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6.2 Water flows through a 2-in.-diameter horizontal pipe at a flow rate of 35 gal/min. The heat transfer to the pipe can be neglected, and frictional forces result in a pressure drop of 10 psi. What is the temperature change of the water?
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6.3 During the test of a centrifugal pump, a Bourdon pressure gage just outside the casing of the 12-in.-diameter suction pipe reads –6 psig (i.e., vacuum). On the 10-in.-diameter discharge pipe, another gage reads 40 psig. The discharge pipe is 5 ft above the suction pipe. The discharge of water through the pump is measured to be 4 ft3/s. Compute the horsepower input of the test pump.
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6.4 Find the change in temperature between stations (1) and (2) in terms of the quantities A1, A3, v1, v3, cv, and θ. The internal energy is given by cvT. The fluid is water and T1 = T3, P1 = P3....
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6.5 The pressurized tank shown has a circular cross section of 6 ft in diameter. Oil is drained through a nozzle 2 in. in diameter in the side of the tank. Assuming that the air pressure is maintained constant, how long does it take to lower the oil surface in the tank by 2 ft? The specific gravity of the oil in the tank is 0.85, and that of mercury is 13.6....
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6.6 Water is discharged from a 1.0-cm-diameter nozzle that is inclined at a 30° angle above the horizontal. If the jet strikes the ground at a horizontal distance of 3.6 m and a vertical distance of 0.6 m from the nozzle as shown, what is the rate of flow in cubic meters per second? What is the total head of the jet? (See equation (6-11b).)...
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6.7 The pump shown in the figure delivers water at 59°F at a rate of 550 gal/min. The inlet pipe has an inside diameter of 5.95 in. and it is 10 ft long. The inlet pipe is submerged 6 ft into the water and is vertical. Estimate the pressure inside the pipe at the pump inlet....
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6.8 In order to maneuver a large ship while docking, pumps are used to issue a jet of water perpendicular to the bow of the ship as shown in the figure. The pump inlet is located far enough away from the outlet that the inlet and outlet do not interact. The inlet is also vertical so that the net thrust of the jets on the ship is independent of the inlet velocity and pressure. Determine the pump horsepower required per pound of thrust. Assume that the inlet and outlet are at the same depth. Which will produce more thrust per horsepower: a low-volume, high-pressure pump, or a high-volume, low-pressure pump?......
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6.9 An “air cushion” vehicle is designed to traverse terrain while floating on a cushion of air. Air, supplied by a compressor, escapes through the clearing between the ground and the skirt of the vehicle. If the skirt has a rectangular shape 3 9 m, the vehicle mass is 8100 kg and the ground clearance is 3 cm, determine the airflow rate needed to maintain the cushion and the power given by the compressor to the air. Assume that the air speeds within the cushion are very low....
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6.10 Residential wateruse, exclusive of fire protection, runs about 80 gallons per person per day. If the water is delivered to a residence at 60 psig, estimate the monthly energy required to pump the water from atmospheric pressure to the delivery pressure. Neglect line losses and elevation changes. Assume the pumps are 75% efficient and are driven by electric motors with 90% efficiency.
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6.11 A 1968 Volkswagen sedan is driving over a 7300-ft-high mountain pass at a speed of v m/s into a headwind of W m/s. Compute the gage pressure in mPa at a point on the auto where the velocity relative to the auto is v – W m=s. The local air density is 0.984 kg/m3.
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6.12 Water flows steadily up the vertical pipe and is then deflected to flow outward with a uniform radial velocity. If friction is neglected, what is the flow rate of water through the pipe if the pressure at A is 10 psig?...
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6.13 The figure illustrates the operation of an air lift pump. Compressed air is forced into a perforated chamber to mix with the water so that the specific gravity of the air–water mixture above the air inlet is 0.5. Neglecting any pressure drop across section (1), compute the discharge velocity v of the air–water mixture. Can Bernoulli's equation be used across section (1)?...
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6.14 Air ofdensity 1.21kg/m3 isflowing as shown. Ifv .15m/s, determine the readings on manometers (a) and (b) in the figures below....
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6.15 Referring to the figure, assume the flow to be frictionless in the siphon. Find the rate of discharge in cubic feet per second, and the pressure head at B if the pipe has a uniform diameter of 1 in. How long will it take for the water level to decrease by 3 ft? The tank diameter is 10 ft....
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6.16 Assume that the level of water in the tank remains the same and that there is no friction loss in the pipe, entrance, or nozzle. Determine
a. The volumetric discharge rate from the nozzle...
b. The pressure and velocity at points A, B, C, and D
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6.17 A fluid of density ρ1 enters a chamber where the fluid is heated so that the density decreases to ρ2 The fluid then escapes through a vertical chimney that has a height L. Neglecting friction and treating the flow processes as incompressible except for the heating, determine the velocity, v, in the stack. The fluid velocity entering the heating chamber may be neglected, and the chimney is immersed in fluid of density ρ1....
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6.18 Consider a 4-cm pipe that runs between a tank open to the atmosphere and a station open to the atmosphere 10 m below the water surface in the tank. Assuming frictionless flow, what will be the mass flow rate? If a nozzle with a 1-cm diameter is placed at the pipe exit, what will be the mass flow rate? Repeat the problem if a head loss of 3 v2/g occurs in the pipe where v is the flow velocity in the pipe.
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6.19 A client has asked you to find the pressure change in a pumping station. The outlet from the pump is 20 ft above the inlet. A Newtonian fluid is being pumped at steady state. At the inlet to the pump where the diameter is 6 in., the temperature of the fluid is 80°F, the viscosity is 1.80 × 10–3 lbm/ft s, the density is 50 lbm/ft3, the heat capacity is 0.580 Btu/lbm °F, and the kinematic viscosity is 3.60 × 10–5 ft2/sec. At the outlet to the pump, where the diameter is 4 in., the temperature of the fluid is 100°F, the viscosity is 1.30 × 10–3 lbm/ft sec, the density is 49.6 lbm/ft3, the heat capacity is 0.610 Btu/lbm °F, and the kinematic viscosity is 2.62 × 10–5 ft2/sec. The flow rate through the system is constant at 20 ft3/sec. The pump provides work to the fluid at 3.85 × 108 lbm ft2/s3, and the heat transferred is 2.32 × 106 Btu/h. You may neglect viscous work in your analysis. Under these circumstances, please calculate the pressure change between the inlet and the outlet of the pumping station.
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6.20 Butyl alcohol, a Newtonian fluid, is being pumped at steady state with the density of 50 lbm/ft3, viscosity of 1.80 × 10–3 lbm/ft s, heat capacity of 0.58 Btu/lbm °F, and kinematic viscosity of 3.60 × 10–5 ft2/s. The inlet to the pump is a pipe with a diameter of 6 in., and the outlet is a pipe with a diameter of 2 in. The outlet is 10 ft above the inlet. The pump provides work to the fluid at 7.1 × 108 lbm ft2/s3. The flow rate through the system is constant at 20 ft3/s. During the pumping process, the fluid undergoes a 20°F increase in temperature. Under these circumstances, please calculate the pressure change between the inlet and the outlet of the pumping station. You may neglect any heat transfer to the control volume from the surroundings and viscous work, as these are very small.
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6.21 Air flows steadily through a turbine that produces 3.5 × 105 ft-lbf/s of work. Using the data below at the inlet and outlet, where the inlet is 10 feet below the outlet, please calculate the heat transferred in units of BTU/hr. You may assume steady flow and ignore viscous work....
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