Boundary layer tripping study on a Generic Submarine Model in water

This paper reports on resistance and qualitative hot film measurements undertaken on a Defence Science and Technology generic conventional submarine model at the Australian Maritime College Towing Tank. The aim of the experiment was to characterise the natural transition to turbulence phenomena on the hull and to investigate the effectiveness of Hama strips to artificially stimulate fully turbulent flow on the hull as there is no existing sizing guidelines for the Hama strips for bodies of revolution under water. Different Hama strip thicknesses were tested with strips located at 5% of model length, aft of the forward most point of the bow.

Kurtosis analysis was used to determine the intermittency of the hot film measurements, which allowed the flow regime to be characterised as either transitional or fully turbulent. Results show that the required Hama strip thickness to stimulate fully turbulent flow on the hull for the speeds tested is much smaller than the predicted thickness using trip dot sizing guidelines. The results also show that the Hama strip with the appropriate thickness does not have any measurable parasitic drag. The outlined Hama strip design and methodology to measure its effectiveness will be used in future investigations on whether fully turbulent flow is induced on a submarine model at various drift and pitch angles. Further work is also planned to investigate the effectiveness of Hama strips to induce turbulent flow over submarine model appendages.