底栏栅坝水力学计算

1、无压廊道进入廊道的流量按如公式计算：其中：Q为进入廊道的流量，m3/s；p为栏栅间隙系数，表示栏栅间隙占栏栅总面积的百分比，p=s/（s+t），s为栏栅间隙，t为栅条宽度；l为栏栅垂直水流方向上的宽度，m；b为栏栅的水平投影长度，m；hcp为栏栅上的平均水深，m，hcp=（h1+h2），h1和h2分别为底栏栅的上下游边缘水深，h1比相应的临界水深小10%，h2比相应的临界水深小27%，因此hcp如式；u为流量系数，u0为栅条水平时的流量系数，当栅高h与栅隙宽度s比大于4时取u0=0.60.65，小于4时u0=0.5，当栅条倾斜时（i=0.10.2），u=u0-0.1i；当栅顶水流全部进入廊道时

2、，h2=0；则进入廊道的流量如公式：由于栅条间隙可能被堵塞，因此实际采用面积比计算面积大20%30%。底栏栅坝特性表Qlb s(mm)t(mm)h(mm)h/siu0515.51.510153030.10.5水流全部引用时流量计算Qqlbpu5.055813 0.424036 11.923081.50.40.49水流部分引用时流量计算Q上Q引计算Q实际Q下泄lbpuhk155.0237835011.923081.50.40.490.261717通过试算下泄流量使此两个流量相等有压廊道2cpQpblghm=28.0kkcphhh +=0.8kQpblghm =23 q k gh =3/22.66

3、()qpbm=hk20其中：Q为进入廊道的流量，m3/s；p为栏栅间隙系数，表示栏栅间隙占栏栅总面积的百分比，p=s/（s+t），s为栏栅间隙，t为栅条宽度；l为栏栅垂直水流方向上的宽度，m；b为栏栅的水平投影长度，m；hcp为栏栅上的平均水深，m，hcp=（h1+h2），h1和h2分别为底栏栅的上下游边缘水深，h1比相应的临界水深小10%，h2比相应的临界水深小27%，因此hcp如式；u为流量系数，u0为栅条水平时的流量系数，当栅高h与栅隙宽度s比大于4时取u0=0.60.65，小于4时u0=0.5，当栅条倾斜时（i=0.10.2），u=u0-0.1i；3/22.66()qpbm=无压廊道廊

4、道特性表QbLin首端水深h2分段长度分段流量51.5160.0750.0161.0221.79949610.3125廊道后过渡段特性表廊道后接渠道特性表QbLi0Qbhi51.500.0755.0002741.51.250.0051、廊道内流态判别矩形明渠临界水深计算GLhkpikpiQb临界水深hk临界流速vk21.042388 0.1302990.07551.51.042388 3.1977852、廊道出口断面水深确定（外侧h1、内侧h2）当廊道为缓流时，根据下游渠道水流情况的不同有两种衔接方式：、渠道正常水深小于廊道出口断面临界水深，廊道水流为自由出流。h1=（1.21.3）hkph2

5、h1hkph2v1Fr1.767294 1.302985 1.042388 0.464309 2.558228 1.391963 0.715542、渠道正常水深大于廊道出口断面水深，渠道为缓坡渠道。由于水深差值大小及过渡段长度的不同，可能出现廊道出口受壅水影响和不受壅水影响两种情况，先按受壅水影响计算出廊道出口断面水深，计算方法是以过渡段末端水深为渠道的正常水深，再往上推求廊道出口断面的水深，如果求得的h1（1.21.3）hkp，则认为廊道出口断面不受壅水影响，则取出口断面水深为h1=（1.21.3）hkp，如果过渡段不长，则可以认为壅水曲线近似水平，则h1=h正常-i0L，h正常为渠道的正常

