헬름홀쯔형 맥동연소기의 연소 및 작동특성에 관한 실험적 연구

Abstract

본 연구에서는 자체 제작된 헬름홀쯔형 맥동 연소기를 이용하여 작동원리와 연소특성을 조사함으로써 맥동연소현상을 물리적으로 이해하는 것이다. 주기적 화염 의 직접가시화, 연소장의 시간평균 온도 및 농도분포, 변동압력의 크기와 공기흡입량 을 조사함으로써 맥동에 영향을 미치는 요인이 무엇인지 그리고 이것이 어떠한 변화를 야기시키는가를 살펴보고자 한다. 이렇게 얻어진 결과의 종합을 통해 장치의 형상이 결정된 일반적인 맥동연소기가 자발적인 상태에서 작동될 때 작동결정인자가 무엇인가 를 알수가 있을 것으로 사료된다.

In spite of the merits of high heat transfer, low NOx emission and compact combustion, direct and/or indirect application of pulsating combustion system is at a low ebb due to the strong noise and the lack of physical understanding. Knowledge on the physical natures of the heat addition process coupled with the accoustic wave is a key factor in determining a way for the effective control of the pulsating combustor. The purpose of this study is physical understanding of the periodic combustion process in the Helmholtz-type pulsating combustor. To realize it, direct visualization, measurements of mean temperature and species concentration and the investigation of the fuel flowrate`s effect to the fluctuating pressure, air suction rate and frequency were performed. Volumetric expansion of the flame attached at the edge of the stabilizer occurs during the main reaction period which corresponds to the pressure increasing. Ignition occurs by mixing fresh reactants with a hot residual flame which has a shape of a sooty luminous flame. Fuel consumption rate is proportional to the operating frequency linearly and square of the fluctuating pressure. In other words, the amount of consumed fuel for a cycle is independent of the operating frequency or the fuel flowrate in a given geometry. If minimum mixing and reaction times can be obtained in a period, expansion of fuel input range and high frequency`s operation will be possible.