实验流体力学
實驗流體力學
실험류체역학
JOURNAL OF EXPERIMENTS IN FLUID MECHANICS
2014年
1期
31-37
,共7页
Ahmed模型%减阻%流动控制%压力扫描阀%眼镜蛇探针
Ahmed模型%減阻%流動控製%壓力掃描閥%眼鏡蛇探針
Ahmed모형%감조%류동공제%압력소묘벌%안경사탐침
Ahmed model%drag reduction%flow control%pressure scanner%cobra probe
在雷诺数8．7×105的条件下，运用眼镜蛇探针、压力扫描阀和表面油膜流动可视化技术对倾角为25°的Ahmed类车体尾流与尾部压力分布进行了研究。对比了模型尾部斜面上边缘和两侧不同宽度导流板对模型尾流与气动阻力的影响规律。实验发现模型尾流中存在一对对称的拖曳涡，其在尾流中心线附近形成强烈的下扫流。拖曳涡强度与模型尾部压力分布和气动阻力有直接关系，较强的拖曳涡对应的模型尾部负压以及气动阻力均较大。斜面两侧导流板宽度为1％模型长度时，不仅无减阻效果，反而会使气动阻力增加约3．0％。当导流板宽度增加为2％和3％模型长度时，能够明显削弱斜面上的分离泡，对应的减阻效果分别为3．5％和7．2％。斜面上边缘导流板可有效地抑制分离流在斜面上的再附，并消除斜面上的分离泡，其抑制拖曳涡强度和降低气动阻力的效果明显优于同等宽度的斜面两侧导流板。上边缘导流板宽度为模型长度的1％，2％和3％时，减阻率分别可达9．3％，10．7％和10．9％。
在雷諾數8．7×105的條件下，運用眼鏡蛇探針、壓力掃描閥和錶麵油膜流動可視化技術對傾角為25°的Ahmed類車體尾流與尾部壓力分佈進行瞭研究。對比瞭模型尾部斜麵上邊緣和兩側不同寬度導流闆對模型尾流與氣動阻力的影響規律。實驗髮現模型尾流中存在一對對稱的拖抴渦，其在尾流中心線附近形成彊烈的下掃流。拖抴渦彊度與模型尾部壓力分佈和氣動阻力有直接關繫，較彊的拖抴渦對應的模型尾部負壓以及氣動阻力均較大。斜麵兩側導流闆寬度為1％模型長度時，不僅無減阻效果，反而會使氣動阻力增加約3．0％。噹導流闆寬度增加為2％和3％模型長度時，能夠明顯削弱斜麵上的分離泡，對應的減阻效果分彆為3．5％和7．2％。斜麵上邊緣導流闆可有效地抑製分離流在斜麵上的再附，併消除斜麵上的分離泡，其抑製拖抴渦彊度和降低氣動阻力的效果明顯優于同等寬度的斜麵兩側導流闆。上邊緣導流闆寬度為模型長度的1％，2％和3％時，減阻率分彆可達9．3％，10．7％和10．9％。
재뢰낙수8．7×105적조건하，운용안경사탐침、압력소묘벌화표면유막류동가시화기술대경각위25°적Ahmed류차체미류여미부압력분포진행료연구。대비료모형미부사면상변연화량측불동관도도류판대모형미류여기동조력적영향규률。실험발현모형미류중존재일대대칭적타예와，기재미류중심선부근형성강렬적하소류。타예와강도여모형미부압력분포화기동조력유직접관계，교강적타예와대응적모형미부부압이급기동조력균교대。사면량측도류판관도위1％모형장도시，불부무감조효과，반이회사기동조력증가약3．0％。당도류판관도증가위2％화3％모형장도시，능구명현삭약사면상적분리포，대응적감조효과분별위3．5％화7．2％。사면상변연도류판가유효지억제분리류재사면상적재부，병소제사면상적분리포，기억제타예와강도화강저기동조력적효과명현우우동등관도적사면량측도류판。상변연도류판관도위모형장도적1％，2％화3％시，감조솔분별가체9．3％，10．7％화10．9％。
The near wake flow and pressure distribution on the rear end of a 25°slant angle Ahmed model were investigated at the Reynolds number of 8.7×105 ,using Cobra probe,pres-sure scanner and oil film flow visualization technique.Deflectors with different width mounted on the top edge and both side edges of the slant were tested to compare their effects on the near wake and aerodynamic drag.It is found that there is a pair of symmetrical tailing vortices in the near wake,which induces strong downwash flow near wake centerline.The strength of tailing vortices is inherently correlated with the pressure distribution on rear end and aerodynamic drag of the model.A stronger trailing vortex corresponds to larger negative pressure on the slant and also a larger aerodynamic drag.The deflectors at both sides of slant with the width of 1% model length result in about 3 .0% increase of the aerodynamic drag.With the width increases to 2% and 3%of model length,deflectors at both sides of slant can noticeably suppress the separation bubble, and result in a drag reduction of 3 .5%and 7 .2%,respectively.Deflector at the top edge prevents flow reattachment on the slant,thus eliminates the separation bubble.It suppresses the tail vor-tices and reduces the aerodynamic drag more effectively than those at the side edges.The drag re-duction rate reaches 9 .3%,1 0 .7% and 1 0 .9% for the top edge deflectors with the width of 1%, 2% and 3% of model length.
