大直径液氧煤油发动机燃烧室抗脉动隔板技术

Investigation on Anti-Pulsating Baffle of Large DiameterLOX/Kerosene Rocket Engine Combustor

关键词:  大直径  液氧煤油补燃发动机  声学特性  抗脉动隔板

Key words:  Large diameter  LOX/Kerosene staged combustion engine  Acoustic characteristics  Anti-pulsating baffle

摘要:

随着发动机推力的增大，燃烧室直径也随之增大，表征燃烧室热声学特性的振型、频率及其组合振型更为复杂，燃烧室带与不带抗脉动隔板以及隔板的结构参数等对声学特性影响明显，直接影响燃烧不稳定性的裕度。为了研究抗脉动隔板结构参数对燃烧室声学特性的影响，本文基于三维柱坐标系声波动理论和COMSOL仿真平台，研究了抗脉动隔板结构对火箭发动机燃烧室声学特性的影响。通过单喷嘴声学模拟实验，验证了该仿真方法的有效性。分析了隔板高度、厚度和冷区长度对燃烧室声学特性的影响规律。研究结果表明:隔板高度由40mm增加至120mm时，燃烧室一阶切向和二阶切向振型的频率分别下降了22%和31%；隔板厚度和冷区长度对燃烧室声学频率的影响不超过5%；大推力补燃发动机燃烧室直径大，需采用结构形式更为复杂的抗脉动隔板来针对性地抑制横向振型。

Abstract:

Diameter of combustion chamber is enlarging as the thrust of engine increases， which makes acoustic frequency， vibration modes as well as their combination modes more complicated. The combustor with or without baffle and its structural parameters could not only significantly affect the acoustic characteristics， but also directly impact the combustion instability margin. In order to study the influence of the structure parameters of anti-pulsating baffle on the acoustic characteristics of the combustor， influence of baffle is systemically analyzed， based on the fundamental acoustic theories in three-dimensional cylindrical coordinates and COMSOL simulation platform. Firstly， acoustic finite element modeling (FEM) analysis results are verified by the experiment of acoustic characteristics with single injector chamber. On this basis， the effect modes of baffle length， thickness and length of cold area on acoustic frequency are established. The results show that the frequency of 1T and 2T falls by 22% and 31%， respectively when the length of baffle increases from 40mm to 120mm. Baffle thickness and cold area length have negligible impact on acoustic characteristics， which is no more than 5%. From the evolution of F-1 engine， it can be concluded that larger combustion chambers require more complex baffle pattern to inhibit the transverse vibration.