JP2006111046A - Propeller for vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propeller for a vessel capable of improving cavitation performance and propeller efficiency. <P>SOLUTION: A maximum value of a camber is made to a shape positioned at a rear edge side more than 0.75 in a chord line direction (x/C), so as to restrain a high negative pressure peak value at a leading edge and delay initial generation of cavitation. The leading edge side of the camber is made small, and the trailing edge side is made large. The camber increment at the rear part is made large compared to the camber decrement at the front part, so as to enlarge a lifting force almost without changing resistance force and improve efficiency of the propeller. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a marine propeller, which improves cavitation resistance, obtains lift without increasing drag, and improves propeller efficiency.

  In a marine propeller that rotates in water at high speed, if the pressure is very small around the wing and a region that partially falls below the saturated vapor pressure at that water temperature occurs, the water in this region evaporates and bubbles are generated. In other words, so-called cavitation occurs.

  When this cavitation occurs in a marine propeller, the cavity generated near the front edge of the propeller blade surface collapses when exposed to the high pressure region of the blade trailing edge or blade tip, and impact pressure reaching hundreds of atmospheres is applied to the blade surface. There are problems such as erosion.

  Various proposals have been made to prevent such cavitation and erosion caused by the cavitation. For example, in the propeller of Patent Document 1, a predetermined region A of the propeller body 1 is used to suppress cavitation as shown in FIG. In FIG. 5, the radius of the front edge portion 1a is reduced, and the thickness of the rear edge portion 1b is increased in another predetermined region C.

  Further, in the marine propeller of Patent Document 2, in order to prevent route erosion, as shown in FIG. 5, the cross-sectional shape of the blade root portion 1c of the propeller body 1 is gradually increased from the maximum thickness position to the rear edge 1b. Further, the thickness is reduced and the rear end is still thick, and the intersection between the rear end face and the wing side face is rounded.

On the other hand, as for the blade cross-sectional shape of a marine propeller capable of suppressing cavitation as much as possible, as shown by a broken line in FIG. The one (NACA cross section) that is positioned at the center (x / C = 0.5) in the chord length direction is widely used.
JP 2000-79897 A JP-A-8-91291

  However, when examining the cross-section shape of a marine propeller widely used until now, it was found that there is room for improvement in cavitation performance and the like.

  That is, as shown by a broken line in FIG. 2, the inventors have obtained knowledge that the negative pressure peak at the leading edge of the blade cross section is large and that the pressure distribution varies greatly.

  This invention is made in view of the subject of this prior art, and intends to provide the marine propeller which can improve a cavitation performance, propeller efficiency, etc.

  In order to solve the above-described problems of the prior art, the marine propeller according to claim 1 of the present invention is configured such that the cross-sectional shape of the marine propeller has a camber maximum position on the trailing edge side from the center in the chord length direction (x / C) It is characterized by having a shape for positioning.

  According to this marine propeller, by setting the maximum position of the camber to the rear edge side from the center portion, it is possible to suppress the negative pressure peak value at the front edge from becoming high, and to delay the initial generation of cavitation.

  Further, in the marine propeller of the present invention, in addition to the above-described configuration, the camber has a maximum position on the trailing edge side of 0.75 in the chord length direction (x / C), or the camber, The front edge side is made smaller and the rear edge side is made larger.

  These marine propellers delay the initial generation of cavitation, reduce cavitation and surface force, and increase the increase in the rear camber against the decrease in the front camber, thereby increasing the lift force with almost no change in the drag force. It is trying to improve.

  According to the marine propeller according to claim 1 of the present invention, since the maximum position of the camber is set to the trailing edge side from the central portion, it is possible to suppress the negative pressure peak value at the leading edge from being increased, and the initial generation of cavitation is achieved. Can be delayed.

  Further, in the marine propeller according to claim 2 of the present invention, the maximum position of the camber is configured to be positioned on the trailing edge side from 0.75 in the chord length direction (x / C), and the marine propeller according to claim 3. Then, because the camber has a shape with a smaller leading edge and a larger trailing edge, it can delay the initial generation of cavitation, reduce cavitation and surface force, and increase the rear camber against the decrease in front camber. By increasing the minutes, the lift can be increased without changing the drag force, and the propeller efficiency can be improved.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
1A and 1B show an embodiment of a marine propeller according to the present invention. FIG. 1A is an explanatory diagram of a schematic blade cross-sectional shape, and FIG. 1B is a cross-sectional shape of an airfoil and a camber line shown in comparison with a conventional shape. FIG.

