Two-dimensional distribution of NH₂ and HNO in low pressure flat flame doped with ammonia

Two-dimensional concentration distributions of NH₃ and HNO were measured using Intracavity Laser Absorption Spectroscopy (ICLAS), which is the most sensitive absorption spectroscopy method, based on the effect of strong competition between different modes in a cavity of a broadband laser. NH₃ and HNO concentration profiles were measured in methane/nitrogen oxygen flames of different equivalent ratios: 0:1, 8:1, 1:1 and 1.17:1. Ammonia was added at very small concentration (0.1-0.2%) of total gas flow. The number density distributions of NH₃ obtained using tomographic reconstruction demonstrated deviations from the expected flat flame profile. The HNO radical exhibited much wider radial distribution than NH₃. The obtained results are compared with model calculations by one-dimensional PREMIX code and different chemical mechanisms. This is an abstract of a paper presented at the 30th International Symposium on Combustion (Chicago, IL 7/25-30/2004).