Fluid Mechanics: Fundamentals and Applications
4th Edition
ISBN: 9781259696534
Author: Yunus A. Cengel Dr., John M. Cimbala
Publisher: McGraw-Hill Education
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Chapter 11, Problem 57P
The forming section of a plastics plant puts out a continuous sheet of plastic that is 1.2 in wide and 2 mm thick at a rate of 18 m/min. The sheet is subjected to airflow at a velocity of 4 m/s on both top and bottom surfaces normal to the direction of motion of the sheet. The width of the air cooling section is such that a fixed point on the plastic sheet passes through that section in 2 s. Using properties of air at 1 atm and
Figure 11.57
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The forming section of a plastics plant puts out a continuous sheet of plastic that is 1.2 m wide and 2 mm thick at a rate of 18 m/min. The sheet is subjected to airflow at a velocity of 4 m/s on both top and bottom surfaces normal to the direction of motion of the sheet. The width of the air cooling section is such that a fixed point on the plastic sheet passes through that section in 2 s. Using properties of air at 1 atm and 60°C, determine the drag force the air exerts on the plastic sheet in the direction of airflow.
The forming section of a plastics plant puts out a continuous sheet of plastic that is 1.2 m wide
and 2 mm thick at a rate of 15 m/min. The temperature of the plastic sheet is 90 °C when it is
exposed to the surrounding air, and the sheet is subjected to airflow at 30 °C at a velocity of 2
m/s on both sides along its surfaces normal to the direction of motion of the sheet. The width
of the air cooling section is such that a fixed point on the plastic sheet passes through that
section in 5 s. Draw the neat figure of the setup and determine the rate of heat transfer from
the plastic sheet to the air.
A sphere of diameter 10 mm and density 7700 kg/ m3 falls under gravity at terminal conditions through a liquid of density 900 kg/ m3 in a tube of diameter 12 mm. After reaching terminal velocity, the ball falls 5 cm in 31.3 seconds. Using the Francis wall correction factor: fw = (1-x/D)2.25 where x is the particle diameter and D is the diameter of the tube and fw is the wall factor (the velocity in the tube / velocity in an infinitely large tube), determine the:
a) viscosity (Pa s) of the fluid if Stokes law applies (Correct Answers: 4.118)
b) Reynolds number if the fluid viscosity is given in the previous part (Correct Answers: 0.1967)
c) minimum viscosity where the Re <= 0.3 (Correct Answers: 2.7)
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Chapter 11 Solutions
Fluid Mechanics: Fundamentals and Applications
Ch. 11 - What is drag? What causes it? Why do we usually...Ch. 11 - Prob. 2CPCh. 11 - Which bicyclist is more likely to go faster: one...Ch. 11 - Prob. 4CPCh. 11 - Define the frontal area of a body subjected to...Ch. 11 - Define the planform area of a body subjected to...Ch. 11 - Prob. 7CPCh. 11 - What is the difference between streamlined and...Ch. 11 - Prob. 9CPCh. 11 - During flow over a given body, the drag force, the...
Ch. 11 - During flow over a given slender body such as a...Ch. 11 - What is terminal velocity? How is it determined?Ch. 11 - What is the difference between skin friction drag...Ch. 11 - What is the effect of surface roughness on the...Ch. 11 - Prob. 15CPCh. 11 - What is flow separation? What causes it? What is...Ch. 11 - Prob. 17CPCh. 11 - Consider laminar flow over a flat plate. How does...Ch. 11 - In general, how does the drag coefficient vary...Ch. 11 - Fairings are attached to the front and back of a...Ch. 11 - Prob. 21PCh. 11 - The resultant of the pressure and wall shear...Ch. 11 - Prob. 23PCh. 11 - Prob. 24PCh. 11 - To reduce the