超声速燃烧室中支杆位置对煤油燃烧的影响

Effects of Injectors Locations on Kerosene Combustion in Supersonic Combustor

关键词:  超声速燃烧室  煤油  支杆位置  燃烧  影响

Key words:  Supersonic combustor  Kerosene  Strut location  Combustion  Influence

摘要:

使用支杆喷注煤油,可以通过喷孔使煤油获得初步的雾化而有利于煤油与气流的混合,从而更快地达到点火条件。为研究支杆在燃烧室中的位置对煤油掺混及燃烧性能的影响,在燃烧室入口马赫数2和3条件下,开展了支杆位于第一位置(燃烧室前部)和第二位置(燃烧室中部)时对煤油燃烧影响的数值模拟及试验。根据试验获得的壁面压力及数值模拟结果,得到以下结论:(1)支杆位置越接近氢气燃烧区,喷出的煤油可以更多、更快地进入该区域进行能量交换,减少煤油点火延迟时间。(2)支杆位于第二位置,支杆前后的近壁面低速区与氢气燃烧区前的回流区连成一片,增加燃料驻留时间,增强混合,有利于火焰向上游传播。(3)在煤油能够点火燃烧的前提下,支杆位于第二位置,煤油与氢气燃烧区域的高度超过燃烧室高度的一半,导致该区域流通面积减小,超声速气流减速,升温,促使煤油燃烧强度更高。 

Abstract:

Injection by struts is propitious to the mixing of kerosene which has been pulverized by injectors with air stream so that the kerosene can be ignited and burned quickly. In order to study the effects of injectors locations in combustor on the mixing and combustion performance, the computation and experiments have been carried out under the condition of combustor entrance Mach number 2 and 3,respectively, where the struts are located in the foreside (the first location) and middle (the second location) of combustor. Based on the investigation results some conclusions can be drawn as follows:the nearer the struts are located to the hydrogen combustion area,the more kerosene can get into that area quickly and the shorter ignition delay time is obtained. When struts are located at the second location, the near wall low-velocity areas before and after the struts are collected with the recirallation area before the hydrogen combustion zone, which can increase kerosene residence time and enhance the fuel mixing and the upstream spread of the flame. For the kerosene steady combustion case, when struts are located at the second location, the height of the combustion zone is greater than the half height of the combustor, which results in narrower area in the main flow stream,lower velocity and higher temperature and more intense combustion of kerosene.