JPH02144296A - Local flow generation preventing structure in discontinuous part of reaction rudder - Google Patents

Abstract

PURPOSE:To improve performance with a local flow prevented from its generation by bridging a horizontal thin blade in a discontinuous part between the bottom part of a rudder upper part and the top part of a rudder lower part in the central part of a reaction rudder. CONSTITUTION:A horizontal thin blade 4 is secured between the bottom part of a rudder upper part Ra and the top part of a rudder lower part Rb. By this horizontal thin blade 4, a flow can be suppressed in an angular part from its positive pressure side to negative pressure side even when the rudder upper and lower parts Ra and Rb generate in their outside a positive pressure and inside a negative pressure. Accordingly, propulsive energy can be effectively utilized of a ship by a large screw contriving the improvement of performance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a structure for preventing the generation of local flow at discontinuous portions of a reaction rudder.

(Prior Art) It is known that as ship propellers become larger and rotate at lower speeds, the resistance of the rudder located in the wake of the ship increases, which adversely affects propulsion performance.

To deal with this, a reaction rudder (Reaction rudder)
udder) R (Figure 5) is being considered. As shown in FIGS. 5 to 8, this is a rudder that swings around a rudder shaft 1, and the nose line of the rudder R (nose 1
ine) is divided into a rudder lower part Ra and a rudder lower part Rb, each of which curves outward in the horizontal direction with respect to the center line C of the screw shaft,
In this case, a discontinuous portion A of the nose line is created.

When this reaction rudder is viewed from the front, it looks like FIG. 6 or FIG. 9. As shown in Figures 7 and 8, due to the water flow S from the front, positive pressure (indicated by Φ) is applied to the outside of the rudder based on the wing theory.
Similarly, the inside becomes negative pressure (indicated by O). Therefore, the flow from the positive pressure side to the negative pressure side (reference numeral 3 in Figure 9) is
occurs in This is an ineffective flow that has no effect on the forward movement of the rudder, in other words, a flow that acts as resistance.

(Problems to be Solved by the Invention) In view of the problems of the reaction rudder, it is an object of the present invention to prevent the flow 3 from occurring at the corner portions 2a and 2b, and to further improve the performance of the reaction rudder.

(Means for Solving the Problems According to the Invention) The reaction rudder is characterized in that a horizontal thin blade is spanned across a discontinuous portion between the bottom of the rudder lower part and the top of the rudder lower part in the central part of the reaction rudder.

(Example) In FIG. 1, 4 is a horizontal thin blade fixed between the bottom of the rudder lower part Ra and the top of the rudder lower part Rb. When this horizontal thin blade is provided, as shown in Fig. 4, the outer side of the rudder lower part Ra and the rudder lower part Rb has positive pressure and the inside has negative pressure, which is exactly the same as before, but there is a positive pressure at the corners 2a and 2b. No flow from the pressure side to the negative pressure side occurs.

Figures 7 and 8 are cross-sectional views of Figure 2, ■-■ and ■-
■It is a sectional view. In the figure, the convex side is the center of the screw shaft v@C
side, concave side or the opposite side. As is clear from the figure, the water flow S from the screw generates a lift force F on the lower rudder parts Ra and Rb, but of this F, a component force Fa in the direction of the center line C of the screw shaft is generated, and this is the force on the ship. It becomes forward energy.

In this case, since the flow 3 generated at the discontinuous portion A in FIG. 9 is attenuated, the energy in the forward direction increases accordingly, and the screw energy can be used more effectively.

(Effects) Since horizontal thin blades are placed across the discontinuous part of the reaction rudder, local flow can be prevented from occurring in this area. Therefore, it became possible to effectively utilize the ship's propulsion energy from the long screw.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a reaction rudder according to the present invention. Figure 2 is also a front view. FIG. 3 is a view taken along the line mm in FIG. 2. FIG. 4 shows the pressure state of the discontinuous portion spanned by the horizontal thin blade in the present invention. FIG. 5 is a perspective view of a known reaction rudder. Figure 6 is also a front view. FIG. 7 is a sectional view taken along the line ■-■ in FIG. 6. FIG. 8 is a sectional view taken along the line ■-■ in FIG. 6. FIG. 9 shows a state in which local flow occurs at a discontinuous portion of a known reaction rudder. In the figure; 1 rudder shaft 2a, 2b corner 3 flow
4 Horizontal thin wing or more Fig. 1 Fig. 5 Fig. 1 Rudder shaft 1 Broadside Fig. 3 R Fig. 4 Fig. 8 Fig. 9 - - 2o Bird Fig. 6 Fig. 7

Claims (1)

[Claims] Prevention of local flow at a discontinuous part of a reaction rudder, characterized in that a horizontal thin blade is spanned over the discontinuous part between the bottom of the upper rudder part and the top of the lower part of the rudder in the central part of the reaction rudder. structure.