Effects of magnetic fields on combustion (abstract)

摘要

We have observed a phenomenon that candle flames are pressed down by magnetic fields. We have also observed that flows of gases such as carbon dioxide and oxygen are blocked by magnetic fields. A model, called a lsquo;lsquo;magnetic curtain,rsquo;rsquo; has been introduced to explain these phenomena. The magnetic curtain is a wall of air which is produced by magnetic fields. We have demonstrated an experiment to show that candle flames are quenched by the magnetic curtain. The present study focuses on the mechanism of the phenomena involving quenching of flames using magnetic fields. An electromagnet with a pair of columnar magnetic poles in which inner sidepieces were hollowed out was used first. Magnetic fields of 1.5 T at the brim gave a gradient of 50ndash;300 T/m in the direction perpendicular to the pole axis. Alcohol was burned in the hollowed space between magnetic poles. Gases around flames in the hollowed space were sampled into gas sensors through an inhalation nozzle. Oxygen, carbon dioxide, and carbon monoxide were simultaneously measured during the combustion of methanol and ethanol. During magnetic field exposures, oxygen concentration decreased, whereas concentrations of carbon dioxide and carbon monoxide increased. However, when flames were quenced in a few seconds, oxygen concentration in the hallowed space was not changed, and very little of carbon dioxide and carbon monoxide were produced. The interception of a small amount of oxygen near the surface of the flames may quench flames. Emission spectra of flames of methanol and ethanol were measured before, during, and after magnetic field exposures, using both uniform and gradient magnetic fields. Intensity of the OH radical was not changed by magnetic fields up to 1.6 T, whereas the emission intensity was increased when the product of magnetic fields and the gradient increased.