The Local Transformation of the Catamaran-stern Hull

XU Na

(Shan Dong Jiao Tong University，Jinan Shandong 250000，China)

The Local Transformation of the Catamaran-stern Hull

XU Na

(Shan Dong Jiao Tong University，Jinan Shandong 250000，China)

Lines plan of a ship related to resistance,structural strength,and economic benefit,is a complicated system engineering.Especially for the catamaran-stern hull,the designers have to modify the lines plan of the ship,in order to combine the catamaran-stern with the main ship hull.This paper use trigonometric function method to achieve the local transformation of catamaran-stern hull;on the other hand,making it programmed can effectively shorten the cycle of shipbuilding.

Local transformation;Catamaran-stern hull;Trigonometric function

0 Introduction

In ship design,lines have a relation with the float state of structure, rapidity and stability ofthe ship,Seakeeping、maneuverability、load capacity and internal layout.Ship design is a complex process,each part is the system of independent design,and has a close relationship between each other,the overall design work is done by a variety of professional cooperation coordination,so in the design process will inevitably conflict; And sometimes in order to improve the performance of the vessel,such as raising the output,increase the structural strength and so on,these need to ship design personnel on the basis of the existing ship lines type line of partial adjustments,in order to meet the requirements of design and use.[1]

In this paper,the trigonometric function is used to realize the ship lines of partial transformation.Through this thesis,we can achieve partial transformation of the ship any direction,and keep the length and breadth of the ship principal dimensions remains the same.

This method is essentially a kind of transformation of the mother ship.In the transformation of the mother ship,often as a result of the need of design,to change the ship type line of a certain position,but still want to keep the ship modalities lines fairing,if there is no appropriate method, need to make a lot of changes to your lines.By means of partial transformation of this article,as long as know ship change the position of a certain amount,you can output values after the change,at the same time, also can realize the direction of the ship other local transformation and maintain smooth lines.This change can be part,also can be for the entire hull lines.[2]

At the time of shipping lines and local transform,to satisfy two basic conditions:(1)change lines to meet the design requirements,after the type line of change after offset type value points;(2)after the change of lines to keep the fairness,namely changed lines at fixed point to tangent with the prototype line.

This paper based on the above two conditions,a trigonometric function to express hull lines.Trigonometric functions of special property, can make the ship’s local transformation,basically maintain the basic characteristic of the original form,the new generation of hull lines can also use the spline curve connect into a curve fairing.

1 Transform principle

This paper put a half-breadth plan as a example to introduce use trigonometric to realize the local transformation.

Curve s1is the 100 water line of ship half-breadth;Curve s2is the 100 water line of ship half-breadth;k1is the offset to the half-breadth water line of x2;k2is the offset to the half-breadth water line of x3;k is the offset to the half-breadth water line of k.x1，x4is the two boundary point coordinates.

With x1，x4for the two boundary point,half width line vessels with local deformation should be between the two endpoints,k1，k2need to change the offset,so the part of the line need to transform can be divided into three sections（x1，x2），（x2，x3）,（x3，x4）.

According to the different properties of trigonometric function,in this paper,by adopting the combination of sine function and cosine function expression to meetthe requirementsofshipping linesand local transformation.Because there are two offset x2and x3,therefore can not be simply a trigonometric function curve is used to express,to solve this problem,this paper adopted the superposition method.

Curve l1for maximum value for k1trigonometric function curve, Curve l2for maximum value for k2trigonometric function curve,the curve of the deviation can be obtained after the s2,The curve s2is superposition results of the curve l1and curve l2.

When x is in different positions of（x1，x2）area,its offset k by different deformation formula:

If x1≤x≤x2，k=k1sin

If x2＜x＜x3，k=k1cos

If x3≤x≤x4，k=k2cos

If x＜x1or x＞x4，k=0

By the function relation between the above can be seen

At the boundary point x1，k(x1)=0 and k'(x1)=0

At the boundary point x4，k(x4)=0 and k'(x4)=0

The curve s2by adding up the half-breadth of the original water line s1,can guarantee the x1，x4two boundary point function values are equal, and tangent directions are equal,so the above function expression of deformation,can guarantee the continuity of curve and fairness.

It is important to note that at the time of local deformation,may be there is only one offset point,namely the（x1，x4）range,there is only a little with the offset.At this time,x2and x3can be two points as a point,and the offset k1=k2.

At this time,

k(x2)=k(x3)，and k(x)=0 a first order to guide

The ship's lines can meet the requirements of smooth continuous.

Through the method of hull lines after partial transformation, deformation can be obtained after the station number or the coordinate values on the waterline,connection,using spline function can ensure the fairness and continuity.

2 Application

Use this method to transform the hull lines,in addition to the hull lines can be calculated at any place of local deformation,also can realize the whole boat hull form,in the case of deformation,and can ensure the fairness and practicality.In the actual ship design,will encounter a lot of kinds of situation the need for the transformation.

