双涡控径向分级燃烧室流场特性

Characteristics of flow field in dual-vortex-controlled radial staged combustor

针对新设计的一种双涡控径向分级燃烧室流场特性,采用粒子图像测速仪试验的方式,获得不同压降(1.5%~5.5%)下该型燃烧室不同展向截面和流向截面上流场结构、流线、流速分布和回流区特性。试验结果表明,燃烧室在凹腔内形成了耦合展向涡与流向涡的三维涡系;主燃级旋流器后外旋螺旋流场与中心回流区共同构成三维涡球结构;凹腔与主燃级流场在主燃孔进气作用下相互耦合。随着压降变化,燃烧室冷态流场存在2种流态,压降小于3.5%时,旋流器旋转气流明显强于凹腔气流,凹腔气流被压至外壁流出,与主流掺混较为困难,在火焰筒下游与主流相互作用;压降大于3.5%时,旋流器旋转气流减弱,凹腔气流一同与旋转气流流出并相互作用,凹腔气流往主流掺混相对较为容易。

In order to study the flow field characteristics of a newly designed dual-vortex-controlled radially graded combustion chamber,a combination of PIV tests was used to obtain the flow field structures,streamlines,flow velocity distributions and return zone characteristics of different spreading and streaming cross-sections of this type of combustion chamber at different pressure drops(1.5%~5.5%).The results show that the combustion chamber forms a three-dimensional vortex coupling the spreading vortex and the flow vortex in the concave cavity;the externally rotating helical flow field after the cyclone of the main combustion stage forms a three-dimensional vortex sphere structure together with the center return zone;the concave cavity and the flow field of the main combustion stage couple with each other under the action of the main combustion orifice inlet.At the same time,under different pressure drops,there are two flow regimes in the cold flow field of the combustion chamber.When the pressure drop is less than 3.5%,the cyclone rotating airflow is significantly stronger than the concave cavity airflow,and the concave cavity airflow is pressed to the outer wall and outflow,which is difficult to mix with the main stream,and interacts with the main stream in the downstream of the flame tube;when the pressure drop is more than 3.5%,the cyclone rotating airflow is weakened,and the concave cavity airflow flows with the rotating airflow and interacts with each other,which is relatively easier to mix with the main stream.