Particle Size Measurement Of Spray In Gasoline Direct Injection Engine Based On Point Mode

Interferometric particle imaging(IPI)technique,based on Mie scattering theory,is a popular particle measuring technique.Scattering light of particles forms glare points on focus image and fringe on defocus image.Particle size is measured by two glare point’s distance of focus image or fringe frequency of defocus image.The points mode of the Laser Interferometer Particle Imaging(IPI)was used to measure the droplet size distribution of GDI spray in a single hole injector.The particle size distribution and SMD variation curves of the same working conditions and different conditions are given.The main works as follows has been done:1.IPI theoretical model is established.The optical field distribution of focus and defocus image with the finite large aperture and the Infinite aperture are given.Analyzing the deviation between the geometric centre of image and particle center image.The expression of the particle size of single beam and double beams irradiation are deduced.2.Verification experiment system of particle position measurement is built.Measured d’/d value of 15、30 and 50 particles are 19.38±0.009、19.36±0.012 and 19.37±0.011,absolute error are 0.028、0.052、0.038 and relative error are 0.15%、0.27% and 0.20%.The experimental results show that the algorithm has good positioning capability.3.Verification experiment system of particle size measurement is built.Standard particle size of 10.9μm、14.9μm、15.0μm、21.3μm、25.0μm、45.0μm and 51.0μm are measured respectively.The measurement results: the particle size are 12.16±0.40μm、16.04±0.45μm、16.36±0.80μm、22.20±0.72μm、25.20±0.86μm、45.43±1.07μm and 50.52±1.11μm respectively.The relative errors are 11.56%、7.65%、9.07%、4.23%、0.80%、0.96% and 0.94% respectively.The measurement accuracy of the algorithm is verified by the measurement results.4.An experimental system of interferometric particle imaging with opposition of two laser-sheets illumination at scattering angle θ=90° is designed and built.The particle size distribution and SMD variation curves of the same working conditions and different conditions(ambient pressure,injection pressure,fuel temperature)are given.