In Tube Wind Turbine

See other identical thread....

Make 1st an attempt to know how much power does the air flow contain. Normally you can recover less 30% of it in mechanical power and further with a loss of round 20% the last in electrical power. The conversion is very simple you compute at which speed the turbine will work (depends on the turbine design) and then you compute which speed amplifier you have to use to obtain the speed you want to have.

Do you really mean 200 meters per hour? That would be .055 meters per second, which is far too slow across a 250 mm tube to obtain anything close to 1-2kW.

More on wind turbines here. You can calculate the energy available for a 250mm disc of breeze at .055 m/s, and you will find that even if you converted 100% of the available energy, you wouldn't produce anything close to a kW (or even a watt).

Here is a spec sheet (http://www.windenergy.com/documents/spec_sheets/3-CMLT-1095_Air_Breeze_spec.pdf - sorry, link no longer available) for an available small wind turbine which produces 200 W. Its rotor is 1.17 meters across, and it requires a wind speed of 12.5 m/s for full output. Power varies with the cube of speed, so this turbine would produce (.055/12.5)³ x 200 W, or 0.0000170368 W. It is larger than your tube, however.

It is 200m/s

sory

Oh here you are gain I am glad. have in mean time understood the deep meaning or have you other questions?

have you computed the energy/power contend of your air stream? With 200m/s you are at about Mach 0.6!

Quite a speed and a tremendous energy behind. How do you generate this flow? Is your intention to recover energy from this flow because 1 kw could be too small. ? Under such conditions the problem will be less the speed amplifier as probably a speed reducer!

You see I am not ashamed to ask questions if I do not understand something.

Ah ha! Then you'd have loads of power available.

Pitch is the distance a propeller would advance through the air if it were simply acting like a wood screw. With a 200m/s wind, the pitch required for 1500 rpm would be 200m/s x 60/1500 = 8 meters. This is an extremely high number for a small propeller. (The leading edge of the blades would appear to be pointing almost straight forward.) If you kept the speed down to 1500 rpm, nothing exotic would be required in terms of bearings or structural materials (if the load is only 1-2 kW). However the drag on the blades, even if very carefully made, would be very high, and the blades could break off at the hub from drag alone, or from excessive torque, if the generator locked up. The lower unit of a very small outboard motor (2-3 hp) could be adapted to mount the blade in the tube. (An ordinary water prop -- pitch around .25m.-- could not be used, however, because the rpm generated would be many times too high, leading to destruction of the prop, bearings, personnel standing near, etc.)

At 200m/s the power available is 3600³ times as great as at 200m/h. Of course, 3600³ is a very large number: 46656000000. This, times the tiny power available at 200m/h (.000017 W) gives you a big number: 793,152 W (793 kW). A good deal of care would be required in design, working around the pipe, etc. This sounds like the output of a jet engine from a biz jet.

In another CR4 post, I put in a link to a windmill blade design paper.