2.1.2 ???(heat conduction) 26

1
?2? ???????

• 2.1 ???? 26
• 2.1.1 ???????? 26
• 2.1.2 ???(heat conduction) 26
• 2.1.3 ????(heat convection) 28
• 2.1.4 ?????(radiation) 28
• 2.2 ????????? 29
• 2.2.1 ????? 29
• 2.2.2 ???????? 30
• 2.3 ???????? 31
• 2.4 ??????????? 35

2
2.1.1 ????????


???q(W/m2),????
3
2.1.2 ???(heat conduction)

• ??????,??????????????????????????

??????????? ???q(W/m2)?
????? ?????,?????? ????????Q?
4
2.1.3 ????(heat convection)

• ???????,??????????????????????,?????????????????
• ???????????????????(heat transfer)???,????????????
  ??q??????????

??????dT?,????????
h?????(heat transfer coefficient)
5
2.1.4 ?????

• ??????(radiation)??,??????????????????????????????
  ?????????,??????T?4?????????T????????????E?,

s???????????? T????(K) ????????????????????,???
???e?????
???,0ltelt1
??????????Q?,???????????A?????,

6
????????

• ?????????????????????????????????,????????????,??
  ?q?????d??????,???????????????

7
?2.1 ???????????

• 1.??1m,???100mm2,???????????,???100?,???0????????,
  ???????,3.7W???????????????????????
  (??370w/(mK)
• 2.??10mm,?????0.1W/(mK)??????????????????20?,???
  ?????10????,?????q????????????????20m2????,???????
  ???????????
  (??100W/m22000W)
• 3. ??????100?????????????,??20?????????????
• h100(w/(m2K))?????,????????????????,?????????
  ???
  
  
  (??8000w/m2)
• 4.???????100W/m????????10mm??????,??20????????????
  ??h100W/(m2K)?????,????????????????
• 
  (??51.8?)
• 5.??5mm????????????,???????1500K??????????????????
  ???????????
  (??22.5W)
• 6.100W?????????????,????5mm??????????????????????,
  ???????????????????,??????????,???????????????????
  ?????????????
  (??2177K)
• 7.??????????,???????3???,????????

8
2.2 ?????????2.2.1 ?????

• ??(velocity)???????????????
• ??(flow rate)??????????????????
• 1)?????????????????? (kg/s)
• 2)?????????????????? (kgf/s)
• 3)?????????????????? (m3/s)

?? 1),2),3)???U,???,????,???A??????????
9
2.2.2 ????????
?????

??
??????????????????,??(?A)????????????
10
2.3 ????????

• ?????????????????????3?????
• ?????(????)??????
• ???

11
2.3.1 ???????????
??????????2?A,B???,?A????x??????u????,?B????
????????dt??????,A????????udt???,B?????
???????,2?????????? ???????,??????????
??????,??????????,?????????????????????????????
?????????,??,???????????????

12
2.3.2 ?????

• ?????????ABCD????,x????y????????u,v
• ???(??)?????,??????ABCD???????????

?????? ???????? ?????????!
13
??????(??)
???????????AB???????(??????????)????????????
??????????????(??AD?????????)
?????2?????????????????DAB??????????????,?????????
????????????????????,???????????????????????
(x-y??)
(y-z??)
(z-x??)
14
2.3.3 ??

• ???????????????????????????????????????????????

?????????????????
15

• ???,??AB??????, ?,????????????,

??????,??AD??????
?,??????????,
????????????????,?????????????????,??? ????
?????????,??!
16
?????,?,?????
???????,??????????????????
?Z???????????2?????????????
???????????????????????1?2????????,?1??2????????
???????????,??????
17
?2.3 ?????,????????????????

• 1.???????1)6)???????????????,2???????????????,???
  ??????????????????????, ?A,B?????????????
• 1) 2)
• 3) 4)
• 5) 6)

18
2.4 ???????????

• ?? ? ?(steady flow)???f???t??????????????f/?t0
• ?????(un steady flow)???f???t?????????????f/?t?0

?????????
19
2.4.2 ????????(????)

• ????(uniform flow)
• ??????????3????(x,y,z)??????????????????????????
  
• ?????(non-uniform flow)??????????????????????????
  
• (????)
• 1.????,????????????????? ?????????????????,???????
  ???????????????
• 2.??????????????????????????????????

20
?2.4.1 ????????????

• 1.??????????,???????????,??????????????,??R??????C
  ????,???RC????????t0?????????????,??E,???t???????
  ????????????????????????????,??,???????????(?????E
  ,?????I???,?????t??????)

21
2.4.3 ???
????(vortex flow)?,2????????????????? 1)????(free
vortex)???V?1/r 2)????(forced vortex)???V?r 1)??
????,???V?????????????r????????????,??????????????
????,2)????????V?????????????r???????????,????????
??????
22
?2.4.3 ????????

• 1.??????????????????,?????,????????
• 2.????????????(???,???????????????)??????????????
• 3.????,?????????????????????????????????????????
• 4.???????????????????,????????????????????????????
  ????????????????? (???????)

23
2.4.4 ?????

• ???(laminar flow) ???????????????????????,???????
  ????
• ???(turbulent flow)???????????????????????,??????
  ????????
• ???????Re(Reynolds number)???(??)
• ReUD/?(???)
• ???,U????,D????,????????
• ????????????????,????????Re?????,Reynolds(?????)?
  ???????
• Relt2300 ??????, Regt4000 ??????
• Re2300 ????????(critical Reynolds number)
• 2300ltRelt4000 ????(transition region)

24
2.4.4 ?????

• ????? De(Equivalent Diameter)

A??????(m2) Wp?????(???????????????)(m)
(Weted Perimeter)
?????? ?2???????
?
25
?2.4.4 ??????????

• 1.??50mm?????????????????????1.00410-6
• m2/s???,????????????,?????????????????????
• 2.????????????????????????????????????????,???????
  ?????????????????,????????????????
• ?? ,
• ???,???X(t0)??0ltX(t0)lt1.0?????????????
• ??
• 1.??X(t1)?t0??t30(??)????????
• 2.?????,??t?,??X(t1)??????????
• 3.?????,??x(t)?,??X(t1)??????????
• 4.????????????-?????????????????

26
???????(??)
27
2.4.5 ??

• ???(stream line)????????,?????????V??????????????
  ?

?2??????? ????????????????????????V,V?x,y???????u,
v???t???? ??????????,?????????????,??????V?x,y????
???????????????????????V?S????????????????????????
?,?????????????????????,2??????????,?????????????

???
?????
28
?2.4.5 ???????

• 1.2???????????????????????,?????????
• 1)uAxv-Ay 2)uAyvBx
• ???,A,B?????????????
• 2.????2????????,???????????????,??????????
• 1)u-2x3yvx2y
• 2)u5xyy2vxy4x

29
??2? ??????(??1)

• 1.?????????????????,??????????????????????,???????
  H,????????U????
• 2.???????????????,??????????????????????,Vr?(V??
  ?,r??,????)???????
• 3.???????????????????,????Vk/r(V???,k??,r??)??
  ?????

30
??2? ??????(??2)

• 4.??10mm?????20?,??1??????????u20m/s?????????????
  ??????????,????????µ1.8110-6(Pas),????1.205(kg
  /m3)????
• 5.??????????????????????,2????????????????????????
  ???????,r2x2y2??????????????
• 1)uABy,v0 2)uAy,vAx
• 3)uAy/r2,v-Ax/r2
• 6.?5???????(x,y)???????????,????????????????????