Design of a new non-contact screw seal and determination of performance characteristics

Advancing machine technology gave rise to increasing performance requirements for sealing solutions with an integral role in service capabilities, service life and efficiency of machinery and mechanical systems.Every seal can be categorized either as a contact or non-contact seal. Contact seals are generally used in sealing applications of low speed machine components. On the other hand, implementation of non-contact seals in high speed machinery is beneficial for avoiding friction and wear. Non-contact seals are referred as dynamical or active seals due to functioning only when the system is running. In this study, sealing concept, leakage types, sealing types are described and various non-contact sealing elements are introduced. One sub-category of non-contact seals, screw seals are studied in detail, including their working principles, operating limits and technical properties. The main purpose of the study is to propose a screw seal design with better sealing capabilities, through physical testing and performance evaluation of new non-contact seal designs with 2 alternative screw profiles. An experimental rig was designed to determine the sealing performance. The effects of operating speed and screw profile on sealing performance of screw seals are investigated. Screw elements consist of two components, a lefthand thread and a righthand thread in order to manufacture the screw elements seperately and easier.In this study, it was proved for any design of screw seals that, increasing rotational speed, increases sealing performance with respect to the pressure. It was also seen that increasing the length of the fluid/air interface through the screw seal, provides better sealing performance. Therefore, the leaking fluid through the leakage path increases the pressure values and this proves screw seals work according to self energising principle.