# 2008_Exam2 - Determine a Wall shear stress ߬ ௪ b...

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57:020 Mechanics of Fluids and Transport Fall 2008 EXAM #2 November 10, 2008 1. For the pipe-flow-reducing section of Fig.1, ܦ = 8 cm, ܦ = 5 cm, and ݌ = 1 atm. All fluids are at 20 ° C. If ܸ = 5 m/s and the manometer reading is ݄ = 58 cm, estimate the total horizontal force resisted by the flange bolts. ( ߩ ௪௔௧௘௥ = 998 Kg/m 3 and ߩ ௠௔௖௨௥௬ = 13,546 Kg/m 3 @ 20 ° C) 2. Gasoline ( ܵܩ = 0.68) flows through a pump at 0.12 m 3 /s as indicated in Fig. 2. The head loss be- tween sections (1) and (2) is ݄ = 0.3 ܸ . What will the difference in pressures between sec- tions (1) and (2) be if ܹ = 20 kW is delivered by the pump to the fluid? ( ߩ = 999 Kg/m 3 for water; 1 W = 1 N m/s; ݃ = 9.81 m/s 2 ) Figure 1 Figure 2 3. Glycerin at 20 ° C flows in a horizontal 75-mm-diameter pipe shown in Fig.3 with ݑ ୫ୟ୶ = 1.0 m/s. It is known that the velocity distribution is ݑሺݎሻ ൌ ݑ ୫ୟ୶ ܴ ሺܴ െݎ
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Unformatted text preview: Determine: a) Wall shear stress ߬ ௪ b) Pressure difference Δ݌ between sections (1) and (2) using the momentum equation c) Head loss ݄ ௅ between section (1) and (2) using the energy equation The distance ܮ between sections (1) and (2) is 10m. ( ߩ = 1,260 Kg/m 3 and ߤ = 1.50 N ⋅ s/m 2 for glycerin at 20 ° C) 4. The water flowrate, ܳ , in an open rectangular channel can be measured by placing a plate across the channel as shown in Fig. 4. This type of a device is called a weir . The height of the water, ܪ , above the weir crest is referred to as the head and can be used to determine the flo-wrate through the channel. Assume that ܳ is a function of the head, ܪ , the channel width, ܾ , and the acceleration of gravity, ݃ . Determine a suitable set of dimensionless variables for this problem. Figure 3 Figure 4 ܮ ݌ ଵ ܣ ݌ ଶ ܣ ߬ ௪ ሺ2ߨܴሻܮ...
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## This note was uploaded on 12/08/2011 for the course MECHANICS 57:020 taught by Professor Fredrickstern during the Fall '10 term at University of Iowa.

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