Experimental and Computational Study of Area and Perimeter Contributions to Radiometer Forces (Preprint); Conference paper

摘要

The relative contribution to the radiometric force of the area and perimeter of the vane is studied experimentally and numerically. Experimentally, a circle, a low-aspect rectangle, and a high-aspect rectangle were all tested on a thrust measurement stand with nano-Newton resolution placed in a stagnant gas. The computational results were obtained through 2-D simulations using the direct simulation Monte Carlo method, as well as a discrete ordinate solution of the ES model kinetic equation. Gas pressure was varied from .006 to 6 Pa, which was a broad enough range to observe the characteristic peak force production of a radiometer in the transition regime, where the peak occurs at Kn approximately 0.1. It was found that the area of a radiometer vane is responsible for a significant amount of the total force production through a wide range of its operation. It is only at the highest background pressures, well after force production has peaked, that the vane perimeter appears to dominate the operation of the radiometer.