Patent ID: 6349734
Filing Date: 2002-02-26
Classification: B63B,F15D,F42B,Y02T,Y10T

Abstract:
A method of conditioning a drag-reducing substance prior to its release into a first fluid, and of releasing it into the first fluid, there being relative motion between said first fluid and a first surface so as to form a first fluid flow path, said method comprising the following steps:(a) conditioning the drag-reducing substance using fluid shear forces by causing a second fluid, which includes said drag-reducing substance, to flow between surfaces having conditioning means to thereby cause the drag-reducing molecules in said second fluid to be in condition for reducing drag; and, (b) releasing the conditioned drag-reducing substance into a region consisting substantially of only the near-wall region of a boundary layer of the first fluid by causing the second fluid to flow over a convex Coanda surface as it enters the flow path of the first fluid, said convex Coanda surface being located on the downstream side of a slot through which the second fluid enters the flow path; wherein, in step (b): vortices are established in said second fluid by causing said second fluid to flow over a concave surface located on the upstream side of a slot through which the second fluid flows into the first fluid such that the vortices pair together and produce pressure differentials having lower pressure regions immediately adjacent said first surface, thereby causing the drag-reducing substance to remain in a vicinity immediately adjacent said first surface while said vortices are operative.