A yellow flame indicates a lack of air mixing with gas before ignition. What is this type of flame called?

A yellow flame is indicative of incomplete combustion due to inadequate air mixing with the gas before it ignites. This type of flame is often referred to as a luminous flame.

Luminous flames produce a characteristic yellow or orange glow, resulting from the presence of unburned carbon particles that are heated to incandescence. The incomplete combustion process not only affects the color and appearance of the flame but also leads to lower efficiency and higher emissions of carbon monoxide and other pollutants.

In contrast, the other terms do not accurately describe the yellow flame phenomenon caused by insufficient air supply. A Bunsen flame, for example, is typically a blue flame achieved by proper air-fuel mixture resulting in complete combustion. The terms "gas-starved flame" and "air-starved flame" might imply issues related to gas supply or air availability but do not specifically capture the visual and combustion characteristics of a luminous flame. Thus, the correct identification of the yellow flame as a luminous flame aligns with the combustion principles and the observable attributes of that type of flame.