热基础课件工程热力学加传热学第十章-.ppt

1、110-1 2xAq dAwfxxAhttdAwfwfxtttt常数wfxAtth dA1xAhh dAAwfxxxqhtt3 45611ppvvtt 7wf,hfuttcl89l310Knl l10uy0,xyxtqy 流体导热系数流体导热系数11wxxxqhtt0,yxty w0,xyxxthtty w0ythtty qx12dxxdyy02xDupFudx 2yDvpFvdy 2222xuuupuuuvFxyxxy2222yvvvpvvuvFxyyxy0uvxy13dxxdyy0 xh xdh x+xdx+xyh ydy+ydh y+yddhUptttcuvxy2222ttxy2Dtat

2、d 2tat 140uvxy2222xuuupuuuvFxyxxy2222yvvvpvvuvFxyyxyptttcuvxy2222ttxy1516w,qf x y zwwqtnw,tf x y z17180.99uul0yuy1956c2 10 3 10cuxRe5c5 10Re ww0.99ttttt20Prattt21tl、220uvxy2222xuuupuuuvFxyxxy2222yvvvpvvuvFxyyxyptttcuvxy2222ttxytl、yxuv230uvxy221uudpuuvxydxy ttuvxy22tayddddpuuxx 240uvxy22uuduuuvuxydxy

3、ttuvxy22tay212pu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,01dlxccxl1/2f,22lClc1/201d

4、lCxxlu lRe1/2f,0.664xxcRe1/2f1.328cRe1/3tPrxu xRe301/21/30.332xxxh xNuRePr01dlxhhxl1/201 dlC xxl1/22 2x lC lh22lx lhlhlNuNu1/21/30.664NuRePrmw12tttxu xRe311/21/30.453xxNuRePr1/21/30.332xxNuRePrwxxfxqhttq常数wfxtt常数ww01dlffxttttxl01dlxqxlh0dlxqxxlNuhlNu1/21/30.680NuRePr1/21/30.664NuRePrwfqltt20dlxlxxNu

5、32221UUUUVXYReY221UVXYRe 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 hhCh0hlwyC CthCtty ww ,ttttCC

6、ttt1hlC CC h lh l NuNu40Re=Re,Pr=Pr41424344nmNuf Re,PrCRe PrnNuf RecRelglglgNucnRehlulNuRe、wfhA tt45nmNuCRe Pr4647 m2300u dRe4230010Re410Re 4864fRe2m2lupfd 49wwf0ttx ttwftt、wwfwfr Rr Rtttrrttttwfwfwfxxxhttqhttttxh 500.05tlRePrd0.05lRed51xxxqht,xxht 52 lnttttt 0.5/2tt12ttt 535455ce4AdP560.141/3ffffw1

7、.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,0.51.5tTTcTT0.11ffww,0.0520tPrPrcPrPr590.452/30

8、.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 0.51000Pr4/51/30.0296xxNuRePr4/51/30.0308xxNuRePr0.

9、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、906869w0ythtty 0uvxy22xuudpuuvFxydxyttuvxy22tayxFg dp

10、gdx 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*w74tRaGr Pr75()nnNuC GrPrcRamw12ttt壁面形状与位置 流动情况 特

11、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 水平圆柱 圆柱外径d0.850.480.1250.1881/41/3 4910 1091310 102410 104710 1071210 10764710 1071110 1051110 10水平热壁上面或水平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 水平热壁下面或水平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 xgtxGrGrNu 1/50.60 xxNuGrPr5111010 xGrPr1/40.17xxNuGrPr13162 1010 xGrPrm,xw,x12ttt7821/68/279/160.3870.82510.492RaNuPr1121010Ra60cosg21/68/279/160.3870.6010.559/RaNuPr1210Ra 798081