可压缩流涡流冷壁发动机数值模拟

Numerical research of compressible vortex combustion cold-wall chamber

为深入探索入射倾角、入射压降、发动机圆柱段长度等参数与涡流冷壁发动机内双向涡流结构特征量之间的内在关系,以三维物理模型为基础,进行了可压缩流涡流冷壁发动机冷流数值模拟。在前期湍流模型选择中,比较了RSM模型、带旋流修正RNG k-ε模型、RNG k-ε模型3种模型的可信度,从准确度和经济性两方面综合考虑选择带旋流修正RNG k-ε模型作为计算模型。研究发现,切向速度及最大切向速度均随入射倾角的增大而减小,随入射压降增大而增大,随长径比的增大而减小。不同入射倾角、不同入射压降、不同长径比下,整个发动机内最大切向速度的无量纲径向位置均恒定在0.19附近。对于不同长径比工况,长径比为1.0时,最大切向速度从发动机顶端到入射口附近逐渐增大,长径比为1.5时,最大切向速度从发动机顶端到入射口附近先增大、后减小。切向速度及最大切向速度的轴向衰减率维持在3%以内。无量纲涡幔半径从发动机顶端开始线性增大到入射口附近,变化范围为0.71~0.82。入射倾角相同时,随入射压降的增大,燃烧室长径比对最大切向速度大小的影响将随之增大。

In order to deeply investigate the inner relationship between the inlet parameters and the structure characteristics of bidirectional vortex in the Vortex Combustion Cold-Wall Chamber（VCCWC）,the compressible cold simulation research of the VCCWC was carried out based on three-dimensional physical model.The inlet parameters included injection angle,injection pressure drop and chamber length.Three models,including RSM model,RNG k-ε model with swirl factor and RNG k-ε model,were compared with the experimental data in the pre-research.The RNG k-ε model with swirl factor was finally selected as the numerical turbulent model based on the performance of the accuracy and the cost.Results show that：the tangential velocity and the maximum tangential velocity decrease with the injection angle and length to diameter ration but increase with the injection pressure drop.The dimensionless radial positon of the maximum tangential velocity is kept around 0.19 in the whole chamber regardless of injection angle,injection pressure drop and the length to diameter ratio.For the different length to diameter ratio,the maximum tangential velocity increases for the length to diameter ratio of 1.0 but increases first and then decreases for the length to diameter ratio of 1.5 from the top of the chamber to the injection section.The axial decay rates of the tangential velocity and the maximum tangential velocity are kept within 3%.The dimensionless mantle radius is not kept constant but linearly increases from the top of the chamber to the injection section.The range of the dimensionless mantle radius is from 0.71 corresponding to 0.82.For the same injection angle,the impact of the length to diameter ratio to the magnitude of the maximum tangential velocity will strengthen with the increase of the injection pressure drop.