교류전기장이 인가된 층류제트유동 불안정성에 대한 실험적 연구

Abstract

The effect of applied electric field on jet flow instability was investigated experimentally by varying the DC voltage and the AC frequency and voltage applied to the nozzle, focusing on elucidating origin of the occurrence of twin lifted jet flame in larminar jet flow configuration with applied AC electric fields. The resuelts showed the twin lifted jet flame was originated from the cold jet instability, caused by interaction of jet flow volume of negative ions via electron attachment as O2 + e → O2- with applied AC electric fields. This was confirmed by designed experiments with various gaseous jets ejected from the nozzle applying the DC voltage and the AC frequency and voltage in ambient air between two deflection plates connected to a DC power source. Further applying AC electric fields in coflow nitrogen, i.e., the flow instability occurred only for oxygen and air jets. Based on these, a hypothesized mechanism was suggested for jet flow instability when AC electric field was applied to the nozzle. Additionally, the jet instability occurred for the applied frequency less than 80 Hz corresponding to a characteristic collision response time. The effect of AC electric fields on overall map of jet flow characteristics was also reported.