Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.


  1. Advanced Patent Search
Publication numberWO2012028890 A1
Publication typeApplication
Application numberPCT/GR2011/000033
Publication date8 Mar 2012
Filing date10 Aug 2011
Priority date1 Sep 2010
Also published asCN102918263A
Publication numberPCT/2011/33, PCT/GR/11/000033, PCT/GR/11/00033, PCT/GR/2011/000033, PCT/GR/2011/00033, PCT/GR11/000033, PCT/GR11/00033, PCT/GR11000033, PCT/GR1100033, PCT/GR2011/000033, PCT/GR2011/00033, PCT/GR2011000033, PCT/GR201100033, WO 2012/028890 A1, WO 2012028890 A1, WO 2012028890A1, WO-A1-2012028890, WO2012/028890A1, WO2012028890 A1, WO2012028890A1
InventorsEmmanuel Michalis, Theodoros Toulas
ApplicantTheodoros Toulas, Emmanuel Michalis
Export CitationBiBTeX, EndNote, RefMan
External Links: Patentscope, Espacenet
Wind turbine blades with dimples
WO 2012028890 A1
Wind turbine blades (2) which are characterised from being equipped with dimples (3) of hemispherical or polygonal shape as many as possible of them and as much as closer one another arranged in rows and alternately between them alongside blade's whole surface. Applying this dimple arrangement technique on blade's surface, a drastic management of specific aerodynamic phenomena contributing to the most possible wind laminar flow and steady blade rotation maximizing quality, reliability, economically and noiseless wind turbine operation which because of diffusion at a significant degree of the two side pressure difference, a speedier rotation is succeeded (more rounds per minute) finally maximizing electric energy production.
Claims  (OCR text may contain errors)
Wind turbine blades, with rotor (1) on a wind turbine tower (4) having blades (2) equipped with dimples (3) characterized by their hemispherical or polygonal (e.g. hexagonal) shape only and their arrangement on blade's surface, which is as many as possible and as much closer to one another, in rows and alternately among them so as in this way to be tangential with one another, covering blade's surface totally at both front and back side.
Wind turbine blades equipped with the hemispherical or polygonal shaped dimple arrangement technique according to claim 1 are characterized by the fact that wind turbine blades surface is totally covered for maximum utilization and management of the displaced air masses coming from blade's front side. Wind turbine blades perform to the maximum degree by making use of the aerodynamic advantages accrued from the specific dimple arrangement technique, achieving at the same time minimum friction and air's most laminar flow on these blade's surfaces, as well as through and outgoing them. Due to this technique, pressure difference between blade's front and back side is virtually eliminated, also the rate of drag form is minimized. Result of this technique is the, as much as possible, maximization of blade rotation (more rounds per minute) therefore producing more electric power.
Wind turbine blades equipped with the hemispherical or polygonal shaped dimple arrangement technique according to claim 1 are characterized by the fact that the dimples are arranged at a precise provision covering completely blade's surfaces, so as to maximise wind management, air molecules laminar flow and thorough wind's mass diffusion. Wind turbine blades are now able to utilise and manage to the maximum degree the aerodynamic phenomena occurring from wind's frontal impact on their front side as well as during air molecules transition towards blade's back side maximising lift force, eliminating simultaneously the negative and decelerating pressure of the outgoing wind from blade's back side (drag force).
Wind turbine blades equipped with the hemispherical or polygonal shaped dimple arrangement technique according to claim 1 are characterized by the fact that the specific technique can be applied to blade's back side surface only, so as this technique encounters for drag force minimization only.
Description  (OCR text may contain errors)


The invention refers to a technique applied on horizontal axis wind turbine blades which are placed on the rotor, on wind turbine's tower. Wind turbines of such type with blades are known, made from known materials such as light plastic reinforced with glass, aluminum, thin wooden layers, etc. The back side of these blades is more curved than the front side. After length, which is of crucial contribution for wind turbine's performance, other factors such as width, thickness and weight are as well contributing for maximizing their rotation which is characterized from a concession between the need for aero dynamical design and durability.

