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As part of an overall program to study droplet-turbulence interactions in fuel sprays, a two-dimensional, fluorescence imaging technique has been developed to make simultaneous measurements of droplet size, position and velocity. This paper describes the technique, discusses sources of error and biasing and presents some sample measurements taken in a polydispersed spray.

The effect of turbulence on flame kernel growth in lean propane-air mixtures has been studied in a flow reactor at atmospheric pressure and 300 K using laser ignition. The flame kernel growth rate was measured using laser shadowgraphy. Measurements were made under two different turbulent flow conditions, with two different ignition energies and over a range of fuel to air ratios. The effects of these parameters on flame kernel growth through changes in the mass burning rate and the expansion velocity are discussed. A comparison of the effect of turbulence on ignition probability and flame kernel growth rate variation is also presented.

Measurements are presented of bulk velocity and its cyclic variation and of turbulence intensity in IC engines with combustion chambers of open shape. Engines with both ported* and valved intakes were tested. The ported engine was tested both with and without swirl and the valved engine without swirl only. The ported engine was motored at 1200, 1800 and 2400 RPM and the valved engine at 600, 1200 and 1800 RPM. In both engines the shape of the combustion chamber was such as not to introduce strong organized gas motion during compression. Thus the in-cylinder gas motion, including turbulence, was due primarily to the intake process. The measurements were made using laser Doppler velocimetry at data rates which were sufficiently high to determine the bulk velocity in each cycle and thereby separate the cyclic fluctuations of the bulk velocity from the turbulence.

The goal of this theoretical-experimental work is to model two-dimensional, unsteady (and steady) two phase flow combustion in internal combustion engines (and steady reactors) and to test and improve the model with parallel experimental programs. The purpose of this research is to make more detailed current understanding of this important family of combustion problems and to aid the development of cleaner and more efficient engines. In this paper, preliminary theoretical-experimental results of our efforts toward the stated goal are presented. The theoretical results are preliminary but prove the feasibility of detailed computations of combustion in internal combustion engines and show how informative such computations can be. In a section of this paper, preliminary results are reported of detailed computations of two-dimensional, unsteady sprays penetrating and vaporizing into an inert gas in a closed volume (without combustion).