premixed flame

A premixed flame occurs when a fuel and oxidant are mixed before entering the combustion zone. The chemical reaction happens in a thin layer called the flame front, often reaching temperatures of several thousand degrees. The speed at which a premixed flame burns, known as the burning velocity, depends on the mixture's properties, pressure, and temperature. Diluting the mixture with inert gases like nitrogen or helium can lower the temperature and slow down the reaction rate, potentially extinguishing the flame.1

In some cases, like a Bunsen burner with adjustable air intake, a premixed flame can also exhibit characteristics of a diffusion flame. This results in an inner core and an outer cone, representing reducing and oxidizing zones, respectively. The outer cone is oxidizing due to excess oxygen.2