Wind turbine blades are designed and manufactured in a particular way, placed on rotor in order to take advantage the most out of the passing, through them, wind energy that causes their rotational motion. Through blade rotation on the axis, conversion is occurred, through the generator, from motional (rotational) energy to electrical. Rotation of these blades is caused and conducted by been affected exclusively from the pressure masses and gusts exercised by the wind. Depending on the proportional implemented rotational velocity can be judged either as negative (economically unprofitable or dangerous) or positive (proper and useful). During wind's molecules collision frontally to the rotating blades, wind's velocity declines, creating increased pressure at front blade's side and decreased at its back side, where eddies and vortexes take place. When blades rotate with enough speed, significant eddies and vortexes are created at the back side of them, creating a pressure difference (uneven distribution) affecting negatively rotation, in consequence obstructing both wind's turbine proper operation and performance. Blades accept wind's aero dynamical pressure initially frontally and their rotational motion is caused, thereafter just because of the accrued pressure difference which is mainly expressed at blade's back side, a negative aerodynamical phenomenon (eddies and vortexes) is created, causing speed deceleration and other complications against to an ideal rotation. Accordingly, these consequences comprise an adversely aim for wind turbine operation, not permitting to maximize its performance. The bigger the turbulence caused by the impacted wind onto them, the bigger is the transmitted energy from blades to the wind and vice versa. This energy interaction between blades and wind is the aero dynamical resistance and more specifically it contains the horizontal wind resistance (drag force) and the vertical or dynamical wind uplift (lift force). The horizontal wind resistance (drag force) acts in the contrary to wind direction decelerating blade's rotational rate, causing the pressure difference, a force (expressed as drag form or pressure resistance) is directing from an area with larger pressure (front blade side) towards an area with smaller pressure (back blade side).

The advantage of this invention is that dimples of hemispherical shape are arranged in specific order on the surface of wind turbine blades, a technique transferred directly from the hemispherical or polygonal (e.g. hexagonal) dimples arranged on golf balls. This technique is taking full advantage of the aero dynamical phenomena, managing to the maximum initially the impacted wind on blades frontally, while passing through them and finally on the outgoing wind masses (exiting) from them contributing at these points to a proper and manageable laminar air flow and a steadier blade rotation offering a quality, reliable, economical and silent wind turbine operation. The reason for transferring gol s ball dimple arrangement technique identically to wind turbine blades surface is to reproduce the formation of the most possible laminar air flow and eventually to manage in the most effective way the attached, incoming and outgoing wind, defusing pressure difference between blade's two sides at the maximum possible degree.

In the case of these wind turbine blades, the outcome is again succeeded, in the form of the fastest possible blade rotation (more rounds per minute) only this time by maximizing electrical energy production. Applying this dimple arrangement technique, alongside blade's both sides surface, wind management is stimulated and simultaneously beneficial maximized, as well as a methodically eddy and vortex relief that tend to accrue, contributing to reduction in the most effective way against the negative impact of horizontal wind resistance (drag force) on blade's back side, reducing drag form. With the specific dimple arrangement technique, wind turbine blades are now performing maximum rotation and manage most effectively the impacted to them and then ingoing through them wind, as well as balancing wind eddies and vortexes, formed at their back side, maximizing lift force. On other words, at the same wind loads now is transmitted to the wind turbine more electric energy, just as in analogue occurs on golf balls where thanks to the already applied and proven successful dimple arrangement technique, either concerning hemispherical or polygonal shaped dimples, applied on its surface, as many and close to one another as possible, in rows and alternately among them, so as covering its surface completely minimizing any flat surfaces, with an equal's strength strike commenced from player's club, a significant larger distance is covered in comparison to older golf balls that had their surface smooth. Accordingly, at a specific wind force manifested on wind turbine blades surface, where the specific dimple arrangement technique is applied, at an exact layout as in golf balls, then blade's rotational maximization is eventually succeeded. Wind turbine blades, according to the present invention are characterized by being applied on their surface precisely the dimple arrangement technique of golf balls, covering either their surface totally or just the back side only, in order for the drag force phenomenon only to be encountered effectively.

