Experimental study of multiple pulsed jets offset from a wall

Multiple pulsed jets offer a novel and efficient means of propulsion and locomotion for aquatic vehicles. The maneuverability offered by pulsed jets, particularly at low Reynolds numbers, is more convenient and effective compared to continuous jets or propeller-based propulsors. Furthermore, for the same expelled mass, the thrust generated by a pulsed jet is greater and requires less input power. The gain in thrust results from the generation of a coherent detached vortex ring that locally increases the pressure in the near-wake. However, in practice, aquatic vehicles must often maneuver around obstacles, over mounds or close to the seabed/lakebed. The presence of obstructions or walls will directly affect the formation of the vortex rings, the surrounding pressure field and, consequently, the resulting thrust vector. The objective of this project is to investigate, experimentally, the fluid dynamics of two parallel pulsed jets in the vicinity of a wall using time-resolved particle image velocimetry. We will explore the effect of the offset distance of the jets from the wall and their spacing on the mean flow, vortex dynamics and thrust characteristics.