Exciplex Fluorescence Method Research Articles

Measurements of the Liquid Phase Temperature in Fuel Sprays via Exciplex Fluorescence Method. 1st Report. Development of the Measuring Technique and Application to Fuel Sprays injected into Atmospheric Pressure and High Temperature Environments.

A measuring method based on the exciplex fluorescence technique has been developed for planar measurements of the liquid phase temperature distribution in fuel sprays. The liquid fuel (n-hexadecane or squalane) was doped with pyrene (C16H10). The fluorescence intensity ratios of the pyrene monomer and excimer emissions has temperature dependence, and were used to determine the liquid phase temperatures in the fuel sprays. The spray was excited by laser radiation at 266 nm, and the resulting fluorescence was imaged by an intensified CCD camera. The cross-sectional distribution of the liquid phase temperature was estimated from the fluorescence image by the temperature dependence of the intensity ratio. The results demonstrate that this laser-based thermometry technique is available for 2-D measurements of the liquid phase temperature in fuel sprays.

Measurements of the Liquid Phase Temperature in Fuel Sprays via Exciplex Fluorescence Method. 2nd Report. Application to Diesel Sprays Injected into High Pressure and High Temperature Environments.

The two-dimensional distributions of the liquid phase temperatures in diesel sprays injected into high-pressure and high-temperature environments were measured using the laser-induced fluorescence technique. The liquid fuel (n-hexadecane) was doped with pyrene (C16H10). The fuel spray doped with pyrene was injected under a high-pressure of 3.1 MPa and a high-temperature of 773K. The evaporating diesel spray was excited by laser radiation at 266 nm, and the resulting fluorescence was imaged by an intensified CCD camera. The fluorescence intensity ratios of the pyrene monomer and excimer emissions have temperature dependence, and were used to determine the liquid phase temperatures in the diesel sprays. The cross-sectional distribution of the liquid phase temperature was estimated from the fluorescence images by the temperature dependence of the intensity ratio. The results demonstrate that the laser-based thermometry technique is available for planar measurements of the liquid phase temperature in evaporating diesel sprays under high-pressure and hightemperature environments.

Visualization and quantitative analysis of the fuel vapor concentration in diesel spray

A single diesel spray of n- tridecane which was miscible with a small dopant was injected from a hole nozzle into a quiescent high-temperature and high-pressure atmosphere, and was impinged vertically on a flat surface with high temperature. It is possible to generate fluorescent emissions from the vapor and liquid phases in this evaporating spray, when a laser light sheet from an Nd: YAG laser is passing through the cross section of this spray. Then, clear 2-dimensional images for the vapor and liquid phases were obtained simultaneously, applying an exciplex fluorescence method. In particular, the vapor concentration was assessed quantitatively by applying Lambert-Beer's law to the measured fluorescence intensity in the vapor phase and by considering the quenching process of its fluorescent emission due to the mixture temperature. Further, we propose an original simulation model which describes the dispersion process of the impinging spray near the wall, considering the breakup phenomena of the impinging droplets and the heat transfer process using the KIVA simulation code.

Visualization of Unsteady Impinging Spray by Means of Exciplex Fluorescence Method.

An unsteady single spray of n-decane which was miscible with a small quantity of exciplex-forming dopants was impinged on a flat wall with high temperature at a normal angle in a quiescent atmosphere in the experiment presented here. It was possible to generate fluorescent emissions from vapor and liquid phase in this evaporating and impinging spray, when a thin sheet of laser light from Nd : YAG laser was passing through the cross section containing the central axis of this spray. Then, clear 2-D images of vapor and liquid in the spray were acquired by this method distance between the outlet of the injection nozzle and the wall.