Experimental Study Of Turbulent Flow Width And The Characteristic Of The Turbulence Around Round-ended Pier

In some rivers for navigation, boats hit the piers event frequently occur because the existence of the pier worsens the condition of the navigation. The area of turbulence eddy around the pier becomes an insecurity area for navigation. Presently, the computation formulas of unsafe areas around pier emphasize particularly on analyzing the change of current . So there is a few studies that analyze the width by the change of the characteristic of turbulence. Therefore, it will have important project practice meaning to carry on experimental study to research the characteristic of turbulence around a pier and turbulent width and analyze the flow condition which is propitious to ascertain the flow width of endangering the safe of a boat around a pier.The method of theoretical analysis and experimental study is used in this article. The characteristic and its width of the turbulence around the round-ended pier have been studied. The speedometer ADV is used to measure the velocity of the flow around the pier in the conceptual flume. The data of the experiment is computed and analyzed by the data processing software, and the flow field around the pier is found. The three-dimensional charts of the velocity vector around the pier, the two-dimensional charts of the velocity vector of cross sections and different vertical sections are drawn. The location of the maximum of the turbulence intensity on the perpendicular line is to present an inhomogeneous distribution from 0 to 0.2h and from 0.8h to 1h but to present a homogeneous distribution relatively from 0.2 to 0.8h. The horizontal distribution of turbulence intensity of 0.883h is chosen to study. the influence to the turbulence intensity of the pier can come to a maximum, and the value of the maximum and the distance from the location where the maximum occurs to the pier both increases along with the increase of the flow velocity is found. Based on the distance, the relation between the width of turbulence with pier and the Froude number has been presented.Many kinds of vortex at different size mixing mutually around each pier is the fundamental reason for the formation of Turbulence. There are a lot of vortex enrich in the surface and wall of flume is important reason for the location of the maximum of the turbulence intensity on the perpendicular line is to present at 0 to 0.2h or from 0.8h to 1h. Intensive point of vortex move out and flow pulse more intensely, which is main reason as the average velocity of the cross-section increases, the existence of pier effects of flow turbulence intensity become larger and appears farther location distant from the pier. Bringing forward the dangerous stream comes into being when the boat and ship comes across navigability bridge opening is the combined action result of wave , streams , pier and so on in fact.