Submission
Internally Geared Twin-Screw Machines
DOI: 10.18462/iir.compr.2017.0241
Session: Rotary, scroll and screw compressors I. Chaired by Cesar J. Deschamps, Changqing Tian, Osami Kataoka
Accept state: Submission accepted
Authors
| Name | Organization | |
|---|---|---|
| Matthew Read, PhD | City, University of London | |
| Ian Smith, PhD | City, University of London | |
| Nikola Stosic, PhD | City, University of London |
Abstract
It is possible to design cylindrical helical gearing profiles such that an externally lobed inner gear rotates inside an internally lobed outer gear while maintaining continuous lines of contact between the gears. The continuous contact between the ‘inner’ and ‘outer’ rotors (analogous to the ‘main’ and ‘gate’ rotors in a conventional twin screw machine) creates a series of separate working chambers. In this type of machine the rotors have parallel axes of rotation, and if both rotors are free to rotate about their own axes, these axes can be fixed in space.
As with conventional twin-screw machines, these internally geared rotors can be used to achieve compression or expansion of a trapped mass of fluid, and the machine geometry can be designed in order to achieve a required built-in volume ratio.
This paper describes a comparison of the geometric characteristics of internally geared and conventional positive displacement machines, including sealing lines, sliding velocities and port geometry. The analysis considers of a range of possible rotor profiles and geometeries and explores the effect on rotor torques and bearing loads for particular applications of the novel internally geared twin screw configuration.
Keywords
twin screw, compressor, expander, postive displacement, internal gear