紧急求救：温度模拟结果和实测结果差别巨大！

bigbigseawaves

现象描述：对一块钢板（316不锈钢）表面加热，不考虑对流和辐射，需要通过模拟知道钢板底面的温度。
问题描述：实测值与模拟值差别很大。在一定加热条件下，模拟得出的底面温度只有20多度（感觉热量传不下来），实测值却有200多读。模型分为5层，对最上面一层的所有单元进行加热（HGEN）。代码如下，关于那个选单元的命令我不会用命令流,在GUI下是通过MIN,MAX,INC很容易得到5，1125，5，但不知道用哪个命令简单描述，抱歉！温度场分布图见附件！
/CONFIG,NRES,1000000
/PREP7  
/COM,  Structural   
/COM,  Thermal  
ET,1,SOLID70   !
MPTEMP,1,0,200,400,600,800,1000,1200   
MPDATA,KXX,1,1,74.7,62.1,49.2,38.2,29.4,29.3,32.2
MPDATA,C,1,1,435,519,602.5,753,832,569,640
MPDATA,ENTH,1,1,0,6.4E8,1.4E9,2.3E9,3.25E9,4.3E9,5.5E9
MP,DENS,1,7890  
MP,EX,1,1.80e11
MP,ALPX,1,15e-6
MP,PRXY,1,0.288
!!!!!!!!!!!!!!!!!!!***************  
BLOCK,-75,75,-75,75,0,10

LAYER=5
FLST,5,4,4,ORDE,2   
FITEM,5,9   
FITEM,5,-12
CM,_Y,LINE  
LSEL, , , ,P51X
CM,_Y1,LINE
CMSEL,,_Y   
!*  
LESIZE,_Y1, , ,LAYER, , , , ,1  
!*  
FLST,5,8,4,ORDE,2   
FITEM,5,1   
FITEM,5,-8  
CM,_Y,LINE  
LSEL, , , ,P51X
CM,_Y1,LINE
CMSEL,,_Y   
!*  
LESIZE,_Y1, , ,15, , , , ,1
!*  
CM,_Y,VOLU  
VSEL, , , ,       1
CM,_Y1,VOLU
CHKMSH,'VOLU'   
CMSEL,S,_Y  
!*  
VSWEEP,_Y1  
!*  
CMDELE,_Y   
CMDELE,_Y1  
CMDELE,_Y2  
!*  

