Premixed Flames

  • Under what conditions will a premixed flame (burning a hydrocarbon) be yellow?
  • Under what conditions will a premixed flame have an inner and outer envelope?
  • What is an approximate flame speed for a premixed stoichiometric methane flame?
  • What is an approximate flame thickness for a premixed stoichiometric methane flame?
  • Why are laminar premixed Bunsen flames triangular?
    • How is the shape/angle related to the flame speed?
  • For a given detailed premixed flame solution (for example, from Cantera/Homework), if you have the heat release and temperature profiles given, label Zone I (prheat) and Zone II (reaction).
  • What is something you learned from the USBM video?
  • What is the relationship between flame thickness and flame speed from the simplified analysis?
    • Was this from the analysis using zone I or zone II or both?
  • If have a fuel with double the reaction rate, by what factor do you expect the flame speed to change?
    • By what factor do you expect the flame thickness to change?
  • Does a smaller flame thickness correspond to a higher or lower flame speed? Why?
  • Does pressure or temperature have a larger effect of flame speed?