FINAL Examination Paper (COVER PAGE) Programme : Diploma in Mechanical Engineering. Time : 8.00 am am Reading Time : 10 Minutes

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1 Session : May 2013 FINAL Examination Paper (COVER PAGE) Programme : Diploma in Mechanical Engineering Course : EGR2180 : FLUIDS MECHANICS 2 Date of Examination : July 25, 2013 Time : 8.00 am am Reading Time : 10 Minutes Duration : 2 Hours 10 Minutes Special Instructions : Instructions : This paper consists of SIX (6) questions. Answer any FOUR (4) questions in the answer booklet provided. All questions carry equal marks. Materials permitted : Non-Programmable Calculator Materials provided : Nil Examiner(s) : Mr. Tony Ow Koon Seong Moderator : Dr Chuah Keng Hoo This paper consists of 5 printed pages, including the cover page.

2 EGR2180 (F) / Page 1 of 4 INTI INTERNATIONAL UNIVERSITY DIPLOMA IN MECHANICAL ENGINEERING PROGRAMME EGR2180 : FLUIDS MECHANICS 2 FINAL EXAMINATION : MAY 2013 SESSION Instructions: This paper consists of SIX (6) questions. Answer any FOUR (4) questions in the answer booklet provided. All questions carry equal marks. Question 1 A pump delivers water from a tank A (water surface elevation = 110 m) to tank B (water surface elevation = 170 m) as shown in Figure Q1. The suction pipe is 45 m long (4f = 0.024) and 35 cm in diameter. The delivery pipe is 950 m long (4f = 0.022) and 25 cm in diameter. The head discharge relationship for the pump is given by Hp = ( Q 2 ), where Hp is in meters and Q in m 3 /s. Neglecting all minor losses. Calculate : the discharge in the pipeline, and the power delivered by the pump. Figure Q1 Describe the water hammer phenomena. (13 marks) (5 marks) (c) In a rigid pipe of 600 mm diameter and 3000 m length, provided with a valve at its end, having a discharge of m 3 /s. The density of water is 1000 kg/ m 3. Find: the rise in pressure if the valve is closed in 20s, assuming the velocity of pressure wave, C = 1500 m/s. The original pipe is extended and the rise in pressure is measured to be MPa when the valve is closed in 2 seconds and the oscillation period of the pressure wave is taken to be 3.53 s. Find the extension of the pipe, Δl. (7 marks)

3 EGR2180 (F) / Page 2 of 4 Question 2 (c) Prove that the diameter of the nozzle, d is (D 5 /(8fL)) 0.25 when the power transmitted through nozzle is maximum where D is the diameter of the pipe, f is the coefficient of friction and L is the length of the pipe. ( 5 marks) Find the maximum power transmitted by a jet of water discharging freely out of the nozzle fitted to a 400 m long pipe with a 120 mm diameter and co-efficient of friction as The available head at the nozzle is 85 m. Neglecting minor losses. A 2500m long pipeline is used for transmission of power. 120kW power is to be transmitted through the pipe in which water having a pressure of 4000 kn/m 2 at inlet is flowing. If the pressure drop over the length of pipe is 800 kn/m 2 and f =0.006, find: the diameter of the pipe, and the efficiency of power transmission Question 3 The rectangular channel will be most economical when the depth of flow, y is equal to half the base width, b and the hydraulic radius, m is equal to half the depth of flow, y. Prove it. (8 marks) A trapezoidal channel having a cross-sectional area A 1, wetted perimeter P 1, Manning s co-efficient N, and laid to a slope, i carries a discharge Q, at a depth of flow equal to y. To increase the discharge, the base width of the channel is widened by x. Keeping all other parameters same, prove that (17 marks) Question 4 A gas with a velocity of 300 m/s is flowing through the upstream of a pipe where the pressure is 78 kn/m 2 absolute and temperature 40 C. The pipe changes in diameter and slopes down at 10 in the flow direction at this section. At the downstream, the gas is flowing at 97 m/s. The length of the pipe is 500 m. Find the pressure of the gas at the downstream if the flow of the gas is adiabatic. Take R = 287 J/kg K and = 1.4. Neglecting all losses. (12 marks) Explain how shock wave occurs. (3 marks)

4 (c) EGR2180 (F) / Page 3 of 4 A normal shock wave occurs in a diverging section when air is flowing at a velocity of 350 m/s, pressure of 100 kpa and temperature of 10 C. Determine : (iii) the Mach number before and after the shock, the pressure rise, and the velocity and temperature after the shock. Question 5 Hydraulic turbines can be classified into impulse turbine and reaction turbine. What are the differences between these two turbines? (6 marks) A Pelton wheel nozzle, for which C v = 0.97, is 350 m below the water surface of a lake. The jet diameter is 90 mm, the pipe diameter is 0.6 m, its length is 4 km and friction factor of The buckets deflect the jet through 165 o and they run at 0.48 times the jet speed, bucket friction reducing the relative velocity at outlet by 15% of the relative velocity at inlet. Mechanical efficiency = 88 %. Determine: the flow rate, the shaft power developed by the turbine. (19 marks) Question 6 List out the names and functions of the four main components of a centrifugal pump. (12 marks) A centrifugal pump delivers water against a net head of 14.5 m and a design speed of 1000 r.p.m.. The vanes are curved back to an angle of 30 with the periphery. The impeller diameter is 300 mm and outlet width 50 mm. Determine the discharge of the pump if manometric efficiency is 95%. (13 marks) - THE END - EGM371(F)/MAY 13/Tony Ow Koon Seong/

5 EGR2180 (F) / Page 4 of 4 APPENDIX I Shock Wave [ ][ ]