drag coefficient and thus to improve...Ch. 11 - A circular sign has a diameter of 50 cm and is...Ch. 11 - Prob. 28PCh. 11 - Prob. 29PCh. 11 - At highway speeds, about half of the power...Ch. 11 - A submarine can be treated as an ellipsoid with a...Ch. 11 - A 70-kg bicyclist is riding her 1 5-kg bicycle...Ch. 11 - A wind turbine with two or four hollow...Ch. 11 - During steady motion of a vehicle on a level road,...Ch. 11 - Prob. 37EPCh. 11 - A 0.80-m-diameter, 1 .2-rn-high garbage can is...Ch. 11 - An 8-mm-diameter plastic sphere whose density is...Ch. 11 - Prob. 40PCh. 11 - The drag coefficient of a vehicle increases when...Ch. 11 - To reduce the drag coefficient and thus to improve...Ch. 11 - During major windstorms, high vehicles such as RVs...Ch. 11 - What does the friction coefficient represent in...Ch. 11 - What fluid property is responsible for the...Ch. 11 - How is the average friction coefficient determined...Ch. 11 - Prob. 47EPCh. 11 - The local atmospheric pressure in Denver, Colorado...Ch. 11 - Prob. 50PCh. 11 - Prob. 51EPCh. 11 - Air at 25C and 1 atm is flowing over a long flat...Ch. 11 - Prob. 54PCh. 11 - During a winter day, wind at 70 km/h, 5C , and I...Ch. 11 - Prob. 56PCh. 11 - The forming section of a plastics plant puts out a...Ch. 11 - Prob. 58CPCh. 11 - Why is flow separation in flow over cylinders...Ch. 11 - Prob. 60CPCh. 11 - A 5-mm-diameter electrical transmission line is...Ch. 11 - A 1ong 5-cm-diameter steam pipe passes through...Ch. 11 - Consider 0.8-cm-diameter hail that is falling...Ch. 11 - Prob. 64EPCh. 11 - Prob. 65PCh. 11 - Prob. 66PCh. 11 - Prob. 67EPCh. 11 - One of the popular demonstrations in science...Ch. 11 - Prob. 69PCh. 11 - What is stall? What causes an airfoil to stall?...Ch. 11 - Prob. 71CPCh. 11 - Air is flowing past a symmetrical airfoil at zero...Ch. 11 - Both the lift and the drag of an airfoil increase...Ch. 11 - Prob. 74CPCh. 11 - Prob. 75CPCh. 11 - Air is flowing past a symmetrical airfoil at an...Ch. 11 - Prob. 77CPCh. 11 - Prob. 78CPCh. 11 - Prob. 79CPCh. 11 - Prob. 80CPCh. 11 - How do flaps affect the lift and the drag of...Ch. 11 - Prob. 82EPCh. 11 - Consider an aircraft that takes off at 260 km/h...Ch. 11 - Prob. 84PCh. 11 - Prob. 85PCh. 11 - A tennis ball with a mass of 57 and a diameter of...Ch. 11 - A small aircraft has a wing area of 40 m2, a lift...Ch. 11 - Prob. 89PCh. 11 - Consider a light plane that has a total weight of...Ch. 11 - A small airplane has a total mass of 1800 kg and a...Ch. 11 - An airplane has a mass of 48.000 k. a wins area of...Ch. 11 - Prob. 93EPCh. 11 - Prob. 94PCh. 11 - Prob. 95EPCh. 11 - A 2-zn-high, 4-zn-wide rectangular advertisement...Ch. 11 - 11-97 A plastic boat whose bottom surface can be...Ch. 11 - Prob. 99PCh. 11 - Prob. 100EPCh. 11 - A commercial airplane has a total mass of 150.000...Ch. 11 - Prob. 102PCh. 11 - Prob. 103PCh. 11 - Prob. 104PCh. 11 - Prob. 105PCh. 11 - Prob. 107PCh. 11 - Prob. 108PCh. 11 - Prob. 109PCh. 11 - Prob. 110PCh. 11 - Prob. 111PCh. 11 - Prob. 113PCh. 11 - Prob. 115PCh. 11 - Prob. 116PCh. 11 - Prob. 117PCh. 11 - Prob. 118PCh. 11 - Prob. 119PCh. 11 - The region of flow trailing the body where the...Ch. 11 - Prob. 121PCh. 11 - Prob. 122PCh. 11 - Prob. 123PCh. 11 - Prob. 124PCh. 11 - Prob. 125PCh. 11 - Prob. 126PCh. 11 - An airplane has a total mass of 3.000kg and a wing...Ch. 11 - Prob. 128PCh. 11 - Write a report on the history of the reduction of...Ch. 11 - Write a report oil the flips used at the leading...Ch. 11 - Discuss how to calculate drag force a unsteady...Ch. 11 - Large commercial airplanes cruise at high...Ch. 11 - Many drivers turn off their air conditioners and...Ch. 11 - Consider the boundary layer growing on a flat...
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