Hi,
I searched and i understood that pitch angle is as attachment(please be careful that diagram illustrates pitch angle, but labels it just "pitch"). But What is turbine pitch?
I simulated an axial turbine and this turbine have straight blades not twisted blades.
I am grateful that explain me about pitch with pictures.
Thanks.
http://www.mpoweruk.com/wind_power.htm
For wind turbines and Kaplan turbines, "the turbine pitch, blade pitch, or simply pitch" refers to the pitch angle.
On the other hand ,i.e. in the steam or gas turbine with large number of blades, The word "pitch" refers to the circumferential distance between two adjacent blades.
Hello Sir,
the pitch angle, also called local pitch angle, is composed of two parts. This parts are the global pitch angle and the twist angle of the blade. The twist angle is fixed.
Therefore, for your blades the local and global pitch angle is equal.
I build a small example for you.#
Sometimes people use the word "turbine pitch" for the wind tracking of the tower.
Mr. Elasakka also mentioned the circumferential distance between two blades, which is also named pitch or pitch angle.
Hansen gives a very good overview. See attachment.
Contact me for any questions.
Regards
Fabian
Article Aerodynamics of wind turbines: Third edition
Always a confusing topic, in my opinion. Pitch is often expressed as an angle, but then you ask, angle where along the blade, from the axis to the tip? Angle varies, when the turbine is efficiently designed. Assuming air speed is constant along the radius of the propeller/turbine, the angle has to be much greater at the center (where blade velocity is lowest) than at the tip of the blade. So, angle is measured at some distance along the radius, typically toward the tip of the blade. See this, for example:
http://propellerhub.com/2-uncategorised/15-measuring-pitch
I have also seen pitch expressed as a percent value, and to make things even more confusing, there are (at least) two different ways of expressing pitch as percent.
A common method, assuming variable pitch propellers or turbines, is to express the percent as "percentage of maximum pitch." So this definition of pitch as percentage only applies to any particular design of propeller.
Another definition of percent pitch is, when the propeller rotates a full 360 degrees, how far does the propeller advance compared with its diameter? So for instance, if a propeller of 1 m diameter moves forward by 1.2 meters, in one full revolution, then its pitch would be expressed as 120%.
So when someone mentions just "pitch," without explaining how he is defining pitch, it can indeed be confusing!
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