EP0024069A1 - Surface structure of a surface adapted for movement relative to a fluid - Google Patents

Surface structure of a surface adapted for movement relative to a fluid

Info

Publication number
EP0024069A1
EP0024069A1 EP80900316A EP80900316A EP0024069A1 EP 0024069 A1 EP0024069 A1 EP 0024069A1 EP 80900316 A EP80900316 A EP 80900316A EP 80900316 A EP80900316 A EP 80900316A EP 0024069 A1 EP0024069 A1 EP 0024069A1
Authority
EP
European Patent Office
Prior art keywords
floor
surface structure
fluid
band systems
ground
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP80900316A
Other languages
German (de)
French (fr)
Inventor
Anders Edvard Hugo MALMSTRÖM
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Malmstroem Anders E H
Original Assignee
Malmstroem Anders E H
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Malmstroem Anders E H filed Critical Malmstroem Anders E H
Publication of EP0024069A1 publication Critical patent/EP0024069A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/32—Other means for varying the inherent hydrodynamic characteristics of hulls
    • B63B1/34—Other means for varying the inherent hydrodynamic characteristics of hulls by reducing surface friction
    • B63B1/36—Other means for varying the inherent hydrodynamic characteristics of hulls by reducing surface friction using mechanical means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C21/00—Influencing air flow over aircraft surfaces by affecting boundary layer flow
    • B64C21/10—Influencing air flow over aircraft surfaces by affecting boundary layer flow using other surface properties, e.g. roughness
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/10—Drag reduction
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T70/00—Maritime or waterways transport
    • Y02T70/10—Measures concerning design or construction of watercraft hulls

