EP2879949A1 - Propeller including a blade back flow guide - Google Patents

Propeller including a blade back flow guide

Info

Publication number
EP2879949A1
EP2879949A1 EP20130776568 EP13776568A EP2879949A1 EP 2879949 A1 EP2879949 A1 EP 2879949A1 EP 20130776568 EP20130776568 EP 20130776568 EP 13776568 A EP13776568 A EP 13776568A EP 2879949 A1 EP2879949 A1 EP 2879949A1
Authority
EP
Grant status
Application
Patent type
Prior art keywords
blade
propeller
edge
flow
guide
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Withdrawn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
EP20130776568
Other languages
German (de)
French (fr)
Inventor
Russel Ian HAWKINS
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.)
Hawkins Russel Ian
Original Assignee
Hawkins, Russel Ian
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

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B63SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63HMARINE PROPULSION OR STEERING
    • B63H1/00Propulsive elements directly acting on water
    • B63H1/02Propulsive elements directly acting on water of rotary type
    • B63H1/12Propulsive elements directly acting on water of rotary type with rotation axis substantially in propulsive direction
    • B63H1/14Propellers
    • B63H1/26Blades
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B63SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63HMARINE PROPULSION OR STEERING
    • B63H1/00Propulsive elements directly acting on water
    • B63H1/02Propulsive elements directly acting on water of rotary type
    • B63H1/12Propulsive elements directly acting on water of rotary type with rotation axis substantially in propulsive direction
    • B63H1/14Propellers
    • B63H1/28Other means for improving propeller efficiency

Abstract

THIS invention relates to a propeller and more particularly but not exclusively, to a propeller for use with inboard and outboard boat engines. The propeller includes a hub, and a plurality of blades, each blade having a blade face, a blade back and a blade peripheral zone comprising a leading edge, a trialing edge and a blade tip zone extending between the leading edge and the trialing edge. The propeller is characterized in that a flow guide is provided on the blade back of each blade.

Description

PROPELLER INCLUDING A BLADE BACK FLOW GUIDE

BACKGROUND TO THE INVENTION

THIS invention relates to a propeller and more particularly but not exclusively, to a propeller for use with inboard and outboard boat engines.

A propeller is a device that transmits power by converting rotational motion into thrust. A pressure differential is produced between forward and rear surfaces of the airfoil-shaped blade, and a fluid (such as air or water) is accelerated behind the blade, thus resulting in thrust required to drive a means of transport to which the propeller is attached. One specific type of propeller is a propeller for use as means of propulsion in boat engines, whether outboard or inboard.

Many different propeller designs are known in the trade, and they all share some of the same design characteristics. A propeller comprises a plurality of blades extending radially outwardly from a central rotating hub. Each blade is in the form of an airfoil having two opposite surfaces, being a blade face (which is the pressure side of the bfade facing the stern), and the blade back (which is the suction side of the blade facing the bow). Each blade furthermore has a leading edge, which is the edge of the propeller adjacent the forward end of the hub. The leading edge leads the blade into the flow when the propeller is providing forward thrust. The opposing edge is referred to as the trailing edge, and the radially outer zone extending between the leading edge and the trailing edge is referred to as the blade tip. The root of the blade is the fillet area in the region of transition between the blade surface to the hub periphery.

A few other terms that are commonly used in in propeller nomenclature include:

Diameter: Two times the distance from the center of the hub to the tip of the blade, i.e. equal to the diameter of a circle that the tip of the propeller would make when rotating.

Pitch: Pitch is defined at the theoretical forward movement of a propeller during one revolution, assuming that there is no 'slippage' between the propeller blade and the water. In practice some slippage does occur, and the design pitch is therefore more than the actual pitch.

Cupping: Many existing propellers incorporate a cup formation at the trailing edge of the propeller blade. Propeller cup is the deformation of a propeller's trailing edge toward the pressure face. Cupping provides a measure of camber to the blade, and therefore changes the pressure distribution along the blade's chord length, adding lift toward the trailing edge. Cavitation: Cavitation, (which is often confused with ventilation), is a phenomena of water vaporizing or "boiling" due to the extreme reduction of pressure on the back of the propeller blade. Many propellers partially cavitate during normal operation, but excessive cavitation can result in physical damage to the propeller's blade surface due to the collapse of microscopic bubbles on the blade. There may be numerous causes of cavitation such as incorrect matching of propeller style to application, incorrect pitch, and physical damage to the blade edges.

