Sure it does. But you are claiming that that momentary increase in the angle of attack is the primary source of propulsive energy, which is not true. It probably contributes much less than 1% of the total energy transfer in each cycle. So you missed the point.

Nonsense

Show me the research that supports your claim. I have never seen any such research. I have explained why you are wrong.

“lift-type” and “drag-type” are shorthand terms that are in common usage. Those terms imply that the torque is prominently produced by one or the other. There are additional types of VAWT, but they are typically described separately, such as a “flutter-foil VAWT”.  Some lift-type VAWT employ drag during starting in order to achieve stronger starting torque than fixed-blade, lift-type VAWT.

Again, you are saying things that are just nonsense. Your technical arguments are based on nonsensical assumptions. There is no sense in correcting them because you have a perpetual fountain of misinformation.

You seem to not even know the difference between lift and drag, as illustrated below when you claim that non-rotating cylinders create lift. They don’t – unless you choose to define lift as equivalent to the oscillations due to vortex shedding which can cause a cylinder to vibrate. But that is not what you said, so that is not what you meant. Yet you insist on making grand pronouncements about aspects of aerodynamics. Why? Are you trying to build a reputation for being ridiculous? If you are, be assured that you are well on your way.

You claim that a Flettner rotor tipped away from vertical, in a wind, develops some lift. If it’s spinning, it’s already producing some lift. Tipping it will redirect the lift and drag vectors. Are you aware that an object can be elevated by the wind due entirely to drag? Think of objects swept up by a tornado or a hurricane.

Once again, you seem to be trying to make grand connections without paying attention to the details.

I have no idea what you are talking about. In sailing, there is no such term as “sailboat tacking phase loss”. How have you managed to never learn colloquial American English?

Now you have it really backwards. It is up to the person making a claim to support that claim as best they can.  It is not up to someone else to show that every crazy idea must be refuted with research. That’s absurd. As usual.

The position of a VAWT blade, relative to the wind, is described by its azimuth angle. Introducing the term “phase position” or “phase state” to replace “azimuth angle” gains nothing and causes confusion.

The azimuth angles are also divided into quadrants.

0 degrees, by convention, is where a fixed blade is heading directly into the wind. Defining the most windward position as 0 degrees can be done, but it is considered non-standard, and it can introduce confusion. So it is generally avoided.

The quadrants can be paired in combinations, so we can talk about the upwind side or the downwind side, or the advancing side or the retreating side.

What you say about VAWT is incorrect. You don’t understand how VAWT work.

So it makes no sense for you to try to theorize about VAWT, or compare them to HAWT, before understanding them.

Once again, you are talking nonsense.

DaveS,

My conclusion is that you are right and I am wrong. A javelin can develop lift. Here is my analysis and the source of my confusion:

I consider it important to distinguish between whether lift is produced predominantly by a pressure increase or by a pressure decrease. That is because, in my experience, careful distinctions can sometimes lead to insights and inventions.

You are correct because lift and drag are defined as vectors. So no attached flow, as on the upper surface of a wing (with an angle of attack below stall) needs be present for an object to be said to develop lift. So a javelin with no attached flow can still develop lift (meaning a lift vector).

The clearest example of lift without attached flow is hydroplaning. The lift is very high. Yet no attached flow on an upper surface is necessary, and it is seldom present.

So an attached flow (to produce a reduced pressure) is only one of the ways to produce a lift vector. An attached flow can greatly increase the lift vector. But it is not essential.

How do we know that a javelin develops lift? I assume that we must throw it the same way each time, but change the angle of attack upon launch. Then we measure how far it flies to determine the best L/D ratio. The farthest throw is the one with the best L/D ratio. No attached flow is necessary. So the best angle of attack seems to be the one that produces the best balance between retarding drag (form drag plus skin drag expressed as the drag vector) and “lifting drag” (drag which creates the lift vector, like apparent wind acting on the underside of a wing).

What was confusing to me was that the physical phenomenon of drag can create a vector of lift. For example, the bottom side of a wing (with an angle of attack) will create a lift vector even though the top of the wing may be completely stalled with no attached flow.

Consequently, that physical phenomenon of attached flow that enhances lift is not itself “lift”. It is not even a form of “lift”. Attached flow that reduces pressure cannot be called “lift”. It is only a contributor to lift, a source of lift. But it is not “lift” itself. That is because lift is not a physical phenomenon. It is only a vector. Attached flow that reduces pressure is a physical phenomenon. But it is not a vector. So it is not “lift”. A physical phenomenon can induce a vector. But a phenomenon cannot be a vector.

All that is necessary to create lift is for a moving object to deflect air so as to alter the direction of that moving object. That creates a lift vector. No attached flow is necessary.

And similarly, all that is necessary to create lift is for a stationary object to deflect air (wind) so as to alter the crosswind force acting on that object. That creates a lift vector. No attached flow is necessary.

The use of lift and drag vectors seems to be a way to simplify the analysis of very complex phenomena, and so they are extremely useful abstract concepts. I tip my hat to the early aerodynamicists for adopting that method of simplifying analysis of aerodynamic lift.

Hi Pierre,

          Flettner rotors do not have a high L/D ratio. They have a low L/D ratio as compared to conventional wings. At best, they achieve 3 to 4. My small paper models that are pre-spun before launch at high spin ratios, and with an aspect ratio of about 4, have a glide ratio of 2 to 1, the same as for Sharp Rotors and for Donaldson rotors.

PeterS

Thank you for your delightful pastiche of gobblygoop.

Minesto has changed the location of their water turbine. They moved it from the front to the back. In the back, it should increase stability.

Minesto claims that ocean currents are reliable. I wish that were so, but it is not. Global warming is causing a slowing of the Gulf Stream which transfers heat from the equator to near the Arctic circle. There are fears that it may stop completely. It has done so in the past. Europe relies on the heat from the Gulf Stream. The Gulf Stream serves to slow global warming by transferring surface heat to great depths when it sinks near Iceland and flows back south. The oceans serve as a heat buffer to slow climate changes. So if it stops, the rate of atmospheric warming will accelerate significantly. If the Greenland ice cap melts quickly enough, that fresh water could stop the Atlantic conveyor belt. And the conveyor belts of all the oceans are connected. So ocean current reliability is not something we can take for granted. Neither are winds. Changes in the Arctic jet stream are changing wind patterns in the Northern Hemisphere. That could have a detrimental impact on wind farms eventually, including energy kite farms.

PeterS