武汉大学水力知识学知识题解答水击.docx

1、武汉大学水力知识学知识题解答水击第十章10-1 解：阀门突然开启过程中，水击波传播四个阶段示意图如下：10-2 解：首先判断水击类型，然后计算各相末水击压强，从中找出最大水击压强。(1) 判断水击类型已知 m，m/s，则相长 s。而阀门关闭时间s，有，为间接水击。(2) 计算首相末水击压强初始全开，有阀门开度；按线性启闭关系，得首相末阀门开度；由于m/s，初始水头m，则管道特性系数 。上述数据代入式(10-4-17) 得 整理 解此二次方程，得 或 m 或 m如果发生直接水击 m而m，故不合理。则首相产生的水击压强增量为 m(水柱高) 或水击压强为 m(水柱高)(3) 计算第二相末水击压强(末

2、相末水击压强)将已知的，代入式(10-4-17) 得 解此方程 或 m(水柱高)则第二相(末相)产生得水击压强为 m(水柱高)如应用式(10-4-20)计算末相水击压强，由于系数 则有 可得水击压强增量 m(水柱高)或水击压强为 m(水柱高) 首相和末相水击压强比较，最大水击压强发生在末相，即为 m(水柱高)或为 m(水柱高)。10-3 解：首先判断水击类型，然后分别计算两种情况下的水击压强。(1) 判断水击类型已知 m，cm，mm，查表10-2-1，由钢管有，可计算水击波速 m/s以及相长s。而阀门关闭时间s，有，为直接水击。由于，阀门关闭结束时水击压强将保持到首相末，故本题所求阀门断面水头

3、为首相末压强水头。(2) 初始开度等，终止开度情况下阀门断面水头已知m，m/s，由于，以及管道特性系数 代入式(10-4-17) 得 整理 解此二次方程，得 (不合理) ， 。可得首相末阀门断面水头 m(水柱高)。(3) 初始开度等，终止开度情况下首相末阀门断面水头此时，代入直接水击压强公式式(10-2-3)或例10-1给出的直接水击压强公式得 m(水柱高)10-4 解：根据题目要求，先对水击类型进行判别，后进行水击压强的计算。(1) 判别水击类型已知 m，m，mm，查表10-2-1，由钢管有，可计算水击波速 m/s以及相长s。当阀门关闭时间s，有，发生直接水击。当关闭时间s，有，则发生间接水

4、击。在设置调压室后，调压室的作用类似于水库，水击波将由调压室而反射，这时管长m，相应的相长s。当阀门关闭时间s，有，则发生间接水击。(2) 管长m时，计算水击压强增量已知流量m3/s，则m/s，水头m，初始开度等，终止开度。当阀门关闭时间s，发生直接水击。则由直接水击压强公式式(10-2-3)，得水击压强增量 m(水柱高)当阀门关闭时间s，发生间接水击。由于，将计算首相末阀门断面水击压强增量，和第二相末(即末相)末水击压强增量。为计算间接水击压强，可令阀门按线性规律启闭，即阀门开度 。在首相末，s，阀门开度，以及管道特性系数 代入式(10-4-17) 得 整理 解此二次方程，得 (不合理) ，

5、 。可得首相末阀门断面压强增量 m(水柱高)。在第二相末，将已知的，代入式(10-4-17) 得 解此方程 或 m(水柱高)最大水击压强增量发生在首相末。(3) 管长m时，计算水击压强增量相应的相长s，当阀门关闭时间s，发生间接水击。由于，将计算首相末、第二相末、第三相末、第四相末阀门断面水击压强增量，从中找出最大水击压强增量。采用例10-3所给的程序进行计算，计算结果如下tttnhnh0.9855 0.6715 0.4495 40.4581.9710 0.3430 0.4714 42.4272.9565 1.4487 0.4639 41.7513.9421 0.0000-4.2282-38.

