Planar Visualization of Vapor and Liquid in a Spray Plume

In liquid fueled combustion systems it is necessary for the fuel to vaporize prior to combustion. As a result, a method to quantify the amount of vapor that exists in the spray plume is desired in order to help understand the evaporation process. Such results are also useful in validating detailed computer models of this same process. Unfortunately, such a measurement is very difficult in practice due to the complex interaction of the spray droplets with any method applied. The objective of the proposed effort is to develop a robust diagnostic method to quantify the planar concentration of fuel vapor, fuel liquid, and gas phase temperature in a spray plume. The method proposed is to use multi-angular light extinction using collinear laser beams of specific wavelengths generated by tunable diode lasers. The wavelengths selected will allow differences in the absorbed light to be used to quantify fuel vapor, fuel liquid and gas temperature. Laser extinction is a very robust reliable method and the use of differential absorption eliminates challenges with windows, droplets effects, and dense spray issues that tend to plaque laser sheet imaging methods typically used. In Phase I, proof of concept will be demonstrated for a fuel spray for a liquid of interest (e.g., gasoline). The spectroscopy of gasoline will be evaluated to select appropriate wavelengths and appropriate tunable diode laser blocks identified. The identified wavelengths will be assembled into a breadboarded system and applied to a series of experiments to demonstrate proof of concept. These will range from particle laden jets of air doped with a hydrocarbon vapor to a gasoline spray injected by a typical automotive injector. Single collinear beams will be used in Phase I and multiple paths through the spray will be measured and deconvolved using tomographic analysis methods. Evaluation of potential time-resolved information will be carried out. Commercial Application and Other Benefits: The proposed instrument fills a significant niche in the diagnostics market for spray characterization. If successful this instrument will be of great interest to a wide range of OEMs and component suppliers for fuel injectors for many applications. The data generated can be used to gain insight into the fuel injection process and also provide important validation data for models. With validated models, fuel injector and combustion designers can more efficiently develop higher efficiency, clean burning liquid fueled engines.