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WO1999062761A1 - Corps profile pour liquide s'ecoulant autour a vitesse elevee - Google Patents

Corps profile pour liquide s'ecoulant autour a vitesse elevee Download PDF

Info

Publication number
WO1999062761A1
WO1999062761A1 PCT/CH1999/000230 CH9900230W WO9962761A1 WO 1999062761 A1 WO1999062761 A1 WO 1999062761A1 CH 9900230 W CH9900230 W CH 9900230W WO 9962761 A1 WO9962761 A1 WO 9962761A1
Authority
WO
WIPO (PCT)
Prior art keywords
streamlined body
liquid
grooves
high speed
water
Prior art date
Application number
PCT/CH1999/000230
Other languages
English (en)
Inventor
Ulrich La Roche
Original Assignee
Supramar Ag
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 Supramar Ag filed Critical Supramar Ag
Priority to AU38084/99A priority Critical patent/AU3808499A/en
Publication of WO1999062761A1 publication Critical patent/WO1999062761A1/fr

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
    • B63B1/16—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces
    • B63B1/24—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type
    • B63B1/28—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type with movable hydrofoils
    • B63B1/285—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type with movable hydrofoils changing the angle of attack or the lift of the foil
    • B63B1/288—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type with movable hydrofoils changing the angle of attack or the lift of the foil using gas exhaust through the foil
    • 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
    • B63B1/16—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces
    • B63B1/24—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type

Definitions

  • the present invention relates to a streamlined body according to the precharacterizing clause of claim I .
  • streamlined body in this case means, in particular, hydrofoils for hydrofoil or hybrid boats, supports for such hydrofoils, control surfaces, propeller blades or turbine blades etc.
  • problems of cavitation occur in the water at high flow speeds, for example above about 25 m/s. Cavitation occurs when the local pressure of the liquid on the streamlined body falls below the vapour pressure at the corresponding temperature. In this case, vapour bubbles are formed, which implode downstream as the pressure rises, leading to cavitation corrosion.
  • the present invention is based on the object of designing a streamlined body in S' ch a manner tnat cavitation damage is avoided even at high flow speeds, and the streamlined body can be used over a wide speed range. This object achieved by the combination of features in the claims.
  • a two phase mixture is the intensive mixing of a liquid phase (for example water) and a gaseous phase (for example air).
  • the compressibility of the mixture corresponds essentially to that of the gas phase, while the density virtually corresponds to the density of the liquid phase.
  • the speed of the sound in the mixture is proportional to the square root of the quotient of the compressibility and the density of the mixture.
  • the speed of sound is in the order of magnitude of 20 m/s over a wide range of the mecanicvoid ratio" (gas volume / total volume) of about 0.1 to 0.9.
  • the speed in such a mixture is thus supersonic.
  • Pressure disturbances can in this case propagate only downstream.
  • a pressure change downstream cannot propagate upstream and cause flow separation.
  • a further characteristic of supersonic flow is that it is accelerated when the flow cross section is enlarged. Enlarging the distance between the outer flow
  • Fig. 1 shows a schematic cross section through a detail of a hydrofoil profile
  • Fig. 2 shov/s a cross section through the hydrofoil profile.
  • Figure 1 shows schematically, part of a detail of a hydrofoil profile 1 in flowing water 2.
  • the local flow speed 3 of the water 2 is more than 25 m/s.
  • the hydrofoil has a groove 4 which extends transversely with respect to the plane of the profile 1 , that is to say essentially in the longitudinal direction of the hydrofoil, and which can be supplied v/ith air 7 via a channel 5 and a transverse holes 6.
  • An intensive vortex 8 is formed in the groove 4 and causes the air 7 which has been sucked in or fed in to be intensively mixed with the water 2 contained in the vortex 8.
  • the two-phase mixture escapes downstream from the groove 4 as a hvo-phase mixed layer 9 between the surface 10 of the profile 1 , and the surface 11 of the flowing water 2 facing the profile 1.
  • the speed of the mixed layer 9 is approximately the same as the speed 3 of the water 2, so that the speed in this layer is supersonic for the flow speeds 3 above about 25 m/s.
  • the amount of a i r 7 supplied is variable.
  • the groove 4 can also be supplied with prepared air/water mixture via the channel 5 and the holes , in which case the amount supplied and/or the void ratio mixture can be varied.
  • the holes 6 are expediently dimensioned and arranged such that air flowing in or the mixture flowing in assists the spinning of the vortex 8.
  • Figure 2 shows, schematically, a hydrofoil profile 9, which is drawn symmetrically. It has tranverse grooves 4 on both sides, approximately at the point of maximum profile thickness, v/ith corresponding air supply channels 5 and holes 6.
  • a hydrofoil profile 9 By varying the ratio of the amounts of air or mixture supplied to the opposite grooves 4, it is possible to influence the ratio of thickness of the mixed layer 9 downstream from the grooves 4 and the hence the circulation around the profile 1 and the lift from the profile 1. Owing to the supersonic speed, a higher static pressure downstream cannot propagate upstream, and increasing the thickness of the two-phase mixed layer 9 does not result in separation, and no cavitation can occur.
  • a plurality of transverse grooves 4, 4' can also be arranged one behind the other in the flow direction, as indicated by dashed-dotted lines in figure 2. The mixed layer 9 can thus be built up or reduced in stages.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

