流体力学 课后习题部分1~4章

1、流体力学课后部分答案2.14密闭容器，压力表的示值为4900n/m2，压力表中心比a点高0.4m，a点在水下1.5m，求水面压强。解： （kpa）相对压强为：kpa。绝对压强为：kpa。答：水面相对压强为kpa，绝对压强为kpa。2.16 盛满水的容器，顶口装有活塞a，直径d=0.4m,容器底的直径d=1.0m,高h=1.8m,如活塞上加力2520n（包括活塞自重），求容器底的压强和总压力。2.17用多管水银测压计测压，图中标高的单位为m，试求水面的压强。解： （kpa）答：水面的压强kpa。2.24矩形平板闸门，一侧挡水，已知长=2m，宽=1m，形心点水深=2m，倾角=，闸门上缘处设有转轴，

2、忽略闸门自重及门轴摩擦力，试求开启闸门所需拉力。解：（1）解析法。（kn）（m）对a点取矩，当开启闸门时，拉力满足：（kn）当kn时，可以开启闸门。（2）图解法。压强分布如图所示：（kpa）（kpa）（kn）对a点取矩，有 （kn）答：开启闸门所需拉力kn。2.25矩形闸门高=3m，宽=2m，上游水深=6m，下游水深=4.5m，试求：（1）作用在闸门上的静水总压力；（2）压力中心的位置。解：（1）图解法。压强分布如图所示： （kpa）（kn）合力作用位置：在闸门的几何中心，即距地面处。（2）解析法。（kn）（m）（kn）（m）合力：（kn）合力作用位置（对闸门与渠底接触点取矩）：（m）答：（1

3、）作用在闸门上的静水总压力kn；（2）压力中心的位置在闸门的几何中心，即距地面处。2。33密闭盛水容器，水深=60cm，=100cm，水银测压计读值=25cm，试求半径=0.5m的半球形盖所受总压力的水平分力和铅垂分力。解：（1）确定水面压强。（kpa）（2）计算水平分量。（kn）（3）计算铅垂分力。（kn）答：半球形盖所受总压力的水平分力为kn，铅垂分力为kn。2.34球形密闭容器内部充满水，已知测压管水面标高=8.5m，球外自由水面标高=3.5m，球直径=2m，球壁重量不计，试求：（1）作用于半球连接螺栓上的总压力；（2）作用于垂直柱上的水平力和竖向力。解：（1）取上半球为研究对象，受力如

4、图所示。（kn）（kn）（2）取下半球为研究对象，受力如图。（kn）答：（1）作用于半球连接螺栓上的总压力为kn；（2）作用于垂直柱上的水平力和竖向力。acknowledgements my deepest gratitude goes first and foremost to professor aaa , my supervisor, for her constant encouragement and guidance. she has walked me through all the stages of the writing of this thesis. without her

5、 consistent and illuminating instruction, this thesis could not havereached its present form. second, i would like to express my heartfelt gratitude to professor aaa, who led me into the world of translation. i am also greatly indebted to the professors and teachers at the department of english: pro

6、fessor dddd, professor ssss, who have instructed and helped me a lot in the past two years. last my thanks would go to my beloved family for their loving considerations and great confidence in me all through these years. i also owe my sincere gratitude to my friends and my fellow classmates who gave

7、 me their help and time in listening to me and helping me work out my problems during the difficult course of the thesis. my deepest gratitude goes first and foremost to professor aaa , my supervisor, for her constant encouragement and guidance. she has walked me through all the stages of the writin

8、g of this thesis. without her consistent and illuminating instruction, this thesis could not havereached its present form. second, i would like to express my heartfelt gratitude to professor aaa, who led me into the world of translation. i am also greatly indebted to the professors and teachers at t

9、he department of english: professor dddd, professor ssss, who have instructed and helped me a lot in the past two years. last my thanks would go to my beloved family for their loving considerations and great confidence in me all through these years. i also owe my sincere gratitude to my friends and my fello