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In-cylinder charge motion plays a key role in optimizing the combustion process of modern reciprocating engines. The present paper describes a method for obtaining the volumetric, isothermal, in-cylinder velocity flow field using Doppler Global Velocimetry (DGV). The DGV system is designed for measuring time-averaged velocity data in three different light sheet directions using a single camera system with the aim of providing planar, spatially resolved, three-component velocity data of the cylindrical cross section. As DGV provides time-averaged data, the results can be directly compared with data obtained by 3-D CFD analysis. An automated program code generates characteristic numbers of the measured velocity fields with the aim of assessing and comparing the results of different engine concepts.

Flow fields and fuel distribution play a critical role in developing the combustion process inside the cylinders of piston engines. This has prompted the development of measurement and diagnostic capabilities including laser techniques like Doppler Global Velocimetry (DGV). The paper provides an overview of the basics of DGV and the type of results that can be obtained. It also includes a short comparison to Particle Image Velocimetry (PIV) which is a popular alternative method. Furthermore, it is shown that DGV can be used simultaneously in combination with droplet distribution visualization inside cylinders based on Mie scattering.

As more virtual product development is integrated into the mass-production development process and overall development times are shortened, efficient intake-port design requires closer cooperation between design, simulation and test engineers. Doppler Global Velocimetry (DGV) has become an important link in the overall intake-port development process as it provides 3D-vector fields of flow velocity. Hence, it can be used to make direct comparisons with 3D-CFD-simulation results. The present paper describes the hardware-assisted inlet port development process for diesel engines, the cooperation among port design, 3D-CFD-simulation with the creation of alternative geometries and DGV flow-measurement of preferred variants with their capability of checking and improving simulation results.