Turbulent Nonpremixed Flames

  • List five practical examples of turbulent diffusion flames in engineering.
  • How do turbulent diffusion flames (nonpremixed flames) differ from turbulent premixed flames?
  • How does flame length vary with:
    • stoichiometric mixture fraction
    • jet exit diameter
    • density ratio (exit to surroundings)
  • How does a turbulent jet flame length vary with volumetric flow rate for a given jet exit diameter?
  • What is the physical interpretation of the Froude number?
    • What physical process/consideration motivates its use?
  • T/F: for a momentum controlled jet, the dimensionless flame length is independent of Fr.
  • Does buoyancy tend to increase or decrease jet flame lengths?
  • What is the typical length-to-width ratio for turbulent jet flames?
  • What are theories for lifted flames?
  • What three quantities does radiative heat loss primarily depend on?
  • Describe how increasing turbulent mixing affects flame temperatures in terms of soot, radiation, and flame strain.