矩形螺纹的螺旋密封计算
矩形螺纹的螺旋密封计算
|
矩形螺纹的螺旋密封计算 |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
|||||||||||
|
表1 |
|||||||||||
|
项 目 |
符号 |
计 算 公 式 |
说 明 |
||||||||
|
螺纹导程/mm |
S |
S＝πdtanα |
d—— 密封轴径，m α—— 螺旋角，(°) w—— 螺纹槽形状比 u—— 相对螺纹槽宽，mm υ—— 相对螺纹槽深，mm c—— 密封间隙，mm μ—— 密封液动力粘度，Pa·s ω—— 轴的角速度，s-1
n—— 轴的转速，r/min Δ p—— 密封压差，MPa Δ p＝p1-p2 p1—— 密封腔压力，MPa p2—— 密封腔外部压力，或大气压力，MPa U—— 密封轴线速度，m/s λ—— 密封油导热系数，W/(m·℃) ρ—— 密封油密封，kg/m3 |
||||||||
|
螺纹槽深/mm |
h |
h＝(υ-1)c |
|||||||||
|
螺纹头数 |
i |
|
|||||||||
|
螺纹槽宽/mm |
a |
|
|||||||||
|
螺纹齿宽/mm |
b |
|
|||||||||
|
螺纹槽形状比 |
w |
|
|||||||||
|
密封系数 |
CΔp |
或查表2，得出1/CΔp |
|||||||||
|
单位压差的浸油长度 /mm·MPa-1 |
l/Δp |
|
|||||||||
|
密封螺纹浸油长度/mm |
l |
|
|||||||||
|
螺纹结构长度/mm |
L |
L＝l+a |
|||||||||
|
功率消耗系数 |
CP |
或查表3 |
|||||||||
|
消耗功率/kW |
P |
|
|||||||||
|
螺纹工作温度/℃ |
T |
|
|||||||||
|
雷诺数 |
Re |
|
|||||||||
|
临界雷诺数 |
Rec |
|
|||||||||
|
表2 密封系数CΔp与螺旋参数(tanα、u、v)的关系 |
|||||||||||
|
v |
α tanα u |
2°33′ |
3°17′ |
4°22′ |
5°6′ |
6°32′ |
8°41′ |
10°7′ |
15°39′ |
19°37′ |
21°17′ |
|
0.04456 |
0.0573 |
0.07639 |
0.08913 |
0.1146 |
0.1528 |
0 .1783 |
0.2801 |
0.3565 |
0.5157 |
||
|
2 |
0.5 |
103.1 |
80.44 |
60.73 |
52.32 |
41.22 |
31.99 |
27.70 |
19.56 |
16.95 |
14.83 |
|
0.7 |
122.7 |
95.69 |
72.19 |
62.17 |
48.91 |
37.52 |
32. 74 |
22.91 |
19.70 |
16.97 |
|
|
0.8 |
106.7 |
125.5 |
94.59 |
81.40 |
63.95 |
48.91 |
42.58 |
29.46 |
25.03 |
21.14 |
|
|
0.9 |
285.9 |
222.7 |
174.2 |
144.2 |
111.6 |
86.11 |
74.73 |
50.85 |
42.64 |
34.78 |
|
|
3 |
0.5 |
46.21 |
37.11 |
28.34 |
24.65 |
19.85 |
15.90 |
14.34 |
11.64 |
11.20 |
11.80 |
|
0.7 |
56.20 |
44.04 |
33.55 |
29.12 |
23.35 |
18.53 |
16.63 |
13.16 |
12.45 |
12.77 |
|
|
0.8 |
73.55 |
57.57 |
43.72 |
37.86 |
30.18 |
23.72 |
21.10 |
16.14 |
14.89 |
14.07 |
|
|
0.9 |
130.3 |
101.8 |
76.96 |
66.40 |
52.49 |
40.62 |
35.70 |
25.85 |
22.87 |
20.87 |
|
|
4 |
0.5 |
30.39 |
24.92 |
19.44 |
17.19 |
14.38 |
12.28 |
11.58 |
11.10 |
11.77 |
14 .15 |
|
0.7 |
37.20 |
29.44 |
22.84 |
20.11 |
16.66 |
14.01 |
13.08 |
12.09 |
12.58 |
14.79 |
|
|
0.8 |
48.53 |
