清华大学热工基础工程热力学加传热学11第十章-对流换热、单相流体ppt课件

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2、txy2Dtatd 2tat 140uvxy2222xuuupuuuvFxyxxy2222yvvvpvvuvFxyyxyptttcuvxy2222ttxy1516w, , ,qf x y zwwqtnw, , ,tf x y z17180.99uul0yuy1956c2 10 3 10cuxRe 5c5 10Re ww0.99ttttt20Prattt21tl、220uvxy2222xuuupuuuvFxyxxy2222yvvvpvvuvFxyyxyptttcuvxy2222ttxytl、yxuv230uvxy221uudpuuvxydxy ttuvxy22tayddddpuuxx 240uv

3、xy22uuduuuvuxydxyttuvxy22tay212pu常常数数dpduudxdx 2526w0ythtty 0YlY w0YwtthttlY 0YhlY0YNuYww,ttxyuvXYUVlluutthlNu270uvxy22uuuuvxyyttuvxy22tay0UVXY221UUUUVXYReY221UVXYRe PrYu lRe(, ,)Uf X Y Re(, ,)Vf X Y Re(, ,)f X Y Re,Pr0YNuY,Nuf Re Pr28,Nuf Re Prwf,hfuttcl1/25.0 xRexxu xRe29w,0,xyxuy2f,2xucf,xcff,01d

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5、4NuRePrwfqltt20dlxlxxNu32221UUUUVXYReY221UVXYRe PrY33pNuhStRePrC u1/21/30.664NuRePr2/31/20.664St PrRe1/2f1.328cRe2/3f2cSt Prf2cSt 3435,ABC ,AAAC ,BBBC ,CCCC,ABCCCC36312123 TCTC/,/TT37312123lrrrRdlCrrrRdllC/,/rR rR 38 30121230uuuuuCuuuuuC0/u u331122000000,uuuuuuuuuuuu39w0 ythtty 0wythtty ,lxylCxyl hh

6、Ch0hlwyC CthCtty ww ,ttttCCttt1hlC CC h lh l NuNu40Re = Re ,Pr = Pr41424344nmNuf Re , PrCRe PrnNuf RecRelglglgNucnRehlulNuRe、wfhA tt45nmNuCRe Pr4647m2300u dRe4230010Re410Re 4864fRe2m2lupfd 49wwf0ttx ttwftt、wwfwfr Rr Rtttrrttttwfwfwfxxxhttqhttttxh 500.05tlRePrd0.05lRed51xxxqht,xxht 52 lnttttt 0.5/2tt

7、12ttt 535455ce4AdP560.141/3ffffw1.86dNuRe Prlf0.4816700Pr0.141/3fffw2dRe Prlfw0.00449.75570.8fff0.023nNuRePrwfwf0.40.3ttntt4f10 , /60Rel df0.7160 ,Pr0.140.81/3ffffw0.027NuRePr4ff0.716700 ,10,/60PrRel d582/3ff1/22/38100011 12.781tfRePrdNuclfPr6ff0.52000 , 23005 10PrRe 2f0.79ln1.64fRe0.45ffww, 0.51.5t

8、TTcTT0.11ffww, 0.0520tPrPrcPrPr590.452/30.80.4ffffw0.02141001dTNuRePrlT6fffw0.61.5, 0.51.5, 230010TPrReT0.112/30.870.4ffffw0.0122801dPrNuRePrlPr6fffw1.5500 , 0.0520 ,230010PrPrRePr602/3ff8fStPrffffpNuhStRe PrC u611/21/30.332xxNuRePr1/21/30.664NuRePr1/21/30.453xxNuRePr1/21/30.680NuRePr55 10 xRe 0.510

9、00Pr4/51/30.0296xxNuRePr4/51/30.0308xxNuRePr0.660Pr575 1010 xRe62,l,t01ccxlxxxhh dxh dxl4/51/30.037871NuRePr0.660Pr575 1010 xRemw12ttt63u dRe64551.2 10Re80 8551.2 10Re 14065h dNuwnmNuCRe PrPr Pr60.7500, 110PrRe66wnmNuCRe PrPr Pr9030 9021 0.54cos 670.250.36ffffwmnPrNuCRe PrPr6ff12 100.6500RePr、906869

10、w0ythtty 0uvxy22xuudpuuvFxydxyttuvxy22tayxFg dpgdx 7022uuuuvgxyyg11ppvvtt 1tt tt22uuuuvgxyy 71w00w,ttxyuvXYUVlluutt22uuuuvgxyy 2212UUGrUUVXYReReY32gtlGr720UVXY221UVXYRe PrY2212UUGrUUVXYReReY0YNuY2/Gr Re2/Gr Re(,)Nuf Re Gr Pr2/1Gr Re (,)Nuf Re Pr2/1Gr Re (,)Nuf Gr Pr73f f TT1/44xGryx1/22xuxfGr ttttT*

11、w74tRaGr Pr75()nnNuC GrPrcRamw12ttt壁面外形与位置 流动情况 特征长度 Cn适用范围GrPr 垂直平壁或圆柱 壁面高度 0.59 0.101/4 1/3 程度圆柱 圆柱外径d0.850.480.1250.1881/41/3 4910 1091310 102410 104710 1071210 10764710 1071110 1051110 10程度热壁上面或程度冷壁下面平壁面积与周长之比A/U圆盘取0.9d0.54 0.15 1/4 1/3 程度热壁下面或程度冷壁上面平壁面积与周长之比A/U圆盘取0.9d 0.27 1/4 1/435dHGr7743w22xxxxh xg q xgtxGr