US3289623A

US3289623A - Frictional resistance reduction using non-newtonian fluid

Info

Publication number: US3289623A
Application number: US438264A
Authority: US
Inventors: William O Gray; Bryant A Hilliard
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1965-03-09
Filing date: 1965-03-09
Publication date: 1966-12-06
Anticipated expiration: 1983-12-06

Description

Dec. 6, 1966 w. o. GRAY ETAL FRICTIONAL RESISTANCE REDUCTION USING NON-NEWTONIAN FLUID 2 Sheets-Sheet l Filed March 9, 1965 FIG. E

FIG. 2

RECOVERY AND RECIRCULATION SYSTEM FIG. 3

D mmm mmm. N l wok. WMM F AIHN LA um U WB ATTORNEY Dec. 6, 1966 w. o. GRAY ETAL FRICTIONAL RESISTANCE REDUCTION USING NON-NEWTONIAN FLUID 2 Sheets-Sheet 2 v FIG. 6

Filed March 9, 1965 FIG. 4

TNVENTOR. WILLIAM O. GRAY Vy l ATTORNEY United States Patent fifice 3,289,623 Patented Dec. 6, i966 3,289,623 FRIC'HNAL RESISTANCE REDUCTION USING NUN-NEWTONHAN FLUID William 0. Gray, Darien, and Bryant A. Hilliard, Norwalk` Conn., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Mar. 9, 1965. Ser. No. 438,264 2 Claims. (Qi. 114-67) This invention relates in general to a method and apparatus for reducing the frictional resistance of a ship, and in particular to improvements in means and methods for frictional resistance reduction ywherein the boundary layer shear characteristics of the vessel supporting liquid is altered by the addition thereto of a non-newtonian fluid.

In general, the shear characteristics of uids may be divided into two basic classes. The great majority of common fluids such as lwater may be broadly classi-fied as newtonian fluids Awherein the shearing stress is a fixed ratio to the rate of shear. Non-newtonian fluids are a class of fluids for which the shearing stress is no lon-ger a fixed ratio to the rate of shear. Non-newtonian fluids could require either more or less shearing force for a given rate of shear than the same rate of shear in a newtonian fluid. Obviously, the present invention having as its purpose the reduction of frictional resistance is directed toward the introduction into the boundary layer of a vessel, such as a ship, of a non-newtonian tiuid which will effect a reduction in lthe shearing stress from that of the supporting and surrounding fluid for any given rate of shear thereof.

With these general relationships in mind, the invention includes in a ship, such as a tanker, means for introducing relatively small amounts of a non-newtonian fluid, as for instance a long-chain polymer such as polyethylene oxide, into the water adjacent the bow of the ship. Such introduction of a non-ne'wtonian fluid -at the |bow alters the shear characteristics of the fluid in the boundary layer of the ship rearwardly toward the stern thereof to decrease the overall frictional drag of the vessel.

It has been found that a substantial reduction in frictional resistance of vessels may be anticipated by this addition of a small quantity of a non-newtonian duid in the order of three, or substantially less, parts .per million relative to the surrounding volume of water. This relatively small quantity of ynonmewtonian tiuid makes it economically sound as a imeans for increasing ship speed or conversely ldecreasing the required power to maintain a lgiven vessel speed.

In accordance with the invention, a reservoir of nonnewtonian fluid such as a polyethylene oxide of longchain polymers is provided with an outlet conduit an-d suitable pumping arrangement to direct a small quantity of the fluid in the reservoir t-o a series of slots, nozzles, etc., disposed at the bow end of the ship. The -ow of the non-newtonian fluid in the reservoir is metered and limited in nature so that a small depletion of the contents stored therein results. The material thus supplied to the bow exterior through the ships hull is dispersed fairly uniformly in the relatively thin boundary layer of the sea water adjacent the bow portion of the ship. Thereafter, as the advance of the shi-p continues, the dispersion :of the non-newtonian fluid in the boundary layer increases toward the rear of the ship. If desired, all or a portion of lthe boundary layer fluid may be pumped back into the ship interior lwhere the recovery of the nonnewtonian iiuild may be accomplished through the use of suitable lilter or other separating means.

Accordingly, it is a principal object of this invention to provide an improved method and apparatus for reducing the frictional resistance of a vessel.

