Questions and Answers of Introduction To Fluid Mechanics

A rotary mixer is constructed from two circular disks as shown. The mixer is rotated at \(60 \mathrm{rpm}\) in a large vessel containing a brine solution \((\mathrm{SG}=1.1)\). Neglect the drag on
An emergency braking parachute system on a military aircraft consists of a large parachute of diameter \(6 \mathrm{~m}\). If the airplane mass is \(8500 \mathrm{~kg}\), and it lands at \(400
Calculate the drag of a smooth sphere of \(0.5 \mathrm{~m}\) diameter when placed in an airstream \(\left(15^{\circ} \mathrm{C}\right.\) and \(\left.101.3 \mathrm{kPa}\right)\) if the velocity is(a)
The resistance to motion of a good bicycle on smooth pavement is nearly all due to aerodynamic drag. Assume that the total weight of rider and bike is \(210 \mathrm{lbf}\). The frontal area measured
A cyclist is able to attain a maximum speed of \(30 \mathrm{~km} / \mathrm{hr}\) on a calm day. The total mass of rider and bike is \(65 \mathrm{~kg}\). The rolling resistance of the tires is
A 0.5 -m-diameter hollow plastic sphere containing pollution test equipment is being dragged through the Hudson River in New York by a diver riding an underwater jet device. The sphere with an
The Willis Tower (formerly the Sears Tower) in Chicago is \(1454 \mathrm{ft}\) tall. Assuming that it is a tall rectangle with a square base of \(120 \mathrm{ft}\) sides, calculate the maximum drag
Calculate the drag forces on a 1/200 scale model of the Willis Tower that is tested in a large water flume under conditions corresponding to those in problem 9.89. Ignore any free surface effects and
A vehicle is built to try for the land-speed record at the Bonneville Salt Flats, elevation \(4400 \mathrm{ft}\). The engine delivers \(500 \mathrm{hp}\) to the rear wheels, and careful streamlining
A tractor-trailer rig has frontal area \(A=102 \mathrm{ft}^{2}\) and drag coefficient \(C_{D}=0.9\). Rolling resistance is \(6 \mathrm{lbf}\) per \(1000 \mathrm{lbf}\) of vehicle weight. The specific
An anemometer to measure wind speed is made from four hemispherical cups of 2-in. diameter, as shown. The center of each cup is placed at \(R=3\) in. from the pivot. Find the theoretical calibration
The antenna on a car is \(10 \mathrm{~mm}\) in diameter and \(1.8 \mathrm{~m}\) long. Estimate the bending moment that tends to snap it off if the car is driven at \(120 \mathrm{~km} / \mathrm{hr}\)
Standard air is drawn into a low-speed wind tunnel. A 30-mm diameter sphere is mounted on a force balance to measure lift and drag. An oil-filled manometer is used to measure static pressure inside
A small sphere with \(D=6 \mathrm{~mm}\) is observed to fall through castor oil at a terminal speed of \(60 \mathrm{~mm} / \mathrm{s}\). The temperature is \(20^{\circ} \mathrm{C}\). Compute the drag
A water tower consists of a 12-m-diameter sphere on top of a vertical tower \(30 \mathrm{~m}\) tall and \(2 \mathrm{~m}\) in diameter. Estimate the bending moment exerted on the base of the tower due
The plot shows pressure difference versus angle measured for air flow around a circular cylinder at \(R e=80,000\). Use these data to estimate \(C_{D}\) for this flow. Compare with data from Fig.
A rectangular airfoil of \(9 \mathrm{~m}\) span and \(1.8 \mathrm{~m}\) chord moves horizontally at an angle of attack through still air at \(240 \mathrm{~km} / \mathrm{h}\). Calculate the lift and
A wing model of \(5 \mathrm{in}\). chord and \(2.5 \mathrm{ft}\) span is tested at a certain angle of attack in a wind tunnel at \(60 \mathrm{mph}\) using air at \(14.5 \mathrm{psia}\) and
A spherical sonar transducer with 15 in. diameter is to be towed in seawater. The transducer must be fully submerged at \(55 \mathrm{ft} / \mathrm{s}\). To avoid cavitation, the minimum pressure on
If the mean velocity adjacent to the top of a wing of \(1.8 \mathrm{~m}\) chord is \(40 \mathrm{~m} / \mathrm{s}\) and that adjacent to the bottom of the wing is \(31 \mathrm{~m} / \mathrm{s}\) when
A human-powered aircraft has a gross weight of \(240 \mathrm{lbf}\) including the pilot. Its wing has a lift coefficient of 1.5 and a liftto-drag ratio of 70. Estimate the wing area needed and the
An antique airplane carries \(50 \mathrm{~m}\) of external guy wires stretched normal to the direction of motion. The wire diameter is \(5 \mathrm{~mm}\). Estimate the maximum power saving that
An airplane with an effective lift area of \(25 \mathrm{~m}^{2}\) is fitted with airfoils of NACA 23012 section (Fig. 9.23). The maximum flap setting that can be used at takeoff corresponds to
A light airplane, with mass \(M=1000 \mathrm{~kg}\), has a conventionalsection (NACA 23015) wing of planform area \(A=10 \mathrm{~m}^{2}\). Find the angle of attack of the wing for a cruising speed
Assume the Boeing 727 aircraft has wings with NACA 23012 section, planform area of \(1600 \mathrm{ft}^{2}\), double-slotted flaps, and effective aspect ratio of 6.5. If the aircraft flies at 150
Air moving over an automobile is accelerated to speeds higher than the travel speed, as shown in Fig. 9.25. This causes changes in interior pressure when windows are opened or closed. Use the data of
Rotating cylinders were proposed as a means of ship propulsion in 1924 by the German engineer, Flettner. The original Flettner rotor ship had two rotors, each about \(10 \mathrm{ft}\) in diameter and

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