부산대학교 도서관

The unstable operation of the engine is found, when the measured pressure in the injection pipe of the DME (CH_3OCH_3) engine is lower than the saturation pressure of DME. This fact means that the flow of DME is choked by the bubbles which are generated by the cavitations and the injection rate of DME to the combustion chamber is too small to run the engine smoothly. The generation points of the cavitations can be estimated by the mathematical model of the flow in the injection system. In order to verify the mathematical model assumed that the fluid in the injection pipe is liquid of DUE, the pressure in the injection pipe of the simple experimental system is measured. The measured pressure in the injection system essentially agrees with the calculated value when it always kept over its saturation pressure which is depend on the fluid temperature.