Journal of Jilin University(Engineering and Technology Edition) ›› 2022, Vol. 52 ›› Issue (4): 745-753.doi: 10.13229/j.cnki.jdxbgxb20200931

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Optimization of the aerodynamic drag reduction of a cab behind engine vehicle

Ying-chao ZHANG(),Yun-hang LI,Zi-yu GUO,Guo-hua WANG,Zhe ZHANG(),Chang SU   

  1. State Key Laboratory of Automotive Simulation and Control，Jilin University，Changchun 130022，China
  • Received:2020-12-02 Online:2022-04-01 Published:2022-04-20
  • Contact: Zhe ZHANG E-mail:yingchao@jlu.edu.cn;zhangzhejlu@jlu.edu.cn

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Abstract:

In this paper, the cab behind engine vehicles are taken as the research object, and the entire aerodynamic performance optimization is carried out. The optimization is composed of two steps, the initial shape optimization of the molding surface in the early modeling stage and the aerodynamic optimization in the later vehicle stage. The optimization process is based on Hyperstudy software to realize the shape parameterization, and CFD software simulation is used to evaluate the aerodynamic performance. An automatic process was built to realize the aerodynamic shape optimization of cab behind engine vehicles with these two kinds of software. Eight design variables that need to be considered (i.e. sunshield rotation, hood deformation, container deformation, fairing optimization, front wheel baffle optimization, side deflector optimization, side skirt at the container, and rear guide device of the container) were determined for aerodynamic optimization design. Finally, the drag coefficient of the vehicle was reduced from 0.432 to 0.387, compared with that of the vehicle base model reduced 45 counts by 10.4%.

Key words: vehicle engineering, cab behind engine vehicles, aerodynamics, aerodynamic drag reduction, optimization design

CLC Number: 

  • U270.1

Fig.1

Simulation model"

Fig.2

Surface mesh"

Fig.3

Schematic diagram of mesh encryption area"

Table 1

Grid sensitivity check result"

A/mmB/mmC/mm网格数量/万Cd值
326412830010.4327
32649630520.4325
32489631810.4322
24489634200.4321
24486435120.4320
24326440170.4320
16326447620.4319

Fig.4

Schematic diagram of optimization process"

Fig.5

Deformation diagram of sunshield"

Table 2

Sunshield optimization results"

旋转角度α/（°）CdΔCd/%
00.4320
-20.428-0.86
-40.428-0.97
-60.427-1.25
-80.427-1.16
-100.426-1.30
-120.426-1.44
-140.425-1.64
-160.426-1.34
-180.428-1.00

Fig.5

Pressure distribution of Y= 0 before and after optimization"

Fig.7

Deformation diagram"

Fig.8

RBF fitting results"

Fig.9

Pressure distribution before and after optimization"

Table 3

Statistical table of optimization results"

参 数计算结果ΔCd/%
Base Cd0.432-
预测Cd0.420-2.78
变量M1.4-
变量N0-
实际计算Cd0.422-2.31
预测误差/%0.46-

Fig.10

Deformation diagram"

Table 4

Container optimization results"

方 案下压距离M/mCdΔCd/countsΔCd/%
10.150.4254-6.60-1.53
20.200.4224-9.60-2.22
30.250.4205-11.5-2.66
40.300.4198-12.2-2.82

Fig.11

Velocity vector of Y=0 section before and after optimization"

Fig.12

Optimization diagram of fairing"

Table 5

Optimization results of fairing"

方 案

X方向

平移/m

Y方向

平移/m

CdΔCd/counts
10.100.0800.4313-0.7
20.090.0720.43250.5
30.080.0640.4313-0.7
40.070.0560.4298-2.2
50.060.0480.4302-1.8
60.050.0400.4306-1.4
70.040.0320.4305-1.5
80.030.0240.4308-1.2

Fig.13

Pressure distribution before and after optimization"

Fig.14

Pressure distribution before and after optimization"

Fig.15

RBF fitting results"

Table 6

Statistical table of optimization results"

参 数差 值ΔCd/%
Base Cd0.42800.926
预测Cd0.4236-1.94
变量H/mm126.7-
变量β/（°）17.4°-
实际计算Cd0.4241-1.83
预测误差0.12-

Fig.16

Pressure distribution before and after optimization"

Fig.17

Side deflector"

Fig.18

RBF fitting results"

Table 7

Statistical table of optimization results"

参 数差 值ΔCd/%
Base Cd0.4320
优化导流板预测Cd0.4226-2.17
变量L/mm0.93-
变量β/（°）6.82-
实际计算Cd0.4249-1.64
预测误差/%0.54-

Fig.19

Turbulent kinetic energy of Y=0 cross section before and after optimization"

Fig.20

Diagrammatic sketch of container tail deformation"

Table 8

Optimization results of container tail"

X向移动距离/mCd值ΔCd/countsΔCd/%
0.20.4267-5.3-1.23
0.40.4256-6.4-1.48
0.60.4254-6.6-1.53
0.80.4253-6.7-1.55
1.00.4245-7.5-1.74
1.20.4239-8.1-1.88
1.40.4231-8.9-2.08
1.60.4265-5.5-1.27
1.80.459527.56.37
2.00.446614.63.38

Fig.21

Velocity vector diagram of Y=0 cross section before and after optimization"

Fig.22

Comparison of cumulated force coefficients of final scheme"

Fig.23

Front view comparison of front pressure distribution before and after optimization"

Fig.24

Side view comparison of front pressure distribution before and after optimization"

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