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A rectangular single-expansion ramp nozzle (SERN) with an aft deck is used to model the exhaust from a three-stream engine. At the nozzle exit two unmixed streams exist. The first is assumed to be ...

Simulations of an ideally expanded supersonic jet for two operating temperatures are conducted with a low aspect ratio of two rectangular nozzle, and an equivalent diameter circular nozzle of the s...

The aim of this study is to develop surrogate models for quick, accurate prediction of thrust forces generated through flapping fin propulsion for given operating conditions and fin geometries. Different network architectures and configurations are explored to model the training data separately for the lead fin and rear fin of a tandem fin setup. We progressively improve the data representation of the input parameter space for model predictions. The models are tested on three unseen fin geometries and the predictions validated with computational fluid dynamics (CFD) data. Finally, the orders of magnitude gains in computational performance of these surrogate models, compared to experimental and CFD runs, vs their tradeoff with accuracy is discussed within the context of this tandem fin configuration., Presented at IEEE/MTS OCEANS 2019 (Seattle)

In this study, the effects of fin stroke phase offset, flapping frequency, and freestream flow speed on thrust production are investigated for a median paired (pectoral) fin – caudal fin configuration. Fin geometries and kinematics are selected to be representative of common bio-inspired unmanned vehicles as well as the fish that inspire them, and for this study the fins are rigid to limit the variable parameter space. Experimental results demonstrate a significant correlation between freestream flow speed and thrust-optimal stroke phase offset, as well as between fin flap speed and thrust-optimal stroke phase offset. The results also highlight differences between the time-histories of thrust at high- and low-thrust generating stroke phase offsets suggesting a significant difference in wake signatures. This study provides the foundation for development of a comprehensive analytical tool for flapping fin and vehicle design.