Shape optimization of an autonomous Underwatervehicle (AUV) in cooperation with the DFKI

In the scope of a project work in the master`s program "Locomotion in fluids" at the Hochschule Bremen, a forming optimization of the AVALON was carried out in cooperation with the DFKI. To this end, the AVALON was abstracted into a model whose different, bionically inspired frontal and rear geometries were tested in the water channel at the Reynold`s numbers 5.53·10 hoch 4, 1.08·10 hoch 5 and 1.63·10 hoch 5. The drag coefficients could be reduced by 70 to 84 % by the optimizations which were inspired by the bottlenose dolphin and the box fish and by simultaneously encasing the middle piece. The original model exhibits a dependency of the drag coefficient on the inflow velocity which the optimized model does not show.

Additionally a numerical simulation of a slightly simplified model of the AVALON as well as a simulation of the most effective combination of the aforementioned experimental optimizations was conducted. At the constant Reynold`s number of 1.08·10 hoch 5, the drag coefficient deviated just inconsiderably and the percentaged improvement of the drag coefficients lay by 55 %, which corresponds to the data of the experiments except for 2 %. Additional simulations of both models at the actual operating speed of the AVALON (approximately 1·10 hoch 6 m/s) yielded to an improvement of 65 %. Due to some simplifications, the results cannot directly be transferred to the AVALON. Yet it could be shown that a considerable amount of energy might be saved just by adapting the outer form of the AUV.