There is a current requirement to detect and quantify the
presence of gas bubbles in oil exploration. For this reason a novel method
has been developed to measure simultaneously the velocity, size and
refractive index of large optically transparent bubbles and droplets. The
method is based on the time displacement of refracted and reflected beams
scattered from the moving particles. Experimental results obtained from
water droplets are included.
Particles emitted from aircraft play a role in the formation of contrails and it is essential to characterize them to understand the physical and chemical processes that are happening. Current methods for measuring aircraft particulate emissions study the reflectance of samples collected in filter papers.A series of experiments to more fully characterize particulates has been performed on a small-scale gas turbine engine. An intrusive sampling system conforming to current ICAO regulations for aircraft emissions was used with a scanning mobility particle sizer (SMPS). Non-intrusive measurements were made using laser induced incandescence (LII) and samples were taken from the exhaust to analyse using a transmission electron microscope. Results obtained from different techniques showed good agreement with each other. As engine power conditions increased, both the SMPS and LII indicated that the mass of soot had decreased. Differences were observed between measurements of diluted and undiluted samples. The mean particle size decreased with dilution but the size distribution became bi-modal.The study has shown how significant the sampling environment is for measuring particulates and careful techniques need to be used to ensure that accurate, consistent results can be obtained.
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