105年 - 105 國立嘉義大學_碩士班(乙組)招生考試試題_土木與水資源工程學系：流體力學#145955

1. Water flows through a horizontal branching pipe as shown in Fig.1. Determine the pressure at section (3) (20％)

2. A piston having a cross-sectional area of 0.09 m² is located in a cylinder containing water as shown in Fig. 2. An open U-tube manometer is connected to the cylinder as shown. For h₁= 60 mm and h= 100mm, what is the applied force, P, acting on the piston? The weight of the piston is negligible. (20%)

3. The pressure drop, $\Delta p$, for incompressible turbulent flow in a horizontal round pipe of diameter $D$ can be written in functional form as \[ \Delta p = F(V, D, l, \epsilon, \mu, \rho) \] where $V$ is the average velocity, $l$ is the pipe length, $\epsilon$ is a measure of the roughness of the pipe wall, $\rho$ and $\mu$ are fluid density and viscosity, respectively. Find a non-dimensional relationship for $\Delta p$. (use $\rho, V, D$ as repeating variables) (20%)

4. 如Fig.3所示，有一閘門設置於蓄水池與供水渠道之間。距渠底0.5 m處有一鉸鏈將活動門與閘門接在一起，以方便開門供水。活動門為均質材料製成，寬度為1.5 m，自重為500公斤。水的單位重為每立方米1公噸重。若欲施一垂直力將活動門打開，這個力至少要多少公噸？(20%)
Fig. 3

(1) 試以算式分析流動方向是從水深0.6 m流往水深1.2 m，還是相反。(5%)

(2) 試求水流流過石堆造成之水頭損失。(5%)

(3) 請算出石堆受水流衝擊之合力有多大。(10%)