Numerical investigation of effect of hydrogen injection frequency on supersonic reactive flow

The pulsed injection strategy is a promising way to improve the mixing and combustion performance in the Scramjet (supersonic combustion ramjet) combustor. However, few researchers focus on the combustion characteristics in the supersonic freestream with the pulsed jet. In this paper, two-dimensional simulation was performed to investigate the effect of hydrogen injection frequency on the supersonic reactive flow field. A detailed 9 species, 19 chemical reactions chemistry mechanism was used to solve the chemical reaction. The results show there is an optimal injection frequency to achieve the best combustion efficiency. The 16 kHz injection frequency is a promising injection strategy which was obtained a global combustion efficiency of about 0.8. Total pressure recovery coefficient increases significantly when the pulsed jet is injected. The combustion improvement mechanism of the pulsed jet is to supply more air for reaction during the injection period.