38.26 |
29.41 |
25.81 |
21.12 |
17.38 |
15.99 |
14.03 |
14.18 |
16.03 |
|
|
0.9 |
85.53 |
67.08 |
51.15 |
44.42 |
35.67 |
28.41 |
25.52 |
20.37 |
19.38 |
20.07 |
|
|
6 |
0.5 |
19.99 |
16.54 |
13.87 |
12.92 |
12 .03 |
11.95 |
12.32 |
15.14 |
17.87 |
22 .18 |
|
0.7 |
24.18 |
19.22 |
15.88 |
14.65 |
13.39 |
12.98 |
13.20 |
15.73 |
18.35 |
24.52 |
|
|
0.8 |
30.15 |
24.45 |
19.82 |
18.03 |
16.03 |
14.98 |
14.93 |
16.88 |
19.30 |
25.26 |
|
|
0.9 |
51.12 |
41.55 |
32.68 |
29.08 |
24.66 |
21.52 |
20.59 |
20.64 |
22.39 |
27.66 |
|
|
8 |
0.5 |
16.13 |
14.21 |
13.16 |
22.98 |
13.43 |
14.99 |
16.33 |
22.65 |
27.83 |
39.05 |
|
0.7 |
18.53 |
16.12 |
14.55 |
14.21 |
14.39 |
15.72 |
16. 96 |
23.07 |
28.18 |
39.32 |
|
|
0.8 |
23.37 |
19.85 |
17.36 |
16.62 |
16.27 |
17.15 |
18.19 |
23.89 |
28.85 |
39.84 |
|
|
0.9 |
39.01 |
32.03 |
26.52 |
24.49 |
22.43 |
21.81 |
22.22 |
26.57 |
31.05 |
41.55 |
|
|
10 |
0.5 |
14.95 |
14.15 |
14.34 |
14.92 |
16.65 |
19.94 |
22.37 |
32.8 |
40.98 |
|
|
0.7 |
16.85 |
15.63 |
15.45 |
15.88 |
17.40 |
20.51 |
22.86 |
33.13 |
41.25 |
|
|
|
0.8 |
20.58 |
18.53 |
17.63 |
17.75 |
18.87 |
21.62 |
23.81 |
33.77 |
41.77 |
|
|
|
0.9 |
32.73 |
28.00 |
24.75 |
23.87 |
23.64 |
25.24 |
26.94 |
35.85 |
43.48 |
|
|
|
12 |
0.5 |
15.18 |
15.37 |
16.78 |
18.11 |
21.21 |
26.43 |
30.10 |
45.37 |
55.43 |
|
|
0.7 |
16.73 |
16.58 |
17.70 |
18.89 |
21.82 |
26.89 |
30.50 |
45.64 |
55.91 |
|
|
|
0.8 |
19.78 |
18.95 |
19.48 |
20.42 |
23.02 |
27.80 |
31.28 |
46.16 |
57.77 |
|
|
|
0.9 |
29.70 |
26.69 |
25.30 |
25.42 |
26.93 |
30.76 |
33.84 |
47.87 |
59.17 |
|
|
|
14 |
0.5 |
16.32 |
17.48 |
20.15 |
22.29 |
26.90 |
34.30 |
39.40 |
60.29 |
76.14 |
|
|
0.7 |
17.64 |
18.50 |
20.94 |
22.95 |
27.42 |
34.69 |
39.74 |
60.51 |
76.38 |
|
|
|
0.8 |
20.21 |
20.51 |
22.45 |
24.24 |
28.43 |
35.46 |
40.40 |
60.95 |
76.74 |
|
|
|
0.9 |
28.59 |
27.06 |
27.37 |
28.47 |
31.74 |
37.97 |
42.57 |
62.39 |
77.92 |
|
|
|
注：表中的α是按α＝arctant求得的近似值(以下类推)。 |
|||||||||||
|
表3 功率消耗系数CP |
|||||||||||
|
v |
α tanα u |
2°33′ |
3°17′ |
4°22′ |
5°6′ |
6°32′ |
8°41′ |
