二甲醚均质压燃发动机爆震特性的研究

n Experimental study on HCCI by port injection of DME was carried out on an engine retrofitted from a diesel engine. The in-cylinder pressure in normal combustion condition and knock condition was processed by discrete wavelet transform. Signal characteristics of different scale were calculated and analyzed to obtain DME HCCI knock characteristics. The analysis shows that the energy distributions in normal combustion condition and knock condition display distinct rule. The energy value of the detail D3 at a level 3 is the largest in normal combustion condition, and that of the detail D1 at a level 1 is the largest in knock condition. With the increase of engine speed, or adding LPG into DME injected in the port have little effects on the characteristics of energy distributions. The intensities of knock, however, play a key role on them. The more intensified the knock is, the larger the energy values of scale D1 goes. The energy value of scale D1, D2 and D3 can be used to detect knock.