Numerical investigation of two-dimensional imaging for temperature and species concentration using tunable diode laser absorption spectroscopy

A technique has been developed to obtain simultaneous tomographic images of temperature and species concentration based on line-of-sight (LOS) diode laser absorption spectroscopy. Multiple LOS measurement paths divide the combustion zone into an M×N grid. With the assumption of uniform distribution around the grid intersection points, spatial distribution of temperature or a particular chemical species can be inferred from the M+N path averages because each measurement path passes through different grid boxes and carries their information of temperature and species concentration. The measurement accuracy and resolution depend on the total number of paths measured. The feasibility of this method is verified by simulated image reconstruction of an engine temperature distribution.