For the purpose of measuring turbulent burning velocity of methane/hydrogen/air premixed flame at high pressure, experimental systems were established which hold stable turbulent combustion at high pressure. Optical measurements below were applied to turbulent flames. Two-dimensional number density distribution of OH radicals near the flame, the image of which is sufficient to reflect the reaction region of the turbulent premixed flame, was measured by using OH-PLIF. The average flame structure can be estimated from the accumulated image of OH-PLIF. By extracting the inclined flat flame region excluding the tip and root of the flame, the turbulent burning velocity was calculated.
