Study On Analysis Theory Of Train Derailment In Strong Wind

Train derailment in strong wind happens frequently in the world, which wil bring big social impact. Train derailment wil lead to interupption of railway traffic, even result in catastrophe. Research of train derailment has been an important subjeet in railway transportation all over the world. The abroad started to research the theory of train derailment since collapse of Tay bridge, which happened in the evening of 28 December 1879. The Tay Bridge Disaster killed 75 persons. Many experts believe that train derailment results in collapse of Tay bridge. An train traveling through level 13 winter winds derailed and overturned in Xinjiang,China in 28 February 2007. which makes bad social impact in China. Train derailment have occupied 70% in all grave and serious accidents. With the widely-developed construction of the high speed railway line for passenger traffic, The influences of wind on the safety of train operation are becoming more and more important, even are top dog. The problem of train derailment has been studied for as long as more than one century and a great number of achievements have been made. However, many problems are up in the air yet. With Zeng's analysis theory of random energy coming forth, many problems can be readily solved. In this dissertation,the analysis of train derailment in wind loads is studied based on analysis theory of random energy. Application range of Zeng's theory can be opened up. One of contribution in this dissertation is making analysis theory of random energy become all weather theory. Further more, considering that goes with train overturn, a complete set of analysis theory of train overturn put forward. The main contents and contributions of the dissertation are as follows.1. On Train AerodynamicsIt is necessary demand that you have complete understand on train aerodynamic performances if you tend to analyse train derailment in strong wind. So characteristics of flow around train and aerodynamic forces on train and wind induced vibration of train are analysed and computed particularly in this dissertation. Theories and methods applied in this dissertation is proved to be validity after the consistency between numerical results and test results have been testified. The main contents and contributions on train aerodynamics of the dissertation are as follows.(1) Detailed academic analysis for train flutter has been done in the dissertation. Duing to non-streamline the transect of train, classical flutter will not take place. Flutter critical wind speed of train is very high, so flutter will not be considered in the dissertation.(2) It is considered that aerodynamic forces acted on train is composed of average and fluctuating part in the view point of math, but it is complicated for mechanism of aerodynamics. aerodynamic forces acted on train are mainly involved of static wind forces, fluctuating aerodynamic forces induced by Karmen eddies and buffet forces.(3) The three-dimensional Reynolds-averaged Navier-Stokes equations (RANS), combined with the k-E turbulence model,were solved using finite volume technique. The pressure-velocity fields were coupled using the SIMPLE algorithm. At each iteration the pressure correction was obtained by solving a velocity divergence-derived Poisson-like equation. With the computed aerodynamic forces, the formula of the limit speed which train passes curved rail in side wind ,was deduced in this paper, and applied to analyse the influences on aerodynamic forces to the limit speed. results of numerical investigations show aerodynamic lift and overtune moment increase more and more rapidly along with train speed and wind speed. The enhancement trends show nonlinear phenomena,enhance risk in the course of train movement. When train travels in high speed and encounters huge side wind, the influence involved by nonlinear risk increment extremly impair safety of train.(4) Unstructured dynamic meshes on fluid field around are generated based on frontal track algorithm. Meshes are looked as quasi-structure when Meshes are moving. Lineal spring attached to line and torsional spring attached to vertex are intrduced to prevent mesh quatity becoming bad. Fluid control equations are discretized by FVM technique. Numerical result for flow around the intsect of train has been gained. The following conclusions can be drawn. Obvious disppached eddies can be observed at upside and downside of leeward surface. Windward surface of train is in the place of positive pressure district. Top surface, bottom surface and leeward surface is in the place of negative pressure district. When train is in the process of overturn, bottom surface is in the place of positive pressure district.(5) For the first time, buffeting responses spectrum is applied to analyse buffeting responses of train. One order heave, lateral and roll buffeting responses spectrum for train body and bogie are computed in this dissertation.2. On analysis theory of train derailment in strong wind Based on analysis theory of random energy of train derailment, analysis theory of random energy of train derailment in wind is suggested in this dissertation after detailed academic analysis for train aerodynamics, including buffeting responses analysis was done. Thus, application range of analysis theory of random energy of train derailment is extended to all weather, i.e. common atmosphic wind field. One aim in this dissertation is for the purpose of enable origin theory further to tend to the consummation. After the first aim has been fulfilled, another aim, i.e. a whole set of analysis theory of train overturn is put forward,also. The main contents and contributions on train derailment and overturn theory of the dissertation are as follows.(1) The train derailment mechanism, which is the result of losing stability in lateral vibration status of train-track(bridge)time-varying system, is proposed in this dissertation.(2) Two kinds of methods are put forward, namely,time-domain method and frequency-method method for the theory of random energy of train derailment involved of wind loads are put forward.(3) With calculated results from former, curveσ_p-v is extended to in different wind speed,which make all-weather theory of random energy of train derailment.(4) Train derailment condition involved of wind is set up in this dissertation.(5) First and second discriminative rule of train derailment in wind is proposed in this dissertation.(6) Condition and discriminative rule of train overturn is put forward for the first time in this dissertation.(7) Characteristics of flow around train and aerodynamic forces on train in the process of train overturn is laboured.(8) The concept of train speedup overturn is put forward for the first time in this dissertation.(9) The process of Xinjiang train,which encountered level 13 winter winds, derailment and overturn is analysed. Derailment and overturn inevitability is explained in reason. The secret of train instant overturn is opened up for the first time in this dissertation.(10) Many cases of train derailment and overturn in strong wind, which occurs frequently in China and other countries of the world, are analysed in this dissertation. All the calculated results conform with the actual status, so the feasibility of the theory of energy random analysis involved of strong wind for train detailment and analysis theory of train overturn are verified.