Submarine Mast Wave and Plume Reduction

The flow generated by a submarine mast piercing the water surface is a complex phenomenon. Visible wakes, which are regions of foamy, churned, turbulent water, appear behind the mast during some modes of submarine operations. Such wakes are capable of affecting the propagation of sound energy through the water by acquiring a greater though transitory capacity for absorbing and scattering sound. Movement through the water also results in "spray sheets" formed on the sides of the surface piercing mast structure. When these spray sheets break up into ligaments/globs/drops which fall to the water surface, they add to "white water" formation and visible sea surface changes.

To reduce the detectability characteristics of the flow around the mast of a deployed submarine, the use of macro-molecule polymer injection in the region around the mast was developed. A number of experimental trials were performed in the special water chamber which was designed and built at Beltran. Direct visual observation was used to determine bow wave height, spray height and all geometric and hydrodynamic characteristics of the cavity.

The uniqueness of this experimental data proves, first, the accuracy of the measurements of all geometric characteristics and second, in the absence of the influence of the bottom end of the mast. The majority of earlier tests of the surface-piercing masts were performed in a towing tank where this influence always exists. The shape of the mast also was investigated revealing circular cylinders of different diameters and four airfoil shapes with a yaw angle range between 0° and 30°.

                                                  Bow wake, cavity and bubble wake behind the mast