Section: Research Program

Flow analysis and CFD assessment: experimental aspects

The capability of producing in-situ experimental data is another originality of our project. By carefully controlling the flow configuration and the type of data we are measuring, we are in situation of assessing in depth the quality of our simulations results over the complete spectrum of possible approaches ranging from DNS, RANS and Hybrid RANS-LES models that the team is developing or LES.

The flow configuration we have chosen is that of a jet in cross-flow since it features large scale coherent structures, flow separation, turbulence and wall-flow interaction.

A great deal of experiments has been devoted to the study of jet in crossflow configurations. They essentially differ one from each other by the hole shape (cylindrical or shaped), the hole axis inclination, the way by which the hole is fed, the characteristics of the crossflow and the jet (turbulent or not, isothermal or not), the number of holes considered and last but not least the techniques used to investigate the flow. A good starting point to assess the diversity of the studies carried out is given by [34] . For inclined cylindrical holes, the experimental database produced by Gustafsson and Johansson (Slanted jet) represents a sound reference base and for normal injection, the work by [40] served as reference for LES simulations [38] . For shaped holes, the studies are less numerous and are aimed at assessing the influence of the hole shape on various flow properties such as the heat transfer at the wall [31] . In 2007, Most [35] developed at UPPA a test facility for studying jet in crossflow issued from shaped holes. The hole shape was chosen as a 12.5 scale of the holes (i.e. at scale 1) drilled by laser in a combustion chamber. His preliminary 2-component PIV results have been used to test RANS simulations [36] and LES [37] . Later, in the framework of the KIAI FP7 European programme, Florenciano [26] upgraded the rig by implementing an acoustic forcing device of the crossflow stream and by performing phase-locked PIV measurements that were used to test the accuracy of LES results. Thus, this test facility is extensively used in the framework of the present project to investigate a 1-hole cylindrical inclined jet interacting with a turbulent crossflow. PIV and LDV metrology are the workhorses as far as metrology is concerned.