Definitions

  • the present invention relates to a surface structure of a surface adapted for movement relative to a fluid.
  • a surface adapted for move ⁇ ment relative to a fluid is to be as smooth as possible.
  • a well-known example of this is the conscientious manner in which the sailor grinds and polishes the outer surface of the hull.
  • Another example is the transport of liquids in pipes where it is endeavoured to make the inside of the pipes as smooth as possible, in the belief that this will reduce friction losses. This belief is unwarranted; a given roughness reduces friction losses.
  • fins of e.g. triangular cross-section are provided along a surface moving in a fluid.
  • longi ⁇ tudinal is meant that the fins are directed in the direction of movement of the surface. This arrangement offers a certain improvement as compared with a smooth surface, but the friction can be reduced to a far greater extent.
  • the ship's motion is restrained by various, factors, ⁇ one of which is the frictional resistance, " two forms of which are active, viz. laminar friction and friction produced by turbulence.
  • the turbulent resistance is * ultimately due to a flow transverse to the direction of movement and is many times greater per surface unit than the laminar resistance. It would be an ideal situation if the water flow along the surface could be kept laminar, n ⁇ if the ' only deviation from the straight line were the water following the hull surface.
  • That part of the turbulent water layer which is adjacent the hull surface has previously been called the laminar sublayer, but recent research has shown that this layer exhibits an intense turbulent activity.
  • the laminar friction and the slightest unevenness, also a microscopic unevenness, in the surface as well as different distances to this surface impart different velocities to the different water particles or particle groups.
  • the different moving layers are not isolated from one another, and that a certain exchange of particle groups having different velocities is continuously taking place.
  • In the contact, or friction, between particles of different velocity different degrees of "crowding" in different areas occur. In areas having a higher "crowding", a higher pressure arises, while in other areas the opposite occurs. This primary crowding effect forces the particles outwardly in different directions, which in turn causes further differences in the crowding intensity.
  • the particle groups having the least kinetic energy (low velocity bands) and therefore requiring the least centripetal force for a change of direction will change- their direction, whereas the particle groups having a higher velocity will exert a smaller lateral pressure (Bernoulli's theorem) , for which reason the particles having the lower velocity and the higher pressure will tend to flow towards .
  • the area of smaller pressure Since neitherwater nor air is compressed or rarefied at velocities below thevelocityof sound, each such transverse flow will be compensated for by a return flow. The total effect of these phenomena results in flows forming an angle with the main direction of movement..
  • the splashes which occur when a jet of water is directed against a surface are not the result of the rebounding of certain water particles; instead the particles are more or less powerfully forced out of the surface of the positive pressure produced by the crowding of the particles when they meet and are distributed along the surface.
  • This positive pressure and consequently the splashes constitute, in principle, the same "crowding effect" as occurs during flow along a surface, the different degrees of the resulting pressure differences producing the bursts.
  • the present invention has for its object to eliminate these transverse flows and thus the formation of bursts by means of a surface structure such that the particles, when they "slide” along the surface, encounter other surfaces - not any type of unevenness - at an angle causing their velocity to be decelerated as far as possible, and that the particles, to the extent that theyhave not been stopped, but have changed their direction at reduced velocity, encounter other surfaces and one another, pre ⁇ ferably from opposite directions.
