JPH02151596A - Rudder for two-shaft two-rudder ship - Google Patents

Abstract

PURPOSE:To contrive the improvement of propulsive efficiency by forming a rudder surface, not receiving a propeller back wash, in a right-left asymmetrical section bending a sectional shape of the rudder surface by a degree half the inflow angle so as to face the flow in the vicinity of a rudder and a rudder surface, receiving the back wash, in a symmetrical section. CONSTITUTION:A rudder surface 2, not receiving an acceleration flow of a propeller (b), is provided with a camber by bending a front end 1a of a rudder 1 about alpha/2 in a direction toward a flow (c) from a ship side. Accordingly, the rudder surface 2 is formed in a right-left asymmetrical section. A rudder surface 3, receiving the acceleration flow of the propeller (b), is formed in an symmetrical blade section as in the past. Accordingly, a shape of the rudder surfaces 2, 3 is discontinuously changed, but a rudder trailing edge 1b is not changed. By the constitution thus obtained, a rudder, partly providing an asymmetrical surface, increases a lift for a flow (e) from the ship side further obtaining a smooth flow, consequently a drag is decreased, enabling resistance to be reduced of the rudder 1 improving propulsive efficiency.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to the structure of a rudder for a two-shaft, two-rudder boat.

(Prior Art) As shown in FIG. 3, the rudder of a conventional two-rudder boat has 82 rudders each having a symmetrical airfoil cross-sectional shape attached to the rear of propeller b.

Also, as an example where the cross-sectional shapes of the left and right rudders a, a are asymmetrical,
It is a one-shaft, one-rudder vessel with a reaction rudder for the purpose of recovering the energy of the propeller rotation flow. Furthermore, as for a two-shaft, two-rudder boat, a high-speed boat with an asymmetrical structure is disclosed in Japanese Patent Application Laid-open No. 54397/1983 for the purpose of improving steering effectiveness.

(Problems to be Solved by the Invention) In a two-axle, two-rudder ship equipped with two propulsors and a rudder behind each of these propulsors, the resistance of the rudder can be improved by partially changing the cross-sectional shape of the ship. The goal is to reduce the amount of energy generated by the ship and improve the propulsion efficiency of the ship.

(Means for Solving the Problems by the Invention) In a two-shaft, two-rudder ship, the cut shape of the rudder surface that does not receive the propeller wake of the rudder installed at the rear of the propeller is adjusted to about half of the inflow angle α so that it faces the flow near the rudder. The blade was bent by an angle to create a bilaterally asymmetric cross section, and the section that received the propeller wake was a bilaterally symmetrical wing cross section.

(Example) As shown in Fig. 3, the flow C at the stern of a two-shaft, two-rudder ship is
There is an angle α in the direction from the side of the ship toward the hull centerline Q (this α varies depending on the hull type).On the other hand, the flow accelerated by propeller b flows parallel to the hull centerline Q while rotating. . In this case, the rudder force from the two rudders is (L
Lsinα−D□cosα)×2.

The rudder of the present invention focuses on this point, and as shown in FIGS. 1 and 2, the rudder 1 is moved in the direction toward the flow C from the gunwale with respect to the control surface 2 (FIG. 2) that does not receive the accelerated flow of the propeller b.
Bend the leading edge (front I#) la by approximately α/2,
This control surface 2 has a camber.

The control surface 3 (Fig. 2) that receives the accelerated flow of propeller b has a symmetric airfoil cross section as before.

Thus, although the shapes of the control surfaces 2 and 3 change discontinuously, the shapes of the front and rear edges 1b do not change and remain the same.

(Function) The rudder of a conventional two-shaft, two-rudder ship is bilaterally symmetrical as shown in Figure 3, and the rudder receives a lift force even when traveling straight against the flow C directed toward the inside of the stern, and the lift force L1 and Drag force D1 occurs (
Figure 3). However, although part of the lift force L contributes to thrust, the drag force D1 increases the resistance of the rudder.

On the other hand, the rudder 1 having a partially asymmetrical cross section as in the present invention,
As shown in Fig. 1, with respect to the flow C from the side, the lift force is increased and the flow becomes smoother, so the drag force D2 is reduced, and as a result, the resistance of the front 1 can be reduced, and the propulsion efficiency is improved. Can be done.

(Effects) In a two-shaft, two-rudder ship, the front surface, which does not receive the propeller flow, is bent by approximately 1/2 the inflow angle of the flow near the rudder to make the cross section asymmetrical.This generates lift and smoothes the flow. , the rudder resistance becomes smaller, the drag force decreases, and as a result, the propulsion efficiency can be further improved. By the way, the first
In the figure, since L2 is large and D2 is small, L2 sin α/2 is larger and D2coscz/2 is smaller, and the rudder resistance is reduced as a whole.

[Brief explanation of the drawing]

FIG. 1 is a bottom view of a ship equipped with a rudder according to the present invention. Figure 2 is also a detailed view of the rudder. FIG. 3 is an explanatory diagram of a conventional two-rudder vessel. In the figure: 1 Rudder la Leading edge 1b
Trailing edge 2, 3 Above the control surface Applicant Sumitomo Heavy Industries, Ltd. sub-agent Patent attorney Isamu Ohashi Figure 1

Claims (1)

[Claims] In a ship with two shafts and two rudders, the cut shape of the rudder surface that does not receive the propeller wake of the rudder installed at the rear of the propeller is bent by about half of the inflow angle α so as to face the flow near the rudder to create a left-right asymmetric cross section. A rudder for a two-shaft, two-rudder vessel, characterized in that the portion receiving the propeller wake has a symmetrical wing cross section.