CN1036180A - Ship's stern bulb - Google Patents

Abstract

The propelling of the present invention and self-propelled ship, especially relevant with its stern shape.The invention describes a kind of new and superior ball nose shape stern, it does not resemble former stern bulb, is not that streamline carries out the transition to hull, and is opposite but interrupt to produce between two surfaces significantly discontinuous suddenly, cause turbulent area, and transform wake near as the propelling unit desirable flow pattern along cross-shaped portion.Form even wake field to improve propeller efficiency and to reduce its vibration in the propelling unit circumferential area, its effect is for improving angle of rake noise and its net effciency, and various advantages are confirmed by each campaign.

Description

Ship's stern bulb

The present invention is relevant with the propelling of self-propelled ship, and is concrete relevant with the form of stern.

The device of self-propelled has early begun as since the propulsion of ship, and vibration and relevant issues that the propelling unit that the propelling unit blade causes when turning round in inhomogeneous wake field causes just have been the problem of research.

In theory, the propelling unit blade can be the specific speed of advance in water and designs, and its parameter (area, spiral shell square or the like) when when rotating under this speed, produces maximum lift and minimum tangential resistance through selecting in water.But unfortunate influence owing to hull, the wake multilated, and the nonuniform speed flow field of crossing screw propeller week area (and near the elsewhere the hull) is arranged, in this zone, turbulent flow is arranged usually.The liquid that blade changes usually through speed in the rotation in a week produces vicissitudinous lift, causes blade vibration and total decrease in efficiency.The existing many designers of this problem in all sorts of ways and tackle, and perhaps design the blade system of various sizes and configuration, or in the angle of rake the place ahead that is right after various forms of spheroids are set, and attempt to cause wake flow pattern uniformly.

Background thought of the present invention and all other systems are different, it be not attempt to force taken place and strained liquid stream change into a new flow pattern, but adopt a kind of sphere, far in propelling unit the place ahead, exactly may be with alteration of form the place upset of current cause turbulent flow, along the surface that suitably limits, be transformed into the ideal uniform flow pattern then.Obtaining of above-mentioned turbulent flow is because make hull surface that a unexpected variation be arranged, and it is long-pending to have increased by a block in current, and the former i.e. handing-over line between this ball nose shape and hull, and the latter is ball nose body itself.In a series of tests of going ahead of the rest, show in order to produce above-mentioned turbulent area, angle between ball nose shape and the hull surface (being shown α among Fig. 2) should be less than 120 degree in the front portion of ball nose shape, the junction of this ball nose shape and hull should not have the stream line pattern transition, or minimum stream line pattern is arranged.And test shows that for common hull size and speed, when the streamline arc radius was about 300mm, this turbulent flow phenomenon began to disappear.In addition,, should make improved wake obtain the characteristics of laminar flow again in the design, and keep reaching propelling unit always making the shape on itself and the incoherent ball nose of hull shape shape surface consciously.Can expect the effect that has additional hull resistance to reduce like this, to be stored in stern usually original because can eliminate, and cause the turbulent flow part of very big resistance.The resistance that causes like this descends, and is equal to or greater than the resistance that itself increase on ball nose shape surface at least.Thereby producing total drag descends.Up to now, this theory of evidence of existing three independent series in an example, illustrates that total drag decline has reached 10%.Except that the characteristics of the invention described above, be the circular ideal flow pattern of the laminar wake field of obtaining screw propeller oar week, it is circular that the cross-sectional plane of this ball nose shape should be, and perhaps to a certain particular vessel, this circle slightly becomes work, reaches the sub-circular that can revise wake field flow spectrum.

Another aspect of the present invention except that saving the running expense, also helps to save investment.After adopting ball nose shape as herein described, can avoid traditional complicated shape at stern rear portion.As if though the shape of ball nose shape itself is special, cost is still quite cheap.

For helping understand better the present invention, now provide description of drawings, wherein:

Fig. 1 shows the outward appearance front elevation of the hull that ball nose shape of the present invention is installed.

Fig. 2 shows the birds-eye view by ball nose center line and adjacent vessels part of horizontal section (along waterline).

The typical cross section of Fig. 3 display ball nose shape.

