Drop characteristics of free-falling nappe for aerated straight-drop spillway

摘要

A parallel study of regression and semi-theoretical equations is presented to forecast the drop force and the drop length of a free-falling nappe for an aerated straight-drop spillway. The ratio between the critical velocity and the exit velocity at the drop wall was introduced to establish semi-theoretical equations. Regression techniques were applied by using the dimensionless channel bed slope and the drop number to describe the drop characteristics. There were 64 groups of test data to calibrate the parameters of equations. Another 36 groups of test data were used to verify the developed model. The simulation results indicate that the semi-theoretical method provides reliable estimates for the drop force, and that the regression method can offer accurate predictions for the drop length.