Question

2(P1-P) B4) Where (1 mark) (iii) Based on relation 1 above, write an expression for the volume flow rate for the two cases: a) Ignoring losses (0.5 mark) b) Accounting for the losses at the obstruction (0.5 mark) (iv) The value of The value of C (coefficient of discharge) depends on both B and the Reynolds number. Discuss this statement considering various types of obstruction meters. (0.5 mark) (V) The flow rate of methanol at 20°C (p=788.4 kg/m3 and -5.857 104 kg/m s) through a 4-cm-diameter pipe is to be measured with a 3-cm-diameter orifice meter equipped with a mercury manometer across the orifice place. If the differential height of the manometer is read to be 11 cm, determine the flow rate of methanol through the pipe and the average flow velocity. The discharge coefficient of the orifice meter is Cd-0.61 (5 mark) (vi) Based on your calculation of part (V), calculate the velocity and Reynolds number for the office. Is the flow laminar or turbulent? Is the value of Cd-0.61 suitable for this orifice? (1 mark) Obstruction Venturi meter Fig 2: Venture Fie 1: Orifice

Answer 1

- Chi V2 = √ (R-B) I can volume How Rate, no losses, Cd-1 Q = AVi = A 2 V2 = A2N2 = A 2X / 3 (Pr Bey) 6) Accounting for losses. d = Cd. A2 V2 = C.Az / ( A - Bey) of Ratio 180) Cd is a function of and Reynolds on umber Cd = Cux Co cross section depends on depends on Reynolds number. 0 0 0

Solo Giren data, 8=788.4kg (m3 de – 5.8576104 legems D=4cm d=3cm = 2 20.03m & -20.3.09 xromols 0 0 1 0 0 ie orife and Calculate velocally at Reynolds number, Q=AN,= A₂ V2 3.09.10 1 V₂ = 4.37 ml

Reynolds number, Re-Sud Re = 788.4 X 4. 37 X 0.03 5.857x104 Re = 176, 530 Re> 2000, so the flow turbulent * Ca=0.61 ff idead this is suitable for meter also . orifice meter. this orifice

Bernoulli's theorem i The sum of Kinetic, Potential, and pressure energy is constant throughout cross-section. Pressure fuergyf kinetic Energyt datum Evergy C Enersy - head in m. weight + I + Z = C Tw ? 29 Assumptions Steady Non-viscous Laminar anviscid) Irrorational,
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