流体静力学方程和应用.ppt

* 1.1.3 APPLICATIONS OF FLUID STATICS 1. Manometers (压差计) 2. Measurement of liquid level 3. Liquid seal of equipment * 1. Manometers (液压计) Figure below shows the simplest form of manometer. Flow direction * Equi-pressure level * Example 2.1. A manometer of the type shown in Fig. 1.33 is used to measure the pressure drop across an orifice (see Fig. 8.18). Liquid A is mercury (density 13,590 kg/m3) and fluid B, flowing through the orifice and filling the manometer leads, is brine (density 1,260 kg/m3). When the pressures at the taps are equal, the level of the mercury in the manometer is 0.9 m below the orifice taps. Under operating conditions, the gauge pressure1 at the upstream tap is 0.14 bar; the pressure at the downstream tap is 250 mm Hg below atmospheric. What is the reading of the manometer in millimeters? * Fig. 1.33 Orifice meter * Solution: * Other type of manometers (absolute pressure ) (gauge) （vacuum） * * * * Differential manometer 微差压差计 △R where If fluid B is a gas * If the height difference of the reservoir can be neglected. * Inclined manometer 斜管压差计 (2.11) * Series manometer * 2. Measurement of liquid level Flash 1-05 * * * * 3. Liquid seal of equipment Flash 1-04 * * * * * 1. A U-tube manometer is being used to measure the height of oil in a tank as shown in the figure. The manometer is filled with mercury (density ρA), and the density of oil is ρ. On the right side of U-tube manometer, oil is also filled above the mercury with height h1. * When the height of oil in the tank is H1, the manometer reads R. Calculate, when the amount of oil in the tank is reduced, the height of oil in the tank becomes (H1-H), calculate the change of reading R. * 2. Pressure drop between two points in a line containing air is 160Pa. Two kinds of U-tube manometer is being used to measure this pressure drop. In the simple U-tube manometer (as shown in fig. a), carbon tetrachloride having a density ρA (1594kg/m3) is filled as a indicating liquid. * In fig. b, t