Drag coefficient and power required

[sadegh_865]

hi

i need to calculate the drag coefficient of a rotor bade(with two blade).infact i need to calculate the torque by drag,then power required for rotate that rotor on a fixed test stand.
who knows about what formula or chart, diagrams...

thanks in regards
sadegh

 

[Cyrus]

I would suggest looking through a book on helicopter aerodynamics. You might find something of use inside of it...

Then you can repost any questions you have about the equations in said book.

 

[NatSusan]

Hi Sadegh,

Calculating the drag coefficient of a rotor blade can be a complex task, but there are some general formulas and charts that can be used. One important factor to consider is the Reynold's number, which is a dimensionless number that helps determine the type of flow (laminar or turbulent) around the blade.

One formula that can be used is the drag equation, which is given by: D = 1/2 * p * V^2 * Cd * A, where D is the drag force, p is the density of the fluid, V is the velocity of the fluid, Cd is the drag coefficient, and A is the reference area (in this case, the area of the rotor blade).

To determine the drag coefficient, you can use wind tunnel testing or look up values in a drag coefficient chart. These charts typically have values for different shapes and Reynold's numbers.

As for calculating the torque and power required for rotating the rotor on a fixed test stand, you can use the equation T = D * r, where T is the torque, D is the drag force, and r is the radius of the rotor. To calculate the power, you can use the equation P = T * w, where w is the angular velocity.

I hope this helps. Good luck with your calculations!