| Flame temperature and radiation characteristic of soot are important parameters to reflect the status of flame combustion.In terms of electricity production,the accurate measurement of flame temperature in the municipal refuse incinerator makes it possible for operators adjusting the operation parameters in time to avoid problems such as uneven transverse grate temperature,local overtemperature of the furnace and the corrosion of the heating surfaces.The characterization of the temporal and spatial dynamic evolution of the flame in the incinerator can reveal the combustion status of the flame in the furnace under different loads and different section heights of furnace,and provide visual data for the accurate and real-time control of the operation of unit.In the field of hypersonic vehicle development,the accurate measurement of flame temperature in combustion chamber of rocket-based combined cycle engine can deeply reflect the combustion pattern of fuel in supersonic flame,and reveal the combustion evolution law of flame in combustion chamber.It is beneficial to the refined design of the structure of supersonic flame combustion chamber.At present,the measurement of the flame temperature with strong disturbance and supersonic condition are mainly based on radiation spectrum and radiation images.High spectral resolution occurs in radiation spectrum temperature measurement technology,but the low spatial resolution makes it impossible to reconstruct flame temperature field.The distributions of flame temperature with high spatial resolution can be measured by the radiation images temperature measurement technology.But the flame temperature with high precision cannot be measured when the radiation image temperature measurement technology is applied to the non-gray flame.The flame radiation intensity images with both spatial and spectral resolution can be generated by the multi-wavelength radiation intensity at each pixel based on multispectral imaging technology.Combined with multispectral radiation temperature measurement technology,high precision reconstruction of flame temperature can be realized.The main research content of this paper is as follows:A multi-wavelength radiation thermometry method based on HOTTEL emissivity model was proposed to measure the flame temperature and emissivity of candles with different wick diameters and different components.The peak flame temperature was 1943 K appeared in the thin-wick paraffin.At any position,the emissivity of the thinwick paraffin flame was lower than that of the thick-wick,but the emissivity of the biomass candle flame near the flame center was the highest.The distributions of flame temperature and emissivity were measured in a 750 ton/d municipal solid waste incinerator.The measured temperatures at different locations varied by 31.25%with a fixed steam evaporation rate.The temperatures and emissivities decreased at upper locations due to the lower local soot particle concentration and the change of the measured flame temperatures with load were correlated with the municipal solid waste caloric values.Flame temperatures near the left wall were higher than those near the right wall.This deviation was caused by the high moisture content of municipal sludge concentrated on the right wall that inhibited combustion.And the emissivities of flame near the right wall were lower than those near the left wall due to the low fixed carbon in municipal sludge.A supersonic flame temperature reconstruction algorithm based on LevenbergMarquarelt(L-M)algorithm was proposed to reconstruct the flame temperature field in the combustion chamber of rocket-based combined cycle(RBCC)engine.When the equivalent ratio was 0.6,the injected fuel and inflow were most fully mixed on the slope at the rear of the cavity,where over 65%of the peak flame temperature points were located.The flame combustion in the RBCC chamber showed an oscillation phenomenon that peak flame temperature and the flame structure oscillated continuously around the central axis. |
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