Calculating prop size for wind generators

In summary, the speaker is trying to create a wind turbine and needs to calculate the size of the prop needed to power an electrical generator. The generator being used is a 2800 watt one with the following specifications: max. AC watts of 3000, rated watts of 2400, HP required of 5, RPM of 3600, kVA rating of 2.4, voltage of 120, amps at 120V of 20, single phase, and frequency of 60Hz. The speaker is seeking help in calculating the size of the prop needed and is considering adding a gearbox to the turbine. They also mention that there are resources available online for calculating prop
  • #1
mazzy187
1
0
It's been a while since I've been in the classroom and I'm having trouble figuring this one out. I'm trying to create a wind turbine and I need to calculate the size of the prop needed to power and electrical generator. For ease of numbers let's say I'm using a 2800watt generator. (http://www.grainger.com/Grainger/items/6HJ87 [Broken])

Max. AC Watts 3000
Rated Watts 2400
HP Required 5
RPM 3600
kVA Rating 2.4
Voltage 120
Amps @ 120V 20
Phase Single
Hz 60

With this information, I'm sure we can calculate the size of the prop that I need to turn it at 3600RPM... I just don't remember how. =)
 
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  • #2
You probably want a gearbox in the way, a wind powered turbine isn't going to be running at 3600rpm (at least not on this planet)

There are a bunch of sites about wind power and calcualtors for sizing props, tower height etc. They also describe which generators are most suitable,
 
  • #3


Hello,

Calculating the size of the prop for a wind turbine is a complex process that involves several factors, such as wind speed, blade design, and generator efficiency. However, we can use the information provided to estimate the size of the prop needed for a 2800-watt generator.

First, we need to determine the power coefficient (Cp) of the wind turbine, which is a measure of its efficiency in converting wind energy into electrical energy. The power coefficient is affected by the blade design and wind speed, among other factors.

Assuming a typical power coefficient of 0.4, we can calculate the rotor area (A) needed to generate 2800 watts of power at 3600 RPM using the following formula:

A = (P / (Cp * ρ * V^3 * n))

Where:
P = Power (2800 watts)
Cp = Power coefficient (0.4)
ρ = Air density (1.225 kg/m^3 at sea level)
V = Wind speed (assumed to be 10 m/s for this calculation)
n = Number of blades (assumed to be 3 for this calculation)

Plugging in the values, we get:

A = (2800 / (0.4 * 1.225 * 10^3 * 10^3)) = 0.57 m^2

Next, we can use the rotor diameter (D) to calculate the rotor area using the following formula:

A = (π/4) * D^2

Rearranging the formula, we get:

D = √(4 * A / π) = √(4 * 0.57 / π) = 0.85 m

Therefore, the estimated size of the prop needed for a 2800-watt generator would be a rotor with a diameter of 0.85 meters. However, this is just an estimation and the actual size may vary depending on other factors.

I hope this helps you in your project. Good luck!
 

1. How do I calculate the appropriate prop size for my wind generator?

The prop size for a wind generator can be calculated by taking into account the wind speed at the installation site and the desired power output. A commonly used formula is P = 0.5 x p x A x v^3, where P is the power output, p is the air density, A is the swept area of the propeller, and v is the wind speed. By rearranging this formula, you can solve for A, which will give you the appropriate prop size for your wind generator.

2. What is the optimal prop size for a wind generator?

The optimal prop size for a wind generator will vary depending on the specific site conditions and desired power output. However, in general, a larger prop size will be more efficient at capturing wind energy, but it may also create more noise and be more expensive. It is important to carefully consider all factors when determining the optimal prop size for your wind generator.

3. How does the shape of the propeller affect its size for a wind generator?

The shape of the propeller can affect its size for a wind generator in several ways. A more streamlined and aerodynamic shape will typically require a smaller size to achieve the same power output as a less efficient shape. Additionally, the number of blades on the propeller can also impact its size, with fewer blades usually requiring a larger size for the same power output.

4. Can I use a prop size calculator to determine the appropriate size for my wind generator?

Yes, there are many online prop size calculators available that can help you determine the appropriate size for your wind generator. However, these calculators may not take into account all site-specific factors, so it is important to use them as a general guide and not rely solely on their results.

5. How often should I reassess the prop size for my wind generator?

It is recommended to reassess the prop size for your wind generator every few years, especially if there have been changes in the site conditions or desired power output. It is also important to regularly monitor the performance of your wind generator to ensure it is functioning optimally and make any necessary adjustments to the prop size if needed.

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