Despite the importance of pulsed jets for underwater propulsion, the effectof multiple-jet interactions remains poorly understood. We experimentallyinvestigate how interactions between neighboring jets in a pulsed-jet thrusteraffect the thruster's propulsive performance. Using high-speed fluorescenceimaging, we investigate the mutual influence of two pulsed jets underconditions relevant to low-speed maneuvering in a vehicle ($Re\approx350,$$L/D\leq2$). Thrust production and propulsive efficiency are evaluated fordifferent nozzle spacings using a new force estimation technique based on thefluorescence data. This analysis reveals that, compared to non-interactingjets, the efficiency and thrust generated by the pair of interacting jets canfall by as much as 10\% when the jets are brought into close proximity.Empirically, the thrust $T$ falls off with the non-dimensional jet spacing$\widetilde{\Delta}$ as $T=T_\infty(1-Co \widetilde{\Delta}^{-6})$ for a thrustcoupling coefficient $Co=2.04 \pm 0.11.$ Finally, we predict this leading orderdependence of thrust on spacing using a model that relates the thrust andefficiency drop to streamline curvature and vortex induction at the nozzles.
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机译：尽管脉冲式射流对于水下推进非常重要，但对多射流相互作用的影响仍知之甚少。我们通过实验研究了脉冲喷气推进器中相邻喷气之间的相互作用如何影响推进器的推进性能。使用高速荧光成像技术，我们研究了在与车辆低速操纵相关的条件下两个脉冲喷射器的相互影响（$ Re \ approx350，$$ L / D \ leq2 $）。使用新的基于荧光数据的力估算技术，针对不同的喷嘴间距评估推力产生和推进效率。该分析表明，与非交互作用的喷气机相比，当相互作用的喷气机靠近时，这对相互作用的喷气机产生的效率和推力下降高达10％。对于推力耦合系数$ Co = 2.04 \ pm 0.11。，无维射流间距$ \ widetilde {\ Delta} $ as $ T = T_ \ infty（1-Co \ widetilde {\ Delta} ^ {-6}）$最后，我们使用将推力和效率下降与流线曲率和喷嘴处的涡流相关联的模型来预测推力对间距的这种前导顺序依赖性。
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