
P0=-0.1KPa
查表得:此时水的密度为ρ=997.6351Kg/m3
水的粘度为μ=9.579×10-4Pa·s
1、光滑管的λ和Re求解:d=0.008058m l=1.70m
表3 光滑管摩擦系数λ数据处理表
| 序号 | V/(L/h) | P1(mm H2O) | P2(mm H2O) | 压差 ΔP | u(m/s) | λ | ||
| mm H2O | KPa | ΔP/(Pa) | ||||||
| 1 | 14 | -5 | 2 | 7 | 68.6 | 0.0763 | 0.1120 | |
| 2 | 20 | -7 | 4 | 11 | 107.8 | 0.1090 | 0.0862 | |
| 3 | 28 | -10 | 5 | 15 | 147 | 0.1526 | 0.0600 | |
| 4 | 36 | -12 | 6 | 18 | 176.4 | 0.1962 | 0.0435 | |
| 5 | 44 | -15 | 12 | 27 | 2.6 | 0.2398 | 0.0437 | |
| 6 | 52 | -21 | 19 | 40 | 392 | 0.2834 | 0.04 | |
| 7 | 60 | -22 | 24 | 46 | 450.8 | 0.3270 | 0.0401 | |
| 8 | 76 | -30 | 36 | 66 | 6.8 | 0.4142 | 0.0358 | |
| 9 | 84 | -35 | 45 | 80 | 784 | 0.4578 | 0.0356 | |
| 10 | 92 | -44 | 56 | 100 | 980 | 0.5014 | 0.0370 | |
| 11 | 120 | 1.3 | 1200 | 0.6540 | 0.0267 | |||
| 12 | 280 | 7.6 | 7500 | 1.5259 | 0.0306 | |||
| 13 | 400 | 14.2 | 14100 | 2.1799 | 0.0282 | |||
| 14 | 600 | 29.2 | 29100 | 3.2698 | 0.0259 | |||
| 15 | 840 | 53.7 | 53600 | 4.5778 | 0.0243 | |||
| 16 | 1000 | 72.8 | 72700 | 5.4497 | 0.0233 | |||
当V=14 L/h时,ΔP=(P2-P1)×9.8=(5+2)×9.8=68.8 Pa
当V=120 L/h时,ΔP=(1.3-0.1)×1000=1200 Pa
表4 光滑管λ与Re数据处理表
| 序号 | u/(m/s) | λ | Re | ln Re | ln λ | 理论λ |
| 1 | 0.0763 | 0.1120 | 0.2951 | 6.4619 | -2.14 | 0.1000 |
| 2 | 0.1090 | 0.0862 | 914.7073 | 6.8186 | -2.4508 | 0.0700 |
| 3 | 0.1526 | 0.0600 | 1280.5902 | 7.1551 | -2.8136 | 0.0500 |
| 4 | 0.1962 | 0.0435 | 16.4731 | 7.40 | -3.1339 | 0.03 |
| 5 | 0.2398 | 0.0437 | 2012.3560 | 7.6071 | -3.1297 | 0.0318 |
| 6 | 0.2834 | 0.04 | 2378.23 | 7.7741 | -3.0708 | 0.0269 |
| 7 | 0.3270 | 0.0401 | 2744.1218 | 7.9172 | -3.2172 | 0.0233 |
| 8 | 0.4142 | 0.0358 | 3475.8876 | 8.1536 | -3.3290 | 0.0412 |
| 9 | 0.4578 | 0.0356 | 3841.7705 | 8.2537 | -3.3368 | 0.0402 |
| 10 | 0.5014 | 0.0370 | 4207.6534 | 8.3447 | -3.2956 | 0.0393 |
| 11 | 0.6540 | 0.0267 | 5488.2435 | 8.6104 | -3.6245 | 0.0368 |
| 12 | 1.5259 | 0.0306 | 12805.9015 | 9.4577 | -3.4865 | 0.0297 |
| 13 | 2.1799 | 0.0282 | 18294.1450 | 9.8143 | -3.5686 | 0.0272 |
| 14 | 3.2698 | 0.0259 | 27441.2176 | 10.2198 | -3.6549 | 0.0246 |
| 15 | 4.5778 | 0.0243 | 38417.7046 | 10.5563 | -3.7171 | 0.0226 |
| 16 | 5.4497 | 0.0233 | 45735.3626 | 10.7306 | -3.7610 | 0.0216 |
