3/4开口试验段汽车风洞的风阻测量误差分析与修正  

Analysis and correction of aerodynamic drag measurement errors in a 3/4-open jet automotive wind tunnel

作　　者：庞加斌[1,2] PANG Jiabin(School of Automotive Studies of Tongji University,Shanghai 201804;Shanghai Automotive Wind Tunnel Center of Tongji University,Shanghai 201804)

机构地区：[1]同济大学汽车学院,上海201804 [2]同济大学上海地面交通工具风洞中心,上海201804

出　　处：《空气动力学学报》2024年第7期112-117,I0002,共7页Acta Aerodynamica Sinica

基　　金：国家重点研发计划(2022YFE0208000)。

摘　　要：汽车风洞用3/4开口试验段模拟真实道路气动环境,有限的试验段尺寸、地面边界层及射流剪切层会干扰流场,从而引起风阻测量误差。根据简化势流模型分析,3/4开口试验段存在模型实体阻塞、喷口阻塞、收集口阻塞以及水平压力梯度4项系统误差源,其中模型实体阻塞让风阻测量值偏低,喷口和收集口阻塞让风阻测量值偏高,彼此平衡抵消机制使3/4开口试验段风洞具有能够适应更大尺寸模型的优势。利用Mercker-Wiedemann修正方法,结合同济大学整车气动声学风洞,计算修正了3辆不同尺寸车型的风阻系数。结果显示:设定风阻系数误差不超过1%为标准,3/4开口试验段汽车风洞最大阻塞比为15%;水平压力梯度对风阻系数误差的影响更大,风洞设计和验收标准应保证dC_(p)(x)/dx≤0.001/m。Automotive wind tunnels are essential in replicating the real-road aerodynamicenvironment for vehicle testing.However,the confined dimensions of the 3/4-open test section,along withthe ground boundary layer and jet shear layers,introduce disturbances to the airflow,leadingto errors in aerodynamic drag measurements.Utilizing a simplified potential flow model,thisstudy identifies and quantifies four critical systematic errors within the test section:solidblockage,nozzle blockage,collector blockage,and horizontal pressure gradient.The solidblockage tends to underestimate the measured aerodynamic drag,while the nozzle andcollector blockages result in overestimations.The interplay of these effects creates a selfcorrecting mechanism that enables the testing of larger vehicle models within the wind tunnel.Employing the Mercker-Wiedemann correction method at Tongji University's full-scale aeroacoustic wind tunnel,this research conducted a correction analysis on three vehicles of varying sizes.The findings indicate that,with a criterion of keeping the aerodynamic drag coefficient error within 1%,the wind tunnel is capable of accommodating vehicles with ablockage ratio of up to 15%.Moreover,the horizontal pressure gradient is identified as asignificant source of error in the drag coefficient measurement.These insights underscore thenecessity for stringent design and acceptance protocols in wind tunnel engineering with dC_(p)(x)/dx≤0.001/m to ensure measurement precision.

关 键 词：汽车风洞 3/4开口试验段 射流剪切层 阻塞效应 水平压力梯度 

分 类 号：U467.13[机械工程—车辆工程]