A Scale Model Investigation of the Effect of Jet Configuration on Skin Friction for the MK-40 Torpedo

An analytical study, combining jet diffusion patterns and jet velocities, indicates that there are four methods of eliminating the clinging jet phenomenon which occurs on the Mk-40 Torpedo Test Vehicle. It is shown that extension of the nozzles along the existing nozzle axis appears to present the simplest method of design improvement. Experiments were conducted on a modified model of the Mk-40 to verify the analysis. It was found that for the operational jet-to-model velocity ratio, (U/V) of 2, a nozzle extension of 6 nozzle diameters is the minimum required to provide cling-free performance. All experiments and calculations were made for the case of a body without exhaust ports or gas discharge.