Cavitation intensity measurements for internal combustion engines

摘要

Recent engine design trends towards increasing power, reducing weight, advancing of injection timing and increasing of injection rate and pressure could result in increased incidence of liner pitting. Liner pitting due to coolant cavitation is a complex function of many engine design parameters and operating conditions. Traditionally, liner cavitation problems were not detected early in the development cycle. Traditional liner vibration and coolant pressure measurements in conjunction with a numerous amount of expensive engine endurance tests were then needed to resolve cavitation problems. A method newly developed by the author for cavitation intensity measurements was successfully utilized to map out engine operating condition and develop limit curves. This method could also be applied in a non-intrusive fashion. The method accounts for both macroscopic and microscopic aspects of the cavitation process in the coolant jacket adjacent to the liner. The macroscopic effects include liner vibrations and coolant pressure drop for cavitation inception. The microscopic effects include bubble dynamic aspects that finally result in formation of intense microjets that cause the damage. Understanding of engine operating condition, coolant type, pressure, temperature and flow rate on cavitation severity have been developed utilizing this method. The method can replace expensive and time consuming endurance testing. The method helped to accelerate the fundamental understanding of the complex nature of coolant cavitation in internal combustion engines.