Is there a limit on how fast a propeller can spin?

Question

If there's even more power would the propeller be able to spin infinitely fast or is there a limit? What is the limit if there is?

Answer 1

The propellers of an aircraft are usually spun with RPM kept such that the tips dont exceed the speed of sound. So depending on the rotor blades length, the spinning speed varies, the smaller ones spinning much faster. I believe structural damage occurs at much higher speeds than these sonic limitations.

Answer 2

For one thing,there is a difference if the propeller rotates in air (airplane) or in water (ship).

I don't think there is an actual limit, other than the power requirements and the resistence of tha material itself. There is, however, a limit on how efficient the propulsionof the propeller is, and this is still a matter of research and development.

for airplanes, only small ones still use propellers. For ships, rotating too fast produces an effect called cavitation, which manifests itself in the apparition of bubbles in water on the propeller, on the back side, due to the reduction in pressure; the bubble then collapses violently, producing a shock wave which damages the propeller.

Answer 3

There are several failure methods for a propeller. Spinning too fast would be a function of the material properties and at what temperature you are using the propeller at. In gas powered turbines (like on an airplane) there are very high temperatures that the turbine blades have to endure, and they spin at high speeds. Pure overspeed will cause the turbine blade to exceed the tensile strength of the material, the blade will tear off and shoot it though the casing at high velocities (a bad thing).

Answer 4

It is obvious that there are limits as to the the power of the engine driving a propellor and like in the previous answer the limits exerted through torque, but then the question has to be re-cast: barring all the limitations, can a propellor's speed go on increasing without limit? I think the answer is no.

Answer 5

Well, eventually the propeller will disintegrate due to centrifugal force. Before that, though, cavitation will occur. That's where the blade leaves a vacuum in its wake. That means the next blade hits the vacuum and thrust drops. It also causes a lot of vibration. In air, this occurs as the speed of sound. In water, it's considerably lower due water's higher density (inertial).

Answer 6

In water, cavitation limits how much force can be exerted by the prop. In air, you are mainly limited by air density, which depends on altitude. Of course, you must also consider blade material and structure as to how much force it can handle. A more specific question might give better answers.

Answer 7

I do not know whether it is true for propellers, but while designing rotors of turbine etc, one factor which is considered is that the speed of the tip of the rotating body should not exceed the speed of sound.

Answer 8

no beacause too much torque will break the propeller
and sometimes will not move if there is too much torque