6、054从计算结果可见，第二相末水击压强增量最大。10-5 解：已知m，mm，可计算水击波速 m/s以及相长s。由于最大水击压强值产生在第一相末，又考虑阀门按线性关闭，则此时阀门开度为。根据题意，可令，其中K为待求系数。由此第一相末的阀门开度为。又根据题给条件，m/s，m，初始开度，可求管道特性系数 并代入式(10-4-17) 得 由于，和题给，则有，代入上式得1解此不等式，得3.64，即阀门关闭时间至少应为相长的3.64倍。10-6 解：本题可使用特征线法进行计算，可采用例10-3所给的程序进行计算，计算结果如下(1) 关闭指数t0L0.2L0.4L0.6L0.8LL开度.000090.089

7、.555789.111488.667188.222887.77851.00000.259290.089.555789.111488.667188.222891.6467.956800.518490.089.555789.111488.667192.075994.7822.913600.777690.089.555789.111492.505295.199698.0647.8704001.036890.089.555792.934595.617198.4702101.4760.8272001.296090.093.364096.034898.8758101.8695105.0463.784000

8、1.555290.096.452599.2815102.2631105.4277108.7569.7408001.814490.095.9082102.6569105.8092109.1261112.6391.6976002.073690.096.2053102.4251109.4955112.9961116.6735.6544002.332890.096.5149103.0426109.6000117.0184120.8927.6112002.592090.096.8355103.6860110.5624117.4837125.2766.5680002.851290.097.1693104.

9、3516111.5643118.8157124.0071.5248003.110490.097.5144105.0442112.6000118.0863123.7999.4816003.369690.097.8733105.7597111.5662117.5868123.3786.4384003.628890.098.2438104.3966110.7502116.8610122.7122.3952003.888090.096.5256103.2387109.6947115.8786121.7814.3520004.147290.094.9996101.8275108.3707114.6187

10、120.5528.3088004.406490.095.3035100.1355106.7554113.0488118.9996.2656004.665690.095.1358100.2330104.8174111.1403117.0849.2224004.924890.094.929999.8180104.6198108.8574114.7726.1792005.184090.094.682599.3173103.8587108.2543112.0208.1360005.443290.094.387798.7237102.9527107.0231112.7560.0928005.702490

11、.094.041598.0236101.8889107.4548112.8002.0496005.961690.093.636097.2070102.5257107.6659112.9935.0064006.220890.093.165698.1381102.9839108.0645108.7584.0000006.480090.094.502098.9424103.6768104.0767103.9403.0000006.739290.095.7762100.0402100.035899.553999.3957.0000006.998490.095.537796.870395.919695.

12、356195.1682.0000007.257690.091.096591.420892.192891.534991.3171.0000007.516890.085.889186.423687.038888.154887.9022.0000007.776090.085.330481.511682.388383.407284.9928.0000008.035290.085.622681.297177.882979.227778.9129.0000008.294490.085.966681.993878.137873.390473.4639.0000008.553690.086.371082.80

13、6877.501472.374767.8690.0000008.812890.086.840281.878677.043971.980071.2856.0000009.072090.085.507681.077476.357475.954576.0904.0000009.331290.084.237879.986979.987480.466580.6227.0000009.590490.084.479783.147184.093884.654384.8419.0000009.849690.088.907088.582987.811788.468188.6853.00000010.108890.

14、094.097393.567092.954691.841892.0938.00000010.368090.094.656898.464597.594396.579194.9980.00000010.627290.094.367198.6821102.0861100.7491101.0638.00000010.886490.094.025497.9888101.8357106.5690106.4991.00000011.145690.093.621997.1794102.4717107.5848112.0731.00000011.404890.093.154098.1047102.9285107

15、.9757108.6705.00000011.664090.094.482798.9029103.6086104.0144103.8790.00000011.923290.095.748399.986299.989499.513299.3590.00000012.182490.095.503096.835695.892995.335495.1480.00000012.441690.091.089691.413592.183791.528991.3124.00000012.700890.085.916386.442387.052088.161687.9102.00000012.960090.08

16、5.355981.559382.422983.434585.0112.00000013.219290.085.643281.338677.944879.273978.9594.00000013.478490.085.982582.028478.190873.471473.5378.00000013.737690.086.385182.834477.555272.455567.9846.00000013.996890.086.851881.911977.099172.068371.3731.00000014.256090.085.526881.116776.425276.016676.1515.

