Numerical and experimental investigation of H2/CH4/Air combustion characteristics and thermal performance in the combustor with multi-bluff-body

Abstract

• Experiments of premixed H 2 /CH 4 /Air combustion is tested at various operating conditions. • Coupling effects of CH 4 addition and multi-bluff-body setting are investigated. • Comprehensive analysis of multi-bluff-body on improvement of thermal performance is conducted. • High efficiency is obtained with proper combustor setting and operating condition. To improve micro combustion stability and energy efficiency, a micro planar with multi-bluff-body is proposed for the burning with varied H 2 /CH 4 blended ratio. The combustion characteristics of H 2 /CH 4 fueled with/without multi-bluff-body setting are investigated. It indicates that the combination of CH 4 addition and bluff-body greatly modifies the flow field and forms recirculation zones, affecting the combustion characteristics and heat transmission in the micro-planar. A small fraction of CH 4 addition is beneficial to the improvement of burner thermal performance, which is strongly affected by the bluff-body setting. Besides, there exists a strong inverse correlation between the optimal CH 4 blending ratio and the input reactants flow rate. Furthermore, the position, width and number of the multi-bluff-body setting also strongly affects the flame regime and distribution of reaction radicals, improving flame stability and heat transmission in the combustion chamber. Particularly, the maximum mean outer wall temperature can be achieved when multi-bluff-body location is 0.45 times to the total length of the combustion chamber from the inlet, with the width of 5.6 mm and 6 bluff-bodies. And the optimal combustor obtains the highest radiation efficiency of 27.03 %, which is 15.03 % improved for the combustor without bluff-body at input fuel flow rate of 485 mL/min with CH 4 blending ratio of 0.05.