声学扰动对燃烧室声学特性的影响研究

Effects of Acoustic Excitation on Acoustic Characteristics for Combustor

关键词:  声学扰动  高频燃烧不稳定性  同轴离心喷嘴  声学特性

Key words:  Acoustic excitation  High frequency combustion instability  Coaxial swirl injector  Acoustic characteristics

摘要:

针对利用旋转齿轮对燃烧过程施加高频声学扰动的方法，为获得其对同轴离心喷嘴燃烧室声学特性的影响，设计了一种带辅喷管的单喷嘴扁平燃烧室，分别在冷试和热试工况下研究了旋转齿轮声学扰动装置对燃烧室声学特性的影响。冷试中当扰动频率等于燃烧室某振型的特征频率时燃烧室内出现驻波特征振荡。热试重点关注了煤油蒸气/富氧空气燃烧过程对声学扰动的响应，改变扰动装置的位置可改变声压波节线的方向，实现推进剂喷入位置为声压波腹或声压波节。研究表明，一阶切向声学振荡对同轴离心喷嘴与声压波腹的相对位置敏感，煤油蒸气/富氧空气燃烧过程易受声压波动的影响，推测液氧煤油补燃循环发动机内的高频燃烧不稳定性可能易被声压波动激发。

Abstract:

In order to acquire effects of spinning wheel acoustic excitation on acoustic characteristics of combustor with coaxial swirl injectors，a flat combustor with a single coaxial swirl injector and an additional exhaust nozzle was developed. A test campaign including cold flow tests and hot fire tests was performed. In cold flow tests，when excitation frequency equalled to eigenfrequency，staying wave oscillations were excited. Hot fire tests were focused on the response of oxygen-enriched air/hot kerosene vapor combustion to acoustic pressure and velocity fluctuations. The orientation of acoustic pressure node line could be changed by changing the position of the excitation equipment. Then propellant could be injected into the position of a pressure node or anti-node. Tests results show that the first tangential mode was sensitive to the relative position between the coaxial swirl injector and the pressure anti-node. And oxygen-enriched air/hot kerosene vapor combustion was sensitive to acoustic pressure fluctuations. High frequency combustion instability for LOx/kerosene staged combustor may be sensitive to acoustic pressure fluctuations，too.