Fluid Mechanics - Fluid-Flow Measurements Problems

Fluid-Flow Measurements Problems

Fluid Mechanics

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1. A water pressure gauge located 4 ft above a pressure source reads 21 lb per sq in.  The connecting tube is full of liquid. What is the actual pressure at the source?

2. The system of problem 1 is initially full of air at atmospheric pressure. The main line was then filled with water, no air being bled from the gage connecting pipe. What is the pressure in the main line if the gage again indicates 21 lb per sq in.?

3. Air at 70° is being measured by a venturi meter with basic diameters of 14 and 10 in., respectively. Gages attached at points 1 and 2, Fig. 3.11a, read 5.75 and 2.10 in. of water. What quantity of air is flowing?

4. The gage on an orifice meter reads 4 ½ lb per sq in. What is the velocity of water if the inside pipe diameter is 1.25 in. and the sharp-edged orifice is 0.89 in. in diameter? (C = 0.76.)

5. A nozzle meter is to be designed to fit into an 18-in. galvanized pipe. Air at room temperature flows through the pipe at velocities varying from 700 to 1400 ft per min. If a 2-in. inclined manometer containing alcohol with an S.G. of 0.89 is to be used with the nozzle, what should be the diameter of the nozzle?

6. A Thomas meter is located in an air duct of 2 sq ft cross-sectional area. The air weighs 0.083 lb per cu ft, and its specific heat is 0.24. Assume a controlled temperature differential of 5° and heater potential of 110 volts. Plot the velocity as abscissa and amperage as ordinate for velocity 0 to 300 ft per min. Assume constant amperage of 3, and plot temperature difference against velocity. Discuss the curves from the standpoint of accuracy of the system.

7. A differential pitot tube located at the center of a cylindrical air tube produces 2.6 in. of water pressure. What is the velocity at the impact end of the pitot tube? The impact gauge reads 2.6, 2.6, 2.5, 2.1, 1.8 when placed at points 1-5 in Fig. 3.10. What is the average velocity in the tube? What factor would be applied to the center reading to indicate a true average velocity? Note: In actual practice it would be necessary to check this factor through the entire range of velocities to be encountered, because variation may be expected.

8. A pump is moving soybean oil through a 1-in. (nominal) pipe. The 110-volt motor is using 285 watts. Assuming an overall pump and motor efficiency of 65 percent, what is the pumping rate in gallons per minute if the suction and discharge pressures are, respectively, -5 and 23 lb per sq in.?

9. Carbon dioxide is metered into an air conduit which is 12 sq ft in cross-sectional area at a constant rate of 7.0 lb per hour. A sample of the mixture downstream was analyzed by an Orsat apparatus and contained 11½ percent CO2 by volume. What is the air velocity?

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Buy the solutions: PM @ Engineering Daily

Buy the solutions: PM @ Engineering Daily