Experimental Study On The Effect Of The Dual Spark Plug On The Constant Volume Combustion Of Nature Gas

With the rapid development of China’s economy, the automotive industry also rapidly rising. Energy shortage and environmental pollution have become important problems to be solved urgently in China. Because of rich reserves, low cost, high safety and other advantages,natural gas become the main automotive alternative fuel. But there are some defects, such as, slower flame propagation velocity and larger heat loss, lower thermal efficiency. This paper has carried on an experimental study on the effect of the dual spark plug on the constant volume combustion of nature gas, to provide theoretical basis for the research of natural gas engine with dual spark plug.Constant volume combustion test of natural gas is carried out on the visual constant volume combustion test system. Firstly, the constant volume combustion test system is improved to make it suitable for experimental research in this paper. Secondly, the test is carried out with the change of ignition mode, initial pressure, initial temperature and equivalence ratio of natural gas, collecting the flame propagation pictures and the combustion pressure. Then this paper compiles the flame front extraction procedure on MATLAB and calculates the flame radius, and obtains flame propagation velocity and flame front surface area. Finally, through changing initial parameters, analyzing the test data, the effect of various of initial conditions on flame propagation velocity, combustion pressure, flame development duration, main combustion duration and heat release rate can be obtained.In the case of different ignition modes, no matter how the initial parameters are changed, under the same initial conditions, the combustion performance of dual spark ignition mode is better than that of single spark ignition mode. Unilateral propagation velocity of the dual spark ignition mode is slower than that of the single ignition mode, the flame radius increases slowly. But both sides of the flame propagation of the dual spark ignition mode is synchronous,and two flame core is synchronous development, which be equivalent to shorten the distance of flame propagation, the flame front surface area is bigger than the single ignition mode. At the same time, because more mixture participate in the chemical reaction, peak combustion pressure and combustion heat release rate peak of dual spark ignition mode is bigger, and flame development duration and main combustion duration are shorter obviously, to improve the efficiency of natural gas combustion.In the case of different initial pressure, with the increase of the initial pressure, the concentration of the mixed gas increases, flame radius having slower growth, flame propagation velocity decreasing, peak pressure of combustion and combustion heat release rate increasing and flame development duration and main combustion duration obviously increasing.In the case of different initial temperature, with the increase of initial temperature, mixed gas activating factor activity increases, flame propagation velocity increasing, flame radius having faster growth, the combustion pressure peak value and combustion heat release rate increasing, the flame development duration and main combustion duration decreasing.In the case of different fuel air equivalence ratio, flame propagation velocity at the stoichiometric ratio near(1.0-1.1) is the fastest, flame radius growth rate being fastest, the combustion peak pressure and combustion heat release rate being largest, the flame development duration and main combustion duration significantly shortening. In the case of too thick or too thin condition, flame propagation velocity decrease, flame radius having slower growth, the flame development duration and the main combustion duration increasing.