Refinement of exhaust system form large diesel engines using one dimensional (ID) simulation

The airborne noise levels for large capacity diesel engines must meet legislative requirements as a minimum and may have additional constraints on level and spectral content. Exhaust system testing and development for this class of engine is generally limited to confirmation testing due to limited availability of test facilities, high cost of test hardware and testing, limited physical access, and low production volumes. Large diesel engines differ significantly from those used for automotive applications in regard to gas flow characteristics, exhaust system design, and operational modes. This study evaluates the applicability of an automotive industry one dimensional (1D) simulation software suite (Ricardo WAVE™) to the refinement of large diesel engine exhaust system performance and describes the modelling approach used. The Defence Science and Technology Group (DSTG) has developed a computer based capability for modelling the acoustic response and flow performance of exhaust systems and exhaust system components representative of large diesel engines. This capability can be used for exhaust system components, complete exhaust systems, and full engine installations. A virtual transmission loss test bench approach was employed to reduce simulation run times compared to that of complete engine installations. The modelling was conducted in order of increasing complexity where simple models were validated before progressing to more complex models. Published research and data were used for validation. The modelling capability described in this study permits assessment and development of exhaust systems, with or without engine source data, at lower cost. Savings are achieved through a reduction in test samples and physical testing.