CEIC2001_2019_T1_Exam 3.pdf - 2019 T1 CEIC2001 Fluid and...

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1 2019 T1 CEIC2001 Fluid and Particle Mechanics Examination 3 (30%) 4:00-6:00 PM Tuesday 16 April 2019 INSTRUCTION 1. YOU MUST PRINT YOUR NAME AND UNSW zID IN THE SPACE ABOVE 2. TIME ALLOWED – 1.5 HOURS 3. THIS EXAMINATION ANSWER SCRIPT HAS 16 PRINTED PAGES 4. TOTAL NUMBER OF QUESTIONS – 3 5. TOTAL MARKS AVAILABLE – 30 MARKS 6. THIS EXAMINATION CONTRIBUTES 30% TO THE FINAL COURSE MARK 7. NOT ALL QUESTIONS OR PARTS OF A QUESTION ARE OF EQUAL MRK 8. THIS EXAMINATION IS OPEN BOOK 9. CANDIDATES MUST USE UNSW APPROVED CALCULATORS 10. NO PART OF THIS PAPER IS TO BE RETAINED BY CANDIDATES
2 Question 1 (12 marks) The characteristics of a centrifugal pump at constant speed are given in the table below: Q (m 3 s -1 ) 0 0.012 0.018 0.024 0.030 0.036 H (m) 22.6 21.3 19.4 16.2 11.6 6.5 η (%) 0 74 86 85 70 The pump is used to lift water continuously through a vertical distance of 5 m via a 50 m long and10 cm in diameter pipe. The Darcy-Weisbach friction factor of the pipe is 0.02. (a) What is the flow rate, head and efficiency at the best efficiency point of this pump? (b) What is the flow rate, head and efficiency at the operating point of this pump? (c) The flow rate has to be increased and this can be achieved by the addition of a second, identical pump. Determine the flow rate, head and efficiency at the operating point of the new setup. 0.042 0.6 46 8 All graphs for Question 1 must be drawn within this text box. 0 1 2 3 4 5 6 7 8 9 1 0 10 20 30 40 50 60 70 80 90 100 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 Head (m) System Resistance (m) Capacity Q (m 3 s -1 )
3 Write your workings and final answers to Question 1 in this text box.
4 Write your workings and final answers to Question 1 in this text box.
5 Write your workings and final answers to Question 1 in this text box.
6 Question 2 (8 marks) The power required by a tank mixer is a function of the impeller diameter of the mixer d, the rotational speed of the impeller (in rpm) N, as well as the density ρ and viscosity μ of the liquid that is being mixed. Use the indicial method to determine the dimensionless group or groups which relate the power required by the tank mixer to the impeller geometry, impeller speed and fluid properties. Write your workings and final answers to Question 2 in this text box.
7 Write your workings and final answers to Question 2 in this text box.
8 Write your workings and final answers to Question 2 in this text box.
9 Write your workings and final answers to Question 2 in this text box.
10 Question 3 (12 marks) Water flows at a steady rate through a rectangular channel of very large aspect ratio, i.e. Height/Width (H/W) and Height/Length (H/L) ratios are both very small. The flow is caused by the movement of the

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