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# Indian Institute of Technology Kharagpur (IIT-K) 2007 B.Tech Chemical Engineering Fluid flow07 - Question Paper

Wednesday, 23 January 2013 11:25Web

Department of Chemical Engineering IIT Kharagpur Mid-Semester Examination 07-08 ,    Fluid Flow

No. of Students - 80 Onen book examination, class notes are not allowed

1. An offshore oil & gas company decided to discharge produced water at the rate of 50m1/s over a depth of 10 m. The tidal velocity approaching the location is 0.2 m/s. Assume that the diffusional mixing between tidal water and produced water is negligible for the time-frame considered. Find (i) how far upstream the discharge effect extends and (ii) how much width of the downstream contains produced

Marks = 8

water.

 Dowstream containing produced water j l

2. The adjoining figure describes an inclined manometer hooked on a pipe through which water is flowing. The liquid deflection in the inclined tube from its neutral (zero-pressure-difference) position is

2 cm. The manometer fluid is oil with specific gravity of 0.92. The manometer reservoir is 10 cm in diameter, the tubing is 0.6 cm in diameter all through, and the tube is inclined at an angle of 30 to the horizontal. The pipe is inclined at 20 to the horizontal and pressure taps are 1 m apart. Find (i) what the pressure difference is in Pa between the two pipe taps, (ii) which way the water is flowing, and (iii) what will the liquid deflection in inclined tube be if the valve is closed. Marks = 9

Starting from rest, the cart (mass = 100 kg) shown aside is propelled by a water jet (velocity = 30 m/s. water density = 1000 kg/m3, cross-sectional area of jet = 0.001 m2). The jet strikes the curved surface and makes a 180 turn, leaving horizontally. Air and rolling resistances can be neglected. Express the cart speed as a function of time.    Marks = 8

4. During the hurry to reach a fire on time, a fireman mistakenly picked a nozzle whose diameter is the same as that of the hose. The length of the hose is 30 m, the diameter of is 8 cm and the roughness of the hose is 0.0008m. He has to deliver a jet of water at 60 to the horizontal (as

shown in the figure) to a height 10 m above the ground. Evaluate the minimum head to be developed by the pump.

 atm. pressure

His fellow fireman, who claims to have studied fluid mechanics, has suggested that the head requirement can be drastically reduced by attaching a reducing nozzle at the exit of the hose and he has given a nozzle of

2.5 cm exit diameter to his friend. Do you think the second fireman has really studied fluid mechanics? Your decision should be,

based on quantitative results. You may neglect minor losses.

Marks = 9

5. (a) The head loss (Hs in m) in a water piping system is given by the equation HS=50+6(Q/10Q)2, where Q is the flow rate in m3/hr.

There are two identical centrifugal pumps whose Head-Capacity characteristics is given by the equation HP=68-0.5(Q/100)-4.5(Q/100)2, where Hp is the head (in m) developed; Q is flow rate (m3/hr).

(i)    What is the altitude difference between the edges of the piping system?

(ii)    What is the maximum water flow rate when the two pumps are joined in series and is a part of the water piping system? Find the corresponding head developed by each pump.

(iii)    What is the maximum water flow rate when the two pumps are joined in parallel and is a part of the water piping system? Find the corresponding total head loss in the piping system.

5.    (b) How will you choose between gate and globe valve for a particular application.

Marks = 7+1

6.    A parallel plate viscometer consists of a stationary, circular plate over which another identical plate rotates as shown in the figure. Fluid is placed in the gap and the torque on the lower plate is measured. Simplify Navier Stokes equation, clearly stating all assumptions with proper justification. Show that Ve = corz/(2h0 ) can be a solution for this situation. Using this expression for V0 obtain an expression for viscosity

 1 & k z CD * W -1 , r * ' ?h

of the liquid in terms of the measured torque on the lower plate.

R

Marks = 8