Myung Taeck Lim

Prediction of spark kernel development in constant volume combustion

Abstract Combustion initiation is studied in atmospheric pressure propane-air mixtures in a constant volume bomb with a high speed (10,000 fps) laser schlieren system. The spark current and voltage waveforms are simultaneously recorded for later model input. A phenomenological model for early flame kernel development is presented which accounts for the initial, breakdown generated, spark kernel and its subsequent growth. The kernel growth is initially controlled by the breakdown process and the subsequent electrical power input. A new, spark power induced, mass entrainment term is shown to model this initially rapid volume increase adequately while later growth is mainly dominated by diffusion. Results and model comparions are presented for the effects of power input, spark energy, and equivalence ratio.

Spark kernel development in constant volume combustion

Abstract Experimental data on the spark kernel development in constant volume propane-air mixtures is re-examined. With a logarithmic interpretation of this data, the early radius of the kernel is found to be R ∼ t1/5. This power law is explained in terms of an original similarity variable.