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					Problems to solve #3


1. What is the maximum discharge (in m3/h) of fuel oil at 30ºC and standard
   atmospheric pressure ( = 2.8x 10-4 m2/s) from a 0.02 m diameter tube if
   laminar flow is maintained?


2. Water having a dynamic viscosity of 5.47x10-4 kg/m/s, flows through a long,
   0.05 m diameter tube at a rate of 7 m3/h. Is the flow laminar or turbulent?


3. An oil with  900 kg/m3 and  0.0002 m2/s flows upward through an inclined
   pipe as shown in the next figure. The pressure is known at sections 1 and 2,
   10 m apart. Assuming steady laminar flow, (a) verify that the flow is upwards,
   (b) calculate h between 1 and 2, (c) calculate the volumetric flow rate, (d),
   velocity and (e) Re number. Confirm whether the flow is laminar or not.




4. Calculate the pressure drop in a 60 m of horizontal 15 cm diameter asphaltic
   cast-iron pipe carrying water with a mean velocity of 1.8 m/s. Rugosity is
   1.2x10-4 m. Which will be the pressure drop if a smooth pipe is used?


5. Oil with  = 900 kg/m3 and  = 0.00001 m2/s, flows at 0.2 m3/s through 500m
   of 200-mm-diameter cast-iron pipe. Determine (a) the head loss and (b) the
   pressure drop if the pipe slopes down at 1º in the flow direction. Rugosity for
   cast-iron pipe is 0.26 mm
Multiple choice questions:

1. When a CV approach is used to solve fluid mechanical problems, the final solution
depends on the CV defined
    a) true
    b) false

2. Fluid velocity in laminar flow has a random motion of fluid particles
    a) true
    b) false

3. Entrance length has a common value for all fluid regimes
    a) true
    b) false

4. Re number has units of:
    a) pressure
    b) velocity
    c) length
    d) none of the previous options

5. Pressure and shear stress are applied over the flow area of a pipe
    a) true
    b) false

6. Calculation of pressure losses has different formulation according to the duct
geometry
    a) true
    b) false

7. Localized pressure losses are calculated using an empirical coefficient K. This
coefficient is:
    a) constant and = 3
    b) variable with temperature
    c) depends on the singularity

8. The pressure loss is calculated for a fluid flowing inside a pipe having a given
rugosity. If the pipe is replaced by a smooth pipe, the pressure drop varies:
    a) only if the flow is in the laminar
    b) only if the flow is turbulent
    c) always
    d) never
    e) none of the previous options

				
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posted:10/31/2011
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