Marine propeller and method of design thereof

Patent metadata

Field	Value
Publication number	US-9745948-B1
Application number	US-201414317409-A
Country	US
Kind code	B1
Filing date	Jun 27, 2014
Priority date	Aug 30, 2013
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

A marine propeller has an outer hub having a central axis and a blade having a blade root attached to the outer hub and extending radially outward from the outer hub toward a blade tip. The blade has a leading edge and a trailing edge. The propeller has a diameter between about 15 inches and about 17 inches and a pitch between about 14 inches and about 24 inches. The blade has a progressive rake angle such that a first local rake angle at the blade root is less than a second local rake angle at the blade tip. A combination of the diameter, pitch, and progressive rake angle provides a marine vessel to which the marine propeller is coupled with minimum drag while the marine vessel is operating at less than a maximum vessel speed. A method of designing a propeller is also disclosed.

First claim

What is claimed is:

1. A marine propeller comprising:
an outer hub having a central axis; and
a blade having a blade root attached to the outer hub and extending radially outward from the outer hub toward a blade tip, the blade having a leading edge and a trailing edge;
wherein the propeller has a diameter between 15.5 inches and 16.5 inches;
wherein the propeller has a pitch between about 17 inches and about 23 inches;
wherein the blade has a progressive rake angle such that a first local rake angle at the blade root is less than a second local rake angle at the blade tip;
wherein the propeller has an expanded blade area ratio between about 0.52 and about 0.61;
wherein the expanded blade area ratio is related to the pitch such that an upper limit of the expanded blade area ratio is defined by the relationship EBAR=−0.005*P+0.685 and a lower limit of the expanded blade area ratio is defined by the relationship EBAR=−0.005*P+0.635, where EBAR is the expanded blade area ratio and P is the pitch;
wherein the blade has an average rake angle from the root to the tip, and the average rake angle is related to the pitch such that an upper limit of the average rake angle is defined by the relationship R=0.02083*P^3−1.4643*P^2+34.372*P−238.44 and a lower limit of the average rake angle is defined by the relationship R=0.02083*P^3−1.42*P^2+32.5506*P−226.209, where R is the average rake angle;
wherein the blade has a maximum cross-sectional thickness at a location between about 25% and about 40% of a length of a chord extending from the leading edge to the trailing edge, as measured from the leading edge; and
wherein a combination of the diameter, pitch, progressive rake angle, expanded blade area ratio, average rake angle, and location of the maximum cross-sectional thickness minimizes a drag on a marine vessel to which the marine propeller is coupled while the marine vessel is operating at less than a maximum vessel speed.

2. The marine propeller of claim 1 , wherein the diameter is about 16 inches.

3. The marine propeller of claim 1 , wherein the expanded blade area ratio is between about 0.56 and about 0.57.

4. The marine propeller of claim 3 , wherein the expanded blade area ratio is related to the pitch such that the expanded blade area ratio is defined by the relationship EBAR=−0.000104*P^3+0.0063*P^2−0.126*P+1.3946.

5. The marine propeller of claim 1 , wherein the average rake angle is between about 12 degrees and about 31 degrees.

6. The marine propeller of claim 5 , wherein the average rake angle is between about 15 degrees and about 29 degrees.

7. The marine propeller of claim 6 , wherein the average rake angle is related to the pitch such that the average rake angle is defined by the relationship R=0.015625*P^3−1.1942*P^2+29.8951*P−217.545.

8. The marine propeller of claim 1 , wherein the maximum cross-sectional thickness is located at about 35% of the length of the chord, as measured from the leading edge.

9. The marine propeller of claim 1 , wherein the propeller optimizes fuel efficiency of the marine vessel to which it is coupled when the marine vessel is operating at a speed that is between 50% and 70% of the maximum vessel speed.

10. The marine propeller of claim 1 , further comprising three blades attached to the outer hub.

11. A marine propeller comprising:
an outer hub having a central axis; and
a blade having a blade root attached to the outer hub and extending radially outward from the outer hub toward a blade tip, the blade having a leading edge and a trailing edge;
wherein the propeller has a diameter of 16 inches;
wherein the propeller has a pitch of one of about 17 inches, about 19 inches, about 21 inches, and about 23 inches;
wherein the propeller has an expanded blade area ratio that is related to the pitch such that the expanded blade area ratio is defined by the relationship EBAR=−0.000104*P^3+0.0063*P^2−0.126*P+1.3946, where EBAR is the expanded blade area ratio and P is the pitch;
wherein the blade has a progressive rake angle such that a first local rake angle at the blade root is less than a second local rake angle at the blade tip;
wherein the blade has an average rake angle from the root to the tip that is related to the pitch such that the average rake angle is defined by the relationship R=0.015625*P^3−1.1942*P^2+29.8951*P−217.545, where R is the average rake angle; and
wherein the blade has a maximum cross-sectional thickness at a location between about 25% and about 40% of a length of a chord extending from the leading edge to the trailing edge, as measured from the leading edge;
wherein a combination of the diameter, pitch, expanded blade area ratio, progressive rake angle, average rake angle, and location of the maximum cross-sectional thickness minimizes a drag on a marine vessel to which the marine propeller is coupled while the marine vessel is operating at a speed that is between 50% and 70% of a maximum vessel speed.

12. The marine propeller of claim 11 , wherein the expanded blade area ratio is between about 0.52 and about 0.61.

13. The marine propeller of claim 12 , wherein the expanded blade area ratio is between about 0.56 and about 0.57.

14. The marine propeller of claim 12 , wherein the average rake angle is between about 12 degrees and about 31 degrees.

15. The marine propeller of claim 14 , wherein the average rake angle is between about 15 degrees and about 29 degrees.

16. The marine propeller of claim 15 , wherein the average rake angle from the root to the tip is about 20 degrees when the pitch is about 17 inches, or is about 27 degrees when the pitch is about 19 inches, about 21 inches, or about 23 inches.

17. A marine propeller comprising:
an outer hub having a central axis; and
three blades, each blade having a blade root attached to the outer hub and extending radially outward from the outer hub toward a blade tip, each blade having a leading edge and a trailing edge;
wherein the propeller has a diameter of 16 inches;
wherein the propeller has a pitch of one of about 17 inches, about 19 inches, about 21 inches, and about 23 inches;
wherein the propeller has an expanded blade area ratio of about 0.56;
wherein each blade has a progressive rake angle such that a first local rake angle at the blade root is less than a second local rake angle at the blade tip;
wherein each blade has an average rake angle from the root to the tip of about 20 degrees when the pitch is about 17 inches, or of about 27 degrees when the pitch is about 19 inches, about 21 inches, or about 23 inches; and
wherein each blade has a maximum cross-sectional thickness at about 35% of a length of a chord extending from the leading edge to the trailing edge, measured from the leading edge;
wherein a combination of the diameter, pitch, expanded blade area ratio, progressive rake angle, average rake angle, and a location of the maximum cross sectional thickness minimizes a drag on a marine vessel to which the marine propeller is coupled while the marine vessel is operating at a speed that is between 50% and 70% of a maximum vessel speed.

Assignees

• Brunswick Corp

Inventors

• Koepsel Roger E

Classifications

• B63H1/18 Primary

  with means for diminishing cavitation, e.g. supercavitation · CPC title

• F03B3/121 Primary

  Blades, their form or construction · CPC title

• B63H1/26

  Blades · CPC title