Effects of water injection pre-cooling on steady combustion characteristics of afterburners

Mass Injection and Pre-compressor Cooling （MIPCC） technology is an effective method for enhancing the upper limit of the TBCC turbine mode and improving thrust performance during the transition from turbine to ramjet modes. However， water injection may influence the combustion characteristics of the turbine-mode afterburner. This study employs numerical simulations to design an optimized nozzle arrangement. Additionally， the effect of inflow conditions on droplet evaporation characteristics is analyzed through numerical simulations， under the condition of a fixed distance between the injection and ignition points. Experimental methods are also used to examine the impact of water injection on the steady combustion characteristics of the afterburner. The results indicate that the incoming temperature is a critical factor influencing the uniformity of the outlet temperature distribution in the pre-cooling section. An increase in incoming temperature leads to a greater degree of unevenness in the outlet temperature distribution. In contrast， the incoming velocity plays a key role in determining the uniformity of the outlet total pressure distribution. As the incoming velocity increases， the uniformity of the total pressure distribution deteriorates significantly. Additionally， water injection within a 0~5% water injection ratio does not significantly compromise flame stability. Moreover， the combustion stability of the flame can be substantially enhanced， under optimal water injection conditions. Under the experimental conditions of this study， at an inlet temperature of above 800 K， a 1% water injection ratio enhanced the total heat release of the flame and improved its resistance to disturbances within the afterburner， which increases the overall stability of the flame. Appropriate water injection enhances the heat release reaction， increases the flame temperature， improves afterburner combustion efficiency， which optimize the overall combustion performance of the afterburner.