煤油燃料超声速燃烧室火焰面模型应用探究

Exploration of Flamelet Model Applications in a Kerosene Fueled Supersonic Combustor

为了探究煤油燃料超燃流场是否满足火焰面特性,基于双支板超燃燃烧室开展试验与数值模拟研究。燃烧室入口马赫数2,总温1436K,燃料由支板分级喷注。根据燃烧室计算结果与火焰面模型判据可知:在微观上,绝大部分燃烧区的Karlovitz数不超过100,耗散涡不会对火焰结构产生显著影响,可近似满足火焰面要求;在宏观上,燃烧区的Damkohler数远高于局部熄火临界值,湍流强脉动导致的破碎火焰时均化具有层流火焰特性,雷诺时均N-S(RANS)方程结合层流火焰面计算与该特性是相符合的。试验中,不同上游当量比导致燃烧室存在两种稳定的燃烧状态:上游燃烧状态和下游燃烧状态,火焰面模型结合煤油23步反应机理可以准确描述两种燃烧状态的湍流燃烧特性,因此RANS结合火焰面模型在煤油燃料超声速燃烧室数值模拟方面具有一定的适用性和准确性。

The applicability of flamelet model in kerosene fueled dual-struts supersonic combustor was studied through experimental methods and numerical simulations.The Mach number of the inflow was 2 and the total temperature was 1436 K,fuel was injected by struts separately.According to the computation results of the combustor and the criterion of the flamelet model,it could be deduced that in microcosmic viewpoint,Karlovitz number does not exceed 100 for most combustion zone and the dissipation vortex shows no obvious effect on the flame structure,the requirement of flamelet model can be satisfied approximately,while in macroscopic viewpoint for the burning area,Damkohler number is much higher than the local extinction critical value,crushed flame caused by the strong fluctuation in turbulence would obtain the characteristic of laminar flame after time averaged,which corresponds to the method combining Reynolds Average Navier-Stokes（RANS） equations with laminar flamelet model.In the experiments,two kinds of combustion states can be obtained with different upstream equivalence ratios： upstream combustion and downstream combustion.The turbulence combustion features of the two combustion states can be predicted with flamelet model using 23 steps reaction of kerosene.The applicability and precision of flamelet model combined with RANS method in kerosene fueled supersonic combustor numerical simulation are partly verified.