10°7′ |
15°39′ |
19°37′ |
27°17′ |
|
0.04456 |
0.05730 |
0.07639 |
0.08913 |
0.1146 |
0.1528 |
0.1783 |
0.2801 |
0.3565 |
0.5157 |
||
|
2 |
0.5 |
0.7508 |
0.7514 |
0.7524 |
0.7533 |
0.7554 |
0.7593 |
0.7624 |
0.7776 |
0.7906 |
0.8171 |
|
0.7 |
0.6509 |
0.6515 |
0.6527 |
0.6536 |
0.6559 |
0.6603 |
0.6638 |
0.6809 |
0.6958 |
0.7268 |
|
|
0.8 |
0.6008 |
0.6013 |
0.6023 |
0.6031 |
0.6051 |
0.6088 |
0.6118 |
0.6269 |
0.6402 |
0.6690 |
|
|
0.9 |
0.5505 |
0.5508 |
0.5514 |
0.5519 |
0.5532 |
0.5556 |
0.5575 |
0.5672 |
0.5762 |
0.5964 |
|
|
3 |
0.5 |
0.6700 |
0.6720 |
0.6757 |
0.6787 |
0.6857 |
0.6981 |
0.7149 |
0.7448 |
0.7698 |
0.8082 |
|
0.7 |
0.5368 |
0.5391 |
0.5436 |
0.5469 |
0.5530 |
0.5698 |
0.5808 |
0.6276 |
0.6602 |
0.7122 |
|
|
0.8 |
0.4697 |
0.4717 |
0.4755 |
0.4785 |
0.4858 |
0.4991 |
0.5092 |
0.5540 |
0.5871 |
0.6435 |
|
|
0.9 |
0.4019 |
0.4032 |
0.4056 |
0.4076 |
0.4123 |
0.4211 |
0.4281 |
0.4610 |
0.4878 |
0.5392 |
|
|
4 |
0.5 |
0.6316 |
0.6357 |
0.6432 |
0.6491 |
0.6620 |
0.6828 |
0.6965 |
0.7422 |
0.755 6 |
0.7942 |
|
0.7 |
0.4827 |
0.4875 |
0.4966 |
0.5038 |
0.5193 |
0.5453 |
0.5629 |
0.6243 |
0.6575 |
0.6997 |
|
|
0.8 |
0.4067 |
0.6410 |
0.4190 |
0.4254 |
0.4398 |
0.4645 |
0.4815 |
0.5466 |
0.5846 |
0.6325 |
|
|
0.9 |
0.3293 |
0.3320 |
0.3370 |
0.3415 |
0.3515 |
0.3693 |
0.3826 |
0.4384 |
0.4766 |
0.5368 |
|
|
6 |
0.5 |
0.6002 |
0.6095 |
0.6250 |
0.6355 |
0.6554 |
0.6797 |
0.6929 |
0.7234 |
0.7343 |
0.7450 |
|
0.7 |
0.4368 |
0.4482 |
0.4675 |
0.4810 |
0.5072 |
0.5411 |
0.5594 |
0.6049 |
0.6220 |
0.6625 |
|
|
0.8 |
0.3511 |
0.3616 |
0.3798 |
0.3929 |
0.4196 |
0.4564 |
0.4774 |
0.5336 |
0.5562 |
0.5797 |
|
|
0.9 |
0.2616 |
0.2687 |
0.2817 |
0.2916 |
0.3130 |
0.3463 |
0.3675 |
0.4341 |
0.4661 |
0.5030 |
|
|
8 |
0.5 |
0.5916 |
0.6050 |
0.6239 |
0.6349 |
0.6525 |
0.6699 |
0.6776 |
0.6928 |
0.697 5 |
0.7017 |
|
0.7 |
0.4228 |
0.4399 |
0.4649 |
0.4799 |
0.5049 |
0.5308 |
0.5425 |
0.5660 |
0.5740 |
0.5808 |
|
|
0.8 |
0.3321 |
0.3486 |
0.3741 |
0.3903 |
0.4186 |
0.4501 |
0.4651 |
0.4976 |
0.5081 |
0.5180 |
