Torpedo drag reduction employing polymer ejection
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsAndrew G. Fabula, James H. Green, William F. Madison
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Abstract
Method and apparatus for reducing torpedo drag in which polymer drag redug material is carried by the torpedo in concentrated form, ambient water is ingested and mixed with the concentrated polymer to produce a seawater-polymer solution of predetermined concentration, and the solution is ejected from the torpedo nose to be swept rearwardly in intimate contact with the exterior surface of the torpedo under torpedo forward motion.
Claims6
In combination with a torpedo of the type having an elongated body having nose and tail ends, and adapted to be self propelled through the water;
- (a) means for continuously ingesting ambient water into the hull at a predetermined flow rate,
- (b) means for receiving and holding a charge of a quick solvation, polymer-amorphous suspension mixture, said mixture containing a powdered form of hydrodynamic drag reducing water soluble polymer material having a high molecular weight and linear, long-chain, molecular structure and a quick solvation suspending medium,
- (c) a liquid solution continuous mixing means having an inlet for solvent, an inlet for additive, and an outlet for the output solution, and having a characteristic residence-mixing time, said ingested seawater being communicated to the mixing means inlet, said mixing means being so constructed and arranged to mix the seawater and the polymer material in a manner in which the solvated and hydrated form of polymer molecules present in the output solution substantially retain their linear, long-chain, molecular structure,
- (d) means for dispensing said charge of polymer-amorphous suspension mixture into the additive inlet of the means for mixing at a predetermined rate to produce a concentration of polymer material in the output solution of the mixing means between the limits of 0.05% and 1.0% by weight,
- (e) said polymer-amorphous suspension mixture adapted to match the characteristic residence-mixing time of the means for mixing to cause the polymer material to be present in the output solution of the mixing means in substantially solvated and hydrated form as it issues from the outlet, and
- (f) ejection port means extending through the hull of the torpedo at the nose end thereof, said output solution from the mixing means being communicated to the ejection port means, said ejection port means being raked in the direction of the adjacent ambient stream flow to cause the solution to be swept rearwardly along the torpedo in intimate contact with its exterior surface under torpedo forward motion.
A method for reducing skin friction drag associated with high Reynolds-number turbulent flows adjacent the surface of a torpedo, said torpedo being of a type having an elongated body and adapted to be self propelled through the water, said method comprising the steps:
- (a) ingesting a continuous flow of ambient seawater,
- (b) adding to the flow of ingested seawater a quick solvation, polymer-amorphous suspension mixture, said mixture containing a powdered form of hydrodynamic drag reducing water soluble polymer material having a high molecular weight and a linear, long-chain, molecular structure, and containing a quick solvation suspending medium, said mixture added to the seawater at a predetermined rate to produce a concentration of polymer material in the flow between the limits 0.05% and 1.0%, by weight,
- (c) mixing the seawater and additive mixture to produce a seawater-polymer solution flow in which the polymer material is present in substantially solvated and hydrated form, and in a manner in which the solvated and hydrated form of polymer molecules retain their linear, long-chain, molecular structure,
- (d) ejecting the seawater-polymer solution from the nose of the torpedo with a component of ejection motion in the direction of flow of the adjacent ambient stream to cause the solution to be swept rearwardly along the torpedo in intimate contact with its exterior surface under torpedo forward motion.
Dependencies are inferred from the claim text.