Experimental Analysis of the Interaction Between the Unidirectional Flow and Spoiler on Mechanism of Self burial Pipelines

To stimulate the artificial self-burial of pipelines to provide safe conditions in erodible beds, the spoiler can be used at the top of the pipeline. The study of the performance of the spoiler that mounted on the naturally moveable pipe is a major gap that not founded in previous research. In this experimental study the parameters affecting the self-burial process of the pipelines were investigated. An equation was proposed for estimating the depth of self-burial in the normal settling of the pipe and was found that the moveable pipe decrease the scour depth by 54 percent in comparison with the fixed pipe. Maximum change in self –buried was obtained at S=D (S is the length of spoiler & D is the diameter of the pipe) that was equal to 70 and 67 percent of the diameter of the pipe in fine and coarse beds, respectively. The length of Lee-wake erosion in the pipe with natural motion was greater than in which the fixed pipe and increase with installed spoiler and spoiler height increases. Maximum length of Lee-wake erosion happened when S=D. The most burying is at zero degrees of the spoiler to the vertical axis.