Research On Measurement And Three Dimensional Reconstruction Of The Flame Temperature Field Based On Image Detection

Acquiring flame temperature information from the dynamic combustion flame image is a very important research in combustion diagnosis field. In this paper, three dimensional temperature field model reconstruction is suitable for space medium, which is combined with radiation heat transfer calculation method and the solving method of the inverse problem by using color CCD camera.In the temperature field reconstruction of space medium, the characteristics of the medium are absorbing, emitting and scattering, and space medium is large but receiver is very small. So it is necessary to establish a temperature field reconstruction model with high efficiency and wide adaptability, Which is a key point in the research of this paper. The other key piont of the reaserch is how to reconstruct the model for symmetrical and asmmetrical flame without considering the shape of flame in reconstruction area.Firstly, the basic principle of the colorimetric temperature measurement method is introduced and error sources of its temperature measurement which are mainly caused by gray value changing and imperfection of response spectral band in CCD are discussed.The relative correction methods are also put forward. Experiments are conducted to verify the accuracy of the temperature measuring method after correcting.Secondly, the Monte Carlo method and the medium of radiative transfer algorithm are introduced in detail. Through comparing with the reconstruction experiments to validate the feasibility of the algorithm. Combining with lens optical imaging principle, calculating medium combustion flame radiation optical imaging.Then, the backward Monte Carlo method is discussed. And the reconstruction of three-dimensional temperature field model based on backward Monte Carlo method is also put forward innovatively. The model fully considers the three characteristics which are absorbing, emitting and scattering of the actual space medium, and reconstruction time is short, which is suitable for large radiation source and small CCD imaging target. Discussing the effects on the reconstruction accuracy, the result shows backward Monte Carlo method for reconstruction is more efficient, and less reconstruction errors.Finally, establish the reconstruction model which is suitable for symmetric and asymmetric flame, and use the numerical simulation to validate the reconstruction model. Experiments imply that the reconstruction resualt of flame temperature field is more reasenable and it is accordant to the temperature distribution in the references. To validate the accuracy of reconstruction temperature distribution, use thermocouple to approxmately measure the temperature distribution and the reconstruction resualt is very similar to the measure result.