Is it true that flames can transition from a premixed to a diffusion flame?

Flames can indeed transition from a premixed flame to a diffusion flame as conditions change. In a premixed flame, fuel and oxidizer are mixed together before ignition, leading to a uniform reaction across the flame front. However, in certain situations, such as when there is a limitation in the fuel supply or changes in airflow, the combustion can shift towards a diffusion flame where fuel and oxidizer mix after ignition.

This transition can be influenced by factors such as changes in temperature, pressure, or the composition and flow rates of the gas being burned. For instance, if there is an increase in the distance between the fuel source and the oxidizer or a disruption in the mixing of these components, the flame's characteristics can change, leading to a diffusion mode of burning. Understanding this transition is crucial for fire investigation technicians, as it can affect fire behavior and the assessment of the fire scene.