航空学报 > 2023, Vol. 44 Issue (5): 126830-126830   doi: 10.7527/S1000-6893.2022.26830

指定流量分配系数的多回流出口边界算法

许开龙1,2(), 刘再刚1,2, 姜胜利1,2, 王星1,2, 张磐1,2   

  1. 1.中物院高性能数值模拟软件中心,北京 100088
    2.北京应用物理与计算数学研究所,北京 100088
  • 收稿日期:2021-12-17 修回日期:2022-01-10 接受日期:2022-01-26 出版日期:2022-03-21 发布日期:2022-02-17
  • 通讯作者: 许开龙 E-mail:xu_kailong@iapcm.ac.cn
  • 基金资助:
    国家自然科学基金(12102060)

Treatment of boundary condition at multiple outlets with recirculating flow and specified flow ratios

Kailong XU1,2(), Zaigang LIU1,2, Shengli JIANG1,2, Xing WANG1,2, Pan ZHANG1,2   

  1. 1.CAEP Software Center for High Performance Numerical Simulation,Beijing 100088,China
    2.Institute of Applied Physics and Computational Mathematics,Beijing 100088,China
  • Received:2021-12-17 Revised:2022-01-10 Accepted:2022-01-26 Online:2022-03-21 Published:2022-02-17
  • Contact: Kailong XU E-mail:xu_kailong@iapcm.ac.cn
  • Supported by:
    National Natural Science Foundation of China(12102060)

摘要:

燃烧室出口处物理量的边界条件处理方法需满足工程设计对出口流量的要求,同时要保证出口回流时的数值稳定性,是工程级燃烧室模拟中重点关注的问题之一。基于流量分配系数发展了一种出口边界处理算法,支持不可压缩流动模拟中指定多个出口流量分配系数、出口存在回流时的稳定模拟。研究表明,在四面体/六面体网格算例中,该方法可实现出口流量分配系数在0~1.0范围内的稳定模拟,与设定值的最大相对偏差<0.001%。在保持出口流量分配系数不变时,改变计算域出口位置使得流动处于未充分发展、回流或旋流状态,计算结果不受明显影响。将该方法应用于TECFLAM旋流燃烧器冷态流场模拟中,计算域缩减至1/3后模拟仍能稳定收敛,预测值和实验数据保持较高的一致性。相比于使用常规出口边界的方法,该方法支持仿真人员根据需要设置出口流量分配系数和计算域大小,可显著减小数值计算开销。

关键词: 自由出口边界, 流量分配系数, 回流, 燃烧室模拟, 不可压缩流动

Abstract:

The treatment of boundary condition at multiple outlets is one of the key issues in the numerical simulation of aero-engine combustors, as the mass flow ratios need to be within the engineering design limits, and the numerical stability needs to be ensured with recirculating flow at the outlets. In the present paper, an incompressible flow outlet boundary condition algorithm is developed to treat the boundary condition at multiple outlets with recirculating flow and specified flow ratios. The results of a series of numerical experiments show that stable and convergent solutions can be obtained using the proposed method. Cases of tetrahedral/hexahedral meshes and the mass flow ratio ranging from 0 to 1.0 are simulated, and the obtained maximum deviation is <0.001%. When the mass flow ratios at the multiple outlets are fixed, the resulted velocity profiles are not obviously affected by the location of outlet boundaries when the flows at the boundaries are not fully-developed or even recirculating. The proposed method is applied to the simulation of TECFLAM swirl burner. The predicted velocity components agree well with the experimental data even when the computational domain is truncated to one third of the original size. Compared to the conventional treatment of outlet boundary conditions, the method proposed enables to specify the mass flow ratios at multiple outlets and to adjust computational domain sizes according to the engineering design limits, which contributes to significant reduction of the overall computational cost.

Key words: free outlet boundary, mass flow ratio, recirculating flow, combustor simulation, incompressible flow

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