摘要
通过对不同马赫数下(Ma=0.7、2.25、6)平板边界层进行直接数值模拟研究,提出比熵增的概念。比熵增表征单位机械能的耗散,并且在数值上表现出较好的单调性和马赫数无关性,因而能够可靠地表征边界层的范围。应用比熵增概念修正BL零方程湍流模型长度尺度,构造BL-entropy,同时采用原始的BL模型,SA一方程模型对后台阶(Ma=0.128)以及高超声速锥柱裙组合体(Ma=7.05)流动进行数值模拟,并与实验数据进行比较,结果表明BL-entropy能够准确地获取长度尺度进而得到均匀合理的涡粘性分布,极大地提升了原始BL模型模拟复杂流动的能力。
The concept of entropy increment ratio （s） is proposed in this paper, based on a series of direct numerical simulations （DNS） of boundary-layer flows on plates at different Mach numbers （Ma=0.7, 2.25, 6）. s represents the dissipation per unit mechanical energy, and is numerically monotonic and independent of Mach number changes, so it can reliably characterize the range of boundary layers. Employing this concept, we reconstruct the length scale of Baldwin-Lomax turbulence model （BID and bring forward BL-entropy. Flow fields of a backward-facing step at low-speeds and a cylinder with conical flare at hypersonic speeds are numerically simulated to evaluate the performance of this new model. The results from the original BL model （BL-origin） and one-equation Spalart-Allmaras model （SA） are also included to be compared with the availa- ble experimental data. The comparison shows that BL-entropy could conquer the essential deficiency of the original model, providing a more physically length scale and smoother eddy viscosity distribution.
出处
《空气动力学学报》
CSCD
北大核心
2013年第3期381-387,共7页
Acta Aerodynamica Sinica
基金
国家973计划资助项目(2009CB724104)
北京航空航天大学博士研究生创新基金
