Research On Pre-ignition In Hydrogen Internal Combustion Engines Based On Characteristic Parameters Of Hot Spot

Nowadays,under the background of energy problems and environmental issues,vehicles are actively looking for new alternative energy sources.Hydrogen,as a renewable and clean energy source,has a wider application prospect with its unique physicochemical properties such as low ignition energy,fast flame propagation and wide combustion range used in internal combustion engines.Abnormal combustion,for instance: pre-ignition and backfire,is prone to occur in the hydrogen internal combustion engine,and these abnormal combustion can lead to a series of damages such as dangerous operation of hydrogen internal combustion engine,damage to parts and even shutdown of work.Among them,pre-ignition is an abnormal combustion that occurs before the spark plug ignition,and the hot spot is one of the factors that cannot be ignored to trigger pre-ignition.In order to research the problem of pre-ignition of hydrogen internal combustion engine,it is necessary to start from the key hot spots,and predict the pre-ignition by studying the influence of hot spots on pre-ignition,so as to help solve the problem of preignition of hydrogen internal combustion engine and to enable the smooth development of hydrogen internal combustion engines.This paper builds a simulation model on the basis of Jialing JH600 hydrogen-gasoline dual-mode engine.And based on AVL-Fire software,the model is validated.To further investigate the connection between the hot spot and the pre-ignition of hydrogen internal combustion engine,representative hot spot parameters(hot spot size,initial temperature of hot spot,hot spot duration and temperature change rate)are selected.Firstly,the influence of each characteristic parameter of the hot spot on the pre-ignition is analyzed by using the isolated factor method.Secondly,the influence of the characteristic parameter of the hot spot on the preignition is comprehensively analyzed by using the analysis of variance and orthogonal analysis method.Finally,on the basis of the previous analysis,the weight analysis of each characteristic parameter of the hot spot is made by using the analytic hierarchy process,and the intensity of the hot spot is characterized by using the weight of each characteristic parameter.At the same time,the influence of pre-ignition at different times on the in-cylinder state parameters is analyzed,which provides a theoretical reference for other abnormal combustion caused by preignition.The results of the study indicate that the occurrence of the pre-ignition in hydrogen internal combustion engine is not caused by the single characteristic parameter of the hot spot,but by the combined action of the multi-characteristic parameters of the hot spot.However,the influence of each characteristic parameter of the hot spot on the pre-ignition of the hydrogen internal combustion engine is different.Among them,the size of the hot spot has the greatest influence on the occurrence time of the pre-ignition of the hydrogen internal combustion engine.When the size of the hot spot is fixed,the order of the influence on the occurrence time of the pre-ignition is as follows : the initial temperature of the hot spot > the temperature change rate of the hot spot > the duration of the hot spot.And according to this order size,the weight of the pre-ignition influence of the hot spot size,the initial temperature of the hot spot,the temperature change rate of the hot spot and the duration of the hot spot on the hydrogen internal combustion engine are 0.5638,0.2634,0.1178 and 0.055,respectively.Finally,after the analysis of the influence of the characteristic parameters of the hot spot on the pre-ignition of the hydrogen internal combustion engine,the in-cylinder peak temperature,pressure and NO mass fraction at different pre-ignition moments are analyzed.