| The parameter measurement of the particles in the multiphase flow is critical for the quantitative characterization of the fluid transport process and has important applications in energy and other industrial processes.Rainbow scattering measurement technology is a light scattering measurement technology.Because it has the characteristics of simultaneous measurement of the apparent parameters and internal parameters of the particles,it is of great scientific significance to develop the rainbow technology to measure the droplet field of the complex atomization.By means of theoretical analysis,numerical simulation and experimental research,the scope,measurement dimension and calibration method of rainbow scattering measurement technology are extended and innovated..In the aspect of design and optimization of rainbow system,quantitative research is carried out from three aspects:inversion algorithm software,optical path imaging system and calibration system.On the basis of the modified Nussenzveig theory,the non-distribution function algorithm is used to optimize the droplet refractive index and particle size distribution,and the algorithm is validated by the simulated full rainbow signal.The relative error of the refractive index is 0.01%to 0.02%.The theoretical analysis of the optical path of the rainbow imaging system from the angle of geometrical optics is carried out.The automatic calculation and simulation optimization of the rainbow system component design are realized with MATLAB and ZEMAX,so as to quantitatively evaluate the effect of aberration.The results show that the control of RMS speckle radius within 160?m can ensure the absolute deviation of refractive index within four decimal places.The calibration curve y = ax + b of the calibration system and the inversion error of the parameters with the coefficients a and b are studied respectively.The results show that the error produced by the calibration system does not play a major role,but there are errors caused by man-made operation,it is necessary to carry out control improvement in this respect.In the improvement of the rainbow measurement method,a one-dimensional rainbow measurement method is proposed.Taking into account the characterization of the droplets at Changes in the parameters of the process of transmission or spatial distribution,such as evaporation or other physical processes.Concidering the limitation of the global rainbow measurement,it is necessary to change the method of modulating the original full-field system by replacing the spatial angle scattering information in different pixel rows of the CCD acquisition signal with the scattering information at different spatial heights.Changing the mode of laser illumination so that the point light source becomes a line light source and changing the design layout of the diaphragm so that the CCD can capture the rainbow signal of the one-dimensional spray area.In addition,calibration and development of a new signal processing algorithm through experiments,to achieve the signal pixel and one-dimensional measurement points within the corresponding match,so that the droplet multi-parameter information of one-dimensional spray area is obtained.Secondly,a dual-wavelength self-calibrating method is proposed.The difference of the refractive index of the medium is found by using the two-wavelength laser.The relation between the rainbow angle and the CCD pixel can calibrate the absolute rainbow scattering angle.By using the simulation program based on Lorenz-Mie scattering theory and the inversion software,the simulation results are verified and the results are in agreement with the experimental results.The results show that the method is feasible.In the aspect of rainbow characterization,the research framework of particle form is summarized,the characteristics of spheroids,especially those with droplet containing solid particles,are analyzed.The experimental results show that the random distribution of solid particles in droplet containing solid particle does not affect the inversion of liquid medium parameters.The solid state core with several different complex refractive index conditions was studied by using the theoretical model.The extinction efficiency factor was 2 near the Mie's oscillations in the range of droplet diameter.The interference effect of the position of the solid particles on the rainbow scattering is studied.It is found that the interference effect of particles distributed along the light propagation path around the scattering angle of the main peak of the rainbow under the same particle size conditions is much larger than the other locations in the droplet.In the aspect of applications,firstly,the is the miscible state of different liquids was studied,especially the inversion algorithm of double-peak rainbow.The algorithm is introduced to get the refractive index of water and ethanol,which is 1.3336 and 1.3653 respectively,consistent with the theoretical value.The average particle size is 39 and 50?m;the volume ratio is 0.51 and 0.49.The change of temperature and particle size at different height in the direction of the flow field was measured,and the decreasing trend of temperature and droplet due to evaporation was observed.Furthermore,the absorption reaction of the alkaline solution with the acidic air is studied.The results show that the chemical composition of the droplet in the reaction process can be well correlated with the solid concentration in the liquid droplet.Based on the above research,a two-dimensional rainbow measurement concept is proposed,which integrates one-dimensional technology and self-calibration technology;a plurality of spatially unknown droplets in one plane are measured,and three variables including the spatial position,particle size,and refractive index;acquisition of speed,evaporation rate,composition or temperature changes in three variables.In particular,consider the introduction of the conclusion that the absorption of solid droplets in terms of absorption,the main peak of the absolute value of light intensity changes can be converted to the solid content of droplets.Explore one highly compressed,highly efficient method of measuring information.In order to further promote the on-line multi-parameter characterization of complex particle flow field,it provides an experimental means. |
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