Optical diagnostic methods for the study of fuel fouling

Abstract

2243the amount of the imbibed cornpitions and increased the intrinsic reactivity. However, the reactivity decreased abruptly in a high concentration of NaCl salts due to the limitation of the rate of ion exchange and the decrease of the degree of hydration of the active catalyst site.An experimental study of fuel fouling using optical measurement methods was performed. These measurements included absorption from 350 to 750 nm, scattering at 514.5 nm, and fluorescence using a probe wavelength of 514.5 nm. Measurements were performed using a constant-temperature heating system which exited into an optical cell. Each of the measurements proved useful in monitoring changes in the test fuel, JP-4, at test temperatures up to 775 K and pressures of 400 psig. Absorption measurements demonstrated both molecular changes in the fuel composition and a marked increase in the particulate present in the flow as a result of thermal stress. Scattering measurements indicated room temperature fuel to contain particulate with average diameters greater than 0.1 pm while thermally stressed fuel contained much larger concentrations of particulate with sizes below 0.06 pm. This work clearly illustrates the possibilities of using optical methods for monitoring the fuel fouling process.

Spectroscopic Study of Aviation Jet Fuel Thermal Oxidative Stability

“…Cheng et al used UV−vis absorption spectroscopy in accelerated oxidation tests to measure the amount of soluble gums. Parker et al studied the fouling phenomena of JP-4 fuel using a combination of optical measurements: light absorption spectra from 350 to 750 nm, elastic light scattering at 514.5 nm for particle size measurements, and monochromatic fluorescence collected in the visible spectrum. The authors concluded that all three techniques showed an ability to monitor changes within the thermally stressed fuel.…”

Technology Development

“…[10][11] Much of this work also developed new infra-red emission and absorption techniques for probing dense particulate-and droplet-laden flowfields associated with diesel spray injection and hightemperature fuel fouling. [12][13][14] In the early 90's, PSI conducted numerous research programs in support of major national projects to develop high-speed propulsion systems for hypersonic flight vehicles. Our reaction kinetics expertise was deployed to measure three-body recombination rates important in designing efficient SCRAMJET engines 15 and to interpret experimental H 2 -air combustion data obtained in a PSI shock tunnel supersonic combustion facility (shown in Figure 2).…”