Influence of turbulent flow conditions on the ignition of flammable gas/air-mixtures

We investigated spark-induced ignition of methane/air- and propane/air-mixt ures under turbulent conditions in a pipe-flow system where turbulence was increased by, the use of grids. A laser-doppler-anemometer was used to char acterize turbulence in the test facility, To determine the actual energy re leased by the spark ignition source, we measured electrical current and vol tage during spark discharge. The results show that turbulent fluctuations h ave the greatest influence on the ignition process, whereas the convective pail of the flow (tip to velocities of 40 m/s) averts little influence. For numerical work, a one-dimensional simulation program, including detailed c hemistry and multi-species molecular transport is used. It is shown that th e main influence on the ignition is due to the rms-value of turbulence. Fur thermore, the influence of increased flow velocity, on flammability, limits , and of different spark duration times and macrolengths on the ignition pr ocess, are demonstrated.