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1.
Under the influence of crosswinds,the running safety of trains will decrease sharply,so it is necessary to optimize the suspension parameters of trains.This paper studies the dynamic performance of high-speed trains under cross-wind conditions,and optimizes the running safety of train.A computational fluid dynamics simulation was used to determine the aerodynamic loads and moments experienced by a train.A series of dynamic models of a train,with different dynamic parameters were constructed,and analyzed,with safety metrics for these being determined.Finally,a surrogate model was built and an optimization algorithm was used upon this surrogate model,to find the mini-mum possible values for:derailment coefficient,vertical wheel-rail contact force,wheel load reduction ratio,wheel lateral force and overturning coefficient.There were 9 design variables,all associated with the dynamic parameters of the bogie.When the train was running with the speed of 350 km/h,under a crosswind speed of 15 m/s,the bench-mark dynamic model performed poorly.The derailment coefficient was 1.31.The vertical wheel-rail contact force was 133.30 kN.The wheel load reduction rate was 0.643.The wheel lateral force was 85.67 kN,and the overturning coef-ficient was 0.425.After optimization,under the same running conditions,the metrics of the train were 0.268,100.44 kN,0.474,34.36 kN,and 0.421,respectively.This paper show that by combining train aerodynamics,vehicle system dynamics and many-objective optimization theory,a train's stability can be more comprehensively analyzed,with more safety metrics being considered.  相似文献   
2.
This paper is devoted to analytical modeling of apparent wind load effects on a tether constraining a power kite performing a fast crosswind motion. The refined crosswind motion law generalized for accounting the kite control is derived in the case of equilibrium motion of the kite. The paper also presents the study of the effect of tether sag based on the mathematical model of a gently sloping tether line.  相似文献   
3.
Experiments with a single fire source were carried out in crosswinds in order to elucidate the correlation between temperature rise and velocity along an inclined fire plume axis. A circular propane burner with a diameter of 0.2 m was used as a model fire source. The temperature and velocity were measured along the inclined fire plume axis, and these were compared with fire plume data obtained in a calm condition. An empirical formula to represent the correlation of the temperature rise and velocity was developed. The values of empirical coefficients and exponents were derived from the experimental results of the circular burner. In order to verify the availability of the proposed empirical formula, the comparison was carried out with the data obtained from square and/or rectangular burners.  相似文献   
4.
针对一种大尺寸储物箱在大风速侧风作用下装卸时存在滑移甚至倾覆风险的安全性问题,采用数值分析方法,分析不同风速作用下储物箱受到的侧向力和倾覆力矩,数值分析计算结果表明:在平均风速15 m/s和瞬时风速25 m/s的情况下,储物箱不会发生滑移和倾覆;针对该储物箱开展加载试验验证,试验结果表明:在3.193 N侧向拉力作用下储物箱未发生滑移和倾覆,佐证了数值分析结果的准确性,证明该储物箱在平均风速15 m/s和瞬时风速25 m/s的情况下装卸是安全的。  相似文献   
5.
Original studies on gust factor buffeting dealt with the alongwind displacement of structures. Research on this topic carried out since the nineties followed two distinct lines: the first determines the maximum effects due to the alongwind response; the second extends the original method from the alongwind response to crosswind and torsional responses. This paper represents the junction point of these research lines with reference to cantilever slender vertical structures. It derives the most relevant effects associated with the three-dimensional (3-D) wind-excited response of this structural type and shows that a suitable definition of one non-dimensional quantity, referred to as the 3-D gust effect factor, provides such effects at any level through a wide set of experimental, numerical and analytical procedures. A new definition of a 3-D equivalent static force consistent with this method is also introduced and critically compared with previous analogous statements.  相似文献   
6.
Energy harvesting based on tethered kites benefits from exploiting higher wind speeds at higher altitudes. The setup considered in this paper is based on a pumping cycle. It generates energy by winching out at high tether forces, driving an electrical generator while flying crosswind. Then it winches in at a stationary neutral position, thus leaving a net amount of generated energy.The focus of this paper is put on the flight control design, which implements an accurate direction control towards target points and allows for a flight with an eight-down pattern. An extended overview on the control system approach, as well as details of each element of the flight controller, is presented. The control architecture is motivated by a simple, yet comprehensive model for the kite dynamics.In addition, winch strategies based on an optimization scheme are presented. In order to demonstrate the real world functionality of the presented algorithms, flight data from a fully automated pumping-cycle operation of a small-scale prototype are given. The setup is based on a 30 m2 kite linked to a ground-based 50 kW electrical motor/generator by a single line.  相似文献   
7.
在侧风为0、1、2-10m/s的情况下,利用计算流体力学软件ansys cfx对某型号简化汽车模型进行数值模拟,并对结果进行处理与分析。分析结果表明,随着侧风的增大,侧向力和升力增大显著。而阻力受侧风影响不大。侧风的增大使得升力、侧向力明显增大,进而严重影响了汽车的行驶稳定性。  相似文献   
8.
Extensive wind tunnel tests have been carried out on train scale models. The experimental tests have been performed on three types of rail vehicles, in different configurations. The wind tunnel tests allowed to point out the most critical wind conditions with respect to running safety and to perform a sensitivity analysis on the principal parameters that can influence the aerodynamic behaviour of rail vehicles. In particular, the effects of the turbulence intensity and of the train motion on the aerodynamic coefficients have been studied.  相似文献   
9.
Qi Bian  Brett Nener  Xinmin Wang 《工程优选》2018,50(11):1914-1925
Crosswind landing is one of the most complex and challenging landing manoeuvres; an aircraft can drift laterally or could even be blown off the runway under extreme crosswind conditions. This article proposes an improved multi-group swarm-based optimization method that can not only optimize the parameters of the lateral flight control system, but also find diversity solutions of the underlying optimization problem. During the optimizing process, several swarm groups are generated to search potential areas for the optimal solution. These groups exchange information with each other during the searching process and focus on their different but continuous spaces. Finally, a diverse range of solutions is presented to the engineer for the flight control system design. A nonlinear 6 degrees-of-freedom rigid model of a Boeing 747 is used as a test bed to verify the robustness and feasibility of the proposed method.  相似文献   
10.
Reliability based analysis of the crosswind stability of railway vehicles   总被引:1,自引:0,他引:1  
The computational models used to assess the crosswind stability of railway vehicles by multibody simulation (MBS) are affected by large uncertainties. Especially, the aerodynamic loads acting on the vehicle are difficult to model and the respective parameters cannot be easily acquired. Such uncertainties are usually neglected in the safety norms even though their effects on the risk assessment can be very large. In this paper the problem is tackled by modelling the most influential but uncertain parameters as stochastic variables. The resulting task can be efficiently managed by reliability techniques, mainly inherited from structural mechanics. This finally leads to the substitution of the conventional characteristic wind curve (CWC) by the probabilistic characteristic wind curve (PCWC). The proposed approach is referred to the most recent European norms for crosswind stability and exemplified on the test case of a German high speed train (ICE2).  相似文献   
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