The Experimental Study Of Nanosecond Pulsed Laser Induced Plasma Assisted Combustion

Laser induced plasma assisted combustion is a new combustion method to realizethe stability of lean burn combustion system and supersonic and hypersonic aircraftengine combustion.Laser induced plasma assisted combustion has the advantages ofplasma function area controlled, electrodeless, intervention and has no electromagneticdisturb.In view of industrial application limitations of femtosecond laser because of itsbig size and complex operation, the article carries out the research on the methane/airmixture gas laser induced plasma combustion experimental.This paper first introduces the development status of discharge plasma assistedcombustion and laser induced plasma assisted combustion methods and mechanism.The shortcomings of current research are analyzed and the research contents and keyproblems to be solved in this paper are come up with. Then, the feasibility of laserinduced plasma assisted combution method is analyzed based on the Flame PropagationDynamics and Chemical Reaction Kinetics.And the fuctional relation between flameblowoff limit and laser parameters are gotten. Meanwhile, the flame stability andstructure theory is analyzed. On this basis, a nanosecond laser induced plasma assistedcombution experimental platform is designed and built.Secondly, the structural of CH4/O2/N2laser direct breakdown plasma assistedcombustion flame is studied for various equivalence ratios, flow rates and pulserepetition frequency, and the blowoff limit of the bunsen flame is increased of124.5%under conditions of pulse energy30mJ and repetition rate50Hz compared to thecondition without laser. By studying the temporal evolution of the initial flame kernel,change rule of flame propagation speed is got along with the equivalent ratio and flowrates, and then by studying the development of the initial flame kernel change into twoflame kernel, the temporal evolution n of the flame kernel is got, as a basis forrealizing and improving the effect of assisted combustion.Finally, in order to reduce the requirement for laser pulse energy, and making thecombustion method more suitable for industrial application, laser induced metallictargets plasma assisted combustion method is proposed. Change rule of stable flamestructure, development of flame and temporal evolution of the initial flame kernel isstudied along with the equivalent ratio, flow rate and pulse repetition frequency. Applyof this method,the blowoff limit of the bunsen flame is increased of185.7%underconditions of pulse energy10mJ and repetition rate50Hz compared to the conditionwithout laser.And the pulse is reduced from30mJ to10mJ.This results presented in the paper will be of importance, both scientifically andpractically, to improve the understanding on the theory and characteristic parameters of laser induced plasma assisted combustion, and to promote the practical applications ofthe laser induced plasma assisted combustion.