  In this marine propeller 10, the maximum position 14 of the camber 13 in the blade cross section 12 of the propeller body 11 is located on the trailing edge 11 b side from the central portion in the chord length direction x / C, preferably in the chord length direction x / C = 0. It is made to shift to the trailing edge 11b side from 75, and the initial generation of cavitation is delayed.

 For this reason, the camber at the leading edge in the blade cross section is made smaller and the camber at the trailing edge is made larger.

  The maximum position 14 of the camber 13 is the center of the chord length direction x / C = 0.5 as shown by the broken line 3 in FIG. 1 in the conventional airfoil, whereas in the marine propeller 10, As indicated by the solid line 13 in FIG. 1, the maximum position 14 of the camber 13 is shifted in the chord length direction x / C = 0.75 on the trailing edge side from the center portion.

  Thus, by shifting the maximum position 14 of the camber 13 in the blade cross section of the marine propeller 10 to the rear edge 11b side from the center, the negative pressure peak at the front edge 11a can be reduced, and the pressure distribution is flattened. In particular, by shifting to the trailing edge 11b side from the chord length direction x / C = 0.75, the negative pressure peak can be further reduced and the pressure distribution can be flattened.

 Therefore, the measurement result of the pressure distribution when the maximum position 14 of the camber 13 is shifted in the chord length direction x / C = 0.75 on the rear end side from the center is shown in FIG. 2 in comparison with the conventional airfoil. Indicated.

 In this figure, the horizontal axis is the chord length direction x / C, and the vertical axis is the pressure distribution Cp. In the case of the new airfoil type indicated by the solid line in FIG. It can be seen that the negative pressure peak at the leading edge 11a of Cp decreases, and the pressure distribution over the entire region becomes flat.

 Thus, by suppressing the negative pressure peak at the leading edge 11a from being high as indicated by a broken line, the initial generation of cavitation can be delayed.

  Further, in the marine propeller 10, the camber on the front edge side (x / C = 0 side) is reduced, and the camber increase on the rear end 11b side (x / C = 1.0 side) is increased.

  In this way, the maximum position 14 of the camber 13 is shifted to the trailing edge 11b side of the chord length direction x / C, and the camber on the leading edge 11a side (x / C = 0 side) is reduced, so that the trailing end (x / By increasing the camber increase of (C = 1.0), the initial generation of cavitation can be delayed, and by suppressing cavitation, the surface force induced on the bottom of the ship can be reduced by increasing cavitation.

  Furthermore, in this marine propeller 10, the camber on the front edge side (x / C = 0 side) is reduced, and the increase in the camber at the rear end (x / C = 1.0) is increased, so that the drag is almost changed. Without gaining lift, thereby improving propeller efficiency.

  According to such a marine propeller 10, for example, when the cavitation performance is set to the same level as the conventional one, by using this marine propeller 10, according to a trial calculation, as shown in FIG. The weight can be reduced by 10%, and the propeller single efficiency can be improved by 2%.

1A is an explanatory view of a schematic blade cross-sectional shape, and FIG. 2B is an explanatory view of a blade shape cross-sectional shape and a camber line shown in comparison with a conventional shape. It is a graph which shows the change of the pressure coefficient of the chord length direction concerning one Embodiment of the ship propeller of this invention. It is a graph which shows the change of the load degree concerning one embodiment of the marine propeller of this invention, and propeller independent efficiency. It is explanatory drawing of the shape of the conventional marine propeller. It is explanatory drawing of the shape of the other conventional marine propeller.

Explanation of symbols

10 Marine Propeller 11 Propeller Body 11a Leading Edge 11b Trailing Edge 12 Blade Cross Section 13 Camber 14 Maximum Position x / C Blade Chord Length Direction

Claims (3)

  A marine propeller characterized in that the cross-sectional shape of a marine propeller is shaped such that the maximum position of the camber is located on the trailing edge side of the center of the chord length direction (x / C).   2. The marine propeller according to claim 1, wherein the maximum position of the camber is configured to be positioned on the trailing edge side of 0.75 in the chord length direction (x / C). 3. The marine propeller according to claim 1 or 2, wherein the camber has a shape in which a front edge side is reduced and a rear edge side is increased.

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