Efficiency Investigation of a Helical Turbine for Harvesting Wind Energy
A Thesis presented by Nathan Willard To The Department of Mechanical and Industrial Engineering In partial fulfillment of the requirements For the degree of Master of Science In Mechanical Engineering
In the field of Thermofluids Engineering
Northeastern University Boston, Massachusetts September 2011 Abstract
In recent times, there has been an increased interest in wind energy due to concerns about the pollution caused by burning fossil fuels and their rising prices. Most wind turbines in use today are conventional wind mills with three airfoil shaped blades arraigned around a horizontal axis. These turbines must be turned to face into the wind and in general require significant air velocities to operate. Another style of turbine is one where the blades are positioned vertically or transverse to the axis of rotation. These turbines will always rotate in the same direction regardless of the fluid flow. Due to the independence from the direction of the fluid flow, these turbines have found applications in tidal and surface current flows. To see how effective this sort of turbine would be in air, a helical turbine based on the designs and patents of Dr. Alexander M. Gorlov was chosen. His turbine was developed to improve upon the design of Georges J. M. Darrius by increasing the efficiency and removing pulsating stresses on the blades, caused by the blades hitting their aerodynamic stall in the course of rotation, which often resulted in fatigue failure in the blades or the joints that secured them to the shaft. The turbine takes the Darrius type turbine, which has a plurality of blades arranged transverse to the axis of rotation, and adds a helical twist to their path, insuring that regardless of the position of the turbine, a portion of the blade is always positioned in the position that gives maximum lift. This feature reduces the pulsations that are common in a Darrius type turbine. In his investigations, Gorlov claims that his turbine is significantly more efficient than Darrius’ and has achieved overall efficiencies between 30% and 35%. For this investigation, a helical turbine was tested inside and outside a wind tunnel using an electric generator
(inside tests only) and a torque meter paired with a tachometer to measure the output power of the turbine and calculate its efficiency. In the end, the turbine did not come close to the claimed 30% efficiency, reaching at best an efficiency of around 0.35%. Further investigations should be made to determine why the results from this investigation were as low as they are.
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Acknowledgements
First, I would like to express my deep appreciation for my advisor; Prof. M. E. Taslim for guiding me through the process of conducting this investigation.
I would also like to give special thanks to Jonathan Doughty and Kevin McCue for the aid that they have given me in the construction and testing of the turbine.
Thirdly, I would like to give thanks to my colleagues, Mehdi Abedi, Nathaniel Rosso and Adebayo Adebiyi for the hints and tips they have given me through conversation regarding this investigation.
Finally, I would like to express my gratitude to my family for supporting me in this endeavor.
