In this study,a dynamic model for the bearing rotor system of a high-speed train under variable speed conditions is established.In contrast to previous studies,the contact stress is simplifed in the proposed model and...In this study,a dynamic model for the bearing rotor system of a high-speed train under variable speed conditions is established.In contrast to previous studies,the contact stress is simplifed in the proposed model and the compensation balance excitation caused by the rotor mass eccentricity considered.The angle iteration method is used to overcome the challenge posed by the inability to determine the roller space position during bearing rotation.The simulation results show that the model accurately describes the dynamics of bearings under varying speed profles that contain acceleration,deceleration,and speed oscillation stages.The order ratio spectrum of the bearing vibration signal indicates that both the single and multiple frequencies in the simulation results are consistent with the theoretical results.Experiments on bearings with outer and inner ring faults under various operating conditions are performed to verify the developed model.展开更多
During a high-speed train operation,the train speed changes frequently,resulting in motion change as a function of time.A dynamic model of a double‐row tapered roller bearing system of a high-speed train under variab...During a high-speed train operation,the train speed changes frequently,resulting in motion change as a function of time.A dynamic model of a double‐row tapered roller bearing system of a high-speed train under variable speed conditions is developed.The model takes into consideration the structural characteristics of one outer ring and two inner rings of the train bearing.The angle iteration method is used to determine the rotation angle of the roller within any time period,solving the difficult problem of determining the location of the roller.The outer ring and inner ring faults are captured by the model,and the model response is obtained under variable speed conditions.Experiments are carried out under two fault conditions to validate the model results.The simulation results are found to be in good agreement with the results of the formula,and the errors between the simulation results and the experimental results when the bearing has outer and inner ring faults are found to be,respectively,5.97% and 2.59%,which demonstrates the effectiveness of the model.The influence of outer ring and inner ring faults on system stability is analyzed quantitatively using the Lempel–Ziv complexity.The results show that for low train acceleration,the inner ring fault has a more significant effect on the system stability,while for high acceleration,the outer ring fault has a more significant effect.However,when the train acceleration changes,the outer ring has a greater influence.In practice,train acceleration is usually small and does not frequently change in one operation cycle.Therefore,the inner ring fault of the bearing deserves more attention.展开更多
The axial piston pump usually works under variable speed conditions.It is important to evaluate the health status of the axial piston pump under the variable speed condition.Aiming at the characteristic signals obtain...The axial piston pump usually works under variable speed conditions.It is important to evaluate the health status of the axial piston pump under the variable speed condition.Aiming at the characteristic signals obtained under different wear levels of the port plate,a feature signal extraction method under variable speed conditions is proposed.Firstly,the combination of complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN)energy spectrum and fast spectral kurtosis principle is used to accurately extract the intrinsic mode function(IMF)component containing the sensitive information of the degraded feature.Then,the aspect ratio analysis method of the angle domain variational mode decomposition(VMD)is used to process the feature index containing the sensitive information of the degraded feature.In order to evaluate the health status of the axial piston pump under variable speed,the vibration reliability analysis method for axial piston pump based on Weibull proportional failure rate model is proposed.The experimental results show that the proposed method can accurately evaluate the health status of the axial piston pump.展开更多
对AHRI Standard 210/240-2017标准中关于HSPF的计算方法进行分析,并对一台额定制热量为17kW的北美定速房间空调器进行试验研究,分析室内风量、室外风量、制冷剂充注量以及制热衰减系数CD对制热季节能效HSPF的影响。结果表明:合理的室...对AHRI Standard 210/240-2017标准中关于HSPF的计算方法进行分析,并对一台额定制热量为17kW的北美定速房间空调器进行试验研究,分析室内风量、室外风量、制冷剂充注量以及制热衰减系数CD对制热季节能效HSPF的影响。结果表明:合理的室内机风量(额定风量100%)有助于提升系统的HSPF;过高的室外风量(超过额定风量100%)对系统的制热能力提升影响并不大,风机功率的增加反而导致HSPF明显下降;存在最佳充注量使HSPF最大,充注量偏大时,在除霜工况下,蒸发器结霜换热恶化,功耗增大,能效降低,且压缩机有湿压缩风险;HSPF随制热衰减系数CD值增大呈下降的趋势,因此,优化设计热泵系统的同时,降低CD值是一种提高HSPF比较直接、经济的途径。展开更多
为研究草鱼养殖饲料颗粒在调质过程中的运动规律和黏结状况,并优化饲料调质条件,开展了基于Hertz-Mindlin with JKR模型的草鱼养殖饲料颗粒EDEM仿真分析。首先,进行了草鱼饲料颗粒的离散元理论研究,并建立了调质颗粒的湿黏模型;其次,通...为研究草鱼养殖饲料颗粒在调质过程中的运动规律和黏结状况,并优化饲料调质条件,开展了基于Hertz-Mindlin with JKR模型的草鱼养殖饲料颗粒EDEM仿真分析。首先,进行了草鱼饲料颗粒的离散元理论研究,并建立了调质颗粒的湿黏模型;其次,通过建立调质轴转速和桨叶安装角度两因素仿真对照组,分析了调质轴转速和桨叶安装角对饲料调质效果的影响;根据饲料调质特性需求,进行了转轴转速和桨叶安装角的最优搭配;并通过理论计算与仿真分析。结果显示,当调质器转轴转速n=250 r/min、桨叶安装角θ=30°时,草鱼饲料颗粒不易黏附腔体内壁,物料混合均匀,可获得最佳调质效果。研究表明,饲料调质器调质效果与桨叶安装角度和转轴转速密切相关。本研究可为饲料厂家生产不同种类饲料优化调质效果提供理论依据和参考。展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.11790282,12032017,11802184,11902205,12002221,11872256)S&T Program of Hebei(Grant No.20310803D)+2 种基金Natural Science Foundation of Hebei Province(Grant No.A2020210028)Postgraduates Innovation Foundation of Hebei Province(Grant No.CXZZBS2019154)State Foundation for Studying Abroad.