6、水深，i0、L为过渡段的底坡和长度。a、受壅水影响过渡段长L（m）计算得LQi0nbh1h正常VK00.71158250.0750.0161.51.0423881.253.197785h2h1h2v1Fr1.767294 1.302985 0.464309 2.558228 1.391963 0.715542b、不受壅水影响h2h1Lh正常i0h2v1Fr1.7994961.2501.250.0750.549496 2.666667 1.516094 0.7615163、廊道出口断面水头损失计算廊道出口断面有明显的水头损失，用h2表示，其值按局部水头损失计算，见式；式中v1为出口断面流速；为水

7、头损失系数，其值随出口断面水流的佛汝德Fr数变化，Fr0.7时，=2.7（Fr-0.2）4、廊道水面曲线推求（差分法）因廊道内的水流状态与侧槽溢洪道侧槽内的水流情况基本相同，因此其计算方法采用计算侧槽溢洪道侧槽内的水面曲线的计算方法1221211221()()()2 QQzJ sgQQnnnnnn+-D =-+ D+ 距首端距离x(m)底宽b(m)间距s(m)底部高程差z/(m)计算的z值(m)假定水面高程差z(m)水深h(m)过水断面积()流量Q(m3/s)123456789161.51.7992.6992445151.510.0750.0382390.0381.7622.6437444.6

8、875141.510.0750.0373430.0371.7242.5867444.375131.510.0750.0363950.0361.6852.5282444.0625121.510.0750.035380.0351.6452.4682443.75111.510.0750.0342810.0341.6042.4067443.4375101.510.0750.0330750.0331.5622.3437443.12591.510.0750.0317340.0321.5192.2792442.812581.510.0750.030150.031.4742.2117442.571.510.0

9、750.0284180.0281.4272.1412442.187561.510.0750.0264830.0261.3782.0677441.87551.510.0750.0242670.0241.3271.9912441.562541.510.0750.0216690.0221.2741.9117441.2531.510.0750.0185330.0191.2181.8277440.937521.510.0750.0147150.0151.1581.7377440.62511.510.0750.0099420.011.0931.6402440.312501.510.0750.0037070

10、.0041.0221.5337440-11.510.075-0.004570.0350.9821.473744 -0.3125-21.510.075-0.015140.0260.9331.400244-0.625-31.510.075-0.029730.0110.8691.304244 -0.9375-41.510.0750.0055791.0111.8052.708244-1.25-51.510.0750.0038792.0113.7415.612244 -1.5625-61.510.0750.0011853.0116.67710.01624-1.875-71.510.0750.000422

11、4.01110.61315.92024 -2.1875-81.510.0750.000185.01115.54923.32424-2.5-91.510.0758.78E-056.01121.48532.22824 -2.8125-101.510.0754.77E-057.01128.42142.63224-3.125-111.510.0752.81E-058.01136.35754.53624 -3.4375-121.510.0751.76E-059.01145.29367.94024-3.75-131.510.0751.16E-0510.01155.22982.84424 -4.0625-1

12、41.510.0757.98E-0611.01166.16599.24824-4.3751221211221()()()2 QQzJ sgQQnnnnnn+-D =-+ D+ nv0.0162.666813水力半径R糙率n谢才系数c临界底坡ik0.4361730.01654.42809 0.007914VK+1RKRK+1V平KR平Kc平KJ平K2.666667 0.436173 0.46875 2.932226 0.452461 54.7617 0.0063372 1 22 v h gxD=、渠道正常水深大于廊道出口断面水深，渠道为缓坡渠道。由于水深差值大小及过渡段长度的不同，可能出现廊道出

13、口受壅水影响和不受壅水影响两种情况，先按受壅水影响计算出廊道出口断面水深，计算方法是以过渡段末端水深为渠道的正常水深，再往上推求廊道出口断面的水深，如果求得的h1（1.21.3）hkp，则认为廊道出口断面不受壅水影响，则取出口断面水深为h1=（1.21.3）hkp，如果过渡段不长，则可以认为壅水曲线近似水平，则h1=h正常-i0L，h正常为渠道的正常水深，i0、L为过渡段的底坡和长度。因廊道内的水流状态与侧槽溢洪道侧槽内的水流情况基本相同，因此其计算方法采用计算侧槽溢洪道侧槽内的水面曲线的计算方法流速v(m/s)水力半径R（m）V平R平c平J平临界水深hkv1+v2(m/s)(v1+v2)/2

