The flame structure in a portable oil heater, which has double cylindrical tubes with many small holes for combustion air and a wick that is immersed in liquid fuel, was investigated to understand the wick burner and combustion. In this study, the flame structure in the combustion chamber was clarified from the calculation of the combustion air velocity and from the measurements of the flame temperature and so on.

The results showed that, from the calculation of the combustion air velocity, combustion air was entrained from two inlets of the combustion chamber near the flame stand and was sent into two-thirds of the upstream region in the combustion chamber from both inside the inner tube and especially outside the outer tube through many small holes. The feature as well as the results of the measurement of the stable species concentration in the flame could be understood.