Ford has used an innovative combustion modelling tool for the development of a new range of highly-efficient diesel engines.
Called EcoBlue, the range features the first engine developed using the Converge CFD software is a 2-litre 4-cylinder turbodiesel for the Ford Transit van. The software was created by Convergent Science, a Madison, Wisconsin an innovative, rapidly expanding computational fluid dynamics (the CFD in the software name) company.
“The use of CONVERGE has allowed us to run high quality in-cylinder CFD simulations,” explained Dr Werner Willems, Ford technical specialist for combustion systems. “We used CONVERGE to refine a number of features on the EcoBlue, including the shape of the combustion chamber, the piston bowl geometry and the fuel injection parameters.”
In particular the engineers used the software to develop the innovative mirror-image intake ports, where the symmetrical design of the integrated inlet manifold causes the air going to cylinders one and two to swirl clockwise, while that going to cylinders three and four swirls counter-clockwise. The design aids in even distribution of air-flow to each cylinder for environmental benefits.
“The two sets of ports are essentially mirror images of each other,” explained Dr Willems. “When you have a lot of variation between the airflow you’re always focusing on getting the weakest cylinder to work properly, which means the others are being held back. Our mirrored port design improves the distribution of air between the cylinders, which reduces emissions and fuel consumption.”
The benefits are a 13% improvement in fuel economy, compared to the current Duratorq turbodiesel, as well as significant reduction in tailpipe emissions.
CFD studies are not new, but have traditionally been a complex and time-consuming process. The software saves time by reducing the amount of manual input required, by automating the meshing process before each simulation.
Adaptive Mesh Refinement (AMR) allows engineers to regenerate the grid at each time step, accommodating changes in geometry or activity without stretching or skewing the mesh with each valve opening or piston movement, a process which previously would lead to deformation errors.
The AMR function is fully integrated with the flow and chemistry solvers, meaning it can automatically vary the mesh density across the model, improving the speed to accuracy ratio of the simulation because it can apply a denser mesh in more critical areas while reducing the cell count in others.
The next step is to develop other engines in the EcoBlue range, with passenger car variants expected to follow quickly.