|
|
0.9 |
0.2341 |
0.2464 |
0.2659 |
0.2814 |
0.3093 |
0.3405 |
0.3645 |
0.4128 |
0.4300 |
0.4476 |
|
|
10 |
0.5 |
0.5903 |
0.6048 |
0.6221 |
0.6308 |
0.6431 |
0.6537 |
0.6578 |
0.6655 |
0.6677 |
|
|
0.7 |
0.4200 |
0.4394 |
0.4636 |
0.4760 |
0.4946 |
0.5110 |
0.5176 |
0.5300 |
0.5336 |
|
|
|
0.8 |
0.3268 |
0.3469 |
0.3737 |
0.3885 |
0.4114 |
0.4329 |
0.4419 |
0.4594 |
0.4646 |
|
|
|
0.9 |
0.2231 |
0.2398 |
0.2651 |
0.2808 |
0.3079 |
0.3373 |
0.3510 |
0.3801 |
0.3895 |
|
|
|
12 |
0.5 |
0.5902 |
0.6033 |
0.6169 |
0.6230 |
0.6310 |
0.6372 |
0.6391 |
0.6437 |
0.6448 |
|
|
0.7 |
0.4198 |
0.4382 |
0.4581 |
0.4674 |
0.4797 |
0.4897 |
0.4935 |
0.5002 |
0.5020 |
|
|
|
0.8 |
0.3262 |
0.3466 |
0.3703 |
0.3820 |
0.3982 |
0.4119 |
0.4173 |
0.4270 |
0.4297 |
|
|
|
0.9 |
0.2195 |
0.2388 |
0.2647 |
0.2792 |
0.3014 |
0.3226 |
0.3316 |
0.3489 |
0.3541 |
|
|
|
14 |
0.5 |
0.5890 |
0.5997 |
0.6696 |
0.6137 |
0.6188 |
0.6226 |
0.6240 |
0.6264 |
0.6270 |
|
|
0.7 |
0.4190 |
0.4346 |
0.4496 |
0.4561 |
0.4642 |
0.4703 |
0.4725 |
0.4764 |
0.4775 |
|
|
|
0.8 |
0.3259 |
0.3443 |
0.3633 |
0.3718 |
0.3829 |
0.3916 |
0.3948 |
0.4005 |
0.4021 |
|
|
|
0.9 |
0.2189 |
0.2386 |
0.2623 |
0.2742 |
0.2911 |
0.3056 |
0.3114 |
0.3216 |
0.3249 |
|
|
|
例 一台离心泵，转速n＝1450r/min，密封腔压力p1＝0.2MPa，密封轴径d＝130mm(0.13m，即螺纹直径)，输送介质为原油，温度T1＝40℃，黏度μ＝0.02041Pa·s，热导率λ＝0.1373W/(m·℃)，密度ρ＝855kg/m3。 (1) 确定螺纹导程S 考虑加工方便，确定采用矩形螺纹槽螺旋密封。根据表螺旋密封设计要点选用螺旋角α＝15°39′(tanα＝0.2801)，并根据已知条件计算螺纹导程： S＝πdtanα＝3.1416×130×0.2801＝114.4(mm) (2) 相对螺纹槽深v 根据表螺旋密封设计要点，取v＝4。 (3) 螺纹槽深h 根据表螺旋密封设计要点，取密封间隙c＝0.2mm，则螺纹深度： h＝(v-1)c＝(4-1)×0.2＝0.6(mm) (4) 计算螺纹槽宽a、齿宽b 根据表螺旋密封设计要点，选用相对螺纹槽宽u＝0.5，螺纹头数i＝４。为了缩短螺纹浸油长度，现取i＝6，则
(5) 核算螺纹槽形状比w
w＞4，符合要求。 (6) 计算密封系数CΔp
或查表2，得1/CΔp＝11.1。 (7) 计算单位压差的浸油长度l/Δp
(8) 密封螺纹浸油长度l 密封腔外的压力为大气压，即p2＝０，所以密封压差Δp＝p1－p2＝0.2-0＝0.2MPa，则密封螺纹浸油长度 l＝(l/Δp)×Δp＝367.5×0.2＝73.5(mm) (9) 螺纹结构长度L L＝l1+a＝73.5+9.53＝83.03(mm) 取螺纹结构长度L＝90mm。 (10) 核算螺纹头数
现取i＝6，符合要求。 (11) 功率消耗系数CP
(12) 消耗功率P
(13) 螺旋密封工作温度T 密封轴的圆周速度
(14) 流态判别 螺纹段流体的雷诺数
螺纹段流体由层流转向紊流的平均雷诺数：
因Re＜Rec，所以螺纹段流体处于层流工况，说明上述计算均适用。 |
|||||||||||