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Table of Contents Abstract ...... ii Acknowledgements ...... iii List of Figures ...... vi List of Tables ...... ix Nomenclature ...... xi Chapter 1 ...... 1 1.1 Introduction ...... 1 1.2 Literature Review ...... 2 Chapter 2 ...... 6 2.1 Overview of Experiment ...... 6 2.2 Design and Construction of the Turbine ...... 7 2.2.1 Overview of Design ...... 7 2.2.2 Shaft Design ...... 8 2.2.3 Flange Design ...... 8 2.2.4 Spoke Arm Design ...... 9 2.2.5 Blade Design ...... 10 2.3 Selection of Instrumentation ...... 12 2.3.1 Torque Meter ...... 12 2.3.2 Tachometer ...... 14 2.3.3 Generator ...... 14 2.3.4 Pitot Tube and Manometer ...... 15 2.3.5 Wind Meter ...... 15 2.4 Test Setup and Procedure ...... 16 2.4.1 Layout of the Test Chamber ...... 16 2.4.2 Wind Tunnel Tests ...... 17 2.4.3 Out of Wind Tunnel Tests ...... 19 2.4.4 Calibration Check on Handheld Wind Meter ...... 20 Chapter 3 ...... 23 3.1 Wind Tunnel Tests with Generator ...... 23 3.1.1 Results from 0.55in Oil Test ...... 24 3.1.2 Results from 0.60in Oil Test ...... 26 3.1.3 Results from 0.65in Oil Test ...... 28 3.1.4 Results from 0.70in Oil Test ...... 30 3.1.5 Results from 0.75in Oil Test ...... 32 3.1.6 Results from 0.80in Oil Test ...... 34
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3.1.7 Results from 0.85in Oil Test ...... 36 3.1.8 Results from 0.90in Oil Test ...... 38 3.1.9 Results from 0.95in Oil Test ...... 40 3.1.10 Results from 1.0in Oil Test ...... 42 3.1.11 Rotational Velocity Results ...... 44 3.1.12 Turbine Power Results ...... 46 3.1.13 Turbine Efficiency Results ...... 48 3.2 Wind Tunnel Tests with Torque Meter ...... 49 3.3 Out of Wind Tunnel Test with Torque Meter ...... 51 3.3.1 Fan 12in from Turbine ...... 52 3.3.2 Fan 24in from Turbine...... 55 3.4 Conclusions ...... 58 3.5 Further Investigations ...... 59 Works Cited ...... 61 Appendix A: Technical Drawings of Turbine ...... 62 Appendix B: Raw Data ...... 67 Appendix C: Calibration Information ...... 88
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List of Figures
Figure 1-1: Figure 3 from Darrius' Patent for his Turbine. (1) ...... 2
Figure 2-1: Exploded View of Turbine Assembly ...... 7
Figure 2-2: Flange Design ...... 9
Figure 2-3: Spoke Arm Design ...... 9
Figure 2-4: NACA0018 Airfoil Profile ...... 10
Figure 2-5: Top View of Turbine Blade ...... 11
Figure 2-6: Side View of Turbine Blade ...... 11
Figure 2-7: Blade Half ...... 12
Figure 2-8: Himmelstein Torque Meter ...... 13
Figure 2-9: LED Tachometer ...... 14
Figure 2-10: Generator ...... 15
Figure 2-11: Kestrel Wind Meter ...... 16
Figure 2-12: Test Chamber Layout, Top Down View and Side View ...... 17
Figure 2-13: Torque Meter Configuration ...... 18
Figure 2-14: Generator Set Up ...... 18
Figure 2-15: Out of Wind Tunnel Set Up ...... 20
Figure 3-1: Rotational Velocity at 0.55in Oil ...... 24
Figure 3-2: Output Power at 0.55in Oil ...... 25
Figure 3-3: Efficiency at 0.55in Oil ...... 25
Figure 3-4: Rotational Velocity at 0.6in Oil ...... 26
Figure 3-5: Output Power at 0.6in Oil ...... 27
Figure 3-6: Efficiency at 0.6in Oil ...... 27
Figure 3-7: Rotational Velocity at 0.65in Oil ...... 28
Figure 3-8: Output Power at 0.65in Oil ...... 29
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Figure 3-9: Efficiency at 0.65in Oil ...... 29
Figure 3-10: Rotational Velocity at 0.7in Oil ...... 30
Figure 3-11: Output Power at 0.7in Oil ...... 31
Figure 3-12: Efficiency at 0.7in Oil ...... 31
Figure 3-13: Rotational Velocity at 0.75in Oil ...... 32
Figure 3-14: Output Power at 0.75in Oil ...... 33
Figure 3-15: Efficiency at 0.75in Oil ...... 33
Figure 3-16: Rotational Velocity at 0.8in Oil ...... 34
Figure 3-17: Output Power at 0.8in Oil ...... 35
Figure 3-18: Efficiency at 0.8in Oil ...... 35
Figure 3-19: Rotational Velocity at 0.85in Oil ...... 36
Figure 3-20: Output Power at 0.85in Oil ...... 37
Figure 3-21: Efficiency at 0.85in Oil ...... 37
Figure 3-22: Rotational Velocity at 0.9in Oil ...... 38
Figure 3-23: Output Power at 0.9in Oil ...... 39
Figure 3-24: Efficiency at 0.9in Oil ...... 39
Figure 3-25: Rotational Velocity at 0.95in Oil ...... 40
Figure 3-26: Output Power at 0.95in Oil ...... 41
Figure 3-27: Efficiency at 0.95in Oil ...... 41
Figure 3-28: Rotational Velocity at 1in Oil ...... 42
Figure 3-29: Output Power at 1in Oil ...... 43
Figure 3-30: Efficiency at 1in Oil ...... 43
