基于红外和纹影技术研究声作用下火焰锋面运动及热量演化

Investigation of heat transfer and flame dynamics under acoustic excitation based on infrared and shadow method

以Rijke型驻波声场为声环境,以本生型层流部分预混火焰为实验对象,研究了火焰在声场作用下的锋面运动及热量演化行为。通过火焰红外图像表征燃烧反应产生的高温产物,借助火焰纹影图像描述径向温度梯度分布,并以红外-纹影信息一体化的图像说明了高温产物与径向温度梯度的关系。结果表明,声场作用下的部分预混火焰,其高温产物附着在锋面上,表现为层分布的对称型尖头结构,下游区域较上游区域幅面更宽;轴向热量演化过程以尖头状分布方式在声周期内经历2次升降过程,向火焰下游方向输运,径向热量传递过程所形成的温度梯度轮廓表现为"手指状",由高温产物的尖头结构及运动决定。

The heat transfer of partially premixed laminar flame under Rijke acoustic standing wave was investigated.The flame dynamics and hot products could be captured by the infrared images and the radial temperature gradient distribution could be shown by schlieren imaging.The relationship between the hot products and the radial temperature is characterized with infraredschlieren information integration.The results show that the hot products attached on the flame front under acoustic excitation present a symmetric structure of tip layer distribution.And the downstream region is wider than the upstream region.In one sound cycle the axial heat evolution shows a tip shape transporting heat to the downstream of the flame through two lifting processes.The temperature gradient induced by the radial heat transfer takes a finger shape whose evolvement is decided by the development of the cusps.