Boundary layer and surface pressure distribution behavior over a submarine nose model with two different nose shapes

Surface pressure distributions and boundary layer profiles are measured over the nose surface of a submarine model in a wind tunnel. The tests are conducted for two different nose shapes in order to study the effects of nose shape on the flow field around the model. The influence of Reynolds numbers, which are 0.5×106, 0.8×106 and 106, and pitch angles, α = 0, 5, 10 and 15°, on the surface pressure distribution over the surface of two nose shapes are investigated. Furthermore, the effect of the longitudinal pressure gradient on the boundary layer velocity profiles and the probability of the separation in the plane of symmetry of the nose are studied. It is found that the Reynolds number does not have a significant influence on the nose surface pressure distribution at all pitch angles. The results show that the presence of the adverse pressure gradient in major portion of the blunter nose shape causes the non-dimensional velocity profiles of boundary layer in locations of 0.1≤X/L≤0.23 are deviated from the log layer profile. Therefore the separation on the blunter nose shape is more likely than the other nose at high pitch angle manoeuvres.