CA2100140A1 - Ice load reduction device for ship propellers - Google Patents
Ice load reduction device for ship propellersInfo
- Publication number
- CA2100140A1 CA2100140A1 CA 2100140 CA2100140A CA2100140A1 CA 2100140 A1 CA2100140 A1 CA 2100140A1 CA 2100140 CA2100140 CA 2100140 CA 2100140 A CA2100140 A CA 2100140A CA 2100140 A1 CA2100140 A1 CA 2100140A1
- Authority
- CA
- Canada
- Prior art keywords
- ice
- propeller
- forces
- propellers
- blades
- 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.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H1/00—Propulsive elements directly acting on water
- B63H1/02—Propulsive elements directly acting on water of rotary type
- B63H1/12—Propulsive elements directly acting on water of rotary type with rotation axis substantially in propulsive direction
- B63H1/14—Propellers
- B63H1/26—Blades
Abstract
Abstract The propellers of an ice-breaking ship can experience very large forces when they contact submerged blocks of ice. The leading edge of a propeller is smoothly rounded to permit it to move easily through the water. This means that the propeller is a very blunt object, ill-suited to cutting ice. As a result ice forces can be very high and propellers on ice-breaking ships are built thicker and stronger than those on open-water ships. In this invention, special devices are fitted to the blades of an ice-worthy propeller, which have the effect of reducing the ice forces on the blades. The devices are cutters which initiate cleavage failure in the ice and consequently lower the total force.
Description
Specification 2~1Q~
I hic in~ ention relatc~s to icc c~ltth~g~le~ ices to l-e fille(l onlo or hlcoll)ol.lte(l illtO chi ~ropel I ers .
Tlle ship propellers referred to here are marine screw propellers. Such propellers have se~ eral blades arranged radially around a central hub. The blades have circulllferential cross sections shaped li}~e wing sections, having a rounded leading edge and a sharp trailing edge.
While these shapes are hydrodynamically efficient, meaning high lift and low drag, they can experience very high ice forces because they present a blunt face to the ice. To overcome high ice forces, propellers for ice-going ships are made 111llCh stronger and are characterized by thicli bl~de sections ancl relative large hub diameters. The thicker blades are less hydrodynamically efficient and are even blunter that normal. Ice-strengthened propeller blades are still often damaged by ice, or experience such high loads that they damage or impair other parts of the propulsion system, such as the blade pitch control mechanism, the shafting, shaft bearings, gearing and propulsion motor.
The use of ice CUttillg devices at the leading edge and extending along the outside (suction face) of the blade will change the mode of ice failure and lower the peak and average ice forces on the blades. Several cuttina devices, spaced along the leading edge, will act together to cut, rather than cmsh, the blocks of ice encountered by the propeller. Failure in the ice will initiate at the tips of the cutters~ so that the magnitude of the force is reduced.
::, :; In dMwings which illustrate embodiments of the invention. Figure ] is a front view of one embodiment with four cutters per blade. Figure ~ is a section of the line III-III, Figure 3 is a ~, section of the line IV-IV showing an embodiment of the cutter pro-file. Figure 4 is a section :` of the line IV-IV showing another embodiment of the cutter profle. Figure 5 is a general 1,'!j view of an embotliment with three cutters per blade and showing variations in the profiles of the cutters. Figure 6 shows an embodiment with an angular tooth shape Figure 7 shows an embodimcnt with thc cutter rcccssed into the blade surface. Fugurc 8 shows an embodiment with the full leading edge formed into an ice cutting profile.
The device illustrated is comprised of a number of cutters d, attached from the leading edge c of a marine screw propeller blade a, along part of the front face of the blade. The cutter profile come to a sharp edge at e and forms a finf that may vary in length, reaching part or ,'j all the way to the tMiling edge b. Various shapes of the fm profile may be used to improve :, cutting and minimize hydrodynamic loss of effeciency. Alternative embodiments of cutter geometry, an angular tooth g, a recessed tooth h, and a blade leading edge modified to Cllt ,!jl ice alona all or part of the leading edaej are versions of the ice load recluction device.
The attachment of the cutters to the blades may be accomp1ished by integral casting.-welding :~ or bolting.
,.,~
;.. -."
., :.' '`'I
~ i ,.;, .. j .
I hic in~ ention relatc~s to icc c~ltth~g~le~ ices to l-e fille(l onlo or hlcoll)ol.lte(l illtO chi ~ropel I ers .