  • the surface has a structure comprising at least two intersecting band systems forming an angle with the direction of move— ent. In this manner, it is " possible, when the optimum effect of this serial velocity deceleration is achieved, to dampen or cancel the intense turbulent activity adjacent the surface so that the innermost layer will be re lace __
  • the surface structure according to the present invention may be in the form of bands of dams.
  • the dams may be replaced by channels- in which the water then flows at a lower velocity and at a higher pressure (Bernoulli's theorem) than in the flow intersecting them.
  • the drawing shows a portion of a surface 10, for instance a surface on a ship or an aircraft with which the water och the air is in contact, or the inner surface of a pipe-line for conveying liquids or gases.
  • the surface has two intersecting band systems of dams or ridges 11 and 12 which are parallel to one another and together constitute a network.
  • the relative direction of movement between the surface 10 and the liquid or gas is indicated by the arrow13.
  • the two band systems intersect one another at right angles, but other angles of intersection are also possible.
  • the band systems form an angle of +45 and -45 , respec tively, relative to the direction movement, but also these values are not critical.
  • the band systems need not necessarily be in the form of dams, but may also consist of intersecting ditches or channels.
  • the height of the ridges and the . depth of the channels, respectively, may vary within certain limits, and it has been established that a height or a depth of less than 1 mm is fully adequate.
  • the drawing also shows continuous ridges, but the desired effect can be achieved also with discontinuous ridges, i.-e. rows of mutually spaced apart elevations.
  • discontinuous ridges i.-e. rows of mutually spaced apart elevations.
  • the production of the surface structure according to the invention is extreme] simple, which is an essential condition for its practical applicability.
  • the ridges or channels may be formed by simple mechanical working of the surfaces that are swept by the water or the gas, but it is also possible to form the ridges or channels in compression moulded sheets which are glued or otherwise secured to the surfaces.
  • the present invention provides a simple and efficient surface structure in the form " of a network effectively preventing the formation of bursts. In this manner, the frictional resistance of a relative movement of the type here concerned is reduced, and this means that the engine power of, for example, a ship can be reduced considerably without restricting the shi 's speed. In other words, the invention offers a considerable saving of energy.

Abstract

Une liaison pour relier des egouts au sol pour plusieurs unites de refoulement, comprend un organe de sol (1) situe dans le sol et un anneau de serrage (2, 9) pour assujettir un couvercle de sol (7) de maniere etanche dans un evidement de l'organe de sol ou dans une piece intermediaire (9) complementaire a l'organe de sol pour reduire les dimensions de la liaison; l'anneau de serrage (2, 9) serre le couvercle de sol (7) dans un espace ajuste sur le couvercle de sol entre l'anneau de serrage (2, 9) et la piece intermediaire (9) ou l'organe de sol (1), l'anneau de serrage (2, 9) etant la piece de sol (1) ou la piece intermediaire (8) par des moyens de prise instantanes (4, 5, 14, 15), et le couvercle de sol etant monte de maniere etanche contre l'organe ou piece de sol ou la piece intermediaire par un joint torique.A connection for connecting sewers to the ground for several delivery units, comprises a ground member (1) located in the ground and a clamping ring (2, 9) for securing a ground cover (7) in a sealed manner in a recess of the floor member or in an intermediate piece (9) complementary to the floor member to reduce the dimensions of the connection; the clamping ring (2, 9) clamps the floor cover (7) in a space fitted on the floor cover between the clamping ring (2, 9) and the intermediate piece (9) or the floor (1), the clamping ring (2, 9) being the floor piece (1) or the intermediate piece (8) by instant gripping means (4, 5, 14, 15), and the floor being mounted in a sealed manner against the body or piece of floor or the intermediate piece by an O-ring.

