鑄鐵管水力計(jì)算p

1、鋼管和鑄鐵管水力計(jì)算,1 計(jì)算公式,鋼管和鑄鐵管水力計(jì)算沿用甫阿舍維列夫著水力計(jì)算表。表中所采用的兩種計(jì)算水頭公式如下：,（1）按水力坡降計(jì)算水頭損失：水管的水力計(jì)算，一般采用公式（1-1）：, （1-1）,式中i 水力坡降；, 摩阻系數(shù)；,d j 管子的計(jì)算內(nèi)徑（m）；, 平均水流速度（m/s）；,g 重力加速度，為9.81（m/s2）,應(yīng)用公式（1-1）時(shí)，必須先確定求取系數(shù)值的依據(jù)。對(duì)于舊的鋼管和鑄鐵管：,當(dāng)/v9.2105/m時(shí)，液體的運(yùn)動(dòng)粘滯度，（m2/s），則, （1-2）,當(dāng)/v9.2105/m時(shí)，則, （1-3）,或采用1.310-6m2/s（水溫為10）時(shí)，則,（1-4）,管

2、壁如發(fā)生銹蝕或沉垢，管壁的粗糙度就增加，從而使系數(shù)值增大。公式（1-2）和公式（1-3）適合于舊鋼管和鑄鐵管這類管材的自然粗糙度。,將公式（1-2）和公式（1-4）中求得的值，代入（1-1）中，得出的舊鋼管和鑄鐵管的計(jì)算公式為：,當(dāng)v1.2m/s 時(shí)，,（1-5）,當(dāng)v1.2m/s 時(shí)，, （1-6）,鋼管和鑄鐵管水力計(jì)算表即按公式（1-5）和公式（1-6）制成。,（2）按比阻計(jì)算水頭損失：由公式（1-5）求得比阻公式（1-7）為：, （1-7）,鋼管和鑄鐵管的A 值，按公式（17），列表于14、5。由于鋼管和鑄鐵管的計(jì)算內(nèi)徑dj 不同，,如公稱直徑DN50mm 時(shí)，鋼管的計(jì)算內(nèi)徑dj52mm

3、；鑄鐵管的計(jì)算內(nèi)徑dj49mm。因此同一公稱直徑，鋼管和鑄鐵管的A 值不同。,2 水力計(jì)算表制表和使用說明,（1）鋼管及鑄鐵管水力計(jì)算表采用管子計(jì)算內(nèi)徑內(nèi)的尺寸，見表21。在確定計(jì)算內(nèi)徑dj 時(shí)，直徑小于300mm 的鋼管及鑄鐵管考慮銹蝕和沉垢的影響，其內(nèi)徑應(yīng)減去1mm 計(jì)算。對(duì)于直徑300 毫米和300毫米以上的管子，這種直徑的減小，沒有實(shí)際意義，可以不必考慮。,編制鋼管和鑄鐵管水力計(jì)算表時(shí)所用的計(jì)算內(nèi)徑尺寸 表21,鋼管（毫米）,鑄鐵管（mm）,普通水煤氣管,中等管徑,大管徑,公稱直徑,外徑,內(nèi)徑,計(jì)算內(nèi)徑,公稱直徑,外徑,計(jì)算內(nèi)徑,公稱直徑,外徑,計(jì)算內(nèi)徑,內(nèi)徑,計(jì)算內(nèi)徑,DN,D,d,

4、dj,DN,D,dj,DN,D,dj,d,dj,8,13.5,9,8,125,146,125,400,426,406,50,49,10,17,12.5,11.5,150,168,147,450,478,458,75,74,15,21.25,15.75,14.75,175,194,173,500,529,509,100,99,20,26.75,21.24,20.25,200,219,198,600,630,610,125,124,25,33.5,27,26,225,245,224,700,720,700,150,149,32,42.25,35.75,34.75,250,273,252,800,8

5、20,800,200,199,40,48,41,40,275,299,279,900,920,900,250,249,50,60,53,52,300,325,305,1000,1020,1000,300,300,70,75.5,68,67,325,351,331,1200,1220,1200,350,350,80,88.5,80.5,79.5,350,377,357,1300,1320,1300,400,400,100,114,106,105,1400,1420,1400,450,450,125,140,131,130,1500,1520,1500,500,500,150,165,156,15

6、5,1600,1620,1600,600,600,1800,1820,1800,700,700,2000,2020,2000,800,800,2200,2220,2200,900,900,2400,2420,2400,1000,1000,2600,2620,2600,1100,1100,1200,1200,1300,1300,1400,1400,1500,1500,為壁厚10mm 的管子。,（2）表2-2、3（中等管徑和大管徑鋼管水力計(jì)算表）管壁厚均采用10mm。使用時(shí)如需精確計(jì)算，應(yīng)根據(jù)所選用的管子壁厚的不同，分別對(duì)表2-2、3 中的1000i 和v 值或?qū)?-4、5 中的A 值加以修正。,

