Project no.015286 CRESMED Cost Efficient and Reliable Rural Electrification Schemes for South Mediterranean Countries Based on Multi User Solar Hybrid Grids STREP Sustainable development, global change and ecosystems - Sustainable Energy Systems<br/><br/>D-16 Two Wind Turbine Prototypes 1 KW<br/><br/>Due date of deliverable: December 2007 Start date of project: January 1, 2006 Duration: 42 Months<br/><br/>Organization name of lead contractor for this deliverable: NERC Revision 02<br/>Project co-funded by the European Commission within the Sixth Framework Programme (2002-2006) PU PP RE CO Dissemination Level Public Restricted to other programme participants (including the Commission Services) Restricted to a group specified by the consortium (including the Commission Services) Confidential, only for members of the consortium (including the Commission Services)<br/><br/>CO<br/><br/><br/>Contract 015286 (INCO) - CRESMED Document: D-16 Two wind turbine prototypes 1 KW WP 3 Task 3.6 Final use- D Description: Description of CRESMED Project Web Site Language: English Responsible: Khaled Daoud Revised by:<br/><br/>Date: 22. 12 .08<br/><br/>Version 02 Level: DF Nº pages:36<br/><br/>Author: Khaled Daoud Date: Comments<br/><br/>D-16 Two Wind Turbine Prototypes 1 KW<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 1/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Table of Contents 1. Introduction.............................................................................................3 1.1 1.2 1.3 General.............................................................................................3 Environmental Aspects.........................................................................3 Scope and Objectives .........................................................................3 1.3.1 Development of rotor blades........... ............................................3 1.3.2 Tower.....................................................................................4 1.3.3 Rotor and Hub..........................................................................4 1.3.4 Design criteria ........................................................................5 1.3.5 Generators and storage ............................................................5 1.3.6 The components of the Wind turbine ...........................................5 2. Wind Regime.............................................................................................5 2.1 2.2 Power from the Wind...........................................................................6 Wind rotor design ...............................................................................7 2.2.1 Rotor connected to the hub..........................................................10 2.2.2 Airfoil selection ........................................................................11 2.2.3 Determination of blade data.........................................................12 2.2.4 Blade root ...............................................................................13 2.2.5 Blade geometry.........................................................................15 2.2.6 Blade twist...............................................................................16 3. 4. Safety Device.........................................................................................17 Manufacturing.........................................................................................18 4.1 Manufacturing the GRP Blades .................................... ......................18 4.1.1 Stage 1: Manufacturing the model.............................. ................18 4.1.2 Stage 2: Manufacturing the mold ................................................19 4.1.3 Stage 3: Manufacturing the blade................................................20 4.2 4.3 5. 6. Manufacturing the hub........................................................................21 Manufacturing the Turn Table..............................................................21<br/><br/>Tower......................................................................................................22 Testing Results.........................................................................................23<br/><br/>References.......................................................................................................25 Annex(1): Technical Drawings of the wind turbine components ...............................26<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 2/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>1. Introduction<br/>1.1 General Wind energy has attracted a great deal of attention in recent years in Jordan as one of the possible alternative energy resources. Almost all of the local research and development activities in this field were directed to explore, develop, and optimally utilize wind energy systems. Given all the previous research work, the time has come to establish a link between local scientific work and local industries to produce a usable technology. Wind energy technology is fairly new to Jordan. It was first introduced in its modern form by the Royal Scientific Society (RSS) in 1983, when a multi-blade ten kilowatt wind turbine was installed to pump water from a desert well then two stand alone wind pumping systems were installed utilizing two blade electric wind turbines. In 1988 the first wind farm connected to the grid was installed in the Northern part of Jordan at Al-Ibrahimya as a pilot plant consists of four wind turbines each one is 80 KW, followed by another one installed in 1996 which consists of five wind turbines each one is 225 KW. Wind energy technology is also multi - dimensional, it encompasses aerodynamics, structural mechanics, machines and power electronics. One of the most complex and costly parts of modern wind turbines is the rotor blade [1]. 1.2 Environmental Aspects Direct use of the mechanical energy of wind turbines or electricity generation by wind turbines is absolutely free of emission. Thus, the saving of primary energy achieved with a wind turbine is also directly accompanied by the corresponding reduction in air pollution. The use of wind energy for generating electricity is very attractive; the well constructed wind turbine at a favorable site delivers more energy within a few months of operation than was needed for its construction. Thus, wind energy systems rate very well on the basis of energy payback times. 