by the GAMA-IMU indirectly from the rolling angular acceleration and quadratic component of rolling angular velocity. Then a single channel rolling angular velocity calculation model was established and the extended Kalman filter (EKF) was used to do state esti- mation. Simulations were carried out and results indicated that the calculation precision of the proposed 6A2G configuration could meet the demand of high precision measurement for a high-speed rotating carrier.
文摘For the purpose to improve a design quality of high-speed spindle units, we have developed mathematical models and software to simulate a rotation accuracy of spindles running on ball bearings. In order to better understand the mechanics of ball bearings, the dynamic interaction of ball bearings and spindle unit, and the influence of the bearing imperfections on the spindle rotation accuracy, we have carried out computer aided analysis and experimental studies. When doing this, we have found that the spindle rotation accuracy can vary drastically with rotational speed. The influence of bearing preload has a secondary importance. Comparison of the results of these studies has demonstrated adequacy of the models developed to the real spindle units.
基金supported by the Key Research&Development Plan of Shanxi Province(201903D321059)Shanxi Scholarship Council of China(HGKY2019071)。
文摘Rotating packed bed has high efficiency of gas-liquid mass transfer.So it is significant to investigate fluid motion in rotating packed bed.Numerical simulations of the effects of packing feature size on liquid flow characteristics in a rotating packed bed are reported in this paper.The particle image velocimetry is compared with the numerical simulations to validate the turbulent model.Results show that the liquid exists in the packing zone in the form of droplet and liquid line,and the cavity is droplet.When the radial thickness of the packing is less than 0.101 m,liquid line and droplets appear in the cavity.When rotational speed and radial thickness of the packing increase,the average diameter of the droplets becomes smaller,and the droplet size distribution becomes uniform.As the initial velocity of the liquid increases,the average droplet diameter increases and the uniformity of particle size distribution become worse.The droplet velocity increases with the radial thickness of the packing increasing,and gradually decreases when it reaches the cavity region.The effect of packing thickness is most substantial through linear fitting.The predicted and simulated values are within±15%.The cumulative volume distribution curves of the experimental and simulated droplets are consistent with the R-R distribution.
基金This work is supported by the National Natural Science Foundation of China(No.52272363)the Foundation of the Key Laboratory of Aerodynamic Noise Control(No.ANCL20200302),China.
文摘The simulation of the ground effect has always been a technical difficulty in wind tunnel tests of high-speed trains.In this paper,large eddy simulation and the curl acoustic integral equation were used to simulate the flow-acoustic field results of high-speed trains under four ground simulation systems(GSSs):“moving ground+rotating wheel”,“stationary ground+rotating wheel”,“moving ground+stationary wheel”,and“stationary ground+stationary wheel”.By comparing the fluid-acoustic field results of the four GSSs,the influence laws of different GSSs on the flow field structure,aero-acoustic source,and far-field radiation noise characteristics were investigated,providing guidance for the acoustic wind tunnel testing of high-speed trains.The calculation results of the aerodynamic noise of a 350 km/h high-speed train show that the moving ground and rotating wheel affect mainly the aero-acoustic performance under the train bottom.The influence of the rotating wheel on the equivalent sound source power of the whole vehicle was not more than 5%,but that of the moving ground slip was more than 15%.The average influence of the rotating wheel on the sound pressure level radiated by the whole vehicle was 0.3 dBA,while that of the moving ground was 1.8 dBA.
文摘旋转设备是现代工业的主要部件,是保证制造系统可靠性和稳定性的关键因素之一。因此,对旋转设备的健康状态监测和剩余寿命预测具有重要的研究意义和理论价值。基于郊狼优化算法,优化了粒子滤波权值退化的问题,提升了剩余寿命的预测精度。首先,采用深度相关对齐(Deep CORrelation alignment, Deep CORAL)域适应方法进行训练集与测试集的特征分布对齐,并利用长短期时间序列网络进行健康指标构建,提高了健康指标构建的准确性;其次,利用基于郊狼优化算法的改进粒子滤波算法,提高了旋转设备剩余寿命预测的精度和可靠性;最后,以刀具为例,引入PHM2010刀具磨损数据集,实验结果验证了所提方法的有效性。