文摘In this study,a dynamic model for the bearing rotor system of a high-speed train under variable speed conditions is established.In contrast to previous studies,the contact stress is simplifed in the proposed model and the compensation balance excitation caused by the rotor mass eccentricity considered.The angle iteration method is used to overcome the challenge posed by the inability to determine the roller space position during bearing rotation.The simulation results show that the model accurately describes the dynamics of bearings under varying speed profles that contain acceleration,deceleration,and speed oscillation stages.The order ratio spectrum of the bearing vibration signal indicates that both the single and multiple frequencies in the simulation results are consistent with the theoretical results.Experiments on bearings with outer and inner ring faults under various operating conditions are performed to verify the developed model.
基金The present work was supported by the National Natural Science Foundation of China (Nos.11790282,12032017,12002221,and 11872256)the National Key R&D Program (2020YFB2007700)+1 种基金the S&T Program of Hebei(20310803D)the Natural Science Foundation of Hebei Province (No.A2020210028).
文摘During a high-speed train operation,the train speed changes frequently,resulting in motion change as a function of time.A dynamic model of a double‐row tapered roller bearing system of a high-speed train under variable speed conditions is developed.The model takes into consideration the structural characteristics of one outer ring and two inner rings of the train bearing.The angle iteration method is used to determine the rotation angle of the roller within any time period,solving the difficult problem of determining the location of the roller.The outer ring and inner ring faults are captured by the model,and the model response is obtained under variable speed conditions.Experiments are carried out under two fault conditions to validate the model results.The simulation results are found to be in good agreement with the results of the formula,and the errors between the simulation results and the experimental results when the bearing has outer and inner ring faults are found to be,respectively,5.97% and 2.59%,which demonstrates the effectiveness of the model.The influence of outer ring and inner ring faults on system stability is analyzed quantitatively using the Lempel–Ziv complexity.The results show that for low train acceleration,the inner ring fault has a more significant effect on the system stability,while for high acceleration,the outer ring fault has a more significant effect.However,when the train acceleration changes,the outer ring has a greater influence.In practice,train acceleration is usually small and does not frequently change in one operation cycle.Therefore,the inner ring fault of the bearing deserves more attention.
基金Supported by the National Key Research and Development Program of China(No.2019YFB2005204)the National Natural Science Foundation of China(No.52075469,51675461,11673040)+1 种基金the Key Research and Development Program of Hebei Province(No.19273708D)the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(No.GZKF-201922).
文摘The axial piston pump usually works under variable speed conditions.It is important to evaluate the health status of the axial piston pump under the variable speed condition.Aiming at the characteristic signals obtained under different wear levels of the port plate,a feature signal extraction method under variable speed conditions is proposed.Firstly,the combination of complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN)energy spectrum and fast spectral kurtosis principle is used to accurately extract the intrinsic mode function(IMF)component containing the sensitive information of the degraded feature.Then,the aspect ratio analysis method of the angle domain variational mode decomposition(VMD)is used to process the feature index containing the sensitive information of the degraded feature.In order to evaluate the health status of the axial piston pump under variable speed,the vibration reliability analysis method for axial piston pump based on Weibull proportional failure rate model is proposed.The experimental results show that the proposed method can accurately evaluate the health status of the axial piston pump.
文摘对AHRI Standard 210/240-2017标准中关于HSPF的计算方法进行分析,并对一台额定制热量为17kW的北美定速房间空调器进行试验研究,分析室内风量、室外风量、制冷剂充注量以及制热衰减系数CD对制热季节能效HSPF的影响。结果表明:合理的室内机风量(额定风量100%)有助于提升系统的HSPF;过高的室外风量(超过额定风量100%)对系统的制热能力提升影响并不大,风机功率的增加反而导致HSPF明显下降;存在最佳充注量使HSPF最大,充注量偏大时,在除霜工况下,蒸发器结霜换热恶化,功耗增大,能效降低,且压缩机有湿压缩风险;HSPF随制热衰减系数CD值增大呈下降的趋势,因此,优化设计热泵系统的同时,降低CD值是一种提高HSPF比较直接、经济的途径。
文摘为研究草鱼养殖饲料颗粒在调质过程中的运动规律和黏结状况,并优化饲料调质条件,开展了基于Hertz-Mindlin with JKR模型的草鱼养殖饲料颗粒EDEM仿真分析。首先,进行了草鱼饲料颗粒的离散元理论研究,并建立了调质颗粒的湿黏模型;其次,通过建立调质轴转速和桨叶安装角度两因素仿真对照组,分析了调质轴转速和桨叶安装角对饲料调质效果的影响;根据饲料调质特性需求,进行了转轴转速和桨叶安装角的最优搭配;并通过理论计算与仿真分析。结果显示,当调质器转轴转速n=250 r/min、桨叶安装角θ=30°时,草鱼饲料颗粒不易黏附腔体内壁,物料混合均匀,可获得最佳调质效果。研究表明,饲料调质器调质效果与桨叶安装角度和转轴转速密切相关。本研究可为饲料厂家生产不同种类饲料优化调质效果提供理论依据和参考。
