Research On The Performance Of Pre-combustion Chamber Spark Plug Natural Gas Engine

With the energy crisis and environment pollution problem increasingly intensified,the internal combustion engine emissions as one of the major source of atmospheric pollution,faced with more and more technical challenges.Looking for new type of clean automobile engine alternative fuel has become the major mission of internal combustion engine researchers domestic and abroad.Natural gas got a lot of attention because of abundant and clean combustion.Pre-combustion chamber structure and operation parameters of natural gas engine affect the combustion process and emission of the mixture in cylinder.Changed pre-combustion chamber structure and natural gas engine operation parameters and studied the effects of these parameters on the combustion process and the discharge of pollutants.It can provide important theoretical basis for subsequent optimization design of pre-combustion chamber spark plug natural gas engine.The project completed model building and simulation calculation of the 6200 pre-combustion chamber spark plug natural gas engine.The professional engine CFD simulation software CONVERGE used G equation combustion model to simulate the progress of intake,compression and expansion work of natural gas engine.Then with the help of the test bench,completing the debugging of the simulation calculation model calibration.Used simulation calculation model to compare and analyze the effects of pre-combustion chamber volume,pre-combustion chamber nozzle diameter and pre-combustion chamber thickness on the heat release rate,fuel consumption,cylinder pressure,temperature and emission.Then analyzed the effects of the mixture concentration and ignition advance angle on the combustion parameters.With the calculation results of pre-combustion chamber volume scheme,increasing volume will decrease heat release rate,pressure and temperature of the mixture in cylinder.Reducing 10%of the volume can speed up combustion,increase the pressure and the combustion temperature.If continue to reduce volume,from the perspective-15%and-20%,because of too small pre-combustion chamber volume and too little pre-combustion indoor mixture,reducing the volume will reduce the combustion heat release rate and delay combustion.With the calculation results of nozzle diameter scheme,the heat release rate,pressure and combustion temperature increased firstly with the appropriate increasing of the nozzle diameter.Because the appropriate increasing of the nozzle diameter can increase the scope of the flame jet and decrease the throttling loss inside the nozzle.Which can promote the combustion to a certain extent.But the combustion temperature rise will increase the discharge of NOx..If the nozzle diameter is too large,it can't form a high-speed jet flame.Instead,it will reduce the speed of flame.Pre-combustion chamber thickness scheme is to set pre-combustion chamber thickness to 1.5 mm,2.0 mm and 2.5 mm.From the compared results,the combustion heat release of 2.0 mm thickness scheme is fastest.But NOx emission will increase.With the calculation results of operation parameters,when the mixture concentration increased,the flame speed increased,which can increase the pressure,temperature in cylinder and the speed of fuel consumption.Then the thin mixture can decrease cylinder pressure and temperature.The simulation calculation results from this model showed that appropriately increasing the ignition advance angle can improve the combustion temperature,increase the speed of flame propagation,which can effectively shorten the combustion duration.