A reliable measurement of drop sizes and liquid fuel distribution in a spray is essential for best combustion efficiency and exhaust emission from I.C. engines. The droplet size and fuel distribution control air-fuel mixture formation and, hence, combustion characteristics. The chapter gives a concise summary of recent advances and developments in the LSD technique as a planar drop-sizing technique. The LSD technique relies on the principle that a ratio of planar laser-induced fluorescence (PLIF) and Mie signals is proportional to Sauter mean diameter (SMD). PLIF signal can also be used to determine the distribution of liquid in a spray. This makes LSD an attractive technique in dense spray characterization that can also provide liquid volume fraction distributions. A brief review of laser-based drop-sizing methods and working principle of LSD measurements are first discussed. Different approaches and limitations of the LSD technique are also summarized. Further, sources of error and ways to compensate these errors are explained in detail. Previous studies on LSD measurements in different fuel sprays of stationary combustion devices and I.C. engines are summarized. Finally, improvements in the LSD techniques are suggested, including structured laser illumination planar imaging (SLIPI) measurements, for reliable measurements in dense sprays.
Part of the book: Diesel and Gasoline Engines