City Research Online

Abstract

Spatial flow field velocities within the discharge cavity of an optical screw compressor have been measured using LDV and PIV techniques. Angle-resolved velocities were obtained over a time window of 1° at a speed of 1000 rpm, pressure ratio of 1 and temperature of 55°C. Comparison between the LDV and PIV results showed very good agreement and provided a good level of confidence in the presented data. Overall, the flow field results revealed the presence of a complex, turbulent, 3D and vortical flow structure within the discharge cavity. LDV measurements at the exit of the discharge port showed that the inflow into the cavity has two distinct flow features that includes undulated velocity profiles with high gradient during the opening of the port, and uniform jet-like flows during the rest of the time. The energy necessary to create that jet-like flow was from the built-in pressure in the rotors. Turbulence fluctuations were high and followed the mean flow variations with values up to 35% of the mean values during the undulating flow. PIV spatial mean flow measurements showed a uniform axial flow close to bottom of cavity that has been transformed to a stable solid body vortex at the top of the cavity. These measurements within the discharge cavity are made for the first time and they are unique and in great detail that can be used for validation of CFD codes and optimisation of compressors to improve their efficiency for different system applications.

Publication Type:	Article
Additional Information:	© IMechE 2023. This article is distributed under the terms of the Creative Commons Attribution 4.0 License (https://creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).
Publisher Keywords:	screw optical compressor, discharge cavity chamber, turbulent flow, LDV/PIV measurements, angle-resolved mean and turbulence velocities
Subjects:	T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Engineering
SWORD Depositor:	Symplectic Administrator

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