17、00000014.515290.084.265580.040680.033580.507180.6592.00000014.774490.084.514283.181684.120384.674984.8620.00000015.033690.088.913888.590287.820888.474188.6900.00000015.292890.094.070293.548592.941591.835092.0858.00000015.552090.094.631598.417097.559996.552094.9796.00000015.811290.094.346698.6408102.

18、0246100.7031101.0175.00000016.070490.094.009697.9544101.7829106.4883106.4255.000000(2) 关闭指数t0L0.2L0.4L0.6L0.8LL开度.000090.089.555789.111488.667188.222887.77851.00000.259290.089.555789.111488.667188.222894.6442.915466.518490.089.555789.111488.667195.0621100.8436.834665.777690.089.555789.111495.4801101

19、.2392107.2383.7575961.036890.089.555795.8983101.6349107.6123113.7543.6842601.296090.096.3165102.0308107.9865114.1077120.3959.6146561.555290.0102.4269108.3610114.4614120.7300127.0777.5487851.814490.0102.0251114.8154121.0644127.3939133.7995.4866462.073690.0102.3886114.7098127.7104134.0992140.4664.4282

20、392.332890.0102.6830115.2824127.7281140.7514147.0756.3735652.592090.0102.8927115.6992128.3221140.6913153.5259.3226242.851290.0103.0156115.9313128.6608141.0961148.0676.2754153.110490.0103.0384115.9769128.7048136.0432143.0135.2319393.369690.0102.9613115.8120123.3640130.6324136.9661.1921953.628890.0102

21、.7737110.3508117.7454124.2954129.9431.1561833.888090.097.3898104.7083111.2856117.0629122.0056.1239044.147290.091.938898.3268104.0275109.0004113.2181.0953574.406490.090.940591.263696.0444100.1856103.6744.0705434.665690.089.326588.663187.427290.721393.4900.0494624.924890.087.724785.493583.344980.73558

22、2.8038.0321135.184090.086.168982.409878.805375.430171.7832.0184965.443290.084.686679.483374.497669.854570.6554.0086125.702490.083.315376.775970.533769.723469.5359.0024605.961690.082.089774.366172.001870.215169.6431.0000416.220890.081.051177.315574.047271.921571.1368.0000006.480090.085.224880.730377.

23、234374.968574.2038.0000006.739290.089.674585.140481.649679.515578.7997.0000006.998490.089.912690.588487.417985.478884.8263.0000007.257690.090.913092.185994.411792.725692.1564.0000007.516890.092.271794.733897.4890101.0850100.6227.0000007.776090.093.818997.5719101.4040105.3833110.0107.0000008.035290.0

24、95.2987100.4867105.4637110.3282110.1431.0000008.294490.096.6668103.1889109.4097110.2231110.6457.0000008.553690.097.8899105.5894107.9482109.7272110.3030.0000008.812890.098.9224102.6492105.9072108.0283108.8087.0000009.072090.094.760399.2420102.7302104.9892105.7537.0000009.331290.090.324494.844498.3259

25、100.4566101.1701.0000009.590490.090.087189.413792.574694.508895.1606.0000009.849690.089.090287.821385.602487.281687.8491.00000010.108890.087.735985.281582.532978.947079.4048.00000010.368090.086.193182.450478.629174.659070.0477.00000010.627290.084.716079.543274.578869.731369.9139.00000010.886490.083.

26、351176.846070.646669.834269.4149.00000011.145690.082.130374.454872.101570.330269.7545.00000011.404890.081.104077.385874.138172.021771.2454.00000011.664090.085.254480.785577.305175.052974.2887.00000011.923290.089.676885.170681.698379.571178.8599.00000012.182490.089.913290.584387.432985.503484.8525.00000012.441690.090.90