Abstract

Purpose/Hypothesis

Literature Review

Experimental Design

Materials/
Equipment

Test Station Construction

Procedure

Observations

Calculations

Results

Discussion
Sources of Error

Applications
Phase 2

Glossary of Terms

Acknowledgements
Bibliography

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Statistical Analysis

Statistics are a way of assessing the quality of the data collected. Standard Deviation (SD) is a mathematical calculation used on a set of data to assess the amount of scatter or dispersion from the mean, or average. It is an indication of accuracy. If all data points are exactly the same, the SD would be equal to 0.

Coefficient of Variation (CV) is a mathematical calculation (standard deviation x 100 /mean) that provides information that can be used to compare different sets of data. A CV of 10% is considered acceptable.

Wind Speed Measurements:
The highest SD was 0.29 and the highest CV was 5.60%.

A grand mean of all low wind speed observations was calculated as 4.51 with a SD of 0.127 and CV of 2.82%.

A grand mean of all medium wind speed observations was calculated as 5.11 with a SD of 0.124 and CV of 2.42%.

A grand mean of all high wind speed observations was calculated as 5.76 with a SD of 0.123 and CV of 2.14%.

Over all, differences in the wind speed at each of the fan speeds for each set of observations was not very significant.

Weight Measurements:

The highest SD was 0.08 and the highest CV was 8.94%.

RPM Measurements:

The highest SD was 29.75 and CV was 3.72%.

Over all, the RPM measurements were the most consistent with the highest CV of 3.72%, followed by wind speed at 5.60% and weight at 8.94%. However, all CVs were less than 10%.

Conclusions

I predicted that the amount of torque and mechanical energy produced would be affected by the number of rotors and their size, placement and orientation on a single horizontal axis windmill. My hypotheses were correct.

1. Larger rotors produce more torque and mechanical energy than smaller rotors.

2. Increasing the number of rotors from one to two increases the amount of torque and energy produced at every fan speed tested.

3. Rotor size, placement and orientation affected the amount of torque and mechanical energy produced. Overall, two 28 cm rotors, placed 3.5 cm apart with the blades offset produced the most torque and mechanical energy and the highest tip speed ratios. This rotor variation produced more than double the amount of torque and mechanical energy than a single 28 cm rotor.

Discussion/Sources of Error