热阻塞与燃烧不稳定性问题的试验研究

在某型涡扇发动机加力燃烧室试验过程中,曾出现过一种燃烧不稳定性,频率为106Hz,其声振频率与一阶纵向振频计算值基本相符。经分析计算表明这是一种气柱振荡不稳定性。原来,在等截面通道中加热时,总压因热阻增大而下降,静压则由于总压下降和比容的增加而急剧降低。在π_c远小于1.35或喷口处于远亚临界时,且进口速度系数又比较高的条件下,

EXPERIMENTAL INVESTIGATION ON HEATING CHOKE AND COMBUSTION INSTABILITY

A phenomenon of combustion instability with frequency 106Hz was found in afterburner of a turbofan engine at testbed. The traditional approaches for excludingcombustion instability, such as resigning damping inner liner, changing fuel concentration distribution, appeared ineffective. Theoretical analysis and experimentalinvestigstion show that this combustion instability is a kind of heating choke due to aerodynamics of internal flow. This heating choke leads up to instableburning in overall afterburner. The conditions of emergence of this combustioninstability and approaches to eliminate it are elaborated in accordance with various test results.