عنوان مقاله [English]
This paper investigates and studies the vanes of radiometric pumps. An example of a radiometric pump is the Crooks radiometer, which consists of an airtight glass bulb containing a partial vacuum, with a set of vanes mounted on a spindle inside. One side of the vane is white, and the other side is black. In this study, for the first time, a mechanism to measure the temperature directly from hot and cold blades is considered. It is observed that the measured force is proportional to the temperature difference between the two blade ends, and this proportionality is linear. But this relationship is only valid up to the maximum temperature difference. The angular velocity of the blades was also measured by a laser tachometer. The measured velocity is used to calculate the force. This study has been performed in three parts. Part 1 (Laboratory): Designing and constructing a radiometer with different types of vanes. Part II includes the study and review of radiometric flow analysis and theories related to radiometric force. In the third part, a comparison of laboratory results and theories is reported. The tests were performed at four working pressures of 30 pa, 6 pa, 0.6pa, and 0.06 pa. These pressures represent the Knudsen numbers of 0.05, 0.1, 1 and 10 and different flow regimes, respectively. Maximum forces were observed at a pressure of 6 pa and maximum velocity at 0.6 pa, which is in a cooperative agreement with the theoretical data.