Description

SURFACE STRUCTURE OF A SURFACE ADAPTED FOR MOVEMENT RELATIVE TO A FLUID
The present invention relates to a surface structure of a surface adapted for movement relative to a fluid. '
It is generally believed that a surface adapted for move¬ ment relative to a fluid is to be as smooth as possible. A well-known example of this is the conscientious manner in which the sailor grinds and polishes the outer surface of the hull. Another example is the transport of liquids in pipes where it is endeavoured to make the inside of the pipes as smooth as possible, in the belief that this will reduce friction losses. This belief is unwarranted; a given roughness reduces friction losses.
On various occasions, attempts have been made to roughen the surfaces of especially ship's hulls in order to reduce friction losses. Thus, British patent specification 357,637 of 27th June 1930 proposes to provide a hull with a coating- having rasp-tooth formations. Here, one was on the right track, but no success was achieved because of the complicated formations and per¬ haps because of difficulty of coating a hull with plates of this type. Also on the right track is NASA Langley
Research Center, Hampton, Virginia, according to a paper published by M.J. Walsh and L.M. Weinstein and entitled "Drag and Heat Transfer on Surfaces with Small Longitudinal Fins" (Seattle, Washington, July 10-12, 1978). According to this paper, fins of e.g. triangular cross-section are provided along a surface moving in a fluid. By "longi¬ tudinal" is meant that the fins are directed in the direction of movement of the surface. This arrangement offers a certain improvement as compared with a smooth surface, but the friction can be reduced to a far greater extent.
To illustrate the activity adjacent a surface adapted for movement relative to a fluid, reference is made to a ship's motion in water.
The ship's motion is restrained by various, factors, ■ one of which is the frictional resistance," two forms of which are active, viz. laminar friction and friction produced by turbulence. The turbulent resistance is * ultimately due to a flow transverse to the direction of movement and is many times greater per surface unit than the laminar resistance. It would be an ideal situation if the water flow along the surface could be kept laminar, nά if the' only deviation from the straight line were the water following the hull surface.
That part of the turbulent water layer which is adjacent the hull surface has previously been called the laminar sublayer, but recent research has shown that this layer exhibits an intense turbulent activity. The laminar friction and the slightest unevenness, also a microscopic unevenness, in the surface as well as different distances to this surface impart different velocities to the different water particles or particle groups. It should be noted that the different moving layers are not isolated from one another, and that a certain exchange of particle groups having different velocities is continuously taking place. In the contact, or friction, between particles of different velocity different degrees of "crowding" in different areas occur. In areas having a higher "crowding", a higher pressure arises, while in other areas the opposite occurs. This primary crowding effect forces the particles outwardly in different directions, which in turn causes further differences in the crowding intensity.
When a positive pressure is to be equalized in one area, the particle groups having the least kinetic energy (low velocity bands) and therefore requiring the least centripetal force for a change of direction, will change- their direction, whereas the particle groups having a higher velocity will exert a smaller lateral pressure (Bernoulli's theorem) , for which reason the particles having the lower velocity and the higher pressure will tend to flow towards .the area of smaller pressure. Since neitherwater nor air is compressed or rarefied at velocities below thevelocityof sound, each such transverse flow will be compensated for by a return flow. The total effect of these phenomena results in flows forming an angle with the main direction of movement..
It has been established that the intensity of these flows shows a certain intermittence resulting in periodi- cally recurrent bursts which constitute the main part of the total turbulence production.
The splashes which occur when a jet of water is directed against a surface are not the result of the rebounding of certain water particles; instead the particles are more or less powerfully forced out of the surface of the positive pressure produced by the crowding of the particles when they meet and are distributed along the surface. This positive pressure and consequently the splashes constitute, in principle, the same "crowding effect" as occurs during flow along a surface, the different degrees of the resulting pressure differences producing the bursts.
The present invention has for its object to eliminate these transverse flows and thus the formation of bursts by means of a surface structure such that the particles, when they "slide" along the surface, encounter other surfaces - not any type of unevenness - at an angle causing their velocity to be decelerated as far as possible, and that the particles, to the extent that theyhave not been stopped, but have changed their direction at reduced velocity, encounter other surfaces and one another, pre¬ ferably from opposite directions. To this end, the surface has a structure comprising at least two intersecting band systems forming an angle with the direction of move— ent. In this manner, it is "possible, when the optimum effect of this serial velocity deceleration is achieved, to dampen or cancel the intense turbulent activity adjacent the surface so that the innermost layer will be re lace __
OMPI by a relatively calm layer where no bursts occur.
The surface structure according to the present invention may be in the form of bands of dams. Where appropriate, the dams may be replaced by channels- in which the water then flows at a lower velocity and at a higher pressure (Bernoulli's theorem) than in the flow intersecting them.
The invention will be described in more detail in the following, reference been "had to the accompanying drawing which diagramatically illustrates an embodiment of the invention.
The drawing shows a portion of a surface 10, for instance a surface on a ship or an aircraft with which the water och the air is in contact, or the inner surface of a pipe-line for conveying liquids or gases. The surface has two intersecting band systems of dams or ridges 11 and 12 which are parallel to one another and together constitute a network. The relative direction of movement between the surface 10 and the liquid or gas is indicated by the arrow13. In the embodiment illustrated, the two band systems intersect one another at right angles, but other angles of intersection are also possible. In the example illus¬ trated, the band systems form an angle of +45 and -45 , respec tively, relative to the direction movement, but also these values are not critical. As has previously been mentioned, the band systems need not necessarily be in the form of dams, but may also consist of intersecting ditches or channels. The height of the ridges and the . depth of the channels, respectively, may vary within certain limits, and it has been established that a height or a depth of less than 1 mm is fully adequate.
The drawing also shows continuous ridges, but the desired effect can be achieved also with discontinuous ridges, i.-e. rows of mutually spaced apart elevations. The same applies, of course, also when the band systems are in the form of channels.
It will be appreciated that the production of the surface structure according to the invention is extreme] simple, which is an essential condition for its practical applicability. In actual practice, the ridges or channels may be formed by simple mechanical working of the surfaces that are swept by the water or the gas, but it is also possible to form the ridges or channels in compression moulded sheets which are glued or otherwise secured to the surfaces.
The present invention provides a simple and efficient surface structure in the form "of a network effectively preventing the formation of bursts. In this manner, the frictional resistance of a relative movement of the type here concerned is reduced, and this means that the engine power of, for example, a ship can be reduced considerably without restricting the shi 's speed. In other words, the invention offers a considerable saving of energy.
OMPI

