Numerical Simulation and Experimental Analysis of Propeller Flow Fields and Motor Temperature Fields in High-altitude Environments for UAVs

doi:10.3969/j.issn.1004-132X.2025.12.011

Abstract

Abstract:

Based on an X2212-type air-cooled permanent magnet synchronous motor for UAVs， a combined approach of numerical simulation and experimental validation was employed to systematically analyze the influence of propeller-induced airflows on the motor temperature fields under three altitudes （510， 2560， 4280 m） and three rotational speeds （4000， 6000， 8000 r/min）. A motor temperature testing platform was constructed to measure the motor temperature rise distribution under different operating conditions. These measurements were compared and analyzed with the simulation results to validate the model's accuracy. The paper finds that as the altitude increases， the maximum motor temperature exhibits a decreasing trend under all three rotational speeds. However， the motor's relative temperature rise increases with increasing altitude. The results indicate that the combined effects of reduced air density， decreased atmospheric pressure， and changes in ambient temperature due to altitude variation synergistically affect the motor's temperature changes. With increasing altitude， the decrease in ambient temperature causes an overall downward trend in motor temperature. Nevertheless， the thinning air weakens the cooling capacity of the propeller-induced airflows， resulting in a decline in the motor's cooling efficiency and an increase in the relative temperature rise.

Key words: unmanned aerial vehicle（UAV）, high-altitude environment, propeller airflow, forced air cooling, motor thermal management, numerical simulation

摘要：

基于一款X2212型无人机风冷永磁同步电机，采用数值模拟与试验验证相结合的方法，系统分析了510、2560、4280 m三种海拔高度及4000、6000、8000 r/min三种转速下螺旋桨气流对电机温度场的影响。通过搭建电机温度测试平台，测试了不同工况下电机温升分布，并与仿真结果进行了对比分析，验证了模型的准确性。研究发现，随着海拔的升高，电机最高温度在三种转速下都呈现逐渐降低的趋势，但电机的相对温升随海拔的升高而增大。结果表明，海拔变化带来的空气密度减小、气压降低与环境温度的变化协同影响电机的温度变化。随着海拔升高，环境温度的降低使电机整体温度呈下降趋势，但空气的稀薄削弱了螺旋桨气流的冷却能力，导致电机的散热效率下降，相对温升增大。

关键词: 无人机, 高海拔环境, 螺旋桨气流, 强迫风冷, 电机热管理, 数值模拟

CLC Number:

TM32

Boyu FU, Zehua XU, Kangshuai LI, Haoyu WANG, Jiaqi HE, Qiang HE. Numerical Simulation and Experimental Analysis of Propeller Flow Fields and Motor Temperature Fields in High-altitude Environments for UAVs[J]. China Mechanical Engineering, 2025, 36(12): 2894-2902.

付博宇, 许泽华, 李康帅, 王浩宇, 贺嘉琪, 何强. 高海拔环境下无人机螺旋桨流场与电机温度场的数值模拟与试验分析[J]. 中国机械工程, 2025, 36(12): 2894-2902.

Figures/Tables 15

Fig.1 The motor units

Tab.1 Basic motor parameters

参数名称	数值
额定功率/W	273
额定电压/V	14.5
额定转速/（r·min $- 1$ ）	10 000
极数2p	12
槽数	14
定子外径/mm	21.5
定子内径/mm	10
转子外径/mm	27.5
转子内径/mm	22
气隙长度/mm	0.25

Tab.1 Basic motor parameters

参数名称	数值
额定功率/W	273
额定电压/V	14.5
额定转速/（r·min $- 1$ ）	10 000
极数2p	12
槽数	14
定子外径/mm	21.5
定子内径/mm	10
转子外径/mm	27.5
转子内径/mm	22
气隙长度/mm	0.25

Tab.2 Loss values at different speeds for four types of losses

电机转速n/

（r·min $- 1$ ）

电流/A

铜损/W

铁损/W

涡流

损耗/W

附加

损耗/W

Tab.2 Loss values at different speeds for four types of losses

电机转速n/

（r·min $- 1$ ）

电流/A

铜损/W

铁损/W

涡流

损耗/W

附加

损耗/W

4000

0.523

0.0293

0.4805

0.0095

0.0009

6000

1.627

0.2216

0.9295

0.0215

0.0017

8000

3.670

1.1271

1.5189

0.0393

0.0036

Fig.2 3D modeling of the electric propulsion system

Fig.3 Flow field establishment and mesh division

Tab.3 Materials and properties of electric motor components

元件	材料	热导率/ （W·m $- 1$ ·K $- 1$ ）	质量热容/ （J·kg $- 1$ ·K $- 1$ ）	密度/ （kg·m $- 3$ ）
绕组	铜	401	385	8933
定子铁芯	M530-65A	30	460	7650
转子铁芯	M530-65A	30	460	7650
永磁体	N42UH	7.6	460	7500
机壳	铝	168	833	2790

Tab.3 Materials and properties of electric motor components

元件	材料	热导率/ （W·m $- 1$ ·K $- 1$ ）	质量热容/ （J·kg $- 1$ ·K $- 1$ ）	密度/ （kg·m $- 3$ ）
绕组	铜	401	385	8933
定子铁芯	M530-65A	30	460	7650
转子铁芯	M530-65A	30	460	7650
永磁体	N42UH	7.6	460	7500
机壳	铝	168	833	2790

Tab.4 Environmental parameters at three different altitude locations

地点

海拔高度/m

气压/Pa

空气密度/

（kg·m $- 3$ ）

Tab.4 Environmental parameters at three different altitude locations

地点

海拔高度/m

气压/Pa

空气密度/

（kg·m $- 3$ ）

温度/℃

四川省广汉市

510

99 346.9

1.6614

18.7

四川省康定市

2560

74 130.8

0.95113

10.4

康定市康定机场

4280

60 446.5

0.79544

-1.2

Tab.5 LY-3KGF power system testing parameters

测量项	范围	精度
电压/V	0 ～30	0.05% + 0.05% FS
电流/A	0 ～20	0.1% + 0.1% FS
转速/（r·min $- 1$ ）	30～12，000	0.05% + 0.05% FS
电机温度/℃	$-$ 20 ～150	±0.5
环境温度/℃	$-$ 20～125	±0.5
气压/kPa	50～120	±0.4

Tab.5 LY-3KGF power system testing parameters

测量项	范围	精度
电压/V	0 ～30	0.05% + 0.05% FS
电流/A	0 ～20	0.1% + 0.1% FS
转速/（r·min $- 1$ ）	30～12，000	0.05% + 0.05% FS
电机温度/℃	$-$ 20 ～150	±0.5
环境温度/℃	$-$ 20～125	±0.5
气压/kPa	50～120	±0.4

Fig.4 Schematic diagram of the experimental setup

Fig.5 Propeller flow field at different altitudes and rotational speeds

Fig.6 Axial airflow velocity on the motor surface at n=8000 r/min

Figure 7 Motor temperature field at different altitudes and speeds

Fig.8 Maximum motor temperature and temperature rise of the motor at different altitudes and rotational speeds

Fig.9 Infrared temperature of the motor at different altitudes and rotational speeds

Fig.10 Comparison of maximum temperature between experimental and simulation results

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