A simple way for presenting this particular dimple arrangement technique on wind turbine blades is made according to the invention by using as many as possible (the dimple number is in ratio to the surface covered) hemispherical or polygonal (e.g. hexagonal) shaped dimples arranged as much as closer to one another, in rows and alternately among them resulting to be tangential, covering totally both blade's surfaces exploiting and managing to the most beneficial degree the aerodynamic phenomena occurred during wind's frontal impact at the front side as well as during wind's movement towards the back side maximizing lift force and at the same time eliminating the negative and retarding pressure (drag force).

Applying this relatively cheap dimple arrangement technique on existing blades surface as well as by constructing from now on new such a type blades the ratio between cost to produce and effectiveness in energy production is improved significantly, operating at the same time more noiselessly and in general more trouble free by offering wind turbine simultaneously a more economical, controlled and rewarding operation. According to the dimple arrangement technique of the present invention, it is permitted on the wind turbine blades surface to be placed hemispherical or polygonal dimples, as many as possible of them, arranged in an as much as closer to one another approach, in rows and alternately among them resulting to be tangential, maximizing laminar air flow and air management displacement, creating less frontal resistance and as a result to maximize lift force causing friction minimization, since next wind mass's molecules are contacting previous air molecules, entrapped in these dimples instead of directly with blade's detrimental smoothly surface or material. Figure 1 shows a front view of three wind turbine blades.

Figure 2 shows a blade's magnification front view.

Figure 3 shows a back view of three wind turbine blades.

A method for applying the dimple arrangement technique on wind turbine blade surfaces is described in reference to the figures. Wind turbine consisting of a rotor (1) blades (2) and hemispherical dimples (3) which are implemented, depending on blade's surface size, at a highest number and at an ideal effectual size, arranged on blade's surface in rows, as much as closer to one another and alternately among them resulting to be tangential, and finally the wind turbine tower (4).

At the figures shown here, on blade's surfaces have been implemented same sized hemispherical shaped dimples only, not however prohibited the implementation of a polygonal shaped dimple arrangement only (e.g. hexagonal shaped dimples) arranged on the basis of hemispherical dimple arrangement technique in order to be as close as possible to one another, in rows and alternately among them resulting to be tangential and thus, covering totally blade's surface both on the front and on the back side.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
WO2006119648A1 *15 May 200616 Nov 2006Arrowind CorporationHelical wind turbine
WO2007065434A1 *5 Dec 200614 Jun 2007Lm Glasfiber A/SBlade for a wind turbine rotor
EP1469198A1 *16 Apr 200420 Oct 2004Eugen RadtkeWind energy converter with lift improving surface structure.
EP2031241A1 *29 Aug 20074 Mar 2009Lm Glasfiber A/SBlade for a rotor of a wind turbine provided with barrier generating means
US20060245928 *21 Oct 20032 Nov 2006Manfred HerbstWind power unit with structured surfaces for improvement of flow
Non-Patent Citations
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
WO2014023739A1 *6 Aug 201313 Feb 2014New World Energy Enterprises LimitedA blade for a rotary machine
WO2017052371A1 *21 Sep 201630 Mar 2017Home Turbine B.V.Device for converting wind energy into at least mechanical energy
US94751413 Aug 201225 Oct 2016Milwaukee Electric Tool CorporationReciprocating saw blade
US9777712 *24 Mar 20153 Oct 2017Rainer MarquardtWind power station for rooftops
US20150275865 *24 Mar 20151 Oct 2015Rainer MarquardtWind Power Station for Rooftops
USD6885432 Oct 201227 Aug 2013Milwaukee Electric Tool CorporationSaw blade
USD7238922 Jul 201310 Mar 2015Milwaukee Electric Tool CorporationSaw blade
USD7296006 May 201419 May 2015Milwaukee Electric Tool CorporationSaw blade
International ClassificationF03D1/06
Cooperative ClassificationY02E10/721, F03D1/0633, F05B2240/32, F05B2250/28, F05B2250/241
European ClassificationF03D1/06B6
Legal Events
25 Apr 2012121Ep: the epo has been informed by wipo that ep was designated in this application
Ref document number: 11749896
Country of ref document: EP
Kind code of ref document: A1
1 Mar 2013NENPNon-entry into the national phase in:
Ref country code: DE
9 Oct 2013122Ep: pct app. not ent. europ. phase
Ref document number: 11749896
Country of ref document: EP
Kind code of ref document: A1