Modeling propeller in heliciel software

Tutorial design a boat propeller (3): Construction adjusting the rotation speed and radius at blade root

Tutorial design a boat propeller (1)

Tutorial design a boat propeller (2)

Tutorial design a boat propeller (3)

Tutorial design a boat propeller (4)

Tutorial design a boat propeller (5)

Understand and master the boat screew propeller design part (3/5): Construction adjusting the rotation speed and radius at blade root:

propeller boat 2 blades

when we have defined the operating point, we have left the rotation speed, it is time to take care of it...

We could test the propeller rotational speeds, changing this setting and rebuilding, until you find a speed with a good efficiency. But these iterations may be long and tedious. We therefore take this opportunity to discover a new function Heliciel: Optimizing the rotational speed depending on the optimum efficiency.

optimum propeller rotational speed

Click "search optimum propeller rotation speed 2 blades". Heliciel execute the search rotational speed with the maximum kinetic efficiency. (the propulsive efficiency is not a reference in this procedure for propellers with fluid velocities close to 0 the propulsive efficiency would not be significant)
Here we get a kinetic efficiency of 0.86 at 200 rev / min:

optimum efficiency of boat propeller

After the search of optimum speed you are asked if you want to rebuild your 3D propeller, click yes .We get our propeller rebuilt with a new twist, suitable for its speed, providing the optimum efficiency:

2 blades boat propeller

The propulsive efficiency of our propeller (thrust * velocity) / (torque shaft *speed rotation) is 0.861 is not far from the maximum!
It's not bad but looking more closely the performance results:

2 blades boat propeller performances

We observe that we are far from our specifications:
  • Cruising speed: 3 knots
  • Thrust required 105 newtons
  • Power available to the propeller shaft: 192 watts
How to increase thrust to get our 105 Newtons? We will take this Question to deepen the problem of optimization of the propeller::
to increase thrust , Several solutions are available to us:
  • Increase rotational speed:
    simple, just change the speed until the desired thrust. let's try now: increasing the speed until reaching our power available to the shaft: after a few tries speed change and reconstruction construire helice, nous obtenons un résultat de 197 watts pour 101.3 newtons de poussée à 360 t/mn avec un rendement de 0.79. It begins approaching our specifications.

boat propellers efficiency

       

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