Doppler Global Velocimetry Measurement of Charge Motion Inside Piston Bowl of a Motored Diesel Engine and Correlation to CFD Results

Charge motion inside the piston bowl is an important parameter in the development of the combustion process of DI Diesel engines. To snapshot this charge motion at the start of injection or the start of combustion, normally CFD simulation has traditionally been used. The use of CFD tools has provided some insight into the combustion process and therefore has shortened the development process of piston engines. To achieve a better understanding of the parameters which influence a low emission diesel-combustion the virtual approach needs hardware assisted validation. A test method has been developed to measure charge motion inside the piston bowl of a motored diesel engine at TDC using laser based Doppler Global Velocimetry (DGV). The use of this new measurement approach is versatile. Investigations can be conducted on charge motion caused by variation of compression ratio and piston bowl design or caused by valve timing or valve seat design. The focus of this paper is on the charge motion measurement approach including new seeding particles, basic flow study results, and a comparison of the measurement results to transient CFD- calculations.