Cummins Showcases 20,000 Hours of R&D at IMechE 2018

Cummins Turbo Technologies is showcasing its latest innovations in Holset turbocharger technology, the result of 20,000 hours of research and development, at the 13th IMechE International Conference on Turbochargers and Turbocharging in London on May 16 and 17.

Cummins is presenting six papers, its strongest contribution at IMechE to date. The unveiling of the papers showcases Cummins’ investment into improving the durability, efficiency and manufacturing of its turbochargers for on-highway and off-highway global markets.

Brett Fathauer, Executive Director of Research and Engineering at Cummins Turbo Technologies, says, “With customers demanding smaller engines with greater power density, along with lower emissions, the turbocharger remains one of the most critical components on a vehicle driveline. Cummins is dedicated to constantly exploring ways to improve turbocharger design, and it is through investing heavily in advanced testing facilities and the top turbocharger engineers, that we bring real benefits to the customer.”

The papers being presented at IMechE are summarised below:

• Optimisation of wastegate bypass flow reintroduction for increased turbine stage efficiency identifies several key design learnings which, when combined, generated a 6.5% increase in wastegate open turbine efficiency, saving the customer $300 on average per year. As a large proportion of modern turbochargers incorporate a wastegate system into their design, the research presents an opportunity to deliver significant efficiency and emissions benefits to OEMs and end users.

• The application of additive manufacturing to turbomachinery examines the advantages and challenges associated with Selective Laser Melting (SLM) in the context of manufacturing turbine wheels. The paper states that the technology could improve turbocharger efficiency by unlocking novel turbine wheel designs, improving prototyping through lead time reduction and allowing onsite manufacturing, provided that metallurgical challenges associated with processing nickel base super-alloys are overcome.

• The tribological performance of coated and non-coated materials in high temperature environments utilizes a robust material selection process to identify suitable coatings with the potential to deliver the required wide temperature range wear and friction performance, at a lower price point than high-performing uncoated materials. Although further turbocharger-based testing is required to validate the laboratory-based test results on application, this development has the potential to ensure high product durability at a reduced cost.

• The development of a lead-free corrosion resistant bearing system for turbocharger applications. Due to its toxicity, the use of lead in bearings is being increasingly restricted by environmental legislation and OEMs. Through the comprehensive lab and turbocharger-based testing and analysis outlined in this paper, Cummins has evaluated the corrosion and tribological performance of a range of lead-free materials for turbocharger applications. Lead-free brass bearing materials provided the most superior overall performance, with a high level of correlation observed between lab-based and turbocharger-based testing.

• Steady and transient conjugate heat transfer of a turbocharger demonstrates the application of computational fluid dynamics to model a turbocharger under non-adiabatic conditions. This analysis approach therefore enables enhanced stage performance prediction to improve turbocharger-engine matching. In addition, prediction of component absolute temperatures becomes possible under a range of steady and transient scenarios which can be used to support further analysis techniques to ultimately improve life cycle predictions.

• Stability optimization of turbocharger rotor-floating ring bearing system: a combination of linear and nonlinear approaches. In an effort to develop an efficient method for the stability optimization of rotor-floating ring bearing system, this paper demonstrates that the traditional linear stability analysis method can be used as a time-saving and qualitative analysis tool to locate the optimum design region in the defined parametric space. The combination of the described linear and nonlinear methods can significantly reduce the required time and experimental cost when developing turbocharger rotor-floating ring bearing systems.