基于DEM的直升机沙盲加速计算方法

谭剑锋; 韩水; 王畅; 于领军

doi:10.13700/j.bh.1001-5965.2021.0450

基于DEM的直升机沙盲加速计算方法

doi: 10.13700/j.bh.1001-5965.2021.0450

谭剑锋^1, ,,
韩水¹,
王畅²,
于领军³

1.
南京工业大学机械与动力工程学院，南京 211816
2.
中国空气动力研究与发展中心旋翼空气动力学重点实验室，绵阳 621000
3.
陆军航空兵学院航空机械工程系，北京 101123

基金项目: 国家自然科学基金(12172165)；江苏省自然科学基金(BK20211259)；旋翼空气动力学重点实验室基金(RAL20200302)；江苏省高校“青蓝工程”优秀青年骨干教师项目

详细信息

通讯作者:
E-mail：Jianfengtan@njtech.edu.cn

中图分类号: V221.52；TB553
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- 被引次数: 0
出版历程
- 收稿日期: 2021-08-09
- 录用日期: 2021-08-27
- 网络出版日期: 2021-09-16
- 整期出版日期: 2023-06-30

Accelerated computational method of helicopter brownout based on DEM

1.
School of Mechanical and Power Engineering，Nanjing Tech University，Nanjing 211816，China
2.
Rotor Aerodynamics Key Laboratory，China Aerodynamics Research and Development Center，Mianyang 621000，China
3.
Department of Aeronautical Mechanical Engineering，Army Aviation Institute，Beijing 101123，China

Funds: National Natural Science Foundation of China (12172165); Natural Science Foundation of Jiangsu Province (BK20211259); Rotor Aerodynamics Key Laboratory Foundation (RAL20200302); Outstanding Young Backbone Teacher Project of Jiangsu Qinglan Project

More Information

Corresponding author: E-mail：Jianfengtan@njtech.edu.cn

摘要

摘要:
直升机沙盲数值模拟是研究沙盲演化特性的重要手段，而沙盲由众多动力学特性复杂的沙粒构成，这导致沙盲数值模拟复杂且计算量庞大。基于离散单元法(DEM)和沙粒动力学方程，将沙粒映射至背景网格实现加速计算，并将背景网格分裂为多子区再次加速计算，构建背景网格映射-分裂加速计算模型，且耦合沙粒接触碰撞模型、沙粒-流场耦合模型、旋翼/地面气动干扰模型，提出基于DEM的直升机沙盲加速计算方法。通过与美国陆军EH-60L着陆-起飞沙盲测试结果对比表明：所提方法能准确捕捉着陆-起飞状态的直升机沙盲，且相比于沙盲直接模拟方法，所提方法计算量显著减小。直接模拟方法的计算量随沙粒数量抛物线增加，而所提方法计算量随沙粒数量线性增加。当沙粒数量大于1×10⁷时，相比于仅背景网格映射模型加速方法，所提方法计算量减小70.29%。
- 沙盲 /
- 离散单元法 /
- 映射-分裂模型 /
- 加速方法 /
- 直升机
Abstract:
Numerical simulation of helicopter brownout is a major analysis method to investigate the evolution characteristics of helicopter brownout. However, the sand cloud is composed by many sand particles with complex characteristics resulting in a large computational cost. Based on a discrete element method (DEM) and dynamic equations of sand particles, a background grid mapping-splitting model is proposed, where sand particles are mapped in background grids to accelerate the numerical simulation and the background grids are divided into several zones to reaccelerate the numerical simulation. Coupling the model with contact model of particle-particle interaction, model of particle-fluid interaction, model of rotor/ground unsteady flow, an accelerated computational method of helicopter brownout based on DEM is established, and is compared with the flight test of US Army EH-60L brownout in an approaching flight. The results show that the present numerical method has ability to accurately capture the process of helicopter brownout. Compared to the numerical simulation with direct method, the present computational cost is significantly reduced. Additionally, the computational cost of the direct method increases as a parabola, whereas that of the present method is a linear growth. The computational cost of the present method is reduced by 70.29% when compared with the just background mapping method for a 1×10⁷ particles case.
- brownout /
- discrete element method /
- mapping-splitting model /
- accelerated method /
- helicopter

HTML全文

图 1 沙粒碰撞的弹簧-阻尼器-滑块系统模型

Figure 1. Contact model of sand particle with spring-dashpot system

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图 2 背景网格映射模型

Figure 2. Background grid mapping model

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图 3 背景网格分裂模型

Figure 3. Background grid splitting model

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图 4 Yuma试验着陆区

Figure 4. Landing zone in Yuma flight test

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图 5 着陆过程中EH-60L位置

Figure 5. EH-60L’s position during approaching

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图 6 EH-60L着陆轨迹

Figure 6. Trajectory of EH-60L during approaching

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图 7 不同时间的沙云俯视图

Figure 7. Dust cloud at different time from top view

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图 8 不同时间的沙云侧视图

Figure 8. Dust cloud at different time from side view

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图 9 不同方法的计算时间随沙粒数量变化

Figure 9. Variations of computational time of different methods with number of particles

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图 10 着陆状态EH-60L沙云俯视图

Figure 10. Dust cloud for EH-60L during approaching from top view

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图 11 着陆状态EH-60L沙云侧视图

Figure 11. Dust cloud for EH-60L during approaching from side view

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图 12 EH-60L旋翼前端流场径向速度（r/R=−1.0）

Figure 12. Radial velocity at forward part of EH-60L(r/R=−1.0)

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表 1 沙云计算相对误差

Table 1. RMSs of computational dust clouds

时间/s	方法	RMS		相对误差/%
时间/s	方法	俯视	侧视	俯视	侧视
2	拉格朗日沙粒跟踪方法	0.343 8	0.203
2	本文方法	0.295 9	0.207 2×10⁻²	−13.912	−89.819
6	拉格朗日沙粒跟踪方法	0.237 5	0.562 1
6	本文方法	0.155 78	0.227	−34.433	−59.539
17	拉格朗日沙粒跟踪方法	0.608 1	0.944
17	本文方法	0.134 9	0.810 5	−77.798	−14.186
25	拉格朗日沙粒跟踪方法	0.672 2	1.151 3
25	本文方法	0.471 7	0.926 4	−29.826	−19.538

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表 2 加速方法计算时间

Table 2. Computational time of accelerated methods

沙粒数量	计算时间/s
沙粒数量	直接模拟法	基于背景网格映射模型	基于背景网格映射- 分裂模型
1×10⁴	246.74	32.22	34.22
5×10⁴	4 055.01	46.60	42.97
1×10⁵	14 304.82	147.69	139.22
5×10⁵	381 144.40	398.08	333.91
1×10⁶	1 493 581.00	795.13	701.25
5×10⁶	75 405 520.00	10 243.89	3 857.50
1×10⁷	117 761 400.00	15 521.87	4 610.95

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