Four Types of Chaotic Dynamics
in Cellular Flames

Experimental Observations of Disordered States

The ordered states disappear above a critical value of the flow rate and disordered states are observed. In these states the rings of cells cannot be discerned, the cells are no longer of similar size and shape, and they move about in an irregular manner. Five consecutive frames of videotape of this state are shown in Figure lb. A dot has been placed on one of the cells so that its position can be traced among the frames. If the ordered state is the analogous state to a crystalline state, then the disordered state is the analogous state to a liquid or "melted" state.

As the equivalence ratio is varied, the onset of disordered state is observed at different values of the flow rate and with different numbers of cells in the inner and outer rings. The transition line between the ordered and disordered states, the "melting curve", is difficult to determine because of the uncertainty in measuring the onset of the disordered states. Experience from our survey of parameter space suggests that at least two rings of cells are required before a transition to a disordered state is observed.

The measured intensity variation of the disordered states is approximately ten times larger than that of the ordered states. The power spectrum shown in Figure 2b has a high frequency fall-off similar to that of an ordered state. The cutoff frequency has increased to 50 Hz.

Forward Forward Forward