Ventilation: Ventilation is a situation where surface air or exhaust gasses are drawn into the propeller blades. When this situation occurs, boat speed is lost and engine RPM climbs rapidly. This can result from excessively tight cornering, a motor that is mounted very high on the transom, or by over-trimming the engine.

Hole Shot: Hole shot refers to rapid acceleration of a boat, i.e. from a standing rest or very slow speed until the boat is "on-plane" and riding on top of the water. During this acceleration phase the engine works particularly hard, and it is therefore important to have the best possible propeller for the particular application. A propeller that offers excessive hole shot (i.e. too much acceleration) will typically yield low tops speeds and may cause the engine to operate above its designed RPM. On the other hand, a propeller that offers too little hole shot typically result in poor acceleration performance! and may not bring the engine up to its designed RPM range. Either of these scenarios cause undue strain on the engine and reduces its overall performance and fuel efficiency. Blade surface area refers to the total surface area of the propeller blade. When a propeller rotates on a fixed axis for any period of time a centrifugal force creating a negative pressure on the blade back of each rotating blade draw water inwards, and when the oncoming blade face comes into contact with the inward flow of water the water is compressed. A positive pressure is therefore induced, and the water in this positive pressure zone then exerts a force against the adjacent body of water, resulting in thrust. Standard blade designs allow the inward flow of water to flow over the entire curvature of the blade back. This is believed to result in about 40% of the energy being wasted because on average only 60% of the negative pressure water mass is compressed by the blade face of an oncoming blade. Further energy is lost between the blade roots of each blade back, which fragments the flow of water when the positive pressure water mass collides with the negative pressure water mass. This disturbance affects the volume of water mass that gets displaced.

It will be appreciated that blade surface area piays an important part in propeller performance. This is important because the more blade surface area a prop has the more water it displaces. However, this can also result in more drag on the blade and thus the engine, due to the effects described hereinbefore. Increased blade area can result in better hole shot, and will allow a boat to remain on plane at lower engine speeds. However, too much blade area can result in excessive drag, and can therefore restrict the RPM that that the engine can develop, and can in addition also result in boat handling issues. The operation of the engine outside its recommended specification results in the engine having to work harder or faster than it is designed to do. This will result in reduced efficiency, fuel economy and possibly also damage to the engine.

It would therefore be beneficial if a propeller can de designed that has a reduced effective blade back area, without reducing the effective area of the blade face. !t is accordingly an object of the invention to provide a propeller that will at least partially alleviate the above disadvantage.

It is also an object of the invention to provide a propeller having reduced drag characteristics without impacting on the surface area of the blade face.

SUMMARY OF THE INVENTION

According to the invention there is provided a propeller including:

a hub;

a plurality of blades, each blade having a blade face, a blade back and a blade peripheral zone comprising a leading edge, a trialing edge and a blade tip zone extending between the leading edge and the trialing edge;

characterized in that a flow guide is provided on the blade back of each blade.

There is provided for the flow guide to be in the form of an elongate ridge extending from a surface of the blade back.

The flow guide may be linear, and may be angularly offset relative to a radially outwardly direction of the propeller.

Preferably the flow guide is at least partially parallel to a trailing edge of the blade.

Preferably the flow guide is located closer to the trialing edge of the blade than to the leading edge of the blade. There is provided for the flow guide to be of a tapering profile when viewed in cross-section.

Preferably a side of the flow guide disposed towards the trialing edge of the blade is higher than a side disposed towards a leading edge of the blade.

An upper surface of the flow guide may be disposed at an angle of between 10 and 40 degrees relative to the surface if the blade back. Preferably, the angle is between 25 and 35 degrees.

There is provided for the flow guide to extend from the blade root towards at least halve the distance to the periphery of the blade.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is described by way of a non- limiting example, and with reference to the accompanying drawings in which:

Figure 1 is a front perspective view of the propeller including flow guides in accordance with one embodiment of the invention;

Figure 2 is a side view of the propeller of Figure 2;

Figure 3 is top plan view of the propeller of Figure 1. DETAILED DESCRIPTION OF INVENTION

Referring to the drawings, in which like numerals indicate like features, a non-limiting example of a propeller in accordance with the invention is generally indicated by reference numeral 10.

