Rapid online tomograph in non-uniform complex combustion fields based on laser absorption spectroscopy

Laser absorption spectroscopy tomography is widely applied to measure the two-dimensional distribution information in complex combustion flow fields. Rapid and accurate estimation of the integrated absorption area (IA) is the key to achieving accurate online reconstruction. In this paper, a novel method is introduced with the wavelength modulation spectroscopy (WMS) for obtaining the IA, which is applied in the reconstruction of temperature and species concentrations distributions of non-uniform complex combustion flames. With this method, the traditional time-consuming line-shape fitting process is no longer required, and the IA is obtained through simple algebraic operations instead. This method has been validated via numerical simulations and field experiments on afterburner flames. The experimental results show that the measurement accuracy is comparable to that achieved with the conventional WMS with line-shape fitting (WMS-F), however the computational efficiency is improved significantly by at least two orders of magnitude, demonstrating its potential for real industrial applications, where often rapid reconstructions are desirable or required.