7、1000i 值和A 值的修正系數(shù)K1 采用式（2-1）計(jì)算：,（2-1）,式中dj壁厚10mm 時(shí)管子的計(jì)算內(nèi)徑(m)；,dj選用管子的計(jì)算內(nèi)徑(m)。,修正系數(shù)K1 值，見表2-2。,中等管徑與大管徑的鋼管1000i 值與A 值的修正系數(shù)K1 表2-2,公稱直徑DN (mm) ,壁厚（毫米）,4,5,6,7,8,9,10,11,12,13,14,125,0.61,0.66,0.72,0.78,0.85,0.92,1,1.09,1.18,1.3,1.42,150,0.66,0.7,0.76,0.81,0.88,0.93,1,1.08,1.16,1.25,1.35,175,0.7,0.74,0.

8、79,0.83,0.89,0.94,1,1.06,1.13,1.21,1.29,200,0.73,0.77,0.81,0.85,0.9,0.95,1,1.06,1.12,1.18,1.24,225,0.76,0.79,0.83,0.87,0.91,0.95,1,1.05,1.1,1.15,1.21,250,0.78,0.81,0.86,0.88,0.92,0.96,1,1.04,1.09,1.14,1.19,275,0.8,0.83,0.86,0.89,0.93,0.96,1,1.04,1.08,1.12,1.17,300,0.81,0.84,0.87,0.9,0.93,0.97,1,1.03

9、,1.07,1.11,1.15,325,0.83,0.85,0.88,0.91,0.94,0.97,1,1.03,1.07,1.1,1.14,350,0.84,0.86,0.89,0.92,0.95,0.97,1,1.03,1.06,1.09,1.13,400,-,0.88,0.93,0.93,0.95,0.97,1,1.03,1.05,1.08,1.11,450,-,0.89,0.93,0.93,0.95,0.98,1,1.02,1.05,1.07,1.1,500,-,0.9,0.94,0.94,0.96,0.98,1,1.02,1.04,1.06,1.09,600,-,0.91,0.95,

10、0.95,0.97,0.98,1,1.02,1.04,1.05,1.07,700,-,-,-,-,-,0.98,1,1.02,1.03,1.05,1.06,800,-,-,-,-,-,0.99,1,1.01,1.03,1.04,1.05,900,-,-,-,-,-,0.99,1,1.01,1.02,1.04,1.05,1000,-,-,-,-,-,0.99,1,1.01,1.02,1.03,1.04,1200,-,-,-,-,-,-,1,1.01,1.02,1.03,1.04,1300,-,-,-,-,-,-,1,1.01,1.02,1.02,1.03,1400,-,-,-,-,-,-,1,1

11、.01,1.02,1.02,1.03,1500,-,-,-,-,-,-,1,1.02,1.03,1600,-,-,-,-,-,-,1,1.02,1.03,1800,-,-,-,-,-,-,1,1.02,1.02,2000,-,-,-,-,-,-,1,1.02,1.02,2200,-,-,-,-,-,-,1,1.01,1.02,2400,-,-,-,-,-,-,1,1.01,1.02,2600,-,-,-,-,-,-,1,1.01,1.02,平均水流速度v 的修正系數(shù)K2 采用下式計(jì)算：, （2-2）,修正系數(shù)K2 值，見表2-3。,中等管徑與大管徑鋼管v 值修正系數(shù)K2 表2-3,公稱直徑DN

12、 (mm) ,壁厚（毫米）,4,5,6,7,8,9,10,11,12,13,14,125,0.83,0.86,0.88,0.91,0.94,0.97,1,1.03,1.07,1.1,1.14,150,0.85,0.88,0.9,0.92,0.95,0.97,1,1.03,1.05,1.09,1.12,175,0.87,0.89,0.91,0.93,0.96,0.98,1,1.02,1.05,1.07,1.1,200,0.89,0.91,0.92,0.94,0.97,0.98,1,1.02,1.04,1.06,1.09,225,0.9,0.92,0.93,0.95,0.97,0.98,1,1.0

13、2,1.04,1.05,1.08,250,0.91,0.93,0.94,0.95,0.97,0.98,1,1.02,1.03,1.05,1.07,275,0.92,0.93,0.94,0.96,0.97,0.99,1,1.01,1.03,1.04,1.06,300,0.93,0.94,0.95,0.96,0.97,0.99,1,1.01,1.03,1.04,1.05,325,0.93,0.94,0.95,0.96,0.98,0.99,1,1.01,1.02,1.04,1.05,350,0.94,0.95,0.96,0.97,0.98,0.99,1,1.01,1.02,1.03,1.04,400

