【摘要】 基于多孔材料边界层动力理论 ,对低温制冷机或热声热机中回热器内的流动特性分析引入临界频率的概念。当频率高于该临界值时 ,系统内假定的泊肃叶 (Poiseuille)流将会被破坏 ,由此会极大地造成压力波的衰减。期望这一概念有助于回热器内动力损失的研究。我们对 7种不同目数丝网和 4种工质 (氦、氮、氩和氢 )进行了计算 ,结果表明临界频率与丝网尺寸以及工作流体的种类有关 ,而且在气体区域随温度而增大 ,在液体区域则相反。更多还原

【Abstract】 The frequency dependency of flow pattern in regenerator is discussed and a critical frequency, above which Poiseuille flow would break down, is introduced with dynamic theory of boundary layer for fluid saturated porous medium Since the breakdown of Poiseuille flow may greatly increase attenuation and then deteriorate the performance of the whole system including the regenerator,the critical frequency could be helpful in the study of dynamic loss inside regenerator Calculations have been conducted for different mesh sizes and various working fluids And the critical frequencies increase with temperature in the gas range, while those in liquid are in reverse depending on mesh size and working fluid type更多还原