FINISH  


/SOL
ANTYPE,4
NROPT,FULL  
OUTRES,ALL,1
tunif,20   
tref,20
kbc,1   
LUMPM,0
!!!!!!!!!!!!!!!!!!!***************  
!tim=0
time,600
AUTOTS,-1   
DELTIM,20,20,20,0  
TSRES,ERASE
TIMINT,1
TINTP,0.005, , ,-1,0.5,-1,  
FLST,2,225,2,ORDE,225   
FITEM,2,5   
FITEM,2,10  
FITEM,2,15  
FITEM,2,20  
FITEM,2,25  
FITEM,2,30  
FITEM,2,35  
FITEM,2,40  
FITEM,2,45  
FITEM,2,50  
FITEM,2,55  
FITEM,2,60  
FITEM,2,65  
FITEM,2,70  
FITEM,2,75  
FITEM,2,80  
FITEM,2,85  
FITEM,2,90  
FITEM,2,95  
FITEM,2,100
FITEM,2,105
FITEM,2,110
FITEM,2,115
FITEM,2,120
FITEM,2,125
FITEM,2,130
FITEM,2,135
FITEM,2,140
FITEM,2,145
FITEM,2,150
FITEM,2,155
FITEM,2,160
FITEM,2,165
FITEM,2,170
FITEM,2,175
FITEM,2,180
FITEM,2,185
FITEM,2,190
FITEM,2,195
FITEM,2,200
FITEM,2,205
FITEM,2,210
FITEM,2,215
FITEM,2,220
FITEM,2,225
FITEM,2,230
FITEM,2,235
FITEM,2,240
FITEM,2,245
FITEM,2,250
FITEM,2,255
FITEM,2,260
FITEM,2,265
FITEM,2,270
FITEM,2,275
FITEM,2,280
FITEM,2,285
FITEM,2,290
FITEM,2,295
FITEM,2,300
FITEM,2,305
FITEM,2,310
FITEM,2,315
FITEM,2,320
FITEM,2,325
FITEM,2,330
FITEM,2,335
FITEM,2,340
FITEM,2,345
FITEM,2,350
FITEM,2,355
FITEM,2,360
FITEM,2,365
FITEM,2,370
FITEM,2,375
FITEM,2,380
FITEM,2,385
FITEM,2,390
FITEM,2,395
FITEM,2,400
FITEM,2,405
FITEM,2,410
FITEM,2,415
FITEM,2,420
FITEM,2,425
FITEM,2,430
FITEM,2,435
FITEM,2,440
FITEM,2,445
FITEM,2,450
FITEM,2,455
FITEM,2,460
FITEM,2,465
FITEM,2,470
FITEM,2,475
FITEM,2,480
FITEM,2,485
FITEM,2,490
FITEM,2,495
FITEM,2,500
FITEM,2,505
FITEM,2,510
FITEM,2,515
FITEM,2,520
FITEM,2,525
FITEM,2,530
FITEM,2,535
FITEM,2,540
FITEM,2,545
FITEM,2,550
FITEM,2,555
FITEM,2,560
FITEM,2,565
FITEM,2,570
FITEM,2,575
FITEM,2,580
FITEM,2,585
FITEM,2,590
FITEM,2,595
FITEM,2,600
FITEM,2,605
FITEM,2,610
FITEM,2,615
FITEM,2,620
FITEM,2,625
FITEM,2,630
FITEM,2,635
FITEM,2,640
FITEM,2,645
FITEM,2,650
FITEM,2,655
FITEM,2,660
FITEM,2,665
FITEM,2,670
FITEM,2,675
FITEM,2,680
FITEM,2,685
FITEM,2,690
FITEM,2,695
FITEM,2,700
FITEM,2,705
FITEM,2,710
FITEM,2,715
FITEM,2,720
FITEM,2,725
FITEM,2,730
FITEM,2,735
FITEM,2,740
FITEM,2,745
FITEM,2,750
FITEM,2,755
FITEM,2,760
FITEM,2,765
FITEM,2,770
FITEM,2,775
FITEM,2,780
FITEM,2,785
FITEM,2,790
FITEM,2,795
FITEM,2,800
FITEM,2,805
FITEM,2,810
FITEM,2,815
FITEM,2,820
FITEM,2,825
FITEM,2,830
FITEM,2,835
FITEM,2,840
FITEM,2,845
FITEM,2,850
FITEM,2,855
FITEM,2,860
FITEM,2,865
FITEM,2,870
FITEM,2,875
FITEM,2,880
FITEM,2,885
FITEM,2,890
FITEM,2,895
FITEM,2,900
FITEM,2,905
FITEM,2,910
FITEM,2,915
FITEM,2,920
FITEM,2,925
FITEM,2,930
FITEM,2,935
FITEM,2,940
FITEM,2,945
FITEM,2,950
FITEM,2,955
FITEM,2,960
FITEM,2,965
FITEM,2,970
FITEM,2,975
FITEM,2,980
FITEM,2,985
FITEM,2,990
FITEM,2,995
FITEM,2,1000
FITEM,2,1005
FITEM,2,1010
FITEM,2,1015
FITEM,2,1020
FITEM,2,1025
FITEM,2,1030
FITEM,2,1035
FITEM,2,1040
FITEM,2,1045
FITEM,2,1050
FITEM,2,1055
FITEM,2,1060
FITEM,2,1065
FITEM,2,1070
FITEM,2,1075
FITEM,2,1080
FITEM,2,1085
FITEM,2,1090
FITEM,2,1095
FITEM,2,1100
FITEM,2,1105
FITEM,2,1110
FITEM,2,1115
FITEM,2,1120
FITEM,2,1125
/GO
!*  
BFE,P51X,HGEN,1,4E6,4E6,4E6,4E6

allsel
outres,all,all
solve
save

aiyouguai

都是GUI。。。

bigbigseawaves

有人帮忙看看原因吗？是要加边界条件吗

bigbigseawaves

急盼各位大侠帮忙！底板温度实测值为380度，模拟值永远都是20度，条件是：在真空环境下，本身无对流，也不考虑辐射。

bigbigseawaves

单元类型为SOLID70,是单元类型选的不对，还是边界条件需要改变？

gringoire

你给底板定义的是20°的温度边界吗？改成热流边界比较合适吧。

双城记2

和你遇到同样的问题，温度不发生变化，和实际差别很大。期待解决！

iomega

The main reason your simulation result does not fit the measurement data is because of:
(1) Your simulation time is only 600s, while the thickness of steel L is around 10m. The thermal diffusivity of steel, alf, is around 2e-5 m^2/s.  So it takes around L^2/alf =  5000000s to reach the bottom. If you increase the simulation time, the temperature will keep increase.

(2) You don't have bottom thermal boundary condition, which means, if time is long enough, the temperature will blow up since no heat can escape. You can set end time = 10^9s to verify that.

aiyouguai

散热很重要

bigbigseawaves

谢谢版主，我犯了一个致命的错误，我的模型尺寸应该为－0.075，0.075,单位差了1000倍。谢谢你的传递时间计算！

aiyouguai

:模型建立很重要 不要忘记单位了

xin__sl

遇到相同的问题，就是温度变化很小，难道是计算时间太短了

zjh274

嗯。版主很强悍啊。