ON THE ISSUE OF RELATIONSHIP OF TURBULENT VELOCITY OF SPREADING AND IONIZATION OF METHANE-HYDROGEN FLAME

The authors proved the application of a new alternative fuel - hythane (mixture of methane and hydrogen) in transport and stationary installations. The experiments showed that for determining of the optimal composition of proposed fuel for different engine operating modes it is necessary to know its influence on the combustion process. For this purpose the characteristics of turbulent premixed flame of methane and hydrogen were investigated. The experiments conducted in a piston engine with spark ignition showed that the turbulent flame velocity determined by the translational motion of the flame front depending on the air-fuel mixture turbulence and kinetics of the burning chemical reactions. The experiment showed the increase of ionization current of methane-hydrogen flame with increasing intensity of its turbulence achieved by increasing the engine shaft rotation speed and mass fraction of carbon in fuel mixture due to the changes in the hydrogen concentration and excess air ratio. The experiment results were explained on the basis of modern combustion theory concepts. According to the research results the authors developed a new empirical-calculated method for determination of the turbulent velocity of methane-hydrogen flame propagation by means of ionization sensor indications. The comparison of flame propagation velocities found experimentally and calculated by means of proposed method revealed the 5% difference when burning poor and stoichiometric fuel mixtures, while the combustion of rich mixture showed the difference up to 10%. This fact confirms the feasibility of using this method at the stage of design of gas-piston internal combustion engine.