Evaluation of numerical turbulent combustion models using flame speed measurements from a recently developed fan-stirred explosion vessel

Computational combustion codes rely on turbulent combustion models (or correlations) for providing flame speed estimates. This method necessitates the need to evaluate the predictive capabilities of these correlations against experimentally measured data. Global displacement speeds were measured in a recently developed fan-stirred, cylindrical flame speed vessel using high-speed schlieren imaging. Measurements were conducted in homogeneous and isotropic turbulent conditions at an average RMS turbulent intensity of 1.5 m/s and at an integral length scale of 27 mm. Methane and a representative synthetic gas or syngas blend containing 50:50 by volume of hydrogen and carbon monoxide, all diluted in air, were studied. A wide range of equivalence ratios was covered, and the flame speeds were estimated when the flame radius was equal to the integral length scale. Turbulent flame speeds were computed using four widely used numerical models: (1) Zimont turbulent burning velocity model (1988); (2) Kerstein pair-exchange model (1988); (3) the coherent flame speed model (1993); and, (4) the distributed reaction zone model (1995). The Kerstein model and the Zimont model agreed well with the experimental measurements. Also, ST/SL was higher for syngas than methane for the same u'/SL, which is indicative of the preferential diffusion effect of hydrogen in increasing the flame surface area by distorting it.

Evaluation of numerical turbulent combustion models using flame speed measurements from a recently developed fan-stirred explosion vessel Conference Paper