4HE Fluid Mechanics - Test 2

Duration: 90 min. Maximum Marks: 30

Part A (10 x 1 = 10 marks)

- Consider a duct of square cross section of side 'b'. The hydraulic radius is given by

(A) b/8 (B) b/4 (C) b/2 (D) b - Define the term 'Mach number'
- For an orifice meter, the pressure recovery is ________ than that for a venturi meter.
- The equilibrium position of the float in a rotameter is determined by the balance of three forces. These are ___________, ___________ and ___________.
- A rotameter, through which air at room temperature and atmospheric pressure is flowing, gives a certain reading for a flow rate of 100 cc/s. If helium (Molecular weight 4) is used and the rotameter shows the same reading, the flow rate is

(A) 26 cc/s (B) 42 cc/s (C) 269 cc/s (D) 325 cc/s - Write down the equation for flow rate through a V-notch
- (i)What is wall drag?

(ii) What is form drag? - Differentiate between Loading and Flooding
- Differentiate between bubbling and particulate fluidization
- What is the theoretical maximum operable velocity for a fluidized bed?
- 2.16 m
^{3}/h water at 320 K is pumped through a 40 mm I.D. pipe through a length of 150 m in a horizontal direction and up through a vertical height of 12 m. In the pipe there are fittings equivalent to 260 pipe diameters. What power must be supplied to the pump if it is 60% efficient? Take the value of fanning friction factor as 0.008. Water viscosity is 0.65 cp, and density = 1 gm/cc. - (a) Explain the construction and working principle of Pitot tube. (6)
- Derive Ergun equation for pressure drop through a packed bed
- (a)Derive an expression for minimum fluidization velocity. (7)

Part B (2 x 10 = 20 marks)

Or

(b) A venturi meter has throat to upstream pipe cross-section ratio of 0.5. The fluid flowing is water. The pressure at the entry of converging cone section is 20 psia. What is the velocity at the throat which corresponds to a pressure of 0.0 psia at the throat? If the water is at 200^{o}F, its vapor pressure is 11.psia. What is the highest velocity possible at the throat at which water at 200^{o}F will boil? (4)

Or

(b)The pressure drop required for fluidizing a coal bed with a liquid petroleum fraction of viscosity 0.015 Ns/m^{2} is 10^{5} N/m^{2}. What is the pressure drop required for fluidizing the same bed with an oil (same density as the petroleum fraction) of viscosity 0.03 Ns/m^{2}? (3)