Papers by Keyword: Leakage Analysis

Abstract: According to the fluid hydrodynamic lubrication theory, and the structural characteristics of the convergence gap seal is combined, the effect of differential pressure and centrifugal force should be considered, then the convergent wedge gap mechanical seals flow field numerical model is established and the influence of the leakage factors are researched, including the geometric parameters and operating parameters. Research has shown that the amount of leakage and the seal clearance were positively correlated. And the larger turning Angle is, the bigger correlation becomes, however, it is negatively correlated with speed and turning radius, the seal leakage is impeded by the centrifugal force and the larger turning radius is, the smaller leakage becomes.

Abstract: Karst caves determine the engineering characteristics of the whole rock in a large extent. A methed to simulate karst caves is described in this paper. Firstly, three-dimensional mathematic description of the geological mass in which karst caves lies is given. Secondly, the determination of the shape and size of ellipsoids which are adopted to simulate karst caves is introduced in detail. The mathematic modeling of three-dimensional random caves is discussed simultaneously. Thirdly, a real three-dimensional random structural model of karst rock based on actual observation records is provided. Lastly, the above model used for the leakage analysis of the karst rock is discussed. The research results illustrates that the Mathematic model for three-dimensional random caves of karst rock put forward in this paper can be very helpful to leakage analysis on Karst rock.

Abstract: This paper describes the vacuum-compatible air bearing designed with a cascaded exhaust scheme to minimize the leakage of air in a vacuum environment. The design of the air bearing, including the differential exhaust system, required great care because several design parameters, such as the number of exhaust stages, diameter and length of the exhaust tube, pumping speed and ultimate pressure of the vacuum pump, and seal length and gap greatly influenced the leakage of air and thus the degree of vacuum. A leakage analysis was performed to estimate the chamber pressure and an optimization method based on the genetic algorithm was proposed under several constraint conditions. The results showed that the degree of vacuum improved dramatically compared to the initial design, and that the distribution of the spatial design parameters and technical limit of the pumping speed were well achieved.