突扩燃烧室低频燃烧不稳定控制方法

Control methods of low frequency combustion instabilities in a dump combustor

关键词:  突扩燃烧室  低频燃烧不稳定  大涡模拟  实验  燃烧控制

Key words:  Dump combustor  Low frequency combustion instabilities  large eddy simulation  Experiment  Combustion control

摘要:

为实现对突扩燃烧室低频燃烧不稳定的高效控制,采用实验手段和数值模拟开展了低频燃烧不稳定的控制方法研究。开展了燃料脉冲喷射开环主动控制实验研究,发现燃料脉冲喷射所形成的周期性放热是抑制压强振动的主要原因。这种周期性放热与压强振动反相时会明显削弱压强振荡幅度,所以喷射相位角是影响控制效果的主要因素。对空气喷射控制方式进行了大涡模拟,这种方式能够比较有效地干扰突扩面上大尺度旋涡的形成,起到较好的抑制效果。对燃烧室突扩构型进行改进,开展了被动控制的数值模拟,通过采用台阶突扩面的被动控制方式指出了破坏大尺度旋涡的形成和切断振动能量的正反馈机制是实现燃烧不稳定被动控制的主要途径。 

Abstract:

In order to control the low frequency combustion instabilities in dump combustor efficiently, control technology of low-frequency combustion instabilities is investigated with numerical simulation and experiment. Combustion instabilities active control experimental system and control equipment are designed. Open loop active control for pulsed liquid fuel injection is experimentally studied. Results show that periodic heat release due to fuel pulse injection is responsible for suppressing pressure oscillations. While the periodic heat release is in reverse phase with pressure oscillation, amplitude is reduced obviously. It can be concluded that injection phase angle is the leading factor of control effect. Air injection control methods are simulated by large eddy simulation (LES). Results indicate that formation of large scale vortices from dump plane is effectively interrupted. Passive control technology is numerically studied with improved dump configuration of combustor by steps dump plane. It is determined that disturbance of large scale vortices formation and interruption of positive feedback mechanism are the primary approaches of low-frequency combustion instabilities passive control.