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Semester I Examinations 2007/ 2008
Exam Code(s) 1MV Exam(s) M.Sc. in Biomedical Science
Module Code(s) BES Module(s)
Paper No. 1 Repeat Paper
External Examiner(s) Internal Examiner(s) Dr. Yuri Rochev, Patrick Fournet
Instructions:
Answer questions from each Section (Section A: 2 questions, Section B: 2 questions and Section C: 1 question). Use a separate answer book for each Section.
Duration (^) 2 hours
No. of Pages 8 (including cover) Department(s) National Centre for Biomedical Engineering Science Course Co-ordinator(s) Dr. Yuri Rochev
Requirements : MCQ Handout 1 Statistical/ Log Tables Cambridge Tables Graph Paper Log Graph Paper Other Materials
Section A: Materials – Structure and Properties
Answer all Questions
Note: Use diagrams where appropriate
Question 1. [20 marks]
Give a description of the following chemicals (e.g. inter- and intramolecular bonds) and reasons why these particular elements bond to each other (see Periodic Table for elements’ atomic structure).
Part A. KCl
Part B. C 2 H 4
Part C. H 2 O
Part D. Cgraphite
Question 2. [20 marks]
Part A. Explain the concept of grain formation and its implication on materials properties
Part B. Give an example of a ceramic material and its properties
Part C. Give an example of a polymer and its properties
Part D. Explain the significant difference of nanomaterials in terms of their electronic energy levels
- Write down a mathematical definition of the Reynolds number, and explain the meaning of each term.
- Name the conservation equations which govern fluid flow.
- Name an experimental technique that is used for velocity field measurement of a fluid flow.
- What does the Reynolds number tell us about the nature of a particular flow?
- What are the differences between laminar and turbulent flow?
Part B
An experimental flow loop is used to test the flow structure downstream of a fully opened mechanical heart valve, see attached figure. A pump drives the test fluid through the heart valve. The pump must maintain a steady flow rate of 2 l/min throughout the experiment. A smooth tube with a constant internal diameter of 15 mm connects the pump to the heart valve. A pump must be selected for the experiment that will maintain the pressure just up stream of the heart valve ( P 2 ) at 102,000 Pa. Calculate the pressure at the pump outlet ( P 1 ) so that the correct flowrate is maintained throughout the experiment.
Useful values:
- The density of the test fluid is 1060 kg/m^3.
- The pressure at location 2 ( P 2 ) is 102,000 Pa.
- The length of tubing between location 1 and location 2 is 4 m.
Pump
Heart valve test region
Location 1
1.5 m
Heart valve
z 2 = 1.5 m
Location 2
z 1 = 0 m
Vertical direction
P 2
- The elevation of location 2 is 1.5 m (z 2 = 1.5 m).
- The elevation of the pump outlet is ground level (z 1 = 0 m).
- Acceleration due to gravity, g, is 9.81 m/s^2.
- 1 litre = 0.001 m^3.
Modified Bernoulli Equation:
v gz gh T
P
v gz
P
2 2
2 1
2 1
1
- Calculate the velocity of the flow in the 15 mm diameter tube. (Hint: Flow rate = cross sectional area x velocity).
- Calculate the Reynolds number for the flow at location 2. What does this Reynolds number imply about the nature of the flow?
- Using the Moody chart, calculate the friction factor f.
- Calculate the total head loss (hT) in the length of tubing between location 1 and location 2 (neglect head losses due to bends in the tubing).
- Using the modified Bernoulli equation, calculate the pressure at the pump exit ( P 1 ). Assume the flow is steady and incompressible.
- What is meant by the assumption that the flow is steady and incompressible?