Tlle ship propellers referred to here are marine screw propellers. Such propellers have se~ eral blades arranged radially around a central hub. The blades have circulllferential cross sections shaped li}~e wing sections, having a rounded leading edge and a sharp trailing edge.
While these shapes are hydrodynamically efficient, meaning high lift and low drag, they can experience very high ice forces because they present a blunt face to the ice. To overcome high ice forces, propellers for ice-going ships are made 111llCh stronger and are characterized by thicli bl~de sections ancl relative large hub diameters. The thicker blades are less hydrodynamically efficient and are even blunter that normal. Ice-strengthened propeller blades are still often damaged by ice, or experience such high loads that they damage or impair other parts of the propulsion system, such as the blade pitch control mechanism, the shafting, shaft bearings, gearing and propulsion motor.
The use of ice CUttillg devices at the leading edge and extending along the outside (suction face) of the blade will change the mode of ice failure and lower the peak and average ice forces on the blades. Several cuttina devices, spaced along the leading edge, will act together to cut, rather than cmsh, the blocks of ice encountered by the propeller. Failure in the ice will initiate at the tips of the cutters~ so that the magnitude of the force is reduced.
::, :; In dMwings which illustrate embodiments of the invention. Figure ] is a front view of one embodiment with four cutters per blade. Figure ~ is a section of the line III-III, Figure 3 is a ~, section of the line IV-IV showing an embodiment of the cutter pro-file. Figure 4 is a section :` of the line IV-IV showing another embodiment of the cutter profle. Figure 5 is a general 1,'!j view of an embotliment with three cutters per blade and showing variations in the profiles of the cutters. Figure 6 shows an embodiment with an angular tooth shape Figure 7 shows an embodimcnt with thc cutter rcccssed into the blade surface. Fugurc 8 shows an embodiment with the full leading edge formed into an ice cutting profile.
The device illustrated is comprised of a number of cutters d, attached from the leading edge c of a marine screw propeller blade a, along part of the front face of the blade. The cutter profile come to a sharp edge at e and forms a finf that may vary in length, reaching part or ,'j all the way to the tMiling edge b. Various shapes of the fm profile may be used to improve :, cutting and minimize hydrodynamic loss of effeciency. Alternative embodiments of cutter geometry, an angular tooth g, a recessed tooth h, and a blade leading edge modified to Cllt ,!jl ice alona all or part of the leading edaej are versions of the ice load recluction device.
The attachment of the cutters to the blades may be accomp1ished by integral casting.-welding :~ or bolting.
,.,~
;.. -."
., :.' '`'I
~ i ,.;, .. j .
Claims (3)
1. The addition of teeth to a marine propeller for the purpose of breaking ice or reducing ice forces on the propeller blade.
2. Groves cut into the propeller blade, whose purpose is the minimization of ice -forces.
3. A complete re-shaping of the leading edge of the propeller blade, so as to make a portion or the entire blade into an ice cutting device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2100140 CA2100140A1 (en) | 1993-07-08 | 1993-07-08 | Ice load reduction device for ship propellers |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2100140 CA2100140A1 (en) | 1993-07-08 | 1993-07-08 | Ice load reduction device for ship propellers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2100140A1 true CA2100140A1 (en) | 1995-01-09 |
Family
ID=4151907
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2100140 Abandoned CA2100140A1 (en) | 1993-07-08 | 1993-07-08 | Ice load reduction device for ship propellers |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2100140A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108974299A (en) * | 2017-09-20 | 2018-12-11 | 航天晨光（福建）管业科技有限公司 | A kind of holding type Propeller Guard device |
| CN110450931A (en) * | 2019-08-20 | 2019-11-15 | 中船重工（上海）节能技术发展有限公司 | A kind of airscrew thrust fin and propeller |
-
1993
- 1993-07-08 CA CA 2100140 patent/CA2100140A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108974299A (en) * | 2017-09-20 | 2018-12-11 | 航天晨光（福建）管业科技有限公司 | A kind of holding type Propeller Guard device |
| CN108974299B (en) * | 2017-09-20 | 2020-01-07 | 航天晨光（福建）管业科技有限公司 | Accommodating type propeller protection device |
| CN110450931A (en) * | 2019-08-20 | 2019-11-15 | 中船重工（上海）节能技术发展有限公司 | A kind of airscrew thrust fin and propeller |
| CN110450931B (en) * | 2019-08-20 | 2020-10-02 | 中船重工（上海）节能技术发展有限公司 | Propeller thrust fin and propeller |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |