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It is now well established that highly turbulent flows in engines are responsible for cycle-to-cycle aerodynamic variations particularly in cylinder. These dispersions may lead to macroscopic changes in flow pattern from one cycle to another one, which are quite different from “true turbulence” (in fact small scale turbulent fluctuations) used to optimize combustion. It is of a great importance to decrease these variations which may effect reliability of combustion concept and particularly when looking to decrease idle engine speed. The difficulty in separating “true turbulence” from cyclic variations is that there is no limit between two kinds of fluctuations. To analyze aerodynamic, PIV is well adapted to study these phenomena and is now currently used in development process, allowing to measure instantaneous aerodynamics field to determine for instance vortex center position for each cycle.

This paper deals with the problem of complex engine part analysis. It presents an original approach based on the use of X-ray Computed Tomography scan digitizing method. In comparison with classical digitizing method, Computed Tomography method proves to be the only solution in the case of complex parts with internal areas. A validation example for which the precision of the method is estimated, is proposed. At last, the potential of the method is illustrated through the complex example of an engine head cooling circuit for which a computational CFD calculation is made.