﻿ 蒸汽动力装置回汽制动工况下倒车级动叶安全性分析
 舰船科学技术  2016, Vol. 38 Issue (8): 39-42 PDF

Bending stress of moving blade of the astern turbines in back-steam braking conditions for steam-powered ships
ZHU Yong, DENG Fei-yun
Naval Military Representative Office in Jangnan Shipyard (Group) Co. Ltd, Shanghai 201913, China
Abstract: For the defect of operational reliability safety in the back-steam braking condition in the moving blade of astern turbines of steam-powered ships. The working process of the variable condition of the astern turbines in the backsteam braking condition was analyzed, and bending stress of the moving blade of astern turbines in the back-steam braking condition was created. Also, the simulation models were created based on the Matlab-Simulink. It was indicated in the simulation results that bending stress of the second moving blade of astern turbines may outstrip the safety allowable value, and damage the astern turbines. Then the safety operations of steam powered plants were affected. So, it is necessary to restrict the open opportunity and range.
Key words: moving blade of the astern turbines     back-steam braking condition     bending stress     modeling and simulation
0 引言

1 回汽制动工况下倒车汽轮机变工况工作过程分析

2 回汽制动工况下倒车级动叶弯曲应力模型

2.1 回汽制动工况下倒车级受力模型

 $\left\{ {\begin{array}{*{20}{l}} {{F_{scus1}} = - \frac{{{D_{dc}}}}{{2{n_{dy1}}}}({C_{21sc}}^\prime \cos {\alpha _{21}}^\prime + {C_{11sc}}\cos {\alpha _{11}}),}\\ {{F_{scas1}} = \frac{{{D_{dc}}}}{{2{n_{dy1}}}}({C_{11sc}}\sin {\alpha _{11}} - {C_{21sc}}^\prime sin{\alpha _{21}}^\prime ),}\\ {{F_{bscs1}} = \sqrt {{F_{scus1}}^2 + {F_{scas1}}^2} .} \end{array}} \right.$ (1)

2.2 倒车级动叶的最大弯曲应力模型

 图 1 汽轮机动叶基面的受力分析图 Fig. 1 Stress analysis diagram of basal plane for moving blade

 $\left\{ {\begin{array}{*{20}{l}} {{F_{1s}} = {F_{bs}}\cos \varphi } \text{，}\\ {{F_{2s}} = {F_{bs}}\sin \varphi } \text{，}\\ {\varphi = {\beta _{ty}}-\arctan \frac{{{F_{as}}}}{{{F_{us}}}}} \text{。} \end{array}} \right.$ (2)

 $\left\{ {\begin{array}{*{20}{c}} {{M_{1s}} = \frac{1}{2}{F_{1s}}{l_{dy}} = \frac{1}{2}{F_{bs}}{l_{dy}}\cos \varphi ,}\\ {{M_{2s}} = \frac{1}{2}{F_{2s}}{l_{dy}} = \frac{1}{2}{F_{bs}}{l_{dy}}\sin \varphi .} \end{array}} \right.$ (3)

 $\left\{ {\begin{array}{*{20}{l}} {{\sigma _{As}} = \frac{{{F_{bs}}{l_{dy}}{e_1}\cos \varphi }}{{2{I_{\rm{I}}} \times {{10}^6}}} - \frac{{{F_{bs}}{l_{dy}}{e_4}\cos \varphi }}{{2{I_{{\rm{II}}}} \times {{10}^6}}},}\\ {{\sigma _{Bs}} = \frac{{{F_{bs}}{l_{dy}}{e_1}\cos \varphi }}{{2{I_{\rm{I}}} \times {{10}^6}}} + \frac{{{F_{bs}}{l_{dy}}{e_1}\cos \varphi }}{{2{I_{{\rm{II}}}} \times {{10}^6}}},}\\ {{\sigma _{Cs}} = - \frac{{{F_{bs}}{l_{dy}}{e_3}\cos \varphi }}{{2{I_{\rm{I}}} \times {{10}^6}}}.} \end{array}} \right.$ (4)

 $\left\{ {\begin{array}{*{20}{l}} {{\sigma _{As}} = {\sigma _{Bs}} = \frac{{{F_{bs}}{l_{dy}}{e_1}}}{{2{I_{\rm{I}}} \times {{10}^6}}},}\\ {{\sigma _{Cs}} = - \frac{{{F_{bs}}{l_{dy}}{e_3}}}{{2{I_{\rm{I}}} \times {{10}^6}}}.} \end{array}} \right.$ (5)

 ${{\sigma _{\max }} = \frac{{{F_{bs}}{l_{dy}}{e_1}}}{{2{I_{\text{I}}} \times {{10}^6}}}}\text{。}$ (6)

 图 1 回汽制动工况下倒车级动叶弯曲应力的仿真模型 Fig. 1 Simulation model of bending stress of moving blade of the astern turbines in the Back-steam braking condition
3.2 仿真曲线及计算结果

 图 2 倒车级两级动叶最大弯曲应力随时间变化曲线 Fig. 2 Change curve of maximum bending stress of the double moving blade according to the time

4 结语

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