Mechanistic Insights into Effects of Outer Stage Flare Angle on Ignition and Flame Propagation of Separated Dual-Swirl Spray Flames  

作　　者：YANG Siheng HUI Xin ZHANG Chi QIAN Weijia GAN Xiaohua 

机构地区：[1]National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics,School of Energy and Power Engineering,Beihang University,Beijing,102206,China [2]Department of Mechanics and Aerospace Engineering,Southern University of Science and Technology,Shenzhen,518000,China

出　　处：《Journal of Thermal Science》2022年第5期1642-1662,共21页热科学学报（英文版）

基　　金：supported by National Natural Science Foundation of China(Grant No.91641109);National Science and Technology Major Project(2017-III-0004-0028)。

摘　　要：The present work investigates the effects of outer stage flare angle on ignition and kernel propagation in a centrally staged optical model combustor based on the kernel dynamics analysis and laser diagnostics of flow and spray fields.Three outer stage flare angles of 8°,16°,and 25°are researched,respectively.The better ignition performances are found for larger outer stage flare angles.Key properties such as the kernel velocity,kernel trajectory extracted from 6 k Hz high-speed flame images are analyzed in combination with the flow and spray measured via Particle Image Velocimetry(PIV)and Planar Mie Scattering(PMie).Results show that the larger outer stage flare angle imposes a larger opening angle of outer swirl jet(SWJ),shifting the vortex in outer recirculation zone(ORZ)and inner recirculation zone(IRZ)upstream.The spray distribution of a smaller flare angle exhibits a fuel-lean zone near the igniter and this is attributed to the presence of low-angle outer swirl jet that prevents the fuel droplets from arriving at the igniter vicinity.The flame kernel propagates along the path where the strain rate and velocity decrease and the spray droplet density is within the flammable limits.A lower outer stage flare angle increases the strain rate and velocity at the early phase of flame propagation,leading to a longer propagation route and thus increasing the risk of ignition failure.

关 键 词：spray ignition flame propagation spray distribution separated dual-swirl 

分 类 号：V231.2[航空宇航科学与技术—航空宇航推进理论与工程]