Reply To: Model Turbines

[Turbine GuyParticipant @turbineguy]

I made the following spreadsheets to calculate the hydraulic torque using the velocities found from a typical velocity diagram like shown below. I coded the velocities in the spreadsheets to match the velocity diagram. The propeller used for the test data was the largest propeller I have that had performance data down to speeds as low as 1,000 rpm. I thought that finding the torque at this low of a speed should be close to the stall torque since the rotational losses would be almost negligible. The hydraulic torque is determined by the entrance velocity in the rotor movement direction, Vw, and the exit velocity in the rotor movement direction, Vw1. As you can see from the spreadsheets, Axial Turbine 4A has a much lower Vw than Tangential Turbine 5B, but a much higher Vw1 so the net result is almost the same torque. These spreadsheets show the importance of the velocity coefficients and how they effect the torque. I will use similar spreadsheets in the next post to illustrate  their effect at higher speed using the GWS EP 2508 propeller.

Edited By Turbine Guy on 23/03/2023 17:45:35