Hydraulic and Flow Measurement Performance of Integrated Sluice Gates in U-Shaped Channels with Varying Slopes

Abstract

Integrated measurement and control sluices (IMCS) are systematically investigated in U-shaped channels through both experimental and numerical methods to examine the effects of channel bottom slopes on measurement accuracy and flow capacity. The sluice gate opening degree considered is e = 4 - 17 cm, corresponding to incoming flow rate Q = 10 - 50 L/s. The hinged support system is applied at the bottom of the channel to flexibly adjust the slope and optimize water flow control, with the slope varying from 1/5000 to 1/100. The longitudinal water surface profile, Froude number, flow velocity distribution, critical state of sluice gate flow and weir flow, calculation equation and flow measurement accuracy are analyzed. Results demonstrate that, under varying operating conditions, the upstream water depth is found to increase directly with increasing flow rate, while decreasing as the gate opening and bottom slope increase. Conversely, the downstream water surface profile displays an inverse trend in response to changes in flow rate and gate opening. Notably, the length of the hydraulic jump significantly increases with steeper bottom slopes. Through a comprehensive analysis of flow formulas under different flow regimes, the derived measurement formula for free outflow demonstrates superior performance, featuring a high correlation coefficient and accuracy. The relative error consistently remains below 5%, thus meeting the required accuracy standards for water measurement in irrigation channels. Furthermore, the proposed integrated measurement and control sluice demonstrates the capability to adapt to variations in the bottom slope, effectively combining measurement and control functions while preserving high accuracy in water measurement. These findings provide valuable insights for the development and application of water measurement infrastructure within irrigation systems.

Keywords: U-shaped channel, Integrated measurement and control sluice (IMCS), flow measurement performance, Distinguishing threshold, Varying slopes