Claims

1. A surface structure of a surface (10) adapted for movement relative to a fluid, c h a r a c t e r i s e in that the structure has at least two intersecting band systems (11, 12) forming an angle with the direction of 5 movement.
2. A surface structure as claimed in claim 1, c h a r a c t e r i s e d in that the two band systems (11, 12) intersect one another approximately at right angles.
10 3. A surface structure as claimed in claim 1, c h a r a c t e r i s e d in that the two band systems (11, 12) form an angle of approximately +45 and -45 , respectively, with the direction of movement (13) .
4. A surface structure as claimed in claim 1, 2 15. or 3, c h a r a c t e r i s e d in that the two'-band systems (11, 12) are formed by ridges parallel to one another.
5. A surface structure as claimed in claim 1, 2 or 3, c h a r a c t e r i s e d in that the two band
20 systems are formed by channels parallel to one another.
6. A surface structure as claimed in claim 1, 2 or 3, c h a r a c t e r i s e d in that the two band systems (11, 12) are formed by spaced apart elongate elevations.
25 7. A surface structure as claimed i claim 1, 2 or 3, c h a r a c t e r i s e d in that the two band systems are formed by spaced apart elongate depressions.
8. A surface structure as claimed in any one of claims 4-7, c h a r a c t e r i s e d in that the
30 ridges or elevations have a height and the channels or depressions have a depth, respectively, which is less than 1 mm.
OMPI
EP80900316A 1979-02-13 1980-08-25 Surface structure of a surface adapted for movement relative to a fluid Withdrawn EP0024069A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE7901244 1979-02-13
SE7901244A SE7901244L (en) 1979-02-13 1979-02-13 SURFACE STRUCTURE OF SURFACES, OR EXPOSED TO FLOW, FLUID OR GAS

Publications (1)

Publication Number Publication Date
EP0024069A1 true EP0024069A1 (en) 1981-02-25

Family

ID=20337276

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80900316A Withdrawn EP0024069A1 (en) 1979-02-13 1980-08-25 Surface structure of a surface adapted for movement relative to a fluid

Country Status (5)

Country Link
EP (1) EP0024069A1 (en)
JP (1) JPS56500564A (en)
DE (1) DE3034321A1 (en)
SE (1) SE7901244L (en)
WO (1) WO1980001673A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3441554A1 (en) * 1984-11-14 1986-05-22 Deutsche Forschungs- und Versuchsanstalt für Luft- und Raumfahrt e.V., 5300 Bonn REDUCED SURFACE RESISTANCE OF A TURBULENT OVERFLOWED BODY
US4986496A (en) * 1985-05-31 1991-01-22 Minnesota Mining And Manufacturing Drag reduction article
US5133516A (en) * 1985-05-31 1992-07-28 Minnesota Mining And Manufacturing Co. Drag reduction article
DE3534293A1 (en) * 1985-09-26 1987-04-02 Messerschmitt Boelkow Blohm DEVICE FOR REDUCING FRICTION RESISTANCE
US5238434A (en) * 1991-03-15 1993-08-24 Kransco Textured bottom skin for bodyboards and method
DE19528406A1 (en) * 1995-08-02 1997-02-06 Bmw Rolls Royce Gmbh Gas turbine combustion chamber with air transfer ports - has shot blasted, rolled raster or fluting design upstream of ports to specified raster dimension
WO1997021931A1 (en) * 1995-12-12 1997-06-19 Roche Ulrich Process for forming a surface for contact with a flowing fluid and body with such surface regions
JP4824190B2 (en) * 2001-03-07 2011-11-30 独立行政法人日本原子力研究開発機構 Turbulent friction resistance reduction surface
NL1029708C2 (en) * 2005-08-10 2007-02-13 Kick Off Ltd Turbulence foil.
WO2009070852A1 (en) * 2007-12-07 2009-06-11 John Gene Foster A watercraft stability control device
ES2322839B1 (en) * 2007-12-27 2010-04-20 Manuel Muñoz Saiz SYSTEM AND REDUCING METHOD OF THE FLUID FRICTION RESISTANCE ON THE SURFACE OF BOATS AND AIRCRAFT.
DE102013020830B4 (en) * 2012-12-20 2020-03-26 Lutz Renkewitz Fluid dynamic profile and a method for improving the glide ratio

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GB190820281A (en) * 1908-09-26 1909-09-23 William Henry Fauber Improvements in and relating to the Construction of Boats and Ships.
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Also Published As

Publication number Publication date
WO1980001673A1 (en) 1980-08-21
JPS56500564A (en) 1981-04-30
SE7901244L (en) 1980-08-14
DE3034321A1 (en) 1981-03-26

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