Interview Dipl.-Ing. Dr. techn. Heidelinde Holzer

1. What are the reasons for you to use the relatively complex Visiolution technology “VisioTomo” in racing?
In all speed ranges in which racing engines mainly are operated the cylinder pressure no longer is a global measurement variable but the information resulting from the cylinder pressure measurement is of a local nature.

The visualisation of the flame propagation does not only support the comparison of the results from testing with those of the 3-D calculations but also provides a decisive contribution to better understand still unclear phenomena for all engineers involved into the development process.

2. Which expectations to you have regarding VisioTomo?
In order to further increase the efficiency of a racing engine, the complexity of the system „internal combustion engine“ has to be understood and all details about the thermodynamic process in the combustion chamber must be known. Efficient combustion process development includes the comprehensive understanding of the interactions between charge motion, mixture formation, flame propagation, combustion stability and wall heat losses. Since it is not only growing more and more difficult to use the full performance potential of current F1 race engines but each additional HP also causes enormous costs, the expectations on VisoTomo with regard to heightening the understanding of combustion processes are very high. VisioTomo has to be able to reliably identify the effects of modifications which are made with regard to gas exchange, mixture formation, combustion chamber design and the parameterization of performance-relevant engine maps. The endurance of the optical cylinder head gasket with respect to temperature and vibration as well as the durability of the measuring system in the testing cell have to be absolutely guaranteed. The repeatability of the measuring results under such extreme load and under restricted time conditions has to be ensured at any time. The evaluation software has to display the results in such a manner that they can be easily understood by the user and it has to provide error-free, user-friendly handling in order to allow customers to use the complex system independently without the help of AVL specialists.

3. In which field of application GCA can contribute to the development of a racing engine?
On the one hand the one-dimensional Gas Exchange and Combustion Analysis (GCA) calculation is the connecting link between the test and the 3D flow calculation using AVL-FIRE and on the other hand it offers the test engineer a valuable addition in the field of thermodynamics development. The GCA calculation provides values such as the volumetric efficiency whose measurement requires a lot of time and complex measurement equipment in order to serve as basis for decisions and as plausibility checks at the one-cylinder development test bed.

Further advantages of the GCA include:

By using the GCA for racing applications the weak points of indicating data processing such as the deviation in thermodynamic zero-level-correction while post-processing can be eliminated. We would like to suggest to integrate the calculation of the dynamic compression ratio in future software releases.

4. How much emphasis do you put on using VisioTomo and GCA combined?
The goal of efficient combustion through optimal utilization of the combustion chamber is to ensure high combustion stability at speed of up to 19,000 rpm. By using VisoTomo and thanks to the synchronization with the 3D flow calculation we expect to be able to satisfy this demand much better in the future, mainly in order to reduce the number of variants. The GCA process analysis also enables the engineer at the test bed to immediately check the plausibility of the measurement results or to quickly conduct sensitivity analyses. This enables the user to obtain information about trends already at a very early stage of development.

Your questions, comments, wishes?