The characteristic wind curve （CWC） was com- monly used in the previous work to evaluate the operational safety of the high-speed trains exposed to crosswinds. How- ever, the CWC only provide the dividing line betwe...The characteristic wind curve （CWC） was com- monly used in the previous work to evaluate the operational safety of the high-speed trains exposed to crosswinds. How- ever, the CWC only provide the dividing line between safety state and failure state of high-speed trains, which can not evaluate the risk of derailment of high-speed trains when ex- posed to natural winds. In the present paper, a more realistic approach taking into account the stochastic characteristics of natural winds is proposed, which can give a reasonable and effective assessment of the operational safety of high-speed trains under stochastic winds. In this approach, the longitudi- nal and lateral components of stochastic winds are simulated based on the Cooper theory and harmonic superposition. An algorithm is set up for calculating the unsteady aerody- namic forces （moments） of the high-speed trains exposed to stochastic winds. A multi-body dynamic model of the rail vehicle is established to compute the vehicle system dynamic response subjected to the unsteady aerodynamic forces （mo- ments） input. Then the statistical method is used to get the mean characteristic wind curve （MCWC） and spread range of the high-speed trains exposed to stochastic winds. It is found that the CWC provided by the previous analyticalmethod produces over-conservative limits. The methodol- ogy proposed in the present paper can provide more signif- icant reference for the safety operation of high-speed trains exposed to stochastic winds.展开更多
The aim of this paper is to present the state-of-the art in computational aeroelasticity methods that are available for analyzing fan blades on modern civil aircraft. Fan blades in modern high-bypass aero-engines typi...The aim of this paper is to present the state-of-the art in computational aeroelasticity methods that are available for analyzing fan blades on modern civil aircraft. Fan blades in modern high-bypass aero-engines typically produce around 80% of the thrust. In order to improve specific fuel consumption and reduce the level of noise emitted from the engine, civil turbofan engine designs are moving toward even larger fan diameters with lower tip speeds and hence the importance of this component of aero-engine becomes even more prominent. To reduce weight, future fan blades will be made of composite materials and shorter intakes are used. The new designs are highly loaded and will be more susceptible to aerodynamic and aeroelastic instabilities, and hence computationally efficient aeroelastic modelling tools for such blades are paramount.展开更多
基金supported by the 2013 Doctoral Innovation Funds of Southwest Jiaotong University and the Fundamental Research Funds for the Central Universitiesthe High-speed Railway Basic Research Fund Key Project of China(U1234208)the National Natural Science Foundation of China(50823004)
文摘The characteristic wind curve （CWC） was com- monly used in the previous work to evaluate the operational safety of the high-speed trains exposed to crosswinds. How- ever, the CWC only provide the dividing line between safety state and failure state of high-speed trains, which can not evaluate the risk of derailment of high-speed trains when ex- posed to natural winds. In the present paper, a more realistic approach taking into account the stochastic characteristics of natural winds is proposed, which can give a reasonable and effective assessment of the operational safety of high-speed trains under stochastic winds. In this approach, the longitudi- nal and lateral components of stochastic winds are simulated based on the Cooper theory and harmonic superposition. An algorithm is set up for calculating the unsteady aerody- namic forces （moments） of the high-speed trains exposed to stochastic winds. A multi-body dynamic model of the rail vehicle is established to compute the vehicle system dynamic response subjected to the unsteady aerodynamic forces （mo- ments） input. Then the statistical method is used to get the mean characteristic wind curve （MCWC） and spread range of the high-speed trains exposed to stochastic winds. It is found that the CWC provided by the previous analyticalmethod produces over-conservative limits. The methodol- ogy proposed in the present paper can provide more signif- icant reference for the safety operation of high-speed trains exposed to stochastic winds.
文摘The aim of this paper is to present the state-of-the art in computational aeroelasticity methods that are available for analyzing fan blades on modern civil aircraft. Fan blades in modern high-bypass aero-engines typically produce around 80% of the thrust. In order to improve specific fuel consumption and reduce the level of noise emitted from the engine, civil turbofan engine designs are moving toward even larger fan diameters with lower tip speeds and hence the importance of this component of aero-engine becomes even more prominent. To reduce weight, future fan blades will be made of composite materials and shorter intakes are used. The new designs are highly loaded and will be more susceptible to aerodynamic and aeroelastic instabilities, and hence computationally efficient aeroelastic modelling tools for such blades are paramount.
