Measurement of the flow field in a diesel engine combustion chamber after combustion by cross-correlation of high-speed photographs

A cellular cross-correlation technique is applied to high-speed photographs of the luminous phase of combustion in a high-speed direct-injection diesel engine. The method enables the velocity and vorticity distributions in the combustion chamber to be evaluated. The results obtained from the basic technique are refined to remove spurious results and to complete the definition of the flow field by applying data validation, interpolation, and smoothing. The velocity and vorticity fields evaluated at two swirl ratios show the way in which the basically solid body swirl motion interacts with the fuel jets in the combustion chamber. A better understanding of the post-combustion fluid motion is obtained, and this should be of help in validating CFD codes and also the design of engines.The combustion photographs which provided the data for this work were obtained by Mr. E. H. Clough, K. K. Rao, P. Gomes and R. Pruce. Funding for the programme was provided by the UK Science and Engineering Research Council. Financial support for one of the authors (J.-H. S.) was provided by the Sino-British Friendship Scholarship Scheme. To all these people and organisations the authors express their grateful thanks.