【摘要】 用时域方法研究了低压低含汽量自然循环系统的非线性密度波不稳定性。发现存在于系统的两种密度波不稳定的非线性振荡形式,研究了两种振荡的特性、机理及其影响因素。得到如下一些重要结论:1.不稳定区域密度波振荡为有限的持续振荡。靠近稳定边界时,系统发展为等幅的持续振荡,且随着过冷度的增加振幅加大;远离稳定边界时,密度波振荡耦合可压缩性密度波振荡,呈变幅的有限振荡。2.核功率和空泡份额耦合反馈对密度波振荡的影响取决于热流密度滞后的相位,对5MW核供热堆主回路系统来说,起激励作用。3.加大堆芯出口水力提升段的质量惯性能有效地抑制可压缩性密度波振荡,提高系统的稳定性。更多还原

【Abstract】 The density wave instability of a system with low pressure and low quality is studied by the time domain method, and two kinds of non-linear density wave oscillation are found. The mechanisms, characteristics and factors effected on these two oscillations have been analyzed. The following conclusions are obtained: 1. the density wave in an unstable area develops a finite continuous oscillation. It becomes a constant amplitude oscillation if the system is approaching to the stable boundary, and the amplitude becomes larger along with the inlet subcooling increasing. If the system is far away from the stable boundary, a varying amplitude oscillation will be produced due to density oscillation coupling to compressible oscillation. 2. the action of feedback of nuclear power and void fraction on the wave oscillation is determined by time lagging phase of heat flux. In the case of 5 MW nuclear heating reactor this action intensifies instability. 3. By increasing the inertia of riser in the core outlet, the compressible density wave oscillation can be suppressed effectively and the system stability can be enhanced.更多还原