The ball nose shape of this paper narration is the desired angle that obtains with the hull handing-over, and depends on the hull shape of given ship, design speed, and the power of installation and many other parameters can have ball nose shape, size and the position of certain scope.For the sake of clarity, most typical giving an example only is shown in the accompanying drawing 1,2 and 3.Generally speaking, ball nose shape is theme of the present invention, and is shown in Figure 1, is the independent solid that a with dashed lines (1) draws, and it incorporates a part of blunt form of hull into, along track (2) and hull handing-over.And the hull shape (3) and the row that are illustrated in midline advance device (5).For stablizing the wake between hull and the ball nose shape, insert one betwixt and connect fin (4).As for butt joint needs, can add the keel (6) of the box section of a weak point.The additional advantage that this ball nose shape is installed is to generate basic configuration along the center line of simplifying, and the traditional and complicated shape that illustrates with Fig. 1 dotted line (7) is different.

The profile (1) of Fig. 2 display ball nose shape and (being easy to like this make) waterline (8) of simplifying, different with traditional ball nose shape waterline (9).So the turbulent area (10) along the current of hull becomes the laminar region (11) that propelling unit is worked therein, this traditional location with turbulent area (12) is different.Fig. 2 goes back the critical angle α between display ball nose shape and the hull surface.

Fig. 3 has shown the section at ball nose shape maximum gauge place, and (13) are the profile of ball nose shape, and (14) are the profiles of the hull afterbody of simplification, and the section of (15) expression " tradition " stern bulb is complicated and difficult during shipbuilding.Shown in the left side that is arranged in section of typical case's skeleton, the extra free space (16) that ball nose shape is caused is described.

Ball nose shape of the present invention and the interface point of hull between, any one cross-sectional plane all is positive circle or sub-circular.Ball nose shape level between its front and rear edge is elongated, and is connected with the hull part non-streamline transition of non-ball nose shape, and between ball nose shape leading edge and the place ahead, maximum cross section, section radius increases gradually.Between the trailing edge in maximum cross section and next-door neighbour's propelling unit the place ahead, section radius reduces gradually therebetween.The shape and size relative with adjacent vessels of this ball nose shape are the handing-over line leading edge rear this hull and ball nose shape, and width increases suddenly.The handing-over line of ball nose shape and hull is that any complete tangent smallest circle and another radius in this line place side is the line between the concentric circles of this tangent circles 75%.

The profile of ball nose shape (longitudinal profile (1) is shown in Fig. 1 and 2) particular importance should be according to concrete hull size, and the propeller shaft degree of depth and design speed and design the most important thing is design speed, but speed are can not be desired by the present inventor.In two series models test mentioned above, use representative type NACA0030 external form.

Claims (5)

1, a kind of angle of rake boats and ships that have as propulsioning means, it is characterized in that: this ship has and then a part and the ball nose shape that cross-sectional plane is a circle of angle of rake hull, this ball nose shape level between its front and rear edge is elongated, partly be connected with the hull of non-ball nose shape, in the place ahead, ball nose shape maximum cross section, be the non-streamline transition, this ball nose shape is between leading edge and midsection, section radius increases gradually, in the midsection be right after between the trailing edge in propelling unit the place ahead, section radius is decrescence little, and the shape and size relative with adjacent vessels of this ball nose shape are the handing-over line leading edge rear this hull and ball nose shape, width increases suddenly, along this handing-over line some points are arranged, the angle between hull on the point and ball nose shape surface is in the plane vertical with the handing-over line at that point, measure from the outside, angle is between 0 and 120 degree.

2, as the ball nose shape in the claim 1, it is characterized in that: ball nose shape enters hull with the curved surface form by streamline contour along the handing-over line, and the curved surface arc radius is equal to or less than 300mm and is suitable for, and can not cause the gap between this circle and the surface.

3, as the ball nose shape in the claim 1, it is characterized in that: and each cross-sectional plane between the handing-over line of hull all is positive circle or sub-circular, the handing-over line is any line between another concentric circles of this circle of contact radius 75% for circle and another radius that is in the tangent minimum of this line in this line outside fully.

4, use the marine vessel of the one or more ball nose shapes that limit in the claim 1,2 or 3.

5, the marine vessel of the one or more ball nose shapes that limit in a kind of use claim 1,2 or 3 is characterized in that: in this ball nose shape and hull separate areas, have a vertical connection fin that the rear portion of at least one this ball nose shape is connected with hull.

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