The propeller 10 comprises a hub 20, which may be of many different configurations. In one embodiment the hub 20 incorporates a secondary propulsion system as described in the applicant's co-pending application ZA2012/05757 entitled "Propeller incorporating a secondary propulsion system", the contents of which is incorporated herein by reference, in one embodiment the propeller also includes the provision of edge members on the blades of the propeller as described in the applicant's co-pending application ZA2012/05753 entitled "Propeller including a discrete edge member", the content of which is also incorporated herein by reference.

A plurality of blades 30 extend radially outwardly from the hub 20, with each blade being in the form of an airfoil extending from the hub 20 at a root 23 section thereof, and terminating in a peripheral tip zone 34. The blade 30 includes a blade face 31 and a blade back 32. The periphery of the blade 30 comprises a leading edge 35, a trailing edge 36, and an outer tip zone 34 extending between the leading edge 35 and the trailing edge 36.

Flow guides 50 in the form of elongate ridges are provided on the surface of the blade backs 32. Each flow guide 50 is in the form of a linear ridge that is somewhat angularly offset relative to a radially outwardiy direction of the propeller. More particularly, each flow guide is at least partially aligned and parallel relative to a trialing edge of the blade 30. The flow guide 50 is disposed towards a proximal zone of the blade surface 32, with a first end 50.1 of the flow guide being located adjacent the hub 20 of the propeller 10, and with a second end 50.2 extending towards the periphery of the blade. In cross-section , the flow guide 50 is of a tapered configuration, with a first side 50.3, which is the side facing the leading edge of the blade, being flush with the surface of the blade back 32, but with an opposite side 50.4, which is the side facing the trialing edge of the blade, being raised relative to the surface of the blade back. The gradient between the first side 50.3 and the second side 50.4, and hence the upper surface of the flow guide, is linear in this particular embodiment, and more particularly forms an angle of about 30 degrees relative to the blade back 32. The gradient and hence upper surface may however vary in terms of profile and magnitude, and may for example also be arcuate, and in particular somewhat convex.

The flow guide has the effect of directing incoming water away from the blade back and towards the oncoming blade face. The incoming water therefore only flow across between 40% and 60 % of the back blade before it is redirected towards the oncoming blade. This results in an increase efficiency accompanied by a reduction in drag, as is discussed in detail in the background to this invention.

The propeller 10 body is made from magnesium or a magnesium alloy, which is made in a moulding process known in the art. The flow guides 50 are integrally formed with the propeller blades and body.

It will be appreciated that the above is only one embodiment of the invention and that there may be many variations without departing from the spirit and/or the scope of the invention.

Claims

CLAIMS:
1. A propeller including:
a hub;
a plurality of blades, each blade having a blade face, a blade back and a blade peripheral zone comprising a leading edge, a trialing edge and a blade tip zone extending between the leading edge and the trialing edge;
characterized in that a flow guide is provided on the blade back of each blade.
2. The propeller of claim 1 in which the flow guide is in the form of an elongate ridge protruding from a surface of the blade back.
3. The propeller of claim 1 or claim 2 in which the flow guide is linear.
4. The propeller of claim 3 in which the flow guide is angularly offset relative to a radially outwardly direction of the propeller blade.
5. The propeller of any one of claims 2 to 4 in which the flow guide is at least partially parallel to a trailing edge of the blade.
6. The propeller of any one of the preceding claims in which the flow guide is located closer to the trialing edge of the blade than the leading edge of the blade.
7. The propeller of any one of the preceding claims in which the flow guide is of a tapering profile when viewed in cross-section.
8. The propeller of claim 7 in which a side of the flow guide disposed towards the trialing edge of the blade is higher than a side disposed towards a leading edge of the blade.
9. The propeller of claim 8 in which an upper surface of the flow guide is disposed at an angle of between 10 and 40 degrees relative to the surface of the blade back.
10. The propeller of claim 9 in which an upper surface of the flow guide is disposed at an angle of between 25 and 35 degrees relative to the surface of the blade back.
11. The propeller of any one of the preceding claims in which the flow guide extends from the blade root towards at least half the distance to the periphery of the blade.
EP20130776568 2012-07-31 2013-07-31 Propeller including a blade back flow guide Withdrawn EP2879949A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
ZA201205758 2012-07-31
PCT/IB2013/056280 WO2014020550A1 (en) 2012-07-31 2013-07-31 Propeller including a blade back flow guide

Publications (1)

Publication Number Publication Date
EP2879949A1 true true EP2879949A1 (en) 2015-06-10

