Project SECRET is set to investigate the physics of leakage flows in clearances of rotating positive displacement machines by numerical and experimental means and to develop concepts for a new generation of efficient and reliable screw compressors for Howden which will help to achieve challenging NetZero targets defined by UK government. The project is supported by the Royal Academy of Engineering. In phase 2 an experimental investigation of leakage flows was completed and methods for numerical simulation of Conjugate heat transfer in leakage flows were developed. The test rig for prototype development and verification was installed and initial tests on the laboratory prototype were performed. As a part of this process, the team came to an idea for discharge valves in oil-free screw compressors and submitted a patent application for this solution.


Findings from PIV results are leading us towards the use of specific geometry on the rotor tip to reduce leakage losses. Results are helping us to generate concepts to design Tip features which is input for WP7. – Brijeshkumar Patel, City, University of London PhD Student, – experimental

One of the concepts we are developing is how to incorporate active control systems to protect the compressor and improve performance. With the novel monitoring systems that will be implemented, we believe we can find new ways to control clearances and minimise leakages. – Thibault Tam, City, University of London PhD Student , Clearance modelling and control techniques

The initial calculations have given an insight into how the current bearing designs can be altered to improve the level of control available; these alterations are what we are going to focus on next. –  James Ure, Analysis specialist at Howden