An experimental setup for inclined water jets at high translational velocities
Type:
Presented during:
CEDA Dredging Days 2026
Authors:
S. Bult, R. Helmons and G. Keetels
Abstract
Erosion performance by jets at high translation velocities can be significantly affected when these high translation velocities are not accounted for. Applications include drag heads for hopper dredgers and, more recently, flatfish stimulation in commercial beam trawling operations, both requiring an accurate prediction of the production by the jets. To this end, we conducted jetting experiments in sand beds to study the effect of jet angle, jet velocity, translational velocity and sand properties. The experiments were performed with a half nozzle aligned to a glass wall to visualize the flow patterns within the bed and to assess the maximum penetration depth for each condition with a high-speed camera. These images were complemented by PIV vector fields to quantitatively analyze the average patterns and error margins. Comparison with a full nozzle showed that the full nozzle penetrates the bed deeper, which should be taken into account for practical applications. Besides high-speed camera images, we acquired the bed geometry after sedimentation from laser scanners, pressure measurements from pressure sensors buried at different depths, and ultrasonic velocity profiling (UVP) measurements. The most remarkable observation is that a forward-directed jet under certain conditions can demonstrate a plowing mechanism, which results in a higher penetration depth than can be expected from the typical deflected jet. The results improve our overall prediction of the penetration depth for inclined jets translating at high speeds. These results, including the maximum penetration depth, post-sedimentation geometry and pressure at depth, are essential for the validation of all CFD models aiming at the jetting process, though we will focus on Euler-Euler in the first place.