Experimental Parameter Study on the Development of an Intake Funnel to Increase the Operating Time of the Crawfish

This paper is situated within the fields of maritime robotics and fluid dynamics. It presents an experimental investigation into the flow characteristics, detachment forces, and suction forces associated with various funnel geometries, with the overarching goal of extending the operational duration of the remotable underwater vehicle Crawfish. By optimizing the funnel design, the required adhesion force can be reduced, consequently lowering the energy consumption of the currently used thrusters. The study demonstrates that both the funnel geometry and its distance from the flow source significantly affect the resulting suction forces. Among the tested configurations, the funnel based on a NACA profile proved to be the most efficient, generating a maximum suction force of up to 11.16 kg at full thruster power. In contrast, the rectangular funnel exhibited the lowest efficiency. For all geometries examined, the peak detachment force was observed at a distance of 8 mm from the surface. Furthermore, the analysis revealed a near-linear scaling of detachment forces in relation to thruster power. The findings provide a robust basis for the optimization of suction systems in underwater robotics. The NACA-profile funnel was identified as the most effective geometry and, through targeted design refinements, has the potential to significantly improve the energy efficiency of the Crawfish system. Future research should focus on integrating the NACA funnel into the overall vehicle architecture and conducting field tests under real-world conditions, while also exploring propeller optimization and advances in manufacturing technologies.