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THE OPENUNIVERSITY OF SRI LANKA

DEPARTMENT OF MECHANICAL ENGINEERINGDIPLOMA IN TECHNOLOGY MEX3235 THERMO-FLUIDSACADEMIC YEAR 2014/2015ASSIGNMENT 02

INSTRUCTIONS(1) This assignment is based on the course material in Book 3(2) Answer all questions.(3) Write your registration number clearly on your answer script(4) Submit your assignments as stipulated in the specimen format for the tutor marked assignment.(5) Send your answer scripts under registered cover to the address given below or put it into the assignment box available in front of the Mechanical Engineering research lab, science and technology building.

THE COURSE COODINATORMEX3235DEPARTMENT OF MECHANICAL ENGINEERING THE OPENUNIVERSITY OF SRI LANKAP.O. BOX 21, NAWALA, NUGEGODA.

(6) Last date of submission 14th June 2015. Strictly no late submissions will be accepted due to any reason. .

1) a) A uniform film of oil 0.13 mm thick separates two discs, each of 200 mm diameter mounted co axially. Ignoring edge effects, calculate the torque necessary to rotate one disc relative to the other at a speed of 7rev/s if the oil has a viscosity of 0.14 Pas.

b) Calculate the Gauge Pressure at point A in Figure Q1 (b)

Figure Q1 (b)2) A 450 reducing bend is connected in a pipe line the diameter at the inlet and outlet of the bend being 600 mm and 300 mm respectively. Find the force exerted by water on the bend if the intensity of pressure at the inlet to bend is 8.829 N/cm 2 and rate flow of water is 600 liters / sec.

3) A sheet piling holds fresh water and salt water (relative density = 1.035) on either sides of it as shown in Figure Q3. Find the moment about the base M of the resultant force per unit length of filing?

Figure Q3

4) A centrifugal pump is required to deliver 50 l/s of water to a height of 30 m through a 100 m long pipe of 150 mm diameter. The inlet losses in the suction pipe are estimated to be 0.35m. Assuming an overall efficiency 70% and taking friction coefficient as 0.015 for the pipe line , determine the power required to drive the pump.

5) A venture section of a pipe develops a low pressure which can be used to aspirate fluid upward from reservoir as shown in Figure Q5. Show the exit velocity V2 is just sufficient to cause the reservoir fluid to rise in the tube up section 1 if

Figure Q5

6) Calculate the flow through each of the pipes of the network shown in Figure Q6.

Figure Q6

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