The demands for a future diesel engine in terms of emission compliance, CO2 emissions, performance and cost effectiveness set new requirements for the development process of the combustion system.
This paper focuses on the development of the next generation Volvo Cars diesel combustion system, which should comply with Euro 6d including Real Driving Emissions (RDE), with emphasis on the novel methods applied throughout the process.
The foundation of a high performing combustion system is formed by first determining the requirements for the system, after which the key factors that affect system performance are selected, such as the charge motion, combustion chamber geometry and injector nozzle geometry.
Based on the requirements, a robust charge motion with desired flow characteristics is defined. A new automated CFD optimization process for combustion chamber geometry and spray target is developed. From the generated Pareto front of optimal designs, the best hardware solutions are selected based on targeted attributes. An increase in knowledge is also gained by looking into the details of the simulation results for these candidates. The selected solutions are then verified by creating rapid prototype pistons for evaluation.
The development of a highly automated test scheme makes it possible to collect large amounts of test data, which allows for models to be build based on the physical testing. Using these models enables the possibility for high modularity as well as doing sensitivity studies. It is possible to reduce the number of development loops when creating combustion system variants for different requirements. The result is a robust modular combustion system that has significant improvement in efficiency in combination with a new injection strategy.