Abstract
The purpose of this paper is to investigate the effect of the ambient pressure on the overall spray characteristics of dimethyl ether (DME) and biodiesel fuel spray in a high-pressure combustion chamber. In order to investigate the spray performance under the various ambient pressure conditions, the high-pressure combustion chamber, which can be controlled by nitrogen gas to obtain the ambient pressure conditions, was applied. To determine the macroscopic structure of the spray, such as the spray development process and the axial/radial distance, frozen images of the spray can be obtained directly using a high-speed camera with a light source according to the elapsed time after energizing begins. At the same time, the results from the DME and biodiesel spray under atmospheric conditions were compared with the results from the spray under various ambient pressure conditions in the chamber. According to the spray characteristics, the axial and maximum radial distances of the biodiesel and DME spray decreased with an increase in the ambient pressure. Also, it was shown that the SMD (Sauter mean diameter) of droplets becomes smaller than that of the spray under the atmosphere condition as the ambient pressure in the high pressure chamber increases.
