Electrostatic dispersion of drops of sprayed liquid fuel has been proposed as a technique for reducing the amount of soot formed during burning of the fuel. It is necessary to disperse fuel drops in order to reduce local concentrations of fuel-rich vapors, because such concentrations favor the nucleation of soot. The present technique can be implemented by use of a previously developed device called an "electrostatic triode"; this device puts like electrostatic charges onto sprayed fuel drops to generate dispersion of the drops.
Another technique for reducing the formation of soot is mechanical dispersion through utilization of turbulence. The effectiveness of electrostatic versus mechanical dispersion for reducing the formation of soot has been investigated in a theoretical and computational study. In the study, the mechanical and thermodynamic interactions between fuel drops and the surrounding gases were simulated numerically by use of a mathematical model similar to the models used in previous studies of sprayed liquid fuels that have been performed by the same innovators and summarized in a number of articles in NASA Tech Briefs. The model includes, among other conservation equations, equations for the momenta of the drops. The electrostatic forces were included in these equations for those drops that were considered to be charged. The calculations for the charged drops were stopped at the Rayleigh limit; that is, secondary atomization was not modeled.
The results of the numerical simulations were interpreted as signifying that electrostatic dispersion would be superior to mechanical dispersion for reducing the nucleation of soot; this finding gave rise to speculation that perhaps a combination of electrostatic and mechanical dispersion might be even more effective. However, further numerical simulation revealed that for the purpose of reducing the formation of soot, the combination electrostatic and mechanical dispersion would not offer a significant advantage over electrostatic dispersion alone.
This work was done by Josette Bellan and Kenneth Harstad of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com under the Physical Sciences category, or circle no. 187on the TSP Order Card in this issue to receive a copy by mail ($5 charge). Refer to NPO-20219
This Brief includes a Technical Support Package (TSP).
Electrostatic dispersion of fuel drops to reduce soot
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Overview
The document is a technical support package from NASA, specifically a NASA Tech Brief, detailing research on the electrostatic dispersion of fuel drops to reduce soot emissions. Authored by Josette Bellan and Kenneth G. Harstad, the report is part of the JPL New Technology Report NPO-20219 and was published in April 1998.
The primary focus of the research is to address the issue of soot formation during fuel combustion, which is a significant concern in various applications, including aerospace and automotive industries. Soot not only contributes to environmental pollution but also affects engine performance and efficiency. The study proposes an innovative approach using electrostatic forces to enhance the dispersion of fuel droplets, thereby minimizing the conditions that lead to soot nucleation.
The document outlines the methodology employed in the research, which includes the use of an electrostatic triode to create an electric field that influences the behavior of fuel droplets. This method is compared to traditional mechanical dispersion techniques, highlighting the advantages of electrostatic dispersion in achieving finer and more uniform fuel droplet sizes. The researchers conducted advanced computational modeling to simulate the combustion process and assess the effectiveness of the electrostatic method.
Results from the study indicate that electrostatic dispersion significantly reduces the concentration of fuel-rich vapors, which are responsible for soot formation. The findings suggest that this technique could lead to more efficient combustion processes, resulting in lower emissions and improved fuel economy.
The document also includes a disclaimer stating that neither the United States Government nor NASA makes any warranties regarding the accuracy or completeness of the information provided. It emphasizes that users of the information do so at their own risk and that NASA does not assume liability for any damages resulting from its use.
In summary, this NASA Tech Brief presents a promising advancement in combustion technology through the electrostatic dispersion of fuel drops, offering potential benefits in reducing soot emissions and enhancing fuel efficiency. The research contributes to ongoing efforts to develop cleaner and more efficient combustion systems, aligning with environmental sustainability goals.