14、g (m/s)1011121314151617181.852370.5293681.0423881.773054 0.526119 1.812712 0.527744 56.18459 0.001972 0.99849 3.625424 0.1847821.691315 0.522681 1.7321840.524456.1251 0.001816 0.953604 3.464369 0.1765731.606846 0.519041 1.649081 0.520861 56.06179 0.001661 0.907636 3.298162 0.1681021.519299 0.515184

15、1.563073 0.517113 55.99435 0.001507 0.860473 3.126145 0.1593351.428278 0.511095 1.4737880.51314 55.92242 0.001354 0.811979 2.947577 0.1502331.333337 0.506756 1.380807 0.508926 55.84562 0.001201 0.76199 2.761615 0.1407551.233962 0.502148 1.283649 0.50445255.7635 0.00105 0.710304 2.567298 0.1308511.13

16、0330.497134 1.182146 0.49964155.6745 0.000902 0.656663 2.364291 0.1205041.021602 0.491676 1.075966 0.494405 55.57683 0.000758 0.600733 2.151932 0.1096810.906785 0.485729 0.964194 0.488702 55.46948 0.000618 0.542064 1.928388 0.0982870.784685 0.479241 0.845735 0.482485 55.35124 0.000484 0.480024 1.691

17、471 0.0862120.653853 0.472153 0.719269 0.475697 55.22068 0.000357 0.413672 1.438538 0.073320.512927 0.464249 0.583390.468201 55.07469 0.00024 0.341479 1.166781 0.0594690.359662 0.455265 0.436295 0.459757 54.90789 0.000137 0.260597 0.872589 0.0444740.190520.444873 0.275091 0.450069 54.71334 5.62E-05

18、0.164166 0.550182 0.02804200.432651 0.095260.438762 54.48181 6.97E-0600.19052 0.009711-0.21204 0.425324 -0.10602 0.428987 54.27762 8.89E-06 0.164166 -0.21204 -0.01081-0.44635 0.415874 -0.32920.420599 54.09927 0.000088 0.260597 -0.6584 -0.03356-0.718810.40267 -0.58258 0.409272 53.85367 0.000286 0.341

19、479 -1.16516 -0.05939-0.46155 0.529886 -0.59018 0.466278 55.03693 0.000247 0.413672 -1.18036 -0.06016-0.27841 0.624763 -0.36998 0.577325 57.03175 7.29E-05 0.480024 -0.73996 -0.03771-0.18720.674268 -0.23280.649516 58.16275 2.47E-05 0.542064 -0.46561 -0.02373-0.13740.700499 -0.16230.687384 58.71466 1.

20、11E-05 0.600733 -0.3246 -0.01654-0.107180.71549 -0.12229 0.707995 59.00448 6.07E-06 0.656663 -0.24459 -0.01247-0.08727 0.724703 -0.09723 0.720096 59.17139 3.75E-06 0.710304 -0.19445 -0.00991-0.07330.730717 -0.080280.72771 59.27521 2.52E-06 0.76199 -0.16057 -0.00818-0.06303 0.734841 -0.06817 0.732779

21、 59.34383 1.8E-06 0.811979 -0.13633 -0.00695-0.05520.737783 -0.05911 0.736312 59.39142 1.35E-06 0.860473 -0.11823 -0.00603-0.04904 0.739952 -0.05212 0.738867 59.42572 1.04E-06 0.907636 -0.10423 -0.00531-0.04408 0.741594 -0.04656 0.740773 59.45123 8.28E-07 0.953604 -0.09312 -0.00475v2-v1(m/s)Q2-Q1(m3/s)Q1+Q2(m3/s)(Q2-Q1)/(Q1+Q2)192021220.0793170.31259.68750.0322580.0817380.31259.06250.0344830.0844690.31258.43750.0370370.0875480.31257.81250.040.091021