Study On Wind-environment Numerical Simulation About Yellow River Diagonal Cable Bridge In Yu-Entranceon

Along with the modern bridge technical level inceasing enhancement, the bridges which surmount the big rivers even channels emerge inceasingly. These bridges which have great span must have to overcome the function of the natural wind, studing effect of wind on bridge result in the subject of bridge wind engineering. Among them, the bridge wind-environment study is the important constituent. The thesis is mainly about the Yellow River diagonal cable bridge of Yu-Entranceon in Shan Xi. Conducting the numerical simulator study to its surrounding terrain wind field, the computed result may provides the wind affording design basis for its structural design and the construction, simultaneously also provides the reference for this kind of bridges design which go against the wind in this topography.At present the study methods for bridge wind-environment includes :the scene observation (including the meteorological observatory stands), the test of wind tunnel and the numerical simulation (numerical wind tunnel) calculating and so on. The first two methods are physical, the test cycle are so long, and they will consume massive manpower and physical resource. The method of " numerical wind tunnel" has the merit of less-invested, rapid, well-duplicated, can not be confined by the size of model, can carry on the simulation overall, the conditions can be controlled easily and so on. It's more free and more nimble than the physical method, and can supplement the insufficiency of physical wind tunnel test. " numerical wind tunnel" is established on the basis of the theory of Computational Fluid Dynamics(CFD), analysing with fluid computed software.This article mainly uses the methods of numerical simulation and the observation and contrast about the characteristic of scene wind to study the wind-environment of bridge site about diagonal cable bridge in Yu-Entranceon. Establishing the model of topography and mountains in bridge site and the three dimensional geometry model of diagonal cable bridge with the grids-produced software GAMBIT2.1 in which the large-scale commercial fluid computed and analysed software FLUENT6.2. Debugging grids and determining the computed basin, selecting the appropriate boundary condition and the soluted parameter and compiling the procedure of UDF, using the improved turbulence model of Realizable k-e. Moreover, in order to explore the more reasonable turbulence model, calculating and analyzing with the turbulence model of SST k-ω. There are the streamlines of wind speed pattern, the wind vector chart, the map of which wind speed and the turbulence distribution on the height of bridge floor, the isograms of which the wind speed vector and pressure on the surface of king post, finally contrasting and analyzing the wind field characteristic in bridge site and the statistic result of wind observation with numerical simulation. The conclusion explained reasonably why the wind speed section of bridge site in plain combination area of mountainous does not conform to the distributed rule of exponential law sometimes, concluding the surface category of Yu-Entranceon bridge site belonged to, has produced the map of wind vector distribution between the tower column in diagonal cable bridge and the bridge floor, had proven that the turbulence model of Realizable k-εmay reasonably simulate this kind of wind-environment, the turbulence model of SST k-ωis not adequate for this kind of wind-environment. The UDF procedure of auto-compilation will be useful for the study of "the numerical wind tunnel" in laboratory in the future.