航空发动机燃烧室热声不稳定的预设性能控制

Prescribed performance control of thermoacoustic instability in aero-engine combustion chambers

为降低航空发动机燃烧室NOx的排放量,贫油预混的燃烧模式被广泛采用,但这将导致燃烧不稳定现象更加频繁地发生。航空发动机燃烧不稳定的能量来自于推进剂的燃烧,热声不稳定是其最主要的一种形式。为抑制热声不稳定现象,首先,在Culick模型的基础上,加入火焰燃烧响应对系统的影响,推导出含状态时滞的热声不稳定的数学模型;其次,基于此模型探究了从燃料喷射到燃烧释放热量的对流时间对热声系统稳定性的影响;然后,设计了预设性能反步主动控制方法,并求解得到在保证系统预设性能的前提下该对流时间的上界;最后,从理论分析和仿真结果两方面都验证了该主动控制方法可使热声不稳定系统的压力振荡渐近收敛,其动态满足预先设定的性能,且具有时滞鲁棒性。

To reduce NOx emissions in aero-engine combustion chambers,lean premixed pre-vaporized combustion technology is widely used,leading to more frequent combustion instability.The energy of aero-engine combustion in⁃stability comes from the combustion of the propellant,with thermoacoustic instability being the main form of combus⁃tion instability.To suppress the thermoacoustic instability,the influence of flame combustion response on the system is firstly considered based on the Culick model,and the mathematical model of thermoacoustic instability with state de⁃lay is derived.Based on the derived model,the influence of the convection time from fuel injection to heat release from combustion on the stability of the thermoacoustic system is then explored,a back-stepping active control method with prescribed performance designed,and the upper bound of the convection time obtained under the premise of ensuring the prescribed performance of the system.Both theoretical analysis and simulation results verify that the active control method can make the pressure oscillation of the thermoacoustic instability system converge asymptotically and satisfy the prescribed performance with time-delay robustness.