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

We investigated spark‐induced ignition of methane/air‐and propane/air‐mixtures under turbulent conditions in a pipe‐flow system where turbulence was increased by the use of grids. A laser‐doppler‐anemometer was used to characterize turbulence in the test facility. To determine the actual energy released by the spark ignition source, we measure delectrical current and voltage during spark discharge. The results show that turbulent fluctuations have the greatest influence on the ignition process, whereas the convective part of the flow (up to velocities of 40 m/s) exerts little influence. For numerical work, a one‐dimensional simulation program, including detailed chemistry and multi‐species molecular transport is used. It is shown that the main influence on the ignition is due to the rms‐value of turbulence. Further more, the influence of increased flow velocity on flammability limits, and of diff e rent spark duration times and macrolengths on the ignition process, are demonstrated.