Numerical Analysis of Lifted Spray Flames in Various Coflow Conditions

ABSTRACT

In the present study, numerical simulations are carried out to understand the combustion characteristics of lifted spray flames for various coflow conditions. Flame structure, lift-off characteristics, and droplet dynamics of kerosene spray flames in various coflow conditions are studied. Numerical results are validated with experimental results. Three different coflow conditions are considered; cold flow, cold flow with N₂ dilution, and simultaneous preheating and dilution. A solid cone fuel spray characteristic is modeled in this present numerical study. The numerical simulations are performed using Reynolds averaged Navier-Stokes approach with standard k-ε turbulence model. Liquid droplets are tracked using Discrete Phase Model. In the current work, non-premixed equilibrium combustion model with the probability density function (PDF) is utilized to model the combustion process. Transport equation for the scalar mixture fraction (Y) is solved using pre-calculated variables and results are stored in a look-up PDF table. Isolines of OH distribution are studied to understand the distribution of the reaction zone for different operating conditions. Maximum temperature of the flame and emissions for different coflow conditions are also presented. Numerical results of all cases are very well validated with experimental results.

KEYWORDS:

• Turbulent spray combustion
• lifted spray flames
• discrete phase model
• Lagrangian model
• dilution and preheating
• MILD combustion