REAL-TIME QUANTITATIVE 2-D IMAGING OF WATER VAPOR IN DIFFUSION FLAMES

An imaging Wavelength Modulation Spectroscopy (WMS) system has been developed for measuring combustion species concentiations in two-dimensional or axisymmetric flames. This system uses a rastered nearinfrared diode laser that provides a two-dimensional absorption image. This technique has the advantage over other laser-based methods as being simple and inexpensive to implement, provides signals which are directly linear in concentration, and is easily calibrated to provide accurate quantitative results. This technique can generate absorption (or concentration) “movies ” at real time rates, showing steady and transient behavior of species within the flame. Qualitative absorption data can be converted into quantitative concentrations using a numerical absorption model that utilizes the HITRAN database. Currently, this system is being used to measure water vapor absorbances in steady and transient methane/air flames from a Wolfhard-Parker slot burner