Shakedown and Preliminary Test on Fin Tip Signature Minimization and AppendageDrag Reduction by Tip Jets Blowing

摘要

Preliminary experimental investigations of tin tip signature and appendage dragreduction using foil tip jets blowing were conducted. Water tunnel tests provided preliminary flow visualization data on how the jets affect the fin tip flow field and the near wake vortex roll-up process. Through testing Model 111, it was inferred that different jet blowing techniques might be required to attain vortex alleviation minimizing detectability and reducing appendage drag. For unswept fins, jet blowing from near the fin tip can alleviate the tip vortex flow effectively (within the observed range and test conditions of the experiment). it was observed that individual jet location, blowing momentum and direction are key control parameters of effectiveness in dispersion of vortices. It was found that lower-surface compared to upper-surface blowing was less effective. A combination of upper surface and fin tip jets at near trailing edge of the fin tip was shown to be effective for unswept fins. Near-total dispersion has been observed, implying that an optimum condition of blowing exists. Some new configurations of combined blowing from top, tip and bottom ports near the fin tip-trailing-edge may yield even better results and should be tried in the future. Drag reduction, Vortices, Boundary layer control