Figure 3-31: Rotational Velocity of the Turbine Across all Wind Velocities...... 44
Figure 3-32: Percent Error ...... 45
Figure 3-33: Output Power from Generator and Air Power ...... 46
Figure 3-34: Output Power Error ...... 47
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Figure 3-35: Efficiency ...... 48
Figure 3-36: Output Power of Turbine using the Torque Meter and Generator ...... 50
Figure 3-37: Rotational Velocity, Torque Meter vs. Generator ...... 51
Figure 3-38: Torque from Tests Taken with Fan 12in from Turbine...... 52
Figure 3-39: Rotational Velocity Taken from Tests with Fan 12in from Turbine ...... 53
Figure 3-40: Output Power Calculated from Tests Taken with Fan 12in from Turbine ...... 54
Figure 3-41: Efficiency Calculated from Tests Taken with Fan 12in from Turbine ...... 54
Figure 3-42: Torque Taken from Tests with Fan 24in from Turbine...... 55
Figure 3-43: Rotational Velocity from Tests Taken with Fan 24in from Turbine ...... 56
Figure 3-44: Output Power Calculated from Tests Taken with Fan 24in from Turbine ...... 57
Figure 3-45: Efficiency Calculated from Tests Taken with Fan 24in from Turbine ...... 57
Figure A-1: Dimensioned Drawing for Turbine Shaft ...... 62
Figure A-2: Dimensioned Drawing of the Flanged Shaft Mount for the Turbine ...... 63
Figure A-3: Dimensioned Drawing of the Spoked Arm Wheel for the Turbine ...... 64
Figure A-4: Dimensioned Drawing of the Top Half of the Turbine Blade ...... 65
Figure A-5: Dimensioned Drawing of Bottom Half of the Turbine Blade ...... 66
Figure C-1: Torque Meter Calibration Sheet ...... 88
Figure C-2: Torque Meter Spec Sheet ...... 89
Figure C-3: Tachometer Spec Sheet Side 1 ...... 90
Figure C-4: Tachometer Spec Sheet Side 2 ...... 91
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List of Tables
Table 2-1: Expected Torque Values ...... 12
Table 2-2: Wind Meter Calibration at 0.85in Oil ...... 21
Table 3-1: Approximate Air Velocities in m/s ...... 23
Table B-1: In Wind Tunnel with Generator, 0.55in Oil ...... 67
Table B-2: In Wind Tunnel with Generator, 0.6in Oil ...... 68
Table B-3: In Wind Tunnel with Generator, 0.65in Oil ...... 69
Table B-4: In Wind Tunnel with Generator, 0.7in Oil ...... 70
Table B-5: In Wind Tunnel with Generator, 0.75in Oil ...... 71
Table B-6: In Wind Tunnel with Generator at 0.8in Oil ...... 72
Table B-7: In Wind Tunnel with Generator at 0.85in Oil ...... 73
Table B-8: In Wind Tunnel with Generator at 0.9in Oil ...... 74
Table B-9: In Wind Tunnel with Generator at 0.95in Oil ...... 75
Table B-10: In Wind Tunnel with Generator at 1in Oil ...... 76
Table B-11: In Wind Tunnel with Generator Averages ...... 77
Table B-12: In Wind Tunnel with Torque Meter, Test 1 ...... 77
Table B-13: In Wind Tunnel with Torque Meter, Test 2 ...... 78
Table B-14: In Wind Tunnel with Torque Meter, Test 3 ...... 79
Table B-15: Out of Wind Tunnel with Torque Meter at 12in, Test 1 ...... 80
Table B-16: Out of Wind Tunnel with Torque Meter at 12in, Test 2 ...... 81
Table B-17: Out of Wind Tunnel with Torque Meter at 12in, Test 3 ...... 82
Table B-18: Out of Wind Tunnel with Torque Meter at 12in, Test 4 ...... 83
Table B-19: Out of Wind Tunnel with Torque Meter at 24in, Test 1 ...... 84
Table B-20: Out of Wind Tunnel with Torque Meter at 24in, Test 2 ...... 85
Table B-21: Out of Wind Tunnel with Torque Meter at 24in, Test 3 ...... 86
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Table B-22: Out of Wind Tunnel with Torque Meter at 24in, Test 4 ...... 87
Table C-1: Wind Meter Calibration at 0.425in Oil ...... 92
Table C-2: Wind Meter Calibration at 0.5in Oil ...... 93
Table C-3: Wind Meter Calibration at 0.65in Oil ...... 94
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Nomenclature
APr : Projected area of the turbine
I: Current
P: Pressure
Patm : Atmospheric Pressure
PT: Power from Turbine
PW: Wind Power
R: Resistance
T: Torque
V: Voltage
VW: Wind Velocity