航空学报 > 2025, Vol. 46 Issue (17): 131713-131713   doi: 10.7527/S100-6893.2025.31713

BOS测量密度场泊松方程源项快速计算方法

张建1, 张征宇2(), 杨洋2, 钱丰学2, 李小霞1, 王材钢1, 罗家杰1   

  1. 1.西南科技大学 信息工程学院,绵阳 621010
    2.中国空气动力研究与发展中心 高速空气动力研究所,绵阳 621000
  • 收稿日期:2024-12-25 修回日期:2025-01-13 接受日期:2025-02-10 出版日期:2025-02-27 发布日期:2025-02-27
  • 通讯作者: 张征宇 E-mail:zhang_zy@189.cn
  • 基金资助:
    国家自然科学基金(11872069)

Fast calculation method of Poisson equation source term for BOS measuring density field

Jian ZHANG1, Zhengyu ZHANG2(), Yang YANG2, Fengxue QIAN2, Xiaoxia LI1, Caigang WANG1, Jiajie LUO1   

  1. 1.School of Information Engineering,Southwest University of Science and Technology,Mianyang 621010,China
    2.High Speed Areodynamics Institute,China Aerodynamics Research and Development Center,Mianyang 621000,China
  • Received:2024-12-25 Revised:2025-01-13 Accepted:2025-02-10 Online:2025-02-27 Published:2025-02-27
  • Contact: Zhengyu ZHANG E-mail:zhang_zy@189.cn
  • Supported by:
    National Natural Science Foundation of China(11872069)

摘要:

背景纹影(BOS)是非接触测量流场密度的重要手段,通常采用有限差分法求解泊松方程计算投影密度场,但现有方法计算泊松方程源项(即网格节点上光线偏折角的一阶偏导数)耗时长、突变处精度差。为此,提出基于BOS测量密度场的泊松方程源项快速计算方法。基于BOS各测量点的光线偏折角数据,创建测量点坐标与光线偏折角场间的哈希函数,旨在快速查找以给定点为中心的局部区域BOS测量点集合及其光线偏折角;建立光线偏折角场中偏折角突变测量点捕捉方法,按突变测量点划分区域,推导并构造区域内偏折角插值型求导公式,基于哈希表和插值型求导公式,分别计算各区域均匀网格节点上光线偏折角的偏导数。仿真试验结果表明:较现有泊松方程源项计算方法,本方法的残差绝对值减小了56.66%,峰值误差减小了75.8%。风洞试验结果表明:较现有方法,本方法解得的空腔模型密度场更精细,加速比为411.85;2 m超风洞“7°(半锥角)的锥柱体模型和某声爆模型”头部微弱激波的测量结果与理论值吻合,激波两侧密度比的最大相对误差为3.9%,流场密度解算正确。因此,本方法提高了密度场测量的速率、精度与微弱激波捕捉能力,工程应用价值大。

关键词: 密度场重建, 光线偏折角, 背景纹影, 泊松方程, 哈希函数

Abstract:

Background-Oriented Schlieren (BOS) is a vital non-intrusive method for measuring fluid density field. The finite difference method is employed to solve the Poisson equation for calculating the projected density field. However, existing approaches for computing the source term of the Poisson equation (which mainly includes the first-order partial derivatives of the light deflection angle at the grid nodes) are time-consuming and poor precision at discontinuities with abrupt changes. To address this issue, a fast calculation method of Poisson equation source term for BOS measuring density field is proposed. A Hash function between the point coordinates and the light deflection angle field data is presented to rapidly locate the BOS measurement points, their deflection angles in a local area centered around a given point, and the interpolation-based derivative formula for this local area are constructed. A region division method is proposed for areas with abrupt changes in light deflection angle, where first-order partial derivatives are computed separately using Hash tables and local interpolation. Simulation results show a 56.66% reduction in residuals and a 75.8% decrease in peak error near abrupt changes. For a cavity wind tunnel model, the method yields a finer density field and achieves a 411.85 speedup over existing Poisson source term methods. Two supersonic wind tunnel tests, on a 7° cone-cylinder and a sonic boom model, validate the method, with weak head shock waves closely matching theory and a maximum density ratio error of only 3.9%. The method proposed in this paper therefore improves the rapid and accuracy of the density field measurement, and can capture weak shock waves, offering substantial application value.

Key words: density field reconstruction, light deflection angle, background-oriented schlieren, Poisson equation, Hash function

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