対向流中における正ヘプタン噴霧拡散火炎の消炎特性(熱工学, 内燃機関, 動力など)

抄録

An experimental study was performed of the extinction characteristics of counterflow diffusion flames in which polydisperse n-heptane sprays carried by a nitrogen stream from the lower duct, burnt in oxidizer streams from the upper duct. The distance between the ducts was varied to vary the strain rate with constant fuel flow rate, so that the upstream spray characteristics were independent of the strain rate. The burning behavior of the spray is observed and the oxygen concentration at extinction was determined as a function of the strain rate. The flat blue diffusion flame was observed between two ducts, which is supported by vaporization of small droplets. Relatively large droplets penetrate the flat blue flame and continue to burn on the oxidizer side with an envelope flame surrounding each single droplet. The burning behaviors and extinction characteristics were discussed based on the characteristic time scales such as the droplet response time to the flow and the vaporization time.