vortex generator

westtm45

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Has anyone used vortex generators on rotor blades? Would they be as helpful in generating lift at low rotor speeds as they are on fixed wings?
Or is it a nonstarter or even applicable to rotor blades .
 

Aerofoam

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At those speeds, they would just create drag. There MAY be a way to implement some sort of augmentation that is useful,
but in general VGs are a band aid to fix a performance spectrum of an airfoil. That being said some airfoils benefit from a textured surface, but this is not usually the case at high speed, or high Reynolds Numbers..
I have rather large VGs on the LE of my solar panels on my van....
 

j4flyer

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Woodland, Ca
Vortex generators are designed to keep the airflow over the flying surface during critical angles of attack. They allow the ailerons to retain authority even at slow forward speed. I don’t believe our rotors suffer from loss of authority during slow speed events. They even maintain authority in vertical descent. If the question is about a better airflow for speed then I believe you have to look at different airfoil designs or a streamlined cover for the hubbar. Probably the people who could answer this best Chuck Beaty and Jim Vanek, have already tried most ideas for improvements on blade systems.
 

Abid

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Vortex generators are designed to keep the airflow over the flying surface during critical angles of attack. They allow the ailerons to retain authority even at slow forward speed. I don’t believe our rotors suffer from loss of authority during slow speed events. They even maintain authority in vertical descent. If the question is about a better airflow for speed then I believe you have to look at different airfoil designs or a streamlined cover for the hubbar. Probably the people who could answer this best Chuck Beaty and Jim Vanek, have already tried most ideas for improvements on blade systems.

I don't think that's correct. You are mixing up slow speed of the aircraft fuselage/system with speed of its wing (rotary). Our rotors will kill you if they get too slow. You got to think like you are a fly on the wing (rotor) when thinking of rotor speed (not airspeed of the gyroplane). Doesn't mean to say that VG's would solve some big problem but just that you are stuck in your seat instead sitting on the rotor blade when conceptualizing this
 

Jean Claude

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VG's work because of their yaw angle which stirs the air in the upper layers and restores speed in the boundary layer.
Unfortunately the angle of the airflow changes according to the azimuthal position and the stirring on the retreating blade would disappear or become harmful for other azimuths.
 

j4flyer

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I don't think that's correct. You are mixing up slow speed of the aircraft fuselage/system with speed of its wing (rotary). Our rotors will kill you if they get too slow. You got to think like you are a fly on the wing (rotor) when thinking of rotor speed (not airspeed of the gyroplane). Doesn't mean to say that VG's would solve some big problem but just that you are stuck in your seat instead sitting on the rotor blade when conceptualizing this
I may not be correct. However, I’m not mixing up the two. I’m merely pointing out the use of VGs. Since VGs are used on fixed wing aircraft I felt it necessary to draw attention to their intended use via examples in type. The below post expounds on VGs use in adhering boundary layers to the surface. I agree with the post. I’m not sure VGs on rotorblades would have a positive effect since we (as far as I’m aware) don’t suffer from boundary layer separation. Anyway, those are my thoughts and I’m just a Forum poster not an engineer.
 

Jean Claude

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I piloted gliders C800, Bijave, C 310, airplanes Piper J3 , PA 28, Jodel D117, DR 220, Cessna 150, C
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About 500 h (FW + ultra light)
The blades also suffer from the phenomenon of stalling, due to which a small part of the auto-rotating torque is lost on the retrating side between 0 and 0.5 R.
But the effect is extremely small and it would be much more efficient and easier to deal with the separations on the rear of the nacelle.
 
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