Study On Combustion Characteristics Of Methane-hydrogen Mixtures Based On Constant Volume Combustion Bomb

With the increasing of the vehicle population in the world, the problem of the oil shortage and the environment pollution become more and more serious. Searching for alternative fuels has been the urgent matter. Compared to alcohol fuels, Dimethyl Ether and biodiesel, natural gas has the advantage of lower emission, higher octane and better antiknock performance. For methane is the main component of natural gas, study on methane combustion characteristics has an great significance in optimization of the natural gas engine design.As a simulation device, CVCB (Constant Volume Combustion Bomb) is commonly used to reveal the mechanism of the combustion process in internal combustion engine. It can simplify the experiment in order to find inner relationship between parameters during combustion process, by selectively controlling some major conditions.In this paper, a self-developed CVCB system will be introduced firstly. It consists of CVCB body, intake and exhaust system, temperature control system, ignition system, flame photograph collection system, pressure collection system and synchronous control system, among which CVCB body is checked by imposed strength in ANSYS. This system can be used to research alternative fuels combustion characteristics for its ability of controlling initial temperature and initial pressure of mixture, collecting instantaneous pressure and flame propagation pictures.Then combustion tests of methane and methane with hydrogen addition will be carried out. Through changing initial temperature, initial pressure, equivalence ratio and hydrogen blend ratio, comparing and analyzing combustion pressure and flame propagation pictures, the effect of various of initial conditions on combustion velocity, maximum combustion pressure, maximum rate of pressure rise, flame development period, combustion duration and combustion stability can be obtained.At last, investigation on auto-ignition phenomenon will be carried out in CVCB with built-in adaptor. Methods of judging auto-ignition phenomenon are brought forward through comparing combustion pressure and flame propagation pictures. Effect of initial pressure, initial temperature, equivalence ratio, hydrogen blend ratio, location of adaptor, hole size and hole number on combustion characteristics are researched. The results shows that combustion chamber with adaptor in it can make methane burn faster.