【作者】 邓维鑫；

【导师】 许明恒； 乐嘉陵；

【作者基本信息】 西南交通大学 ， 机械电子工程， 2013， 博士

【摘要】 本文以掌握飞行马赫数4-7条件下超燃冲压发动机燃烧组织技术为研究目标,采用试验与数值计算相结合的方法,对多个典型来流状态下的点火方式以及燃烧性能进行了研究。试验在脉冲燃烧风洞完成,该风洞利用氢气和富氧空气燃烧产生试验来流,模拟参数为总温、总压、马赫数。在飞行马赫数4-7范围内选择了3个典型的设计点进行直连式试验,即：4、5.5和6.5,分别对应隔离段入口马赫数2、2.6和3。根据风洞设备的需要,设计了一套多油位多时序高精度燃料供应系统,实现了模型燃料、点火器气源和节流气源的精确供应。在Ma2状态下实现了乙烯燃料的可靠点火和稳定燃烧。共试验了7种点火方式,分别是：乙烯自燃点火、氢氧火炬点火、空气节流点火、氢氧火炬加空气节流点火、氢氧火炬加引导氢点火、空气节流加引导氢点火以及单独使用引导氢点火。试验表明,后3种点火方式能够可靠地点燃常温气态乙烯。开展了单油位注油特性试验以及多油位燃烧性能试验。利用光学显示手段,揭示了火焰发展历程,得到了不同油位的贫油极限和富油极限,建立了燃烧压力和燃料当量比之间关系的数学模型。以隔离段段未扰动区域长度、燃烧室推力以及燃料比冲为指标,进行了多种注油方式的燃烧性能试验。试验表明,在Ma2.6状态下引导氢仍能可靠点燃常温乙烯,但引导氢关闭后,乙烯能否自持稳定燃烧则取决于乙烯的流量大小。上壁面单独注油时,火焰主要位于上壁面附近区域,不能充分利用流道内的氧气。上下壁面同时注油时,下壁面注入的乙烯能够被上壁面火焰引燃,待下壁面发生燃烧后,其火焰又能对上壁面的燃料提供正向激励,上下壁面的火焰之间存在耦合作用。试验中,在Ma3状态下采用空气节流方法实现了乙烯燃料的可靠点火。定量考察了多个节流参数,包括：节流流量、燃料当量比以及节流时间,以点火时间的长短来评判各参数对点火性能的影响,绘制了点火时间与各参数之间的分布曲线,利用多元回归分析方法,建立起了空气节流点火的数学模型。基于上述3个典型来流状态的试验研究成果,提出了宽范围马赫数条件下固定几何形状超燃冲压发动机的燃烧组织方案的设计思路,可为工程应用提供了一定的参考。更多还原

【Abstract】 The object of this research is to obtain the combustion organizing technology for scramjet working at flight Ma4-7conditions. Both experimental and numerical methods are employed to investigate the ignition and combustion performances at three typical inflow conditions.All the experiments are conducted in pulse combustion wind tunnel. The wind tunnel produces test inflow with hydrogen and oxygen-rich air combusting. The simulating parameters include total temperature, total pressure and Mach number. Three typical inflow conditions at scramjet isolator entry are chosen to represent the flow conditions in the range of flight Ma4-7, which are Ma2,2.6and3respectively. A high precision fuel supply system with multi scheduling for multi fuel supply pipelines is designed to meet the need of wind tunnel. Functions of the system include fuel supplying to scramjet model, air and hydrogen supplying to torch igniter and air supplying for throttling. All these functions are achieved very well.Room temperature ethylene is ignited reliably at Ma2condition. Seven igniting methods are investigated under this condition, including ethylene auto-igniting, torch igniting, air-throttling igniting, torch plus air-throttling igniting, torch plus pilot hydrogen igniting, air-throttling plus pilot hydrogen igniting, pilot hydrogen igniting. The experiments show that the last three methods can ignite ethylene reliably.Combustion characters with fueling at single injector and performances with fueling at multi injectors are investigated. Flame development processes of different injector are explored by high speed photograph. Lean and rich limits of ethylene equivalence ratio (ER) for these injectors are gained. A mathematic model is employed to analysis the relationship between ER and combustion pressure. Three indexes are used to evaluate combustion performance, including isolator undisturbed length, combustor thrust and fuel specific impulse.Pilot hydrogen can ignite ethylene at Ma2.6condition yet in experiments. However, whether ethylene can combust steady or not after hydrogen turning off depends on the quantity of ethylene. When fueling at upper wall only, the main combustion area occurs near upper wall which causes oxidizer cannot be comsued completely. When fueling at upper and lower walls simultaneously, the ethylene injected from lower wall can be ignited by flame anchored at upper wall. Then the flame at lower wall can improve combustion at upper wall inversely. So there is an interactive mechanism between upper and lower wall flame.Ethylene is ignited reliably by air-throttling at Ma3condition. Three parameters of air-throttling are investigated quantitatively, including throttling mass flux, ethylene equivalence ratio and throttling duration. The ignition time is used to evaluate the effect of throttling parameters. The relation curves between these parameters and ignition time are ploted respectively. Multiple unlinear regression method is used to establish a mathematic model of air-throttling ignition.The data got in these experiments are analysed comprehensively. Detailed insight is obtained to put forward a combustion organzing draft for scramjet working at a wide range of Mach number. This draft could be a reference for the engineering application.更多还原