Experimental study of the hydraulic characteristics of a coal log train in a pipe

Abstract

AbstractThe pressure distribution around two coal logs in tandem (a coal log train) flowing in a horizontal pipe (inner diameter of 50 mm) is experimentally studied. Experiments are conducted at three water velocities (0.92, 1.10, and 1.50 m/s; corresponding Reynolds numbers 45 771, 54 726, and 74 627, respectively). The hydraulic characteristics of the coal log train are analyzed, and the results are used to calculate the lift and drag forces together with the lift and drag coefficients. The pressure at the faces and surfaces of the coal log train increases at rising water velocity, enhancing the lift and drag forces. The forces acting on the first coal log are the largest, and forces on other coal logs decrease stepwise. The hydraulic characteristics of the first coal log are more complex than that of other coal logs. The lift and drag coefficients decrease with increasing water velocity. Both the lift and drag forces on individual coal logs are smaller than those on a single coal log in a pipe, when the coal logs follow one another. These results show the great difference in hydraulic characteristics between a coal log train and a single coal log in a pipe.