Abstract
In order to investigate the applicability of the skin-friction reduction technique using hydrogen injecting into turbulent boundary layer, three-dimensional numerical simulation was carried out for a constant-cross-confined-space with rearward facing steps. The flow characteristics near wall surface and development of wall shear stress were analyzed and compared under different coming flow and injection conditions. The simulation results show that the hydrogen injection can achieve around 13.5% skin-friction drag reduction under the coming flow Mach number of 2.3Ma or 2.8Ma. At 2.8Ma, the optimal reduction profit is 13.5% which is obtained when the equivalent ratio is 0.06. The gases mixings are gradually enhanced along the flow path. At the positions of shock wave-boundary-layer interactions, the mixings are first strengthened and then suppressed, and meanwhile, the wall shear stress and density changes with similar law that first decreases and then rebounds at the positions. The declines of skin-friction drag decrease along the flow direction, the best reduction area can profit nearly 60%.
Highlights
[16] WANG S, HE G Q, YAN D K, et al Analysis and Reduction of Skin⁃Friction in a Rocket⁃Based Combined⁃Cycle Engine Flow Path Operating from Mach 1.5 to 6.0[ J]
In order to investigate the applicability of the skin⁃friction reduction technique using hydrogen injecting into turbulent boundary layer, three⁃dimensional numerical simulation was carried out for a constant⁃cross⁃confined⁃ space with rearward facing steps
The simulation results show that the hydrogen injection can achieve around 13.5% skin⁃friction drag reduction under the coming flow Mach number of 2.3Ma or 2.8Ma
Summary
西北工业大学学报 Journal of Northwestern Polytechnical University https: / / doi.org / 10.1051 / jnwpu / 20193730449 摘 要:针对带有后向台阶的等截面受限空间,通过三维数值模拟,开展了超声速内流道边界层氢气 喷注减阻的研究,分析对比了 2.3Ma,2.8Ma 来流条件下等质量氢气喷注、2.8Ma 来流条件下氢气以当 量比 0.03,0.06,0.1 喷注后近壁区流动特征以及壁面摩擦阻力的发展。 研究表明边界层氢气喷注在 2.3Ma 和 2.8Ma 来流条件下可以达到 13.5% 左右的减阻效果。 2.8Ma 来流条件下,当量比为 0.06 时减 阻效果最优,降幅为 13.5%。 气体的扩散与掺混沿流向逐渐加强,激波与边界层相互作用处掺混会被 先加强后抑制,壁面剪应力在该位置伴随密度先降低后反弹呈现相同的变化规律。 摩阻降幅沿流向 也逐渐减弱,最佳的减阻区域内可达到将近 60%的减阻收益。 实验构 型 如 图 1 所 示, 实验段是横截面为 147 mm×32 mm 的二元矩形等直冲压流道,总共由 4 段组成,全长 980 mm。 传感器安装在长 80 mm 的 测试段,图中所示长 400 mm 的部分在实验中进行 了拆卸,实验分 2 次进行,分别将测试段安装在等直 管道的出口 1 和出口 2,根据这 2 处的测量结果得 到出口 1 至出口 2 的平均壁面剪应力。 数值计算模 拟了喷管出口以后 980 mm 长的区域,为节省计算 资源,厚度方向上取 5 mm。 近壁区网格加密,距壁 面最近的第一层网格落在对数层内(30
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