Experimental Study on the Effect of an Expanding Conjunction Between a Spilling Basin and the Downstream Channel on the Height After Jump

In order to study the impact of an expanding conjunction (with a divergent conjunction or with an abruptly expanding conjunction) between a stilling basin and the downstream channel on the height after jump, systematic experimental studies were carried out with different divergent angles and different abrupt expansion ratios at the conjunction. The link between the conjunction type and the height after jump is explored. The height after jump without an expanding conjunction is larger than that with a divergent conjunction, while the height after a jump without an expanding conjunction is larger than that with the abrupt expanding conjunction. Furthermore, with a larger divergent angle or larger expansion ratio, the impact on the height after jump becomes more variable. It is proposed that the existing formula which is used to calculate the height after jump in a straight channel is not appropriate for a jump with an expanding conjunction. This paper proposes a corrected formula to calculate the height after jump with an expanding conjunction, which is suggested for application in the engineering design process.