DID YOU KNOW? DTIC has over 3.5 million final reports on DoD funded research, development, test, and evaluation activities available to our registered users. Click HERE
to register or log in.
The Drag of an Accelerating Submarine. Part I. Skin Friction
ADMIRALTY EXPERIMENT WORKS HASLAR (UNITED KINGDOM)
Pagination or Media Count:
Potential flow theory predicts that a body accelerated or decelerated in motion in a straight line in a fluid will experience an inertia force greater than that due to the mass of the body - a so called added mass effect. Submarine trials confirm the phenomenon but indicate that for motion in the fore and aft direction the added mass is much greater than predicted. This could be due to 1 transient loss of thrust from the propeller, 2 changes in skin friction due to the acceleration, 3 changes in form drag due to the acceleration. Towing testa have been conducted on a body without propeller. These eliminate 1 as the primary cause. A theoretical and experimental study of 2 has been made for a flat plate. Theory predicts an increase in skin friction for both laminar and turbulent boundary layers, but experiment on the turbulent layer only partially supports the theory. Although further analysis of the data is desirable, the results suggest that acceleration may restore a measure of laminar flow in the boundary layer. Further work should concentrate on this aspect and on the effect of acceleration on form drag.
APPROVED FOR PUBLIC RELEASE