带驻涡凹腔的径向钝体稳定器燃烧特性研究

Combustion Characteristics of Radial Bluff-Body Flameholder Combined with Trapped-Vortex Cavity

关键词:  驻涡凹腔  钝体稳定器  流场  燃烧效率  温度分布

Key words:  Trapped vortex cavity  Bluff-body flameholder  Flow field  Combustion efficiency  Temperature distribution

摘要:

针对燃烧室高速气流中低压组织燃烧需求，本文分析驻涡稳定器-径向稳定器组合结构的燃烧性能，对驻涡燃烧室传焰和稳焰结构的优化设计提供支撑。研究采用实验和数值模拟相结合的方法，在0.06~0.08MPa的负压条件下，获得了组合稳定器结构的燃烧效率、出口温度分布和热态流场。结果表明，径向稳定器的存在使得燃烧室出口产生了明显的温度不均匀现象；降低燃烧室总压将导致燃烧效率明显恶化，总压每下降0.01MPa，对应的燃烧效率将下降约5%。燃烧区的位置与流场息息相关，在热态燃烧过程中，高温区集中在凹腔侧边和径向稳定器外侧，燃烧室中央部分存在来源于凹腔值班级、并沿径向稳定器传播的火焰。余气系数的提升将增加主流供油的穿透深度，导致燃烧区进一步集中在燃烧室两侧，出口温度不均匀程度将由此上升，当余气系数下降到2以下时，燃烧室两侧燃油的富集将导致燃烧效率下降。

Abstract:

In view of the combustion needs of low-pressure tissue combustion in the high-speed air flow of the combustion chamber， this paper analyzes the combustion performance of the combined structure of trapped vortex cavity and radial flameholder， and provides support for the optimal design of flame transmission and flame stabilization structure of the vortex combustion chamber. Through experimental method and numerical simulation， the combustion efficiency of combined stabilizer structure， outlet temperature distribution， and thermal flow field were studied under the negative pressure of 0.06~0.08MPa. As the results have shown， the existence of radial flameholder caused a significant temperature non-uniformity at the outlet of the combustion chamber. Reducing the total pressure of the combustion chamber will lead to a significant deterioration in combustion efficiency. For every 0.01MPa decrease in total pressure， the corresponding combustion efficiency will decrease by about 5%. The position of the combustion zone is closely related to the flow field. During the mainstream stage combustion， the high-temperature zone is concentrated on both sides of the cavity and the outside of the radial flameholder， while in the central part of the combustor， the cavity flame continuously propagates along the radial flameholder. A higher air excess coefficient will increase the penetration depth of the mainstream fuel jet， cause the mainstream stage combustion zone to be more concentrated on both sides of the combustion chamber， and raise the non-uniformity of outlet temperature. With the air excess coefficient dropping below 2， the excessive enrichment of fuel on both sides of the combustion chamber will lead to the decline of combustion efficiency.