![]() Solution: Situation: The application is a helium filled balloon of radius r = 1.3 m. When inflated prior to launch, the balloon is spherical (radius 1.3 m) and the inflation pressure equals the local atmospheric pressure. ![]() The balloon is inflated at a site where the atmospheric pressure is 0.89 bar and the temperature is 22☌. Estimate the weight (in Newton’s) of the helium inside the balloon. ![]() As the balloon ascends, the upward force (buoyant force) will need to exceed the total weight. A team is designing a helium-filled balloon that will fly to an altitude of 80,000 ft. What are the values of its density, specific volume, and specific gravity relative to air weighing 12 N/m3? Solution: Solving for ρg: g g g N m g 9.81 2 3 m s kg g 1.63 3 answer m 16 Solving for υg: g g 1 g 1 kg 1.63 3 m Solving for SGg: SGg 0.613 m3 kg answer g a N 3 SGg m 1.33 answer N 12 3 m 16 Fluid Mechanics Lecture Manual 5 Chapter 2: Properties of Fluids Example 2. A certain gas weighs 16 N/m3 at a certain temperature and pressure. Whether the laboratory experiments used to develop this correlation can be accurately compared to the mixing action that occurs in turbulent flow is certainly open to question.įigure 3-12 can be used to estimate the viscosity of a hydrocarbon gas at various conditions of temperature and pressure if the specific gravity of the gas at standard conditions is known.Chapter 2: Properties of Fluids CHAPTER 2 Fluid Properties Example 1. The laboratory data plotted in Figure 3-11 agree closely with a modified Vand’s equation assuming a 70% breakover point. Thus, at approximately 70% water cut, it appears as if oil ceases to be the continuous phase and water For 70% water cut, the emulsion began to break before viscosity readings could be made, and for water cuts greater than this, the oil and water began to separate as soon as the mixing was stopped. Produced oil and water were mixed vigorously by hand, and viscosity was measured for various percentages of water. Figure 3-11 shows some experimental data for a mixture of produced oil and water taken from a south Louisiana field. ![]() When an emulsion of oil and water is formed, the viscosity of the mixture may be substantially higher than either the viscosity of the oil or that of the water taken by themselves. The viscosity of produced water depends on the amount of dissolved solids in water as well as the temperature, but for most practical situations it varies from 1.5 to 2 centipoise at 50☏, 0.7 to 1 centipoise at 100☏, and 0.4 to 0.6 centipoise at 150☏. Figure 3-10 is a graphical representation of another correlation. The data set from which this relationship was obtained included a range of between 16° and 58° API and 70☏ to 295°R It has been the author’s experience that the correlation tends to overstate the viscosity of the crude oil when dealing in temperature ranges below 100 to 150☏. The following equation relating viscosity, gravity, and temperature was developed by Beggs and Robinson after observing 460 oil systems: In the absence of any laboratory data, correlations exist that relate viscosity and temperature, given the oil gravity. ![]()
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