Talk:Wind-turbine aerodynamics

Untitled

This article seems to cover a lot on Horizontal Axis Wind Turbines, maybe it should have "Horizontal Axis Wind Turbine Aerodynamics" as a title. There are some interesting topics concerning wind turbine aerodynamics in a general nature...

One example is the comparison of optimum power for a drag based or lift based machine.... —Preceding unsigned comment added by 142.104.84.53 (talk) 23:34, 15 February 2011 (UTC)

I propose that eventually as content is added, there is some branching to discuss the aerodynamics of each specific topology...

Possible additional photos

metal tabs

closeup look at the tabs

The tabs near the leading edge of the upper surface (more convex surface) of the wind turbine blades appear designed to limit the "lift" of the blade at extreme wind velocities by causing turbulance - but that is purely speculation. They are clearly there for some purpose. Before adding them to the article, they are posted here in hope someone can provide an accurate discussion of their aerodynamic function.

Insights or thoughts? Williamborg (Bill) 19:13, 9 August 2009 (UTC)

They look like vortex generators to me, (I'm no expert however!) similar to what one see's on the wing of an airplane before the control surfaces. For the airplane I believe they reduce the effect of the slow-moving boundary layer on the control surfaces. For the turbine blades it may be that they intentionally create small vortices allowing the airflow to curve around the blade easier, rather than have the flow separate from the blade and causing a stall effect. This is pure guess though. —Preceding unsigned comment added by 210.54.148.98 (talk) 02:44, 2 February 2010 (UTC)

Just a comment on those images... those are in fact vortex generators. It is a method of suppressing aerodynamic stall at the blade. It does re-energize the boundary layer suppressing turbulent stall. Note, that it does nothing for leading edge laminar BL stall though. Hence they are not applied towards the tip where high L/D profiles are used, but exhibit more leading edge stall. For those to be explained, then someone needs to talk about blade element theory and how it applies to turbines. For variable speed turbines (constant tip speed ratio), they are only useful in dealing with strong gusts. However for constant speed operation (stall regulated) it is applied to alter the stall behavior. Peak power prediction for stall regulated machines is not very accurate, hence engineers will design for early stall. However, if once tested it stalls too early, then you apply these vortex generators and you get the desired —Preceding unsigned comment added by 142.104.118.9 (talk) 18:35, 4 February 2010 (UTC)

Please Define Your Variables

There should be a wikipedia policy that all variables used in equations should be defined immediately before or after their first use. I see missing definiition at first glance: P, L, D. Power, lift, drag? Why wait until using γ the 4th time before giving it a name? What do you call Ywaz (talk) 11:22, 18 September 2011 (UTC)

If there were any references in the article for all the maths, anyone could look up what the original source gave as the definitions. Sadly, we lack references. --Wtshymanski (talk) 15:09, 18 September 2011 (UTC)

The first equation in this analysis bothered me until I realized that the radius is hiding in the speed term. The usual equation for rotational power (see hyperphysics site) is [power = torque x angular speed] where [torque = radius x force]. Since this analysis starts off [power = force x speed], the units of speed here must be distance/sec not radians/sec. This needs to be made clear. — Preceding unsigned comment added by 24.61.212.124 (talk) 06:28, 13 January 2012 (UTC)

Challenged Content

The section addresses the statement "This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (September 2011)" pertaining to section "Maximum power of a drag based wind turbine".

This analysis was not taken out of a book or an academic article thus cannot be cited. The material was developed by a PhD student who has 7 years of experience working in the wind energy field. The analysis given is highly contrived but demonstrates a fundamental difference between drag based wind turbine and lift based wind turbines. Mainly that there is a ceiling to drag based machines that is not present in lift based machines. That in itself is an important point. The analysis alone is too abstract to be applied to real turbines.

Before one makes the decision to remove this content please ensure that you completely understand the content itself. There are several idealizations that may seem strange to a knowledgeable wind energy engineer. First and foremost is the normalization of the coefficient of power. The conventional approach is to use the swept area of the rotor, while this analysis makes no assumptions on the topology and takes the plan-form area of the wing. Ignoring the swept area leads to the second idealization that induction has no influence. The assumption here is that the swept area is so large that thrust per unit swept area is small thus induction is small.

One improvement to this article is to explicitly state these idealizations up-front and state the limitations of the analysis. Furthermore the article could justify these analysis as a means to compare the fundamental limitations to either lift and drag based topologies. — Preceding unsigned comment added by 142.104.84.96 (talk) 21:25, 24 November 2011 (UTC)

The previous poster said "This analysis was not taken out of a book or an academic article thus cannot be cited. The material was developed by a PhD student who has 7 years of experience working in the wind energy field." That is simply not true. These formulae and analysis is available in multiple sources. — Preceding unsigned comment added by 75.87.249.48 (talk) 03:16, 18 September 2013 (UTC)

Response to the above response "That is simply not true. These formulae and analysis is available in multiple sources." This poster 'the original PhD student' is not aware of someone trying to solve the fundamental limit to power for a lift based machine, the limit to a drag based machine is trivial. I would not be surprised if the drag based analysis is published somewhere. If you have a source on the lift based analysis please share, I would be interested, furthermore I think it would be best if this article cited those sources. I would agree that the equation from which this analysis is derived are common place however I am not sure if they have been applied in this way in the lift based machine analysis. I do know of many example of analytical solutions for the maximum power of conventional lift based turbines (i.e. Betz limit from axial momentum theory). Unlike other similar analysis, this work makes no assumption of the topology, so it is somewhat unique. I will clean up the article a bit... — Preceding unsigned comment added by 75.156.74.196 (talk) 08:13, 14 May 2015 (UTC)