Three-Stream Flamelet Model for Industrial Applications

Efficient turbulent combustion models are typically designed for the numerical simulation of two-stream problems, namely, the combustion of fuel in air. There are applications, however, where large amounts of a diluent such as water steam or recirculated exhaust gas is supplied to the combustor independent of fuel and air supplies. In such cases, classical approaches become quite time-consuming. In the present paper, a new three-stream flamelet model is presented, which is essentially an extension of the two-stream flamelet model for diffusion flames. Key points of the approach are the introduction of a second mixture fraction variable and the efficient establishment of the flamelet library. After presentation of the theory, the applicability of the new model is demonstrated by comparison with experimental results for the lift-off height of jet diffusion flames.