Engineering: Wind Turbine Blade Pitch Data Analysis
Using data to choose efficient wind turbine blade angles
Engineering: Wind Turbine Blade Pitch Data Analysis
Using data to choose efficient wind turbine blade angles
Engineering - Grade 6-8
- 1
A student team tested a model wind turbine at four blade pitch angles. The electrical output was measured in volts. Data: 0 degrees = 1.2 V, 10 degrees = 2.4 V, 20 degrees = 3.1 V, 30 degrees = 2.0 V. Which blade pitch produced the highest voltage?
Look for the largest voltage value in the data set.
The 20 degree blade pitch produced the highest voltage because it had the greatest output, 3.1 V. - 2
Using the same data, describe the pattern in voltage as the blade pitch changes from 0 degrees to 30 degrees.
The voltage increases from 0 degrees to 20 degrees, then decreases at 30 degrees. This suggests that 20 degrees may be close to the best blade pitch for this test setup. - 3
A turbine produces 2.8 V at a 15 degree pitch and 3.4 V at a 25 degree pitch. How much did the voltage increase?
Subtract the smaller voltage from the larger voltage.
The voltage increased by 0.6 V because 3.4 V minus 2.8 V equals 0.6 V. - 4
A team ran three trials at a 20 degree blade pitch. The voltage readings were 3.0 V, 3.2 V, and 3.1 V. Find the mean voltage.
Mean means average.
The mean voltage is 3.1 V. Add the values to get 9.3 V, then divide by 3 trials: 9.3 ÷ 3 = 3.1 V. - 5
A team ran three trials at a 30 degree blade pitch. The voltage readings were 2.1 V, 2.0 V, and 2.2 V. Find the mean voltage.
The mean voltage is 2.1 V. Add the values to get 6.3 V, then divide by 3 trials: 6.3 ÷ 3 = 2.1 V. - 6
Compare the mean outputs from a 20 degree pitch and a 30 degree pitch. The 20 degree pitch mean was 3.1 V. The 30 degree pitch mean was 2.1 V. Which pitch performed better, and by how much?
Better performance means a higher voltage output in this test.
The 20 degree pitch performed better by 1.0 V because 3.1 V minus 2.1 V equals 1.0 V. - 7
A graph shows voltage output on the y-axis and blade pitch angle on the x-axis. The graph rises until 20 degrees and then falls after 20 degrees. What engineering conclusion can you make from this graph?
An engineering conclusion is that the best tested blade pitch is about 20 degrees because it produced the highest voltage before the output began to decrease. - 8
A wind turbine test used these average outputs: 5 degrees = 1.8 V, 15 degrees = 2.9 V, 25 degrees = 3.0 V, 35 degrees = 1.9 V. Which two pitch angles had nearly the same output?
Look for two voltage values that are closest together.
The 15 degree and 25 degree pitch angles had nearly the same output because 2.9 V and 3.0 V differ by only 0.1 V. - 9
A team wants to choose between 15 degrees and 25 degrees. The 15 degree pitch produced 2.9 V, and the 25 degree pitch produced 3.0 V. If the 15 degree pitch is easier to build accurately, which pitch might be the better engineering choice? Explain.
The 15 degree pitch might be the better engineering choice because it produces almost the same voltage as 25 degrees but is easier to build accurately. Engineers often consider performance and practicality together. - 10
In one test, the wind speed was not kept the same for every pitch angle. Why is this a problem when analyzing blade pitch data?
A fair test changes only one main variable at a time.
This is a problem because changes in wind speed can also change the voltage output. If wind speed is not controlled, it is harder to know whether the blade pitch or the wind speed caused the result. - 11
Identify the independent variable and dependent variable in this experiment: Students change the blade pitch angle and measure the voltage output.
The independent variable is the blade pitch angle because it is changed by the students. The dependent variable is the voltage output because it is measured as the result. - 12
A data table lists these results: 0 degrees = 0.9 V, 10 degrees = 1.7 V, 20 degrees = 2.6 V, 30 degrees = 2.4 V, 40 degrees = 1.5 V. Which pitch angle would you recommend for this turbine, and what evidence supports your choice?
Choose the pitch angle with the strongest measured performance.
I would recommend 20 degrees because it produced the highest voltage, 2.6 V, in the data table. This evidence shows it was the most effective tested pitch angle. - 13
A team thinks a 45 degree pitch will always produce more power because the blades face the wind more directly. Their data show: 15 degrees = 3.0 V, 30 degrees = 2.5 V, 45 degrees = 1.6 V. Does the data support their claim? Explain.
The data does not support their claim. The 45 degree pitch produced only 1.6 V, while the 15 degree pitch produced 3.0 V, so facing the wind more directly did not create more voltage in this test. - 14
A model turbine has a 20 degree blade pitch and produces 3.2 V. After adjusting the pitch to 25 degrees, it produces 3.5 V. What percent increase is this? Round to the nearest whole percent.
Use percent increase = increase ÷ original value × 100.
The percent increase is about 9%. The increase is 0.3 V, and 0.3 ÷ 3.2 = 0.09375, which is about 9% when rounded to the nearest whole percent. - 15
You are planning the next test after seeing this data: 10 degrees = 2.2 V, 20 degrees = 3.5 V, 30 degrees = 3.3 V, 40 degrees = 2.0 V. What two new pitch angles would you test next to find the best design more precisely? Explain your choices.
Choose angles near the best result, not far away from it.
I would test 15 degrees and 25 degrees next because the best result was near 20 degrees, and these angles are close to it. Testing nearby angles could help find whether the true best pitch is slightly below or above 20 degrees.