セル状火炎の横方向への移動に及ぼす外力効果

抄録

We calculate the two-dimensional unsteady reactive flow to study the body-force effect on the lateral movement of cellular flames. The equation used is the compressible Navier-Stokes equation including an exothermic one-step irreversible chemical reaction, where the hydrodynamic effect caused by thermal expansion is taken into account. We superimpose the disturbance with the peculiar wavelength on a stationary plane flame and simulate the evolution of the disturbed flame front. The disturbance superimposed grows initially with time, and then the flame front changes from a sinusoidal to a cellular shape. After the formation of a cellular flame, cells on the flame move laterally when the Lewis number is lower than unity. Because, the diffusive-thermal effect and the nonlinear effect of the flame front play a primary role in the appearance of the lateral movement of cells. The body-force effect has a great influence on the lateral velocity of cells. When the flame is propagated upward, i.e., the body-force effect has a destabilizing influence, the lateral velocity becomes smaller as the acceleration increases. When the flame is propagated downward, on the other hand, the lateral velocity takes the maximum value at the specific acceleration and becomes smaller with an increase in the acceleration. The change in the lateral velocity is due to the increase and decrease in high-temperature regions and to the variation of the maximum flame temperature at the convex flame front toward the unburned gas.