JPS5830896A - Reaction rudder without discontinuous part - Google Patents

Abstract

PURPOSE:To increase the rotative flow energy recovery ratio and lessen the rudder resistance by determining specially the distribution of the amount of twist of a rudder plate in relation to a propeller shaft line. CONSTITUTION:A reaction rudder 1 is symmetrical in shape which has no twist at its three points: the extension (a) of the propeller shaft line and the top and bottom ends of the rudder. The leading edge of the rudder plate in way of an upper section (b) above the extension of the propeller shaft line and that in way of a lower section (c) below the extension of the propeller shaft line are twisted conversely, or twisted toward the port side in the former (b), while the starboard side in the latter (b), and the amount of twist varies continuously with respect to a vertical direction. This constitution gives a better accord with the stream.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a reaction rudder among rudders for ships.

A normal rudder on a ship has a symmetrical airfoil shape, as shown in the cross-sectional view in Figure 1, and does not have a shape suitable for rectifying the flow behind the propeller, so the thrust of the rudder itself is smaller than that of a reaction rudder. .

A reaction rudder has a special airfoil-shaped fin attached to its leading edge, which can rectify the flow behind the propeller and generate thrust on the rudder itself, increasing the ship's propulsion force.

However, the conventional reaction rudder is as shown in Fig. 2 (A) (B) (
As shown in C), the part (α) above the extension line of the propeller axis and the part (A) below the extension line of the propeller axis are mutually adjacent to each other with the vicinity of the extension line of the propeller axis as a boundary. It is twisted in opposite directions and the upper and lower cross sections are discontinuous.

Therefore, there was a tendency not only to increase resistance due to discontinuity, but also to increase forward resistance due to the cross-sectional shape opposing the flow.

The present invention aims to save energy by modifying the rudder of not only new ships but also existing ships, avoiding the increase in resistance as in the past.In order to rectify the wake of the propeller, the The blade has a symmetrical airfoil shape without twisting, and the portions above and below the extension line of the propeller axis are twisted in opposite directions with the extension line of the propeller axis as the boundary, thereby making the twist continuous. It is characterized by having been changed to.

Embodiments of the present invention will be briefly described below with reference to the drawings.

Figure 3 shows the installation state of the reaction rudder of the present invention, and Figure 4 (A)
(As E9 shows the reaction rudder of the present invention (, the reaction rudder of the present invention (
The propeller (2) has a symmetrical airfoil shape with no twist in the vicinity of the extension line of the o-axis center (A) and in the vicinity of both the upper and lower ends of the rudder.
The front edges of the upper part (B) and lower part (C) of the fine extension line of 1) are moved in opposite directions, that is, the upper part (
In (b), it twists to the port side, and in the lower part (c), it twists to the starboard side, so that the amount of twist changes continuously in the vertical direction as shown in FIG. 4 (B).・ With the above configuration, the propeller wake is directed to the port side in the part (b) above the propeller axis extension line as shown in Fig. 5 (A).
It flows in at an inflow angle of α from the center, and near the propeller axis extension line, it flows in as shown in Figure 5 (03), and in the part (c) below the propeller axis extension line, it flows on the starboard side as shown in Figure 5 (c). It flows in from. Also, at the position of the extension of the propeller axis, the velocity component perpendicular to the control surface is almost zero, as shown in FIG. 6, unlike the potential theory result.

Therefore, in the reaction rudder of the present invention, the propeller trailing flow is not disturbed, there is little resistance, and thrust can be generated.

In this regard, in the conventional reaction rudder shown in Fig. 2, the cross section is twisted to the maximum in a vertically discontinuous manner at the extension line of the propeller axis, so not only does the discontinuity increase resistance, but also the cross-sectional shape is against the flow. There is also an increase in resistance due to

In addition to twisting the front surface of the rudder as shown in FIG. 4, there are also cases in which the rudder's entire section is twisted, such as twisting the rear surface. The amount of twist and the shape of the asymmetric airfoil due to twist are:
The shape is such that (shape resistance + induced resistance) decreases and lift increases as the flow progresses. At this time, the thrust exerted by the rudder is at its maximum. Now, the thrust force T is generated by the thrust generating mechanism shown in Fig. 7.
occurs at T = L' sin α−CDi+Dp)・Co5a.

However, Di = Induced resistance DP = Shape resistance L': Lift ■ = Inflow speed (including propeller induced speed) WI: Induced speed of rudder α: Inflow angle of V αe: Actual inflow angle L: Lift for αe Thus, the reaction rudder of the present invention has a symmetrical airfoil shape with no twist in the vicinity of the extension line of the propeller axis and in the vicinity of both the upper and lower ends of the rudder. Since the twist amount changes continuously in the opposite direction, it matches the flow 2 better than the conventional discontinuous type, improving the rotational flow energy recovery rate and reducing resistance. Therefore, by installing the reaction rudder of the present invention, a horsepower reduction of 2 to 3% can be achieved.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional rudder, Figure 2 (A) is a perspective view of a conventional reaction rudder, and Figure 2 (B) &'! FIG. 2(A) is a front view, FIG. 2(c) is a cross-sectional view of FIG. 2(A), FIG. 3 is a side view showing the installed state of the reaction rudder of the present invention, and FIG. ) is a perspective view for detailed explanation of the present invention, and FIG. 4(B) is a perspective view for explaining the invention in detail.
A) is a front view, FIGS. 5(A), (B), and (C) are cross-sectional views of the reaction rudder of the present invention at different positions in the vertical direction, and FIG. 6 is a diagram showing the speed acting on the control surface of the reaction rudder of the present invention. Diagram showing components, No. 7
The figure shows a mechanism that generates thrust. (1)...Reaction rudder, (2)...Propeller. Patent applicant: Ishikawajima-Harima Heavy Industries Co., Ltd.

Claims (1)

[Claims] 1) In order to rectify the flow behind the propeller, the airfoils should be symmetrical without twisting near the extension line of the propeller axis, and the parts above and below the extension line of the propeller axis should be shaped like an extension of the propeller axis. A reaction rudder without a discontinuous part characterized by continuously changing the twist by twisting in opposite directions near the line.