Numerical Analysis Of Aerodynamic Interference Effect Of Bluff Bodies On Pylon And Sling Of Long-span Suspension Bridge

With the development of social economy, more and more long span suspension bridges are being built, the problem that the wind-resistant performance of bridge construction and operation is a very outstanding issue. Pylon and sling is an important part of suspension bridge, cable-stayed bridge and arch bridge, and there was the aerodynamic interference effect in pylon and sling of long span suspension bridge, and the aerodynamic interference effect has a major impact on wind-resistant performance of pylon and sling. According to the problem about the advantages and disadvantages in the aerodynamic performance of kinds of section of pylon of suspension bridge, the aerodynamic interference effect of galloping of paralleled pylon in the reconstruction and extension of bridge, the aerodynamic interference effect has significant effect on the fatigue property of four strand of ride across type sling of suspension bridge respectively, based on Xi houmen suspension bridge, the aerodynamic interference effects of static aerodynamic coefficients and galloping of four kinds of cross section of pylon and the aerodynamic interference effect of galloping ride across type sling were studied by numerical wind tunnel test. The main contribution of the dissertation are given as follows:1. Based on the finite volume method and the SIMPLE algorithm and aimed at single and multiple blunt body for rectangular section, fall right section, pour concave arc cross-section and pour the convex arc cross-section, the uniform viscous and incompressible flow across blunt bodies when Reynolds number was in the supercritical area was simulated by computation fluid dynamics (CFD) technology. The change of aerodynamic coefficient was analyzed and the aerodynamic coefficient was calculated during various conditions such as different the wind angle of attack, different chamfer dimension and different cylinder spacing etc. The result show that the drag and lift as well as torque coefficient of each section for single blunt decrease in accordance to sequence of rectangular section, fall right section, pour concave arc cross-section and pour the convex arc cross-section as a whole during different the wind angle of attack, and the drag and lift as well as torque coefficient of fall right section, pour concave arc cross-section and pour the convex arc cross-section decrease successively when chamfer dimension increase; the downstream blunt body produced bigger change than upstream blunt body both variation trend and value due to aerodynamic interference effect.2. The performance of galloping change greatly by the influence of aerodynamic interference effect of bluff bodies with different the number of bluff and section. The aerodynamic interference effect of galloping in four types of sections and four bluff body conditions was studied by means of the CFD, with a reference to a suspension bridge, its advantage and disadvantage was compared and analyzed with the same section of single and two bluff bodies. The result show that the galloping instabilities could occur in rectangular section of two pylons at upstream of fall right section of two pylons and the pour the convex arc cross-section of two pylons at downstream of fall right section of two pylons. The galloping instabilities of downstream pylon could occur in the near vicinity of angles of incidence of0and the bigger the possibility of galloping, the nearer the distance between bluff bodies in two pylons condition. The galloping instabilities not easily occur in the fourth of pylon and could occur in the second and third of pylon under rectangular section and pour the convex arc cross-section condition as a result of aerodynamic interference effect.3. Combined with the parameter of sling of Xi Hou-men suspension bridge, the aerodynamic interference effect of galloping on four cylinders of ride across type sling was studied by numerical method aim at the aerodynamic interference effect of ride across type sling of suspension. The drag and lift coefficients as well as aerodynamic derivative was obtained. However, stability analysis of downstream bluff bodies in the wake flow of the upstream bluff bodies was studied. The results indicate that galloping would be occurred when the upstream bluff of downwind was in a state of flux within the context of the various of wind attack angle from-8°to6°, the downstream bluff of downwind was in a state of flux within the context of the various of wind attack angle from-6°to0°nd from4°to6°. The article provide a theory to fatigue performance analyses of wind induced vibration of ride across type sling of suspension bridge.