Experimental and CFD research on the minimum height of the combined type hydraulic-driven system in hydro-floating ship lifts

The hydro-floating ship lift, an innovative design originating from China, relies on a unique hydraulic-driven system (HDS) where synchronization of shaft water levels plays a critical role in reducing torque on synchronous shafts and ensuring safe and stable lift operation. Based on the residual energy theory, this study proposed a novel index, m2, to evaluate the flow velocity uniformity within the pressure-stabilizing chamber (PSC). A combination of a 1:13 scaled physical model and CFD simulation was used to clarify the mechanisms of asynchrony shaft water level in the combined-type HDS. The results show that (i) Based on the spatiotemporal distribution characteristics of the flow field uniformity index within the PSC, m2 = 75 can serve as a threshold for flow uniformity, dividing the water flow into ‘uniform' and ‘non-uniform' regions; (ii) To ensure shaft water-level synchronization, the top elevation of the PSC should avoid the ‘non-uniform region’ of velocity distribution; (iii) Through dimensional analysis, a dimensionless expression for the minimum height of the PSC and different initial submergence depths, lifting heights and valve opening times were derived. This work can provide a basis for determining the height of the PSC in the combined-type HDS.