Numerical analysis on effect of variable radiative heating on ignition of single fuel droplet

Numerical analysis on the effect of fluctuating radiative heating on ignition of a n-heptane droplet under high-temperature condition is conducted. A model of the radiative heat transfer to the fuel droplet, which is based on the electromagnetic wave theory, is employed in the analytical model. Governing equations in one-dimensional coordinate system are discretized by the finite volume method and numerically solved by SIMPLE algorithm. Chemical kinetics model of n-heptane, which consists of 160 species and 1 540 reactions, is employed. The results indicate that ignition delay time of a n-heptane droplet with continuous radiative heating decreases with increase in the intensity of radiative heating. When fluctuating radiative heating starts as the leading edge of the pulse, the ignition process with lower-frequency of the fluctuating radiative heating is asymptotic to that with continuous one of the same amplitude. When fluctuating radiative heating starts as the leading edge of the pulse with 180 degree phase delay, the ignition process with lower-frequency of the fluctuating radiative heating is asymptotic to that without radiative heating. On the other hand, the ignition process with higher-frequency of the fluctuating radiative heating is asymptotic to that with continuous one of the same mean energy.