当λ=0.1120时,u=0.0763 m/s
当λ=0.0267时,u=0.6540 m/s
图1 光滑管层流区λ—Re双对数关系
图2 光滑管过渡区λ—Re双对数关系
图3 光滑管湍流区λ—Re双对数关系
图4 光滑管λ实际值与理论值对比关系曲线
2、粗糙管的λ和Re求解:d=0.010m l=1.70m
| 序号 | V/(L/h) | P1(mm H2O) | P2(mm H2O) | 压差 ΔP | u(m/s) | λ | ||
| mm H2O | KPa | ΔP/(Pa) | ||||||
| 1 | 16 | -11 | 8 | 19 | 186.2 | 0.0566 | 0.6850 | |
| 2 | 24 | -18 | 21 | 39 | 382.2 | 0.0849 | 0.6249 | |
| 3 | 36 | -32 | 42 | 74 | 725.2 | 0.1274 | 0.5270 | |
| 4 | 40 | -39 | 53 | 92 | 901.6 | 0.1415 | 0.5307 | |
| 5 | 48 | -52 | 75 | 127 | 1244.6 | 0.1699 | 0.5087 | |
| 6 | 52 | -58 | 84 | 142 | 1391.6 | 0.1840 | 0.4847 | |
| 7 | 60 | -70 | 102 | 172 | 1685.6 | 0.2123 | 0.4410 | |
| 8 | 72 | -93 | 139 | 232 | 2273.6 | 0.2548 | 0.4131 | |
| 9 | 84 | 2.8 | 2700 | 0.2972 | 0.3604 | |||
| 10 | 92 | 3.5 | 3400 | 0.3255 | 0.3783 | |||
| 11 | 120 | 5.4 | 5300 | 0.4246 | 0.3466 | |||
| 12 | 280 | 27.4 | 27300 | 0.9908 | 0.3279 | |||
| 13 | 400 | 51.8 | 51700 | 1.4154 | 0.3043 | |||
| 14 | 600 | 108.8 | 108700 | 2.1231 | 0.2844 | |||
| 15 | 720 | 155.3 | 155200 | 2.5478 | 0.2820 | |||
计算实例:以V=16 L/h和V=84 L/h为例
当V=16 L/h时,ΔP=(P2-P1)×9.8=(8+11)×9.8=186.2 Pa
当V=84 L/h时,ΔP=(2.8-0.1)×1000=2700 Pa
表6 粗糙管λ与Re数据处理表
| 序号 | u/(m/s) | λ | Re | ln Re | ln λ |
| 1 | 0.0566 | 0.6850 | 5.6569 | 6.3795 | -0.3783 |
| 2 | 0.0849 | 0.6249 | 884.4853 | 6.7850 | -0.4701 |
| 3 | 0.1274 | 0.5270 | 1326.7280 | 7.1905 | -0.06 |
| 4 | 0.1415 | 0.5307 | 1474.1422 | 7.2958 | -0.6336 |
| 5 | 0.1699 | 0.5087 | 1768.9706 | 7.4782 | -0.6758 |
| 6 | 0.1840 | 0.4847 | 1916.3849 | 7.5582 | -0.7243 |
| 7 | 0.2123 | 0.4410 | 2211.2133 | 7.7013 | -0.8188 |
| 8 | 0.2548 | 0.4131 | 2653.4560 | 7.8836 | -0.8842 |
| 9 | 0.2972 | 0.3604 | 3095.6986 | 8.0378 | -1.0206 |
| 10 | 0.3255 | 0.3783 | 3390.5271 | 8.1287 | -0.9720 |
| 11 | 0.4246 | 0.3466 | 4422.4266 | 8.3944 | -1.0595 |
| 12 | 0.9908 | 0.3279 | 10318.9955 | 9.2417 | -1.1149 |
| 13 | 1.4154 | 0.3043 | 14741.4221 | 9.5984 | -1.17 |
| 14 | 2.1231 | 0.2844 | 22112.1331 | 10.0039 | -1.2575 |
| 15 | 2.5478 | 0.2820 | 26534.5597 | 10.1862 | -1.2660 |
当λ=0.6850时,u=0.0566 m/s
当λ=0.3604时,u=0.2976 m/s
图5 光滑管层流区λ—Re双对数
图6 光滑管过渡区λ—Re双对数关系
图7 光滑管湍流区λ—Re双对数关系
图8 光滑管与粗糙管λ—Re双对数关系对比
