微型缩放喷管中氢气/空气预混燃烧实验研究

Experiments on H_2 /Air Premixed Combustion in a Micro Laval Nozzle

在最大内径2mm，喉部内径1mm的微型缩放喷管中进行氢气／空气的预混燃烧实验，获取稳燃范围、壁面温度、火焰起始位置等燃烧特性。缩放的喷管结构相比于等直径的圆直管和T形管拓展了稳燃范围，合适的当量比下，入口流速在3．4～41．4m／s的范围内火焰根部能稳定在缩放段燃烧。壁面温度和火焰位置受到流速和当量比的双重影响。壁面温度最大值出现在燃料稍有富余，当量比为1．4时。火焰起始位置随流量的增大向下游移动，随当量比的增大先向上游移动后向下游移动。通过选择合适的当量比和流速，能控制微喷管内的燃烧温度和位置，为微推进、微喷射等系统的设计和改进提供依据。

Experiments of H2/air premixed combustion were carried out in a micro Laval nozzle with inner throat diameter of 1 mm and inlet/outlet diameter of 2 mm. This paper focused on the stable combustion range, wall temperature, flame starting position and flame feature. The experimental results show that the stable combustion range is extended significantly compared with the combustion in circular and T-type tube because of the converging-diverging structure, and flame can stabilize in this region with appropriate equivalence ratio as the inlet flow rate varies in the range of 3.4 m/s to 41.4 rods. Wall temperature and flame starting position are both affected by the inlet flow rate and equivalence ratio （Ф）. The maximum wall temperature is observed at the fuel-rich condition of Ф = 1.4. Flame starting position moves downstream with the increase of flow rate. But it moves upstream firstly, then downstream, with the increase of equivalence ratio. By optimizing the selection of equivalence ratio and flow rate, the temperature and flame location can be controlled in the nozzle, which provides guidance for the design and improvement of micro-propulsion system.