Crookes辐射计内最佳真空度的实验和仿真研究

应用实验和蒙特卡罗(DSMC)方法,研究了Crookes 辐射计工作的最佳真空条件.在辐射计内转子可以自由转动的条件下,测量了辐射计转子的转速与腔内真空度的关系,实验表明,转子的转速与腔内的真空度、转子叶片的边长有关.在叶片边长分别为20 mm和10 mm的情况下,最大转速分别出现在0.1 Pa和3 Pa.应用DSMC方法,仿真得到了在不同真空度条件下,作用在转子叶片两边的压力差分布,结果表明,在叶片边长分别为20 mm和10 mm的情况下,最大压力差分别出现在0.1～0.5 Pa和2～5 Pa.文中给出了腔内稀薄气体的速度矢量图.

Experimental and simulative study on optimal vacuum pressure within Crookes radiometer

The optimal vacuum pressure within Crookes radiometer is studied by way of experiments and direct simulation Monte Carlo (DSMC) method. The relationship between the rotational rate of the rotor in Crookes radiometer and vacuum pressure was tested using freely rotating rotors of two different sizes, ie., a 20mm rotor of which the side length of blade is 20mm and the other a 10mm one. The experimental results indicated that the optimal vacuum pressure varies with the side length of rotor blade and shows 0.1Pa and 3Pa in cases the rotor is 20mm and 10mm, respectively. The pressure difference distribution of gas on the back and front surfaces of the rotor blades were tested by DSMC method. It was found that the maximum pressure difference shows 0.1~0.5Pa for 20mm rotor and 2~5Pa for 10mm rotor. The results are consistent with the experiment results. The velocity vector fields of gas within Crookes radiometer with 20mm rotor under 4 different pressures are also presented.