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本文以JS-2磁流体发电机的一种陶瓷电极和二种金属电极为例,从工程角度描述了求解电极温度场及热应力的控制方程。给出了相应的热边界条件和位移约束条件。文中特别指出,由于通道中强磁场和强电场的存在,一方面由于哈特曼效应和气流分层化使燃气向通道壁的放热系数减小,另一方面由于附面层内电流的焦耳热使放热增强,其对流放热系数的修正由数学关系式给出。文中并根据理论分析和实验结果对电极内部由于非均匀分布的电流的焦耳效应作了讨论,确定电流沿壁面按指数规律分布,其焦耳效应作不均匀内热源计入运算。对导电燃气和电极壁面热辐射对应的放热系数文中也作了估计。文中的计算采用有限单元法进行。材料的物性认为是随温度变化的函数。用迭代方法达到温度分布与选取物性的耦合。燃气热力性质和流动状态系依据燃气组分计算及通道准一维计算的结果。文章计算结果给出了电极上的等溫线分布和热应力分布。为分析电极结构的合理性和进行新电极的设计提供了理论依据。
Taking a kind of ceramic electrode and two kinds of metal electrodes of JS-2 magnetoelectric generator as an example, the control equations for solving the temperature field and thermal stress of electrodes are described from an engineering point of view. The corresponding thermal boundary conditions and displacement constraints are given. In particular, it is pointed out that due to the presence of strong magnetic fields and strong electric fields in the channel, on the one hand the heat release coefficient of the gas to the channel wall is reduced due to the Hartmann effect and the stratification of the gas flow, on the other hand, Heat increases the exotherm, and the correction of its convective exotherm is given by the mathematical relationship. According to the theoretical analysis and experimental results, the Joule effect of the non-uniformly distributed current in the electrode is discussed. The current distribution along the wall is determined exponentially, and the Joule effect is calculated as the non-uniform heat source. Radiation coefficients corresponding to the thermal radiation from the wall of the conductive gas and electrode are also estimated. The calculation in this paper is carried out by finite element method. Material properties are considered as a function of temperature. Iteration method to achieve the temperature distribution and the selection of physical coupling. Gas thermal properties and flow conditions are based on gas composition and channel quasi-one-dimensional calculation results. The calculation results of the article give the isothermal distribution and thermal stress distribution on the electrode. It provides a theoretical basis for analyzing the rationality of the electrode structure and designing a new electrode.