14、,-,0.95,0.96,0.97,0.98,0.99,1,1.01,1.02,1.03,1.04,450,-,0.96,0.97,0.97,0.98,0.99,1,1.01,1.02,1.03,1.03,500,-,0.96,0.97,0.98,0.98,0.99,1,1.01,1.01,1.03,1.03,600,-,0.97,0.97,0.98,0.99,0.99,1,1.01,1.01,1.02,1.03,700,-,-,-,-,-,0.99,1,1.01,1.01,1.02,1.02,800,-,-,-,-,-,1,1,1,1.01,1.01,1.02,900,-,-,-,-,-,1

15、,1,1,1.01,1.01,1.02,1000,-,-,-,-,-,1,1,1,1.01,1.01,1.02,1200,-,-,-,-,-,-,1,1,1.01,1.01,1.02,1300,-,-,-,-,-,-,1,1,1.01,1.01,1.02,1400,-,-,-,-,-,-,1,1,1.01,1.01,1.01,1500,-,-,-,-,-,-,1,1.01,1.01,1600,-,-,-,-,-,-,1,1.01,1.01,1800,-,-,-,-,-,-,1,1.01,1.01,2000,-,-,-,-,-,-,1,1.01,1.01,2200,-,-,-,-,-,-,1,1

16、.005,1.007,2400,-,-,-,-,-,-,1,1.005,1.0067,2600,-,-,-,-,-,-,1,1.004,1.006,（3）按比阻計(jì)算水頭損失時(shí)，公式（1-7）只適用于平均水流速度v1.2m/s 的情況。當(dāng)v1.2m/s 時(shí)，表24、5 中的比阻A 值，應(yīng)乘以修正系數(shù)K3。K3 可按式（2-3）計(jì)算：, （2-3）,鋼管的比阻A 值 表2-4,水煤氣管,中等管徑,大管徑,公稱直徑,A ,A ,公稱直徑,A ,公稱直徑,A ,DN （mm） ,（Qm 3/s） ,（QL/s） ,DN （mm） ,（Qm 3/s） ,DN （mm） ,（Qm 3/s） ,8,2255

17、00000,225.5,125,106.2,400,0.2062,10,32950000,32.95,150,44.95,450,0.1089,15,8809000,8.809,175,18.96,500,0.06222,20,1643000,1.643,200,9.273,600,0.02384,25,436700,0.4367,225,4.822,700,0.0115,32,93860,0.09386,250,2.583,800,0.005665,40,44530,0.04453,275,1.535,900,0.003034,50,11080,0.01108,300,0.9392,1000

18、,0.001736,70,2893,0.002893,325,0.6088,1200,0.0006605,80,1168,0.001168,350,0.4078,1300,0.0004322,100,267.4,0.0002674,1400,0.0002918,125,86.23,0.00008623,1500,0.0002024,150,33.95,0.00003395,1600,0.0001438,1800,0.00007702,2000,0.00004406,0.00002659,0.00001677,0.00001097,鑄鐵管的比阻A 值 表25,內(nèi)徑（mm）,A（Qm 3/s）,內(nèi)

19、徑（mm）,A（Qm3/s）,50,15190,500,0.06839,75,1709,600,0.02602,100,365.3,700,0.0115,125,110.8,800,0.005665,150,41.85,900,0.003034,200,9.029,1000,0.001736,250,2.752,1100,0.001048,300,1.025,1200,0.0006605,350,0.4529,1300,0.0004322,400,0.2232,1400,0.0002918,450,0.1195,1500,0.0002024,修正系數(shù)K3 值，見表26。,鋼管和鑄鐵管A 值的修

20、正系數(shù)K3 表2-6,v(m/s) ,0.2,0.25,0.3,0.35,0.4,0.45,0.5,0.55,0.6,0.65,0.7,0.75,0.8,0.85,0.9,1,1.1,1.2 K3 ,1.41,1.33,1.28,1.24,1.2,1.175,1.15,1.13,1.115,1.1,1.085,1.07,1.06,1.05,1.04,1.03,1.015,1（4）鋼管（水煤氣管）的1000i 和v 值，鋼管DN=1252000mm 的1000i 和v 值，鑄鐵管DN=501500mm 的1000i 和v 值見水力計(jì)算表；表中v 為平均水流速度（m/s）。,3 計(jì)算示例:,【例】當(dāng)流量Q=14L/s=0.014m3/s 時(shí)，求管長l=3500m，外徑壁厚=194mm6mm 的鋼管的水頭損失。,【解】由表2-1 中查得外徑D194mm 的鋼管公稱直徑為DN=175mm，又由表8 中