Gaseous flow measurements in an internal combustion engine assembly using molecular tagging velocimetry

A molecular tagging velocimetry (MTV) system was applied for mapping in-cylinder flows in an internal combustion engine. The images were captured inside an optical engine assembly that reproduces operation of a 2.2 L four stroke gasoline engine. A recently developed algorithm to process MTV images is based on a fast-normalized spatial correlation approach implemented using MATLAB software. The code allows accurate detection of the MTV grid nodes displacements. It processes simultaneously velocity vector and circulation fields for individual cycles, and ensemble averages of those over a few hundred sequential cycles to obtain mean and standard deviation values. Then probability density functions are reconstructed to quantify cycle-to-cycle variability of the in-cylinder flow.