Rarefied dynamic pressure distribution measurement near a vacuum pump

Rarefied Background Flow in a Vacuum Chamber

Spacecraft propulsion systems, such as Hall thrusters, are designed and tested in large vacuum chambers. The pumping capacity of modern facilities makes it possible to maintain pressures as low as 3 10 4 10 Pa. In this study, several free molecular models are developed to analyze the background flow inside a vacuum chamber. These models lead to various sets of analytical results including veloc...

Modeling Plain Vacuum Drying by Considering a Dynamic Capillary Pressure

A coupled drying model for wood is proposed by introducing a dynamic capillary pressure. The pressures of non-wetting phase, the wetting phase, and the capillary pressure at equilibrium has been considered as non-static; this approach includes a two-scale model. According to numerical results, liquid, water vapor and air dynamics in the chamber have strong interactions with re-homogenization in...

Vacuum Gauge to Vacuum Pump Valve

Rarefied gas dynamics and its applications to vacuum technology

Basic concepts of rarefied gas dynamics are given in a concise form. Some problems of rarefied gas flows are considered, namely, calculations of velocity slip and temperature jump coefficients, gas flow through a tube due to pressure and temperature gradients, and gas flow through a thin orifice. Results on the two last problems are given over the whole range of gas rarefaction. A methodology f...

DYNAMIC SIMULATION OF A HIGH PRESSURE REGULATOR

In this paper, the dynamic simulation for a high pressure regulator is performed to obtain the regulator behavior. To analyze the regulator performance, the equation of motion for inner parts, the continuity equation for diverse chambers and the equation for mass flow rate were derived. Because of nonlinearity and coupling, these equations are solved using numerical methods and the results are ...