, It is another object of the invention to provide a novel method by which the shear characteristics ofthe boundary layer surrounding the ship may be altered from newtonian characteristics to non-newtonian characteristics.

It is another object of the `present invention to provide a novel means for introducing a relatively minute quan-v tity of nonnewtonian fluid through a 'bow portion of a ships hull to provide a substantially uniform dispersion of such fluid in a forward portion of the lboundary layer.

A further object of the invention is to provide a novel ship speed increasing means which is simple in design, trou-bleafree in operation, economical to install, and has a minimum of moving parts.

These and other objects .and advantages of the invention will become apparent and the inventi-on will be fully understood from the following description and drawings in which:

FIG. l is a diagrammatic side elevation view of a typical vessel incorporating the invention;

FIG. 2 is a schematic top plan view of a ship embodying the invention showing the recovery and recirculation system;

FIG. 3 is an enlarged fragmentary view of the bow portion of the vessel;

FIG. 4 is an enlarged perspective view partially in section (along line 4 4 of FIG. 5) showing the uid introduction slots at the bow of the vessel;

PIG. 5 is a fragment-ary cross-sectional view taken along line 5-5 of FIG. 4;

FIG. 6 is a view similar to FIG. 4 showing a further embodiment of the invention as it would be applied to ships traveling in a ballast condition; and

FIG. 7 is a cross-sectional View taken along line 7-7 of FIG. 6.

Referring to the FIGS. 1 5 in particular, a typical ship such as a vessel 10 includes a bow having a Huid introduction means generally indicated at l2 and optionally at its stern a fluid recovery means generally designated I4. A fluid recovery pump I6 (see FIG. 2) receives fluid from the recovery means 14 and discharges to a recovery and recirculation system 18. The recovery and recirculation system 18 supplies non-newtonian fluid via a forwardly extending conduit 32 to the fluid introduction means I2.

Referring to FIGS. 3, 4 and 5 in particular, the forward end of the conduit 32 is attached to a reservoir 26 having an outlet conduit 28. A pump 30 connected to conduit 218 delivers the non-newtonian uid 25 within the reservoir 26 via a discharge conduit 29 to a fluid supply manifold 24 extending vertically on the interior of the ships hull plate 22. In this way the fluid in the reservoir 26 is supplied under pressure to the interior of the manifold 24 so that it m-ay be discharged in minute quantity in the desired amounts through a plurality of thin staggered slots or

nozzles

20, 20 extending through the ships hull plate 22. The arrangement and size of the staggered slots or nozzles Ztl' is such that the structural integrity of the hull plate is undisturbed due to the fact that the slots extend in several vertical planes. In this way a tine uniform dispersion of the non-newtonian fluid into the boundary layer of the ship at a forward bow portion of the hull is assured. While the invention has shown a simple slotted arrangement for the controlled introduction of the non-newtonian fluid, those skilled in the art will readily appreciate that alternate nozzle or slot means may be employed for such purpose without departing from the scope of the invention. For instance, it would also be within the scope of this invention to provide one or more perforated conduits connected to the conduit 29 and attached `directly to the exterior of the ships hull in place of the illustrated slot arrangement as will be discussed later in connection with FIG. 6.

In operation, a non-newtonian fluid which will alter the shear characteristics of the surrounding liquid is contained in the reservoir 26 and pumped via

conduits

28 and 29 to the interior of the manifold 24. Suitable metering orices (not shown) may be provided as required in the

conduit system

28, 29 to limit the flow of fluid from the reservoir 26. The non-newtonian fluid is thus discharged in small amounts through the slots 20 and gradually dispe-rses in the ships boundary layer of Water to reduce the shear characteristics in a decreasing non-newtonian fashion. Thereafter, as the ship progresses under these conditions of reduced hull friction, the stern uid recovery means 14 may or may not be activated to recover the bow introduced non-newtonian uid. Should it be desirable to recover a portion or all of the non-newtonian uid, it may be pumped from the boundary layer at the stern of the ship by operation of the pump 16 and the recovery and recirculation system 18 and be reintroduced via the conduit 32 and a valve 34 into the reservoir 26. VOther suitable valves (not shown) similar to valve 34 are provided to permit closing off lthe system of the invention when its use is not desired. The recovery and recirculation system 18 may include a centrifugal separator for separating the non-newtonian fluid having a density different from tha-t of the water or may alternatively or additionally include use of a filter separation means for a similar recovery of the non-newtonian from the water prior to its reintroduction to the reservoir 26.

