Abstract: A method of calculating the local head loss coefficient of R-type hydraulic jump via energy equation is provided to improve the theoretical calculation of sequent depth of hydraulic jump. The energy equations for the outlet’s abruptly expanding section and the subcritical flow section are established to analyze the change law of local head loss coefficient and conjugate depth ratio of R-jump in an abruptly expanding stilling basin. Result shows that relative local head loss coefficient is the function of the Froude number of outlet’s abruptly expanding section and the abruptly expanding ratio of stilling basin. The local head loss coefficient conforms to linear distribution and exponentiation distribution. Moreover, conjugate depth ratio is the function of the Froude number of outlet’s abruptly expanding section and the abruptly expanding ratio. The calculation equations for the local head loss coefficient and the conjugate depth ratio are proposed and verified.

Key words: R-jump in abruptly expanding stilling basin, energy equation, local head loss coefficient, sequent depth, abruptly expanding ratio, conjugate depth ratio