Researchers from NTU 

• Assoc. Prof. Alessandro Romagnoli, PI

• Dr. Zheng Liu, Research Fellow

 

University of Cambridge

• Prof. Epaminondas Mastorakos, Project Coordinator for CARES C4T

• Prof. Markus Kraft, Programme Director for CARES C4T

 

Collaborators ​

• Prof. Srithar Rajoo, Director of the Low Carbon Research Centre in Collaboration with Imperial College London

• Dr. Torsten Palenschat, R&D Engineer at Daimler

 

Description of the project

This research seeks to improve the turbine performance by injecting the secondary flow through an injector over the shroud section. A secondary flow injection system has been developed to fit for an asymmetric twin-scroll turbocharger turbine, designed for a 6-cylinder heavy-duty diesel engine, aiming at reducing the brake specific fuel consumption at 1100 rpm under full-loading conditions. The shape of the flow injector is similar to a single-entry volute but can produce the flow angle in both circumferential and meridional directions, when the flow leaves the injector and enters the shroud.

 

In order to find the optimal injector design that maximizes the turbine performances, ten design parameters have been considered, which control circumferential area distributions, exit flow angles, and flow velocities. The source for the flow injection can be either from the engine exhaust flow or an external compressor. With the flow injection, the blade loading is significantly improved downstream to the location where the flow is injected. The lower pressure of the blade’s suction side is the main reason that leads to the improvement of performance.

 

The secondary flow can effectively reduce the vortex separation on the suction side and reduce associated losses. A secondary flow injection system can be integrated into a conventional turbine without affecting its original design parameters, including the rotor, volute, and back disk. Therefore, the swallowing capacity and thrust loading characteristics are kept the same as the original turbine, thereby maintaining the same turbocharger-engine matching and turbine-compressor matching.