Referring to FIGS. 6 and 7, an alternate embodiment is shown which is particularly useful in :the practice of the invention on ships traveling in a ballast condition. This form of the invention includes a non-newtoni an fluid supply conduit 40 Ihaving an upper branch portion 42 and a lower branch portion 44 which communicate with a generally vertical conduit 46 secured 'to the outer surface of the ship hu-ll 22. The conduit 46 includes a plug 48 positioned therein at a level approximating the ballast water line of the ship indicated by the level of the arrow B. The conduit 46 also includes a plurality of small outlet apertures 50 through which the non-newtonian fluid from the supply conduit 40 may be discharged to the boundary layer.

In `operation of the vessel under a normal load condition indicated by the vertical level of the arrow A, a valve 52 would be opened so that non-newtonian fluid will be discharged from the apertures S0 over the entire length of the conduit 46. Under ballast operating conditions of the ship, valve S2 is closed so that non-newtonian huid is only emitted from the lower portion of conduit 46 below the level of the plug 48 and therefore below the ballast level B. Supply conduit 40 may be connected to a pressure pump such as pump 30 of FIG. 4 or if sufficient static head is present it may be connected directly to the supply reservoir.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. Apparatus for reducing the frictional resistance of a liquid-supported vessel in a ballast as well as loaded condition comprising, in combination, a hull having a bow and a stern and means carried by said vessel for introducing a small quantity of non-newtonian iiuid at the bow into the adjacent vessel supporting liquid to thereby alter the shear characteristic of said liquid from a newtonian to a n-on-newtonian relationship wherein the shearing stress is no longer a fixed ratio to the rate of shear; said introducing means including, a substantially vertical conduit atxed .to the exterior of the hull and having a plurality of fluid discharge apertures throughout the length thereof, said conduit extending above and below the ballast Water line of said hull, plug means in said conduit in the area of said ballast water line for uid isolating the upper portion of said conduit from the lower portion thereof, and valve means for controlling the flow of nonnewtonian iluid to the upper portion of said conduit above said plug means to thereby prevent the discharge of fluid from said upper portion during travel of the vessel in a ballast condition while permitting discharge of fluid from the lower portion of said conduit during travel in a ballast condition.

2. Apparatus in accordance with claim 1 including means for recovering the non-newtonian uid from the vessel supporting liquid at the stern of said hull, and means for recirculating said non-newtonian uid to the introducing means at the bow of said hull.

References Cited by the Examiner UNITED STATES PATENTS 1,894,256 1/1933 De Ganahl et al 114--67 3,075,489 1/ 1963 Eichenberger 114-67 3,196,823 7/1965 Thurston 114-67 3,205,846 9/1965 Lang 114-67 3,230,919 1/1966 Crawford 114-67 FOREIGN PATENTS 468,325 7/1914 France. 517,508 10/ 1955 Canada.

MILTON BUCHLER, Primary Examiner.

ANDREW H. FARRELL, Examiner.

Claims

1. APPARATUS FOR REDUCING THE FRICTIONAL RESISTANCE OF A LIQUID-SUPPORTED VESSEL IN A BALLAST AS WELL AS LOADED CONDITION COMPRISING, IN COMBINATION, A HULL HAVING A BOW AND A STERN AMD MEANS CARRIED BY SAID VESSEL FOR INTRODUCING A SMALL QUANTITY OF NON-NEWTONIAN FLUID AT THE BOW INTO THE ADJACENT VESSEL SUPPORTING LIQUID TO THEREBY ALTER THE SHEAR CHARACTERISTIC OF SAID LIQUID FROM A NEWTONIAN TO A NON-NEWTONIAN RELATIONSHIP WHEREIN THE SHEARING STRESS IS NO LONGER A FIXED RATIO TO THE RATE OF SHEAR; AND INTRODUCING MEANS INCLUDING, A SUBSTANTIALLY VERTICAL CONDUIT AFFIXED TO THE EXTERIOR OF THE HULL AND HAVING A PLURALITY OF FLUID DISCHARGE APERTURRES THROUGHOUT THE LENGTH THEREOF, SAID CONDUIT EXTENDING ABOVE AND BELOW THE BAL-