﻿ 船用汽轮发电机端部涡流损耗优化研究
 舰船科学技术  2022, Vol. 44 Issue (16): 105-109    DOI: 10.3404/j.issn.1672-7649.2022.16.021 PDF

Research on optimization of end eddy current loss of ship-spectific steam turbine generator
LIU Ming-wang, FU Xiao-jin, ZHU Hong-yan
School of Mechanical Engineering, Shanghai Dianji University, Shanghai 201306, China
Abstract: Under the background of the vigorous development of ship-specific steam turbine generators, the optimization of generator loss and the reduction of this study are put forward in view of the current problem of high generator manufacturing cost. The accurate calculation of vortex loss is an important basis for studying end electromagnetics. First, combined with the electromagnetic field theory, the principle of end eddy current loss was deduced, and a three-dimensional finite element model of the end was established; second, in view of the time-consuming problem of traditional transient simulation methods, a time-harmonic simulation method was proposed to save a lot of time. Finally, in order to solve the problem of the increase in the manufacturing cost of the generator caused by the excessive thickness of the magnetic shield, a parametric modeling method is proposed, which only modifies the parameters of the target structure to achieve rapid modeling and establish multiple case models with different magnetic shield thicknesses. Get the eddy current loss of different structural parts under different magnetic shield thickness and analyze the specific influence of magnetic shield thickness. Combined with the economic index to choose the appropriate magnetic shield thickness, for marine turbine generator end design to provide a certain guiding significance.
Key words: double internal water cooling generator     eddy current loss     time harmonic simulation     parametric modeling     optimization research
0 引　言

1 发电机端部涡流场数学模型

A法和T[8]常应用于涡流损耗中。通常把A法又称为A−ϕ 法，T法又称为T − Ω 法。这2种方法各有其使用的特定条件，在实际应用的时候需要对比选用[9]

 图 1 涡流场求解区域示意图 Fig. 1 Schematic diagram of eddy current field solution area

V1内：

 \left. \begin{aligned} &\nabla \times (\nu \nabla \times A)-\nabla (\nu \nabla \times A)+\sigma \dfrac{\partial A}{\partial t}\text+\sigma \nabla \varphi \text{=0}\\ &\nabla \cdot\left(-\sigma \dfrac{\partial A}{\partial t}-\sigma \nabla \varphi \right)=0 \end{aligned} \right\} ， (1)

V2内：

 $\nabla \times (\nu \nabla \times A)-\nabla (\nu \nabla ·A)={J}_{s} ，$ (2)

 \left.\begin{aligned} n\times A=0\\ \nu \nabla \cdot A=0 \end{aligned} \right\} ， (3)

 \left. \begin{aligned} &n \times A = 0 \\ & (\nu \nabla \times A) \times n = 0 \end{aligned} \right\} ， (4)

 $\left. \begin{array}{l} {A}_{1}={A}_{2}\\ {\nu }_{1}\nabla \cdot {A}_{1}={\nu }_{2}\nabla \cdot {A}_{2}\\ {\nu }_{1}\nabla \cdot {A}_{1}\times {n}_{12}={\nu }_{2}\nabla \cdot {A}_{2}\times {n}_{12}\\ n\cdot \left(-\sigma \dfrac{\partial A}{\partial t}-\sigma \nabla \varphi \right)=0\end{array} \right\}。$ (5)

2 端部涡流场三维建模及仿真 2.1 电磁仿真方法

2.2 发电机端部三维建模

 图 2 定转子线圈简化模型图 Fig. 2 Simplified model of stator and rotor coils

 图 3 双水内冷发电机端部仿真模型 Fig. 3 Simulation model of the end of a dual water internal cooling generator
2.3 仿真计算 2.3.1 有限元网格剖分

JMAG软件采用Skin Depth方式来处理一些需要考虑趋肤效应的结构件，但是这个方式的使用要在特定的条件下才能得到最好的效果[10-11]。考虑到端部的结构件数量多，形状各异，材料不同的特点，对各结构件，采用独立的尺度进行剖分。一些关键的研究对象，如压圈、齿压板和边段铁心损耗部件，为了反映其细节之处，满足实际的计算需要，设置独立的剖分尺度来获得较细的剖分单元。其余部分可以适当稀疏一些。端部模型的剖分三维图如图4所示。

 图 4 端部模型剖分三维图 Fig. 4 3D image of end model dissection
2.3.2 边界处理及电流加载

Aϕ-A法计算涡流损耗，保证了在含有多种媒质的求解域内的涡流连续性。考察涡流分布时，涡流区和非涡流区分别由齿压板、分块压板、压圈和绕组、磁屏蔽、定子铁心和转子组成。

 图 5 边界条件设置 Fig. 5 Boundary condition setting

3 结果与分析 3.1 计算方法有效性验证

 图 6 压圈损耗分布云图 Fig. 6 Contour map of pressure ring loss distribution

 图 7 仿真步骤记录 Fig. 7 Simulation step record

3.2 磁屏蔽厚度优化对比

 图 8 损耗计算 Fig. 8 Loss calculation

 图 9 不同磁屏蔽厚度各部件涡流损耗 Fig. 9 Eddy current loss of various components with different magnetic shielding thickness

4 结　语

1）针对瞬态仿真耗时长浪费资源的问题，提出了时谐仿真方法，以脉振磁场代替旋转行波磁场，大大节省了计算时间，并以压圈为例进行了现场测试，该方法的准确性和可行性得到很好的验证。

2）针对磁屏蔽厚度过厚带来的发电机制造成本增加的问题，提出了参数化建模方法，只修改目标结构件参数，实现快速建模，研究了不同厚度的磁屏蔽对漏磁的阻挡作用。结果表明，当厚度削减为100 mm时，是比较经济的做法，既保证了磁屏蔽的屏蔽效果，又降低了成本，为船用汽轮发电机端部设计提供一定参考。

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