CAJ | 학술논문

利用SQLAB Ⅱ振动噪声分析仪对贫氧、预混层流火焰和湍流火焰的热声耦合振荡过程进行声场分析.随着化学当量比φ的增大,燃烧室和预混室内声压振动的特征频率逐渐降低,而对虚的声功率峰值逐渐提高.在特征频率附近,燃烧室与预混室内的声压振动趋于同频、同相,两者具有明显的耦合关系;在高频情况下,两者不会发生耦合.在化学当量比φ相同而燃烧室入口雷诺数不同的工况下,燃烧室内的声压振动频谱基本相似,说明可燃预混气的组分浓度变化是火焰发生低频振荡的主要原因,当燃烧在偏离化学恰当比情况下进行时,局部空气系数波动所导致的火焰表面大尺度涡团交替脱落是诱发火焰热声耦合振荡的主要原因.
이용SQLAB Ⅱ진동조성분석의대빈양、예혼층류화염화단류화염적열성우합진탕과정진행성장분석.수착화학당량비φ적증대,연소실화예혼실내성압진동적특정빈솔축점강저,이대허적성공솔봉치축점제고.재특정빈솔부근,연소실여예혼실내적성압진동추우동빈、동상,량자구유명현적우합관계;재고빈정황하,량자불회발생우합.재화학당량비φ상동이연소실입구뢰낙수불동적공황하,연소실내적성압진동빈보기본상사,설명가연예혼기적조분농도변화시화염발생저빈진탕적주요원인,당연소재편리화학흡당비정황하진행시,국부공기계수파동소도치적화염표면대척도와단교체탈락시유발화염열성우합진탕적주요원인.
The characteristics of sound field of thermoacoustic oscillations in lean oxygen premixed laminar flames and turbulent flames were investigated using a noise and vibration analyzer,SQLABⅡ. The results reveal that with the increasing of equivalent ratio,the characteristic frequencies of pressure in premixing chamber and combustion chamber both decrease gradually,while the corresponding power levels increase. Close to the characteristic frequency,the frequency and phase of vibration in premixing chamber are same to those in combustion chamber. They couple each other distinctly. But within the range of high frequency,there is no coupling relationship. The power spectral distributions are similar when the equivalent ratio is fixed but the Reynolds number is changing, which means that concentration of premixture influences thermoacoustic oscillations of flame remarkably. As the equivalent ratio is quite larger than 1.0,fluctuation of local equivalent ratio in premixture will cause the separation of large eddies from the surface of flame alternately,which induces thermoacoustic oscillations radically.