Analysis of the flow in the grooves of a molecular pump

A computational procedure used to solve conservation equations governing th e slip flow in a molecular pump of the Holweck type is developed, The finit e volume method is used for discretization and the gr id is arranged in the curvilinear, nonstaggered form The slip boundary condition is imposed on t he solid walls. The clearance gap between the rotor and the casing is ignor ed It is evident fi um the calculation that the pressure difference between the two side walls of the channel, iel med pressure side and suction sick, varies in accordance with the pressure difference between the inlet and th e outlet of the pump, Thus, the side-wall pressure difference can play. the role of an indicator of pumping effectiveness, Tests on a variety. of conf igurations show that to achieve the best performance both the spiral angle and the channel height need to be optimized, Besides, it is better to have fewer flow channels and to place these channels on the rotor instead of on the casing.