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Plasma assisted ignition of combustible mixtures. Effect of electronically excited O(1D) atoms and vibrationally excited moleculesстатья
- Автор: Popov N.A.
- Сборник: Proc. 53rd AIAA Aerospace Sciences Meeting (5-9 January, 2015, Kissimmee, Florida)
- Серия: AIAA 2015-1391
- Год издания: 2015
- Место издания: Kissimmee, Florida
- Первая страница: 1
- Последняя страница: 15
- Аннотация: A review of experimental and theoretical investigations of the effect of atomic particles, electronically and vibrationally excited molecules on the induction delay time and a shift of the ignition temperature threshold of combustible mixtures is presented. The addition of oxygen and hydrogen atoms to combustible mixtures may cause a significant reduction of the induction delay time and decrease the ignition threshold. However, at the relatively low initial temperatures, the non-equilibrium effect on the addition of atomic particles is not pronounced. Therefore, it is of interest to search for other forms of non-equilibrium excitation, for example, the introduction of non-equilibrium concentrations of vibrationally and electronically excited particles. At relatively low initial temperatures, the effect of electronically excited O(1D) atoms on the oxidation and reforming of combustible mixtures can be quite significant due to high rates of reactions of O(1D) atoms with hydrogen and hydrocarbon molecules. At low gas temperatures, when the rate of the processes involving atomic particles in the ground electronic state is low, the role of reactions of excited atoms can be high enough. The effect of vibrational excitation of N2(v) molecules on the temporal evolution of OH density in lean hydrogen-air and hydrocarbon-air mixtures excited by a pulsed nanosecond discharge is discussed. Rapid decomposition of HO2 molecules in reactions with vibrationally excited nitrogen molecules blocks the chain-termination mechanism and can explain the experimental data on the increase of OH decay time with increasing the initial gas temperature. It should be noted that experimentally observed increase of OH decay time can be linked with a gas heating due to the VT- relaxation of N2 vibrational excitation on the hydrogen or the hydrocarbons. The rate of gas heating depends significantly on the initial gas temperature, so the OH decay time also essentially depends on T0. For the rapid HO2 decomposition in reactions with vibrationally excited N2(v) molecules, the discharge with a sufficiently high specific deposited energy should be used. That is why in the afterglow of the discharges with relatively low N2(v) vibrational excitation, the effect of an abnormal increase of OH decay time was not observed, despite the fact that ultra lean combustible mixtures at relatively high pressures was also investigated.
- Добавил в систему: Попов Николай Александрович