工程流体力学英文试题

英文习题

1. A pump delivers water against a head of l5m of water.It also raises the water from a reservoir to the pump against a suction head equal to 250mm of mercury. Convert these heads into N/m2and find the total head against which the pump works in N/m2and in metres of water.

(147kN/m2, 33.4kN/m2, 180.4kN/m2, 18.4m) 2.Two cylinders with pistons are connected by a pipe containing water. Their diameters are 75mm and 600mm and the face of the smaller piston is 6m above the larger. What force on the smaller piston is required to maintain a load of 3500kg on the larger piston?

(276N)

3.What is the atmospheric pressure in N/m2 if the barometer reading is 750mm of mercury? What would be the height of the column of water required to produce this pressure? (105N/m2, 10.2m)

4.At the foot of a mountain a mercury barometer reads 740mm and a similar barometer at the top of the mountain reads 590mm. What is the approximate height of the mountain, assuming that the density of air is constant and equal to 1.225kg/m3? (1670m)

5.In Fig. 1 fluid A is water and fluid B is mercury (sp. gr.13. 6). What Will be the difference in level h. if the pressure at X is 140kN/mz and a= 1.5m?

6.In Fig. 1. fluid A is oil (sp.gr. 0.8) , flaid B is brine (sp. gr.1.25). If a=2. 5 m and h=0.3m what are (a) the pressure head, and (b)the pressure in N/m2at X? (-2.03m of oil, -15.9kN/m2 gaug)

7. Assuming that the atmospheric pressure is 101.3kN/m2 find the absolute pressure at X in Fig.2-2 when(a) Fluid A is water, fluid B is mercury (sp.gr.13.6),a=lm and h=0.4,(b) Fluid A is oil (sp. gr.0.82), fluid B is brine (sp.gr.1.10), a=20cm and h=55cm.

((a)38.2kN/m2, (b)93.8kN/m2)

8.An oil and mercury manometer consists of a U-tube 5mm diam with both limbs vertical. The right-hand limb is enlarged at its upper end to 25mm diam. The enlarged end contains oil with its free surface in the enlarged portion and the surface of separation between mercury and oil is below the enlarged end. The left-hand limb contains mercury only, its upper end being open to the atmosphere. The right-hand side is connected to a vessel containing gas under pressure and the surface of separation is observed to fall 2cm. Calculate the pressure of the gas in N/m2 if the specific gravity of mercury and oil are 13.6 and 0.85 respectively. The surface of the oil remains in the enlarged ends.

(0.00517N/m2)

9. In Fig.3 fluid A is water and fluid B is mercury(sp.gr.1.36).If the pressure difference between M and N is 35kN/m2, a=lm and b=30cm,what is the difference of level h?

(30.7cm)

10. In Fig.3 fluid A is oil (sp.gr.0.85)and fluid B is water.If a=120cm, b=60cm and h=45cm, what is the difference of pressure in kN/m2 between M and N?

(-5.23kN/m2)

11. In Fig.4 fluid A is water and fluid B is oil (sp.gr.0.9). If h is 69cm and z is 23cm, what is the difference of pressure in kN/m2 between M and N?

(-1.57kN/m2)

12. A

mercury U-tube manometer is used to measure the pressure above atmospheric of water in a pipe, the water being in contact with the mercury in the left-hand limb.(a) Sketch the arrangement and explain its action. (b) If the mercury is 30cm below A(Fig. 5) in the left-hand limb and 20cm above A in the right-hand limb, what is the gauge pressure at A? Specific gravity of mercury =13.6.

13. A U-tube manometer (Fig.6) measures the pressure difference between two points A and

B in a liquid of specific weight w1. The U-tube contains mercury of specific weight w2. Calculate the difference in pressure if a=l.5m b=0.75m and h=0.5m, if the liquid at A and B