Through the wind tunnel lab the engineers were able to study the effects of various propeller configurations of changing motor power. This allowed the students to calculate the propulsion efficiency and in turn determine which propeller configuration would be most efficient for the AEV. Students tested the pusher configuration which spun the propeller in the clockwise direction and the puller configuration which spun the propeller in the counterclockwise direction. Wind speed was constant and power setting for motor began at 60% and decreased by increments of 5%. The thrust reading, current, and RPM were measured and were then used to determine all of the following results as well as which propeller configuration was more efficient and at what arduino power setting.
3030 Puller Configuration:
wind tunnel speed: 3.0 m/s and battery supply: 7.4 volts
For the 3030 Puller configuration we collected the data as seen in the table. With this data we are able to determine many things such as propulsion efficiency and the advanced ratio of power output and input. We were also able to see trends in thrust and % power.
The second graph shows that the maximum on the graph occurs at (0.311,9.792). It occurs at a power of 45% and propulsion efficiency of 9.792%. Which basically tells us that in order to have a propulsion efficient AEV the power would need to be set at motorSpeed(4,45) and in turn require less power from the battery. There are a lot of what ifs, however, with this experiment and would need further testing to check that the AEV would even move at this power.
The graph shows that as thrust, which is a sudden “push” on the AEV, increases the amount of power for the motor increases. This makes sense because we know from lab that as the power increases, the AEV moves at a higher speed.
3030 Pusher Configuration:
wind tunnel speed: 2.9 m/s, battery supply: 7.4 volts
Wind Tunnel Analysis Data for 3030 Pusher
The data shown in the above table allowed our team to determine propulsion efficiency and the advanced ratio of power output and input. We were also able to see trends in thrust and % power just as we did for the 3030 Puller.
Propulsion Efficiency versus Advance Ratio
This graph shows that the maximum occurs at (1.36, 194.9). The power at this point is 10%. This tells us that in order to have a propulsion efficient AEV, the power would need to be set at motorSpeed(4,10) and in turn will require more power from the battery over time. Because the power is set so low, the AEV may not even move. If it does, it most likely not finish the mission in the allotted time.
Thrust (grams) versus % Power
The graph is much like the graph above for the puller configuration. It also shows the direct relationship between thrust and power for the motors. This is feasible considering previous labs have show that the AEV has a higher speed as the power increases.
Results:
While comparing the results from each configuration, the team can conclude that the 3030 puller propeller configuration produces a more efficient propulsion. This can be used to determine what speed the team sets the motor to for the AEV in order to have the most efficient AEV running and prevent using unnecessary power from the battery.
*side notes: the wind tunnel lab was a simulation and not all numbers, such as speed and efficiency, will be exact while programming when the propellers are attached to the AEV*