Effects of turbulator angle and hydrogen addition on a biogas turbulent diffusion flame

Abstract

This study is concerned with combustion characteristics of a biogas under varying turbulator angle conditions and hydrogen addition in a combustor. Turbulator angles have been changed 15°–45° at intervals of 15°. Investigations have been performed by using a CFD code. PDF/Mixture Fraction combustion and k-Ɛ standard turbulence models were used during predictions. The predicted temperature and emission profiles of the biogas are compared with the existing experimental measurements under turbulator angle of 15°. These predictions are in good agreement with the measurements in terms of distributions and values. It has been determined that percentage differences between the measured and the predicted values vary from about 0% to 12%. Then, predictions have been performed under 30° and 45° of turbulator angle cases and compared with each other. The effect of the hydrogen addition to the biogas fuel on combustion performances of the biogas has also been studied in the present study. Findings show that changes in turbulator angles highly affect the temperature and emission profiles of the biogas throughout the combustion chamber. Especially, the flame temperature zones move to the downstream of the burner. It may be also said that the flame temperatures of the biogas increase as the turbulator angle is changed due to better fuel–air mixture. In addition to these findings, it is demonstrated that the axial temperature levels increase as the hydrogen is added into the biogas.