课程名称︰流体力学
课程性质︰土木系必修
课程教师︰詹益齐
开课学院：工学院
开课系所︰土木系
考试日期（年月日）︰2018/4/24
考试时限（分钟）：10:30~13:00 共150分钟
不得携带计算机 考试期间可上洗手间，同时间最多一个
试题 :
试题说明
1.共四页 (前两页为试题，后两页为附图)
2.请依序回答所有问题
3.各题占分比重标示于[]内
4.请说明各项假设条件并详列解题过程
https://imgur.com/N4OQ52N
https://imgur.com/MNJxDlA
问题1 [5%]
The temperature-dependence of gas viscosity can be approximated by
μ(T) = CT^(3/2)/(T+S)
where μ is the dynamic viscosity, T the absolute temperature, C and S two
empirical constants. For liquids, an exponential model has been proposed
ν(T) = De^(B/T)
where ν is the kinematic viscosity, B and D two empirical parameters.
Determine the dimensions of C and D.
问题2[5%]
Consider the rise of water level in a clean glass tube due to surface tension
as in Fig. 2. If pi denotes the pressure right above the meniscus and pe the
pressure right below the meniscus, find the pressure jump across the surface,
i.e. pi - pe, in terms of the specific weight of water γ, the radius of the
tube R, and the value of the surface tension σ.
问题3[10%]
A suction cup is used to support a plate of weight W as is shown in Fig. 3.
Find W in terms of the acceleration of gravity g, the density of water ρ, the
plate radius R, the cup radius d, and two readings H and h.
问题4[15%]
As shown in Fig.4, a right-angle gate witht negligible mass is free to pivot
about a frictionless hinge at point O. The horizontalportion of the gate
covers a drain pipe of diameter D, which contains air at atmospheric pressure.
Determine the minimum water depth, h, at which the gate will pivot to allow
water to flow into the pipe.
问题5[10%]
A tank of cross-sectional area A is filled with a liquid of specfic weight γ1
as in Fig. 5. Determine the liquid level rises, i.e. Δh, when a cylinder of
specific weight γ2 and volume -V- is floated in the liquid.
问题6[10%]
A cylindrical mass M is connected to a rectangular gate with a width b as
shown in Fig. 6. The gate is to open when the water level h drops below 0.5H.
Determine the required M. Neglect friction at the gate hinge and the pulley.
问题7[10%]
Water is siphoned from the tank through a hose of constant diameter. A small
hole is found in the hose as indicated in Fig. 7. Will water leak out of the
hose or will air leak into the hose? Use the concept of energy line and
hydralic grade line to support your answer.
问题8[15%]
As shown in Fig. 8, water from a large reservoir flows through a siphon of
diameter D and into a tank. It exits from a hole in the bottom of the tank as
a stream of diameter d. The surface of the reservior remains H above the
bottom of the tank. For steady-state conditions, the water depth in the tank,
h, is constant. Determine the depth ratio h/H as a function of the diameter
ratio d/D.
问题9[20%]
Consider flow of a liquid from a large tank as in Fig. 9. A jet of liquid of
diameter d flows from the nozzle with velocity V.
(a)Find the pressure at the middle point of the nozzle exit as indicated in
the figure.
(b)To estimate the time required to empty the tank, derive an equation for the
depth in the tank, H(t).
(c)Calculate the time required to empty the tank if the initial depth is H0.
[试题结束]