Measurement of flame thickness by ion current method

The ion current method was used to obtain the flame thickness of CH₄/hydrogen mixture under different operating conditions, the calculation method for flame thickness was established, the experimental conclusions were compared with those of references. The results show that for the CH₄/air mixture, at the excess air ratio of 0.75, 0.80, 0.85, 0.90, 1.00, 1.10, the flame thickness measured by the ion current method was 1.337 mm, 1.316 mm, 1.273 mm, 1.260 mm, 1.309 mm, 1.353 mm, respectively. At the excess air ratio of 0.8, when the hydrogen fraction was 0-80%(10% increment), the flame thickness of CH₄/hydrogen mixture was 1.456 mm, 1.371 mm, 1.216 mm, 1.111 mm, 1.062 mm, 0.951 mm, 0.857 mm, 0.871 mm, 0.818 mm, respectively. The results show good agreement with those of previous research work, indicating that it is possible to evaluate the flame stability utilizing the thickness of laminar flame obtained by ion current method. Both flame speed and flame thickness can be obtained by ion current method.