Family

ID=49354719

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20130776568 Withdrawn EP2879949A1 (en) 2012-07-31 2013-07-31 Propeller including a blade back flow guide

Country Status (3)

Country Link
US (1) US20150217846A1 (en)
EP (1) EP2879949A1 (en)
WO (1) WO2014020550A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160121985A1 (en) * 2014-10-29 2016-05-05 Scott Baumann Marine propeller blades with reverse cupping

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1531967A (en) * 1923-07-26 1925-03-31 Gen Electric Propeller
US2990889A (en) * 1959-10-19 1961-07-04 Merrell V Welch Propeller blade sock
US3812812A (en) * 1973-06-25 1974-05-28 M Hurwitz Trolling propeller with self adjusting hydrodynamic spoilers
JP2931256B2 (en) * 1995-11-01 1999-08-09 神鋼パンテツク株式会社 Axial flow type stirring blades
US5810561A (en) * 1997-04-21 1998-09-22 Cossette; Thomas C. Variable pitch propeller apparatus
US6699016B1 (en) * 2001-06-12 2004-03-02 Peter Dean Boat propeller
US7255387B2 (en) * 2003-08-21 2007-08-14 Solus Solutions And Technologies, Llc Vortex strake device and method for reducing the aerodynamic drag of ground vehicles
US7040940B2 (en) * 2004-04-20 2006-05-09 Ab Volvo Rotatable lifting surface device having selected pitch distribution and camber profile
US7223073B2 (en) * 2005-05-19 2007-05-29 Peter Dean Boat propeller
US7637722B1 (en) * 2006-09-26 2009-12-29 Brunswick Corporation Marine propeller
US8517683B2 (en) * 2007-02-08 2013-08-27 Veem Engineering Group Pty Ltd. Marine propeller pitch adjustment means
EP2360374A1 (en) * 2009-10-08 2011-08-24 Lm Glasfiber A/S Wind turbine blade having a forwardly oriented flow guiding device
EP2311726B1 (en) * 2009-10-16 2012-12-05 Charles Steven Powers Marine propeller with reverse thrust cup
US7909576B1 (en) * 2010-06-24 2011-03-22 General Electric Company Fastening device for rotor blade component
US9494132B2 (en) * 2013-05-07 2016-11-15 General Electric Company Airflow modifying assembly for a rotor blade of a wind turbine

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2014020550A1 *

Also Published As

Publication number Publication date Type
WO2014020550A1 (en) 2014-02-06 application
US20150217846A1 (en) 2015-08-06 application

Similar Documents

Publication Publication Date Title
US20060018759A1 (en) Rotor blade
US5405243A (en) Propeller with shrouding ring attached to blade
US4093402A (en) Propeller or a set of wings for a wind mill
US20020152947A1 (en) Bow mounted system and method for jet-propelling a submarine or torpedo through water
US20100181432A1 (en) Curved Wing Tip
US4789306A (en) Marine propeller
US3697193A (en) Fluidfoil section
US7229251B2 (en) Rotor hub fairing system for a counter-rotating, coaxial rotor system
US20100303634A1 (en) Fluid dynamic section having escapelet openings for reducing induced and interference drag, and energizing stagnant flow
US4632636A (en) Propeller with blades having regressive pitch
US5190441A (en) Noise reduction in aircraft propellers
US6302652B1 (en) Elliptical propeller and windmill blade assembly
US1758560A (en) Aircraft propeller
US4844698A (en) Propeller blade
JP2007247542A (en) Turbine blade cascade end wall
JP2006306304A (en) Propulsion device and its manufacturing method
US20050281676A1 (en) Multi-hedral rotary wing
JP2008239060A (en) Stern oblong duct and vessel
US6840741B1 (en) Leading edge slat airfoil for multi-element rotor blade airfoils
US5752865A (en) Ship
US5209642A (en) Modified optimum pitch propeller
CN202593838U (en) Ship hydrodynamic front guide wheel energy-saving device
US6371726B1 (en) Foldable propeller
US4921404A (en) Propellors for watercraft
US1949611A (en) Propeller blade

Legal Events

Date Code Title Description
17P Request for examination filed

Effective date: 20150302

AK Designated contracting states:

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent to

Countries concerned: BAME

DAX Request for extension of the european patent (to any country) deleted
18D Deemed to be withdrawn

Effective date: 20160122