Quantitative Measurement of 2-D Fuel Vapor Concentration in a Transient Spray via a Laser-Induced Fluorescence Technique

Abstract

A new method of quantitative measurement of fuel vapor concentration in transient evaporating sprays is described. TMPD, a fluorescence dopant, was doped in n-tridecane fuel, and the blended fuel was injected into high-temperature and high-pressure nitrogen to form an evaporating spray. A sheet of laser light from a pulsed Nd : YAG laser illuminated a cross section of the evaporated spray to induce a fluorescence emission from TMPD vapor in the spray. The laser-induced fluorescence image taken from a direction perpendicular to the illuminated plane was analyzed based on a detailed calibration concentration conducted at high-temperature and high-pressure conditions and an assumption of the thermal equilibrium state for fuel vapor and nitrogen mixture. The quantitative fuel vapor concentration distribution at an instant in an evaporating spray was thus obtained by the analysis, and its accuracy was proved satisfactory through a comparison of the mass of fuel vapor integrated over the entire spray and the mass of injected fuel. © 1995, The Japan Society of Mechanical Engineers. All rights reserved.