Burning Flame Temperature Measuring And Temperature Field Reconstruction

Combustion is an important way for energy transformation in human lives and society production.Measuring key-point temperature or the whole temperature field is vital for acknowledging,controlling the combustion processes,which is helpful in saving fuel,decreasing pollution and forming an efficient,safe working condition.Tunable Diode Laser Absorption Spectroscopy(TDLAS)uses the relationship between gas absorption spectrum and temperature for thermometry.It is a sensitive,reliable way which has many advantages such as non-intrusive,fast and strong noise-resistant ability.TDLAS is also used in many industries like metal smelting,aerospace,electric power and so on.This paper uses TDLAS technology for real-time gas temperature measuring and introduces a new way to reconstruct flame temperature field,including:According to the research about the relationship between gas absorption spectrum and temperature in TDLAS and the characteristics of double-line method and concentration-inversion method,the paper chooses double-line method which needs different absorption lines for simulation that has no wavelength limitation,and concentration-inversion method for experiments which uses a single-wavelength system with a concentration-measuring function.HITRAN database is visited to pick suitable absorption line and a method which can combine all nearby lines into an equivalent one is presented.The combine error is less than 3.26%.Besides,a measuring system is built to get the flame temperature.A thermocouple system is also used to give references.The reconstruct error is less than 10% after the abnormal point is removed.An iterative algorithm called the least modulus iterative algorithm is introduced in the paper.By turning the reconstruction of temperature field into an optimize problem,the algorithm uses least modulus function to control the iteration.It can distribute the reconstruction error into every area according to area weight,making the error as small as possible.The least modulus iterative algorithm can reconstruct two-dimension temperature field in 0.3s with a reconstruction error less than 10%.It only needs several steps of matrix calculation,and is faster,simpler,more accurate and less sensitive about the number of light paths than Algebraic Reconstruction Technique(ART),which meets the need of a real-time measurement better.