SHIP PROPELLER
A ship propeller includes a hub having an outer periphery, a first blade set including a plurality of first blades each having a span-chord ratio substantially in a range of 3 to 8 and a second blade set including a plurality of second blades each having a span-chord ratio substantially in a range of 3 to 8. The first blade set and the second blade set are situated in different planes of rotation and working at the same rotation direction and the same rotation speed. Furthermore, the distance between the first blade set and the second blade set is 30 percent less than the mean blade radius. Specifically, the ship propeller has a total expanded area ratio substantially no less than 0.7.
The present invention relates to a ship propeller and, in particular, to a ship propeller for further improving propulsion efficiency of the ship.
BACKGROUND OF THE INVENTION
where R is the blade radius, rh is the hub radius and Cm is the mean chord length, wherein the mean chord length is defined as:
where Ab is the blade area.
As natural resources become rarer and rarer, how to save energy is gradually becoming a very important issue. Accordingly, how to make a propulsion device work with higher efficiency is always pursued.
One of the attempts is the contra-rotating propeller. However, one drawback of contra-rotating propeller is that it has more complicated structure causing difficulties in fabrication and control. Therefore, there is a need to improve propulsion efficiency of a ship propeller in order to reduce energy consumption and running cost in a prerequisite of not increasing the fabrication complexity.
SUMMARY OF THE INVENTIONAn object of this invention is to provide an energy-saving ship propeller for further improving propulsion efficiency so as to reduce energy consumption to reach the goal of saving energy and reducing the running cost in a prerequisite of not increasing the fabrication complexity.
To solve the foregoing problem, the ship propeller of the present invention includes: a hub having an outer periphery; a first blade set including a plurality of first blades, wherein each first blade has a span-chord ratio substantially in a range of 3 to 8 and projects outward from the outer periphery of the hub; and a second blade set including a plurality of second blades, wherein each second blade has a span-chord ratio substantially in a range of 3 to 8 and projects outward from the outer periphery of the hub. The first blade set and the second blade set are situated in different planes of rotation and working at the same rotation direction and the same rotation speed; and the distance between the first blade set and the second blade set is 30 percent less than the mean blade radius. Specifically, the ship propeller has a total expanded area ratio substantially no less than 0.7, and the cross-section of each first blade and the cross-section of each second blade are streamlined foil shape respectively. The plurality of second blades can be disposed without overlapping the plurality of first blades or alternatively disposed at least partially overlapping the plurality of first blades from the rotation axis view angle. The plurality of first blades and the plurality of second blades are evenly distributed around the outer periphery of the hub respectively.
The detailed technology and above preferred embodiments implemented for the present invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention.
The foregoing aspects and many of the accompanying advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description when taken in conjunction with the accompanying drawings, wherein:
The detailed explanation of the present invention is described as following. The described preferred embodiments are presented for purposes of illustrations and descriptions, and they are not intended to limit the scope of the present invention.
The present invention discloses a ship propeller having a total expanded area ratio substantially no less than 0.7, in which the total expanded area ratio is the ratio of total blade area of the ship propeller divided by the propeller disc area. The ship propeller includes a hub having an outer periphery and a plurality of blade sets. Each of the plurality of blade sets includes a plurality of blades each having a span-chord ratio substantially in a range of 3 to 8 and projecting outward from the outer periphery of the hub. Moreover, the blade radius of each blade set can be identical or varied from one to another. In addition, the plurality of blade sets are situated in different planes of rotation and working at the same rotation direction and the same rotation speed, and the distance between two adjacent blade sets is 30 percent less than the mean blade radius. The mean blade radius for a number of blade sets is defined as:
where n is the number of blade sets and R1 to Rn are the blade radii of the blade sets respectively.
In one preferred embodiment as shown in
Ad=π·(Rg)2
where Ad is the propeller disc area, it is circumference ratio and Rg is the greater one of R1 and R2.
In general, the total expanded area ratio of the ship propeller 2 is usually less than 1.
In this preferred embodiment, as shown in
However, the plurality of second blades can also be disposed at least partially overlapping the plurality of first blades from rotation axis view angle in other embodiments. For example, as shown in
Similarly, in
The effect of the present invention has been verified in experiments and numerical analysis, and the results of which are shown in
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
1. A ship propeller, comprising:
- a hub having an outer periphery; and
- a plurality of blade sets, wherein each of the plurality of blade sets comprises a plurality of blades, wherein each blade has a span-chord ratio substantially in a range of 3 to 8 and projects outward from the outer periphery of the hub, wherein the plurality of blade sets are situated in different planes of rotation and working at the same rotation direction and the same rotation speed, wherein the ship propeller has a total expanded area ratio substantially no less than 0.7.
2. A ship propeller according to claim 1, wherein the distance between two adjacent blade sets is 30 percent less than the mean blade radius.
3. A ship propeller, comprising:
- a hub having an outer periphery;
- a first blade set comprising a first plurality of blades, wherein each of the first plurality of blades has a span-chord ratio substantially in a range of 3 to 8 and projects outward from the outer periphery of the hub; and
- a second blade set comprising a second plurality of blades, wherein each of the second plurality of blades has a span-chord ratio substantially in a range of 3 to 8 and projects outward from the outer periphery of the hub, wherein the first blade set and the second blade set are situated in different planes of rotation and working at the same rotation direction and the same rotation speed, wherein the ship propeller has a total expanded area ratio substantially no less than 0.7.
4. A ship propeller according to claim 3, wherein the distance between the first blade set and the second blade set is 30 percent less than the mean blade radius.
5. A ship propeller according to claim 3, wherein the cross-section of each of the first plurality of blades and the cross-section of each of the second plurality of blades are streamlined foil shape respectively.
6. A ship propeller according to claim 3, wherein the second plurality of blades are disposed without overlapping the first plurality of blades from rotation axis view angle.
7. A ship propeller according to claim 3, wherein the second plurality of blades are disposed at least partially overlapping the first plurality of blades from rotation axis view angle.
8. A ship propeller according to claim 3, wherein the first plurality of blades and the second plurality of blades are evenly distributed around the outer periphery of the hub respectively.
9. A ship propeller according to claim 3, wherein each of the first plurality of blades is forwardly skewed.
10. A ship propeller according to claim 3, wherein each of the first plurality of blades is backwardly skewed.
11. A ship propeller according to claim 3, wherein each of the first plurality of blades is backwardly skewed in the region adjacent to the root portion and forwardly skewed in the region adjacent to the tip portion.
12. A ship propeller according to claim 3, wherein each of the first plurality of blades is forwardly skewed in the region adjacent to the root portion and backwardly skewed in the region adjacent to the tip portion.
13. A ship propeller according to claim 3, wherein each of the second plurality of blades is forwardly skewed.
14. A ship propeller according to claim 3, wherein each of the second plurality of blades is backwardly skewed.
15. A ship propeller according to claim 3, wherein each of the second plurality of blades is backwardly skewed in the region adjacent to the root portion and forwardly skewed in the region adjacent to the tip portion.
16. A ship propeller according to claim 3, wherein each of the second plurality of blades is forwardly skewed in the region adjacent to the root portion and backwardly skewed in the region adjacent to the tip portion.
Type: Application
Filed: Apr 3, 2012
Publication Date: Oct 3, 2013
Inventor: Yih-Wei Tzeng (New Taipei City)
Application Number: 13/437,948
International Classification: B63H 1/14 (20060101);