Search

Orifice restriction is a traditional form of throttle used in aerostatic guide way. Practically, self-excited vibration or even air hammer phenomenon will appear in gas film interior when supply gas enlarges or the film thickness decreases to micron scale. In order to analyze the process from the pressure inlet to the entrance of completely developed laminar flow, Reynolds Equation coupled with the first order velocity slip is used. Since it has rarefied property, turbulence model and molecular dynamics theory are adopted based on molecular collision theory. This paper reveals the internal cyclone law in gas chamber and the relationship between essence of the shock formation and the gas molecule velocity excitation. Further study shows that, supply pressure, film parameters and chamber parameters have important influences on cyclone phenomenon and shock wave.

Micro vibration of the aerostatic guide way has a significant impact on its dynamic characteristics and stability, which limits the development of pneumatic component. High pressure gas molecules have been collided with the supporting surface and the internal surface of the throttle during the flow process. Variable impulse of the surfaces aside for the gas film are affected by the changes of impulse which formed irregular impact force in horizontal and vertical direction. Micro-vibration takes place based on the natural frequency of the system and its frequency doubling. In this paper, the vibration model was established to describe the dynamic characteristics of the gas film, and the formation mechanism of micro vibration in the film is defined. Through the simulation analysis and experimental comparison, formation mechanism of the micro vibration in the gas film is confirmed. It was proposed that the micro vibration of gas film can be produced no matter whether there is a gas chamber or not in the throttle. Under the same conditions, the micro vibration of the guide way with air chamber is greater than that without any chamber. The frequency points of the vibration peaks are almost the same, as well as the vibration pattern in the frequency domain.