（1）Catamaran-stern hull after line design.Because of the complexity of the catamaran-stern hull line,the existing ship lines design method of catamaran-stern hull after lines processing research is not a lot.Using the calculation method of this article,we can according to the stern line at local design analysis,for example,as long as the known the ship’s stern spacing between the variable,you can directly output values after thetransformation,and still be able to keep the length and breadth of the ship principal dimensions remains the same.

（2）The general form of local transformation.Most of the time,due to the performance requirements,requirements,structural design and interior layout,need shipping lines of the existing local appropriate changes,such as increasing or decreasing the length of the parallel middle body, increase or decrease the deep,and so on,using the calculation method of this article,can keep the original form of the basic features,the new generation of hull lines fairing,and don’t need to make a lot of changes to your lines,reduce the workload.

In this article,through VB.NET programming language,would be the principle of the computer program,can reduce the design personnel’s work time,shorten the shipbuilding period.

3 The instance

As to a patrol boats of catamaran-stern hull,for example,is introduced in this paper,the application of the software in the practical engineering. The ship Principal Dimensions is as follows:

Loa33.15 m LWL32.30 m

B 8.00 m D 3.600 m

T 2.700 m CB0.47

Shaft spacing is an important parameter of the double tail ship form design,the size is determined by the end of a measure of obesity. According to the demand of design,to local transformation of patrol boat tail,change the shaft spacing,to make the ship get better performance of the ship.Change the shaft spacing,has no effect on the main hull lines,so local transform is only considered in caudal part.The original shaft spacing is 2.6m,the modified shaft spacing is 2.7m,due to the change of tail shaft spacing values change by the main hull,therefore this article with only 2 standing type catamaran-stern hull part of the value change, for example.

By the local transform software available to new values

4 Conclusion

This article around the ship lines transformation requirements,using trigonometric functions to partial transformation of the vessel,and compiled a set of effective procedures to implement.Taking a patrol vessel as an example,using the program,can be meet the requirements of offset table,that can be used in the ship lines design,to improve the design of the vessel curve surface,shorten shipbuilding cycle has certain positive role.

【Reference】

［1］Zhang Dayou,Zhu Tao,Li Shaobo.Double tail fin type analysis research and development[J].Marine engineering,2006(6).

［2］Bi Yi,Wang Bo.The drag reduction of high speed of the fore stern fin stabilizer experiment research[J].Journal of naval engineering university,2002(2).

［3］Dong Meihua,Ma Rujian,Zhao Dong,.Ship anti-rolling technology is reviewed [J].Journal of Jinan university(natural science edition),2008(2).

［责任编辑：李书培］

表1 主变压器常见故障现象及处理表

3.2 主变压器相关辅助电源丧失故障分析和处理

3.2.1 AC380V动力电源失电

冷却器动力电源采用AC380V、50HZ、三相三线制、双回路。当任一回路电源失电时，控制箱自动切换至另一回路，冷却器继续运行，控制箱发出I回路或II回路电源故障信号，不影响变压器运行。此时应检查回路电源，恢复供电，避免出现另一回路电源失电时，冷却器无动力电源不能运行，影响变压器运行。当双回路电源都失电时，AC380V动力电源下的负荷不能运行使用。动力箱无电源；各变压器冷却控制箱AC380V电源部分无电源，冷却器风扇、油泵、油流指示器不能运行，及控制箱内加热不能使用；由于1#、2#主变压器的冷却方式为强迫油循环导向风冷方式（ODAF），冷却器不运行时，变压器不允许持续运行。此时可：降下负荷，额定负载下允许运行20min；如20min后顶层油温尚未达到75℃，在这种状态下运行的最长时间不超过1小时；如有必要，要使电站相应设备停运。

3.2.2 DC110V控制电源失电

DC110V控制电源连接冷却控制箱控制部分，此部分失去电源，冷却器的运行投入及故障信号不能送出，油泵、风机的故障跳闸及报警等元件失灵，直至变压器其它保护装置动作，致使事故扩大，威胁变压器的正常安全运行。应及时查找原因，恢复控制电源的供电或者尽快停运变压器。

4 结论

加强核电厂主变压器的运行维护质量，可以及时消除不安全隐患，延长主变压器的使用寿命；快速准确的故障处理，可以减少损失，提高变压器的运行可靠性。本文基于秦山核电厂CP1000机组（方家山核电工程机组），首先对核电厂主变压器的结构进行了介绍，其次阐述了核电厂主变压器的运行维护事项，然后通过对主变压器常见故障的原因分析，提出了处理方法和步骤。为同类型核电厂主变压器的运行维护和故障处理提供了参考借鉴。

［1］华东电力设计院.主变压器和高压厂用变压器（GEV）系统手册C版[S].上海，2010.

［2］保定天威保变电气股份有限公司.主变运行维护手册A版[S].保定，2010.

［3］顾颖宾，王略.核电厂电气原理与设备[M].原子能出版社,2012.

［责任编辑：田吉捷］