L'invention vise à prévenir les phénomènes de cavitation dans le cas de corps profilés autour desquels s'écoule de l'eau (2) à vitesse élevée (3) et à permettre simultanément que lesdits corps profilés puissent s'utiliser sur des plages de vitesses plus importantes. A cet effet, de l'air qui est acheminé et de l'eau sont utilisés pour produire un mélange à deux phases, en un vortex intensif, dans une gorge transversale (4). Le mélange à deux phases forme une couche mixte à deux phases (9) passant à vitesse supersonique en aval de la gorge (4).
PCT/CH1999/000230 1998-05-29 1999-05-26 Corps profile pour liquide s'ecoulant autour a vitesse elevee WO1999062761A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU38084/99A AU3808499A (en) 1998-05-29 1999-05-26 Streamlined body for a liquid to flow around at high speed

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH117798 1998-05-29
CH1177/98 1998-05-29

Publications (1)

Publication Number Publication Date
WO1999062761A1 true WO1999062761A1 (fr) 1999-12-09

Family

ID=4204308

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CH1999/000230 WO1999062761A1 (fr) 1998-05-29 1999-05-26 Corps profile pour liquide s'ecoulant autour a vitesse elevee

Country Status (2)

Country Link
AU (1) AU3808499A (fr)
WO (1) WO1999062761A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001053147A1 (fr) 2000-01-18 2001-07-26 Supramar Ag Corps profile destine a etre immerge dans un liquide a vitesse relative elevee
EP2143629A1 (fr) 2008-07-08 2010-01-13 Siemens Aktiengesellschaft Agencement pour la stabilisation d'une fondation flottante

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3896752A (en) * 1973-06-04 1975-07-29 Supramar Ag Hydrofoil for watercraft with lift generation through air supply of the foil underside
DE3210498A1 (de) * 1982-03-23 1983-10-06 Hans Raehmer Grenzschichtbeeinflussung von fluiddynamischen wirkflaechen
EP0264326A1 (fr) * 1986-10-17 1988-04-20 ETAT-FRANCAIS représenté par le DELEGUE GENERAL POUR L'ARMEMENT (DPAG) Dispositif de propulsion et de sustentation pour navires rapides à aile portante immergée

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3896752A (en) * 1973-06-04 1975-07-29 Supramar Ag Hydrofoil for watercraft with lift generation through air supply of the foil underside
DE3210498A1 (de) * 1982-03-23 1983-10-06 Hans Raehmer Grenzschichtbeeinflussung von fluiddynamischen wirkflaechen
EP0264326A1 (fr) * 1986-10-17 1988-04-20 ETAT-FRANCAIS représenté par le DELEGUE GENERAL POUR L'ARMEMENT (DPAG) Dispositif de propulsion et de sustentation pour navires rapides à aile portante immergée

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001053147A1 (fr) 2000-01-18 2001-07-26 Supramar Ag Corps profile destine a etre immerge dans un liquide a vitesse relative elevee
EP2143629A1 (fr) 2008-07-08 2010-01-13 Siemens Aktiengesellschaft Agencement pour la stabilisation d'une fondation flottante

Also Published As

Publication number Publication date
AU3808499A (en) 1999-12-20

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