Energy dissipation characteristics of an in- chamber longitudinal culvert system with three- layer side ports designed for a large-scale lock with 60m water head

With the rapid development of the water transportation industry in China, the scale of ships navigating in the inland waterway is increasing. However, the water head formed by dams is very high, especially for the hydroelectric projects constructed in the upper mountain river. Therefore, it is critically urgent to build several high-head and large-scale locks. Moreover, when the water head is increased to 60 m, huge water energy could be generated and then introduced into the corresponding lock chamber if the valve operating time is limited. This paper presented the in-chamber longitudinal culvert system with three-layer side ports to efficiently dissipate the water energy to ensure safe mooring conditions for ships during a lock operation. A three-dimensional CFD model for 1/4 local region of the corresponding chamber was developed to predict its hydraulic behavior. The numerical simulations were conducted to examine the effect of the vertical spacing between side ports on the energy dissipation result. Results showed that good energy dissipation performance was gained when the relative vertical spacing was set B/D=0.25 (B is the vertical spacing between side ports, D is the inner height of the culvert). Furthermore, the energy dissipation mechanism of this arrangement was presented based on the results of a threedimensional hydraulic characteristic. In addition, the corresponding dissipation result of the present arrangement was compared with those of the single-layer and two-layer side ports. The dissipation performance of the present design was found to be the best if all the side ports' cross-section area of each arrangement keeps the same.