In order to reveal combustion characteristics of H_2/air mixture in a micro-combustor with and without bluff body, the effects of inlet velocities, equivalence ratios and bluff body's blockage ratios on the temper...In order to reveal combustion characteristics of H_2/air mixture in a micro-combustor with and without bluff body, the effects of inlet velocities, equivalence ratios and bluff body's blockage ratios on the temperature field, pressure of the combustor wall, combustion efficiency and blow-off limit were investigated. The numerical results indicate that the sudden expansion plate micro combustor with bluff body could enhance the turbulent disturbance of the mixed gas in the combustion chamber and the combustion condition is improved. Moreover, a low-speed and high temperature recirculation region was formed between the sudden expansion step and the bluff body so that the high and uniform wall temperature(>1000 K) could be gotten. As a result, it could strengthen the mixing process, prolong the residence time of gas, control the flame position effectively and widen the operation range by the synergistic effect of the bluff body and steps. When the blockage ratio ranged from 0.3 to 0.6, it could be found that the bluff body could play a stabilizing effect and expand combustion blow burning limit, and combustion efficiency firstly was increased with the inlet velocity and equivalence ratio, and then was decreased.展开更多
本文针对微型涡喷发动机的氢气分级微混燃烧室出口温度场进行优化,通过构建Work-bench和UG联合仿真优化方法,且基于近似模型和遗传算法,建立了多参数驱动的优化设计流程,获得了氢气微混燃烧室最优参数组合的掺混孔孔径和轴向位置,以及...本文针对微型涡喷发动机的氢气分级微混燃烧室出口温度场进行优化,通过构建Work-bench和UG联合仿真优化方法,且基于近似模型和遗传算法,建立了多参数驱动的优化设计流程,获得了氢气微混燃烧室最优参数组合的掺混孔孔径和轴向位置,以及关键参数对出口热点温度的影响规律,并针对最优方案详细分析了燃烧室内流场、组分场和温度场的演化规律。研究结果表明:高温区集中在微混单元出口的0~20 mm内,燃烧室出口热点受外壁孔径影响最为敏感,减小外火焰筒掺混孔径和增加内火焰筒掺混孔径有利于提升出口温度分布均匀性。最优方案中内、外火焰筒掺混射流涡长度分别达到了29 mm和34 mm,出口温度分布系数(Outlet Temperature Distribution Factor,OTDF)仅为0.13,NO_(x)排放为3×10^(-6)。展开更多
基金Project(51176045)supported by the National Natural Science Foundation of ChinaProject(201208430262)supported by the National Studying Abroad Foundation of China
文摘In order to reveal combustion characteristics of H_2/air mixture in a micro-combustor with and without bluff body, the effects of inlet velocities, equivalence ratios and bluff body's blockage ratios on the temperature field, pressure of the combustor wall, combustion efficiency and blow-off limit were investigated. The numerical results indicate that the sudden expansion plate micro combustor with bluff body could enhance the turbulent disturbance of the mixed gas in the combustion chamber and the combustion condition is improved. Moreover, a low-speed and high temperature recirculation region was formed between the sudden expansion step and the bluff body so that the high and uniform wall temperature(>1000 K) could be gotten. As a result, it could strengthen the mixing process, prolong the residence time of gas, control the flame position effectively and widen the operation range by the synergistic effect of the bluff body and steps. When the blockage ratio ranged from 0.3 to 0.6, it could be found that the bluff body could play a stabilizing effect and expand combustion blow burning limit, and combustion efficiency firstly was increased with the inlet velocity and equivalence ratio, and then was decreased.
文摘本文针对微型涡喷发动机的氢气分级微混燃烧室出口温度场进行优化,通过构建Work-bench和UG联合仿真优化方法,且基于近似模型和遗传算法,建立了多参数驱动的优化设计流程,获得了氢气微混燃烧室最优参数组合的掺混孔孔径和轴向位置,以及关键参数对出口热点温度的影响规律,并针对最优方案详细分析了燃烧室内流场、组分场和温度场的演化规律。研究结果表明:高温区集中在微混单元出口的0~20 mm内,燃烧室出口热点受外壁孔径影响最为敏感,减小外火焰筒掺混孔径和增加内火焰筒掺混孔径有利于提升出口温度分布均匀性。最优方案中内、外火焰筒掺混射流涡长度分别达到了29 mm和34 mm,出口温度分布系数(Outlet Temperature Distribution Factor,OTDF)仅为0.13,NO_(x)排放为3×10^(-6)。
