Inter-lobe clearance estimation for twin-screw rotor pairs with point-meshing features

Abstract

In practical production, it is impossible even to measure the inter-lobe (meshing) clearance of a screw rotor pair. However, understanding of the clearance distribution is essential since it is a major leakage path which greatly affects the twin-screw pump performance. Previous publications did not disclose explicit detail on how to calculate the meshing clearance for screw rotor pairs with point-meshing features. Therefore, this study proposes a meshing clearance calculation method for screw rotor pairs with point-meshing features. The complex meshing clearance can be simply determined by calculating the shortest distance between two normal-rack profiles generated using point-enveloping principle. Clearance distributions are much more intelligible to be exhibited on a 3-D contact line and the rotor profile. Due to its immeasurability in practice, the adaptability and the solution accuracy of the proposed numerical method are verified by applications on different rotor profiles and comparisons with measured results from a 3-D CAD model. The meshing clearance in a variable-pitch screw rotor pair and the clearance adjustability are also illustrated through the proposed examples.

Prediction of Interlobe Leakages in Screw Compressors

“…It is very difficult to measure the interlobe clearance of a rotor pair because of complexity, Wu and Hoang proposed a simplified method to estimate this interlobe clearance (Hoàng and Wu 2020). A mathematical model was presented by Yuan et al (1992) to calculate the rotor tip housing and interlobe leakages with consideration of both the viscous and inertia forces and compared with the experimental results.…”

Methodology for generating a general profile of asymmetrical rotors of twin-screw vacuum pumps with point meshing feature by a pre-defined sealing line

“…The parameterized sealing line, however, does not generate the claw-type rotor with an asymmetric profile on one side, such as the rotor profile shown in previous literature. 3,15 Moreover, that study did not propose a mathematical model for optimizing the rotor profile based on the sealing line. Besides, no previous studies proposed the method to generate the screw rotor with both variable pitch and cross-section based on a sealing line.…”