1.3 1.3.1 Scope and Objectives Development of the rotor blades The decision was made to experiment two rotor blade types with different characteristics, which will be presented in the design section. One of the objectives was to test the capabilities of local manufacturers in the execution of such designs and to examine their performance in adapting to this new technology. The choice of the blade material will fall on a material that can be easily adapted to mass production such as fiberglass, which is a composite material that has more than one component. The objective of using Glass-fiber Reinforced Plastic (GRP) material can be related to many attributes; one is the availability of the polyester resin which is locally produced. This is important to the economics of the overall system. Rotor blade design relies heavily on the aerodynamic theory. The blade is an aerodynamic body having a special geometry mainly characterized by an airfoil<br/>D 16 Project: Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA Page 3/36 Date: 22/12/2008<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>cores section. Extensive calculations are necessary in order to determine the blade parameters such as chord and thickness distributions, twist distribution and taper that is matched with the selected airfoil sections. For practical purposes, more than one airfoil section must be chosen to fit the thickness distribution where closer to the root a thick section is needed, and thinner sections are applied a long the blade to give a smooth transition from root to tip. Wind turbine blades must be designed to operate in one of the most unperfected environments and still give satisfactory performance for the life time of the system. The blade is subjected to cyclic loading of different magnitudes which may cause fatigue failure if not designed properly. Manufacturing the blade which is one of the prime objectives of this system is divided into three integrated parts; the model, the mold, and the prototype. The model is made from soft white wood to simplify shaping the exact geometry of the airfoil, taper, and twist. The model will also facilitate verification and modification to certain parts of the blade especially ensuring streamlining. A mold having the exact imprint of the model is then produced from fiberglass material. The mold will have two cavities; upper and lower, to facilitate ease of extracting the molded blade. The interior surfaces of the mold cavities are carefully treated and highly polished to yield a fine surface finish on the blade surface. A method that is simple and practical is developed for the local manufacturer to apply which produces a strong and exact geometry blade. The method also includes a proof - load test procedure, when applied and passed, it will guarantee fatigue strength capabilities. 1.3.2 Tower The strength of tower and supports must be sufficient to resist the maximum expected transient loading (proof load) with adequate safety margin, and the tower stiffness must be determined to avoid tower resonance at the rotor frequencies. The first prototype of wind turbine has a 9 m tripod tubular tower which is hinged at the base consists of 3- sections all bolted. The tower is supposed to withstand storm condition of 40 m/s winds. The second prototype of wind turbine has a 6 m tubular mast which is hinged at the base. The mast is supported by four guy wires. It is suppose to withstand storm condition of 40 m/s winds. 1.3.3 Rotor and hub The first prototype of wind turbine has a hub produced from recycled Aluminum which is available in the market and cheap. The second prototype of wind turbine has a hub produced from two plates that sandwich the blades at the centre. This type of hub was chosen for simplicity in manufacturing and installation and cheaper in cost.<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 4/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Manufacturing the blade which is one of the prime objectives of this system is divided into three integrated steps: the model, the mold and the sand casting hub. 1.3.4 Design criteria Normally the Wind Turbine (WT) for individual use should not be too large or too high in power installation; therefore, the power of the wind turbine is 1000 W rated power for battery charging. The first rotor diameter was calculated to be 3.4 m. A three - bladed rotor with middle tip speed ratio 3.3 was chosen. The second rotor diameter was calculated to be 2.7 m. A three - bladed rotor with tip speed ratio about 6.3 was chosen. Aerodynamic performance, Balance, stability and system cost represent the three bladed rotors the best trade. The basic conditions of the design are: 1.3.5 Application of series production components. Easy assembling. Easy maintenance. Long maintenance intervals. Low components weight. High reliability of the regulating system. Long lifetime.<br/><br/>Generators and storage Two permanent magnet generators (PMG) were chosen to be used for the two prototypes: the first with 200 rated RPM and the second with 400 rated RPM. The well-known batteries are the lead-acid batteries. They are cheap and easily available. The local industry can provide these types of battery.<br/><br/>1.3.6<br/><br/>The components of the wind turbine The main components of the wind turbine are: Generator, Hub, Hub Cover, Rotor and Vane. The practical realization of each component is designed according to local conditions and available materials.<br/><br/>2. Wind Regime<br/>The wind regime in any site can be described through the evaluation of the hourly averages of wind data that is collected during one month or one year in that site. The evaluation of wind data should give us the wind speed distribution and the available power which is very important for the design of the wind rotor and for wind turbine sizing for a specific site.<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 5/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>2.1<br/><br/>Power from the Wind Air mass flowing with a velocity V [m/s] through an area A [m2] represent a mass flow rate in [Kg/s] of: m =   A  [Kg/s] Which is a flow of kinetic energy per second or kinetic power Pkin [W] of:<br/><br/>Pkin =<br/><br/>1 . m. v 2 2<br/><br/>[W]<br/><br/>1 Pkin = .(  . A. ) 2 2 1 [W] = . . A. 3 2<br/>where :<br/><br/> =air density [kg/m3] = 1.225<br/><br/>A = area swept by the rotor blades [m2]  = undisturbed wind velocity [m/s] Figures 1 &amp; 2 show the schematic diagram of the energy flow.<br/><br/>Turbine Generator Control Load<br/><br/>V<br/><br/>Storage<br/><br/>Figure (1): Schematic representation of the energy flow through a wind electricity conversion system<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 6/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>A<br/><br/>V<br/><br/>V meters<br/><br/>Figure (2): Schematic diagram of a volume of air (V.A) flowing through an area (A).<br/><br/>The function of the wind rotor is to slow down (disturb) the wind velocity, thus transforming part of the kinetic power to mechanical power at the rotor shaft. The theoretically maximum available mechanical power at the shaft is (as derived by Betz) equal to:<br/><br/>Pshaft =<br/>2.2<br/><br/>16 * P [W ] 27 Kin<br/><br/>Wind Turbine Rotor Design Rotor Design of first prototype: The net power of the first wind turbine prototype will be 1000 Watt. The rotor area (A) can be calculated using the following formula:<br/><br/>P=<br/>where: P<br/><br/>1 . 3 * A * sys 2<br/>: Required power output = 1000 W : Air density = 1.225 kg/m3 : Design wind speed = 11 m/s : Rotor area : System efficiency<br/><br/> <br/><br/>sys<br/><br/>A<br/><br/>The system efficiency is assumed as follows: Assumed power coefficient: Cp = 0.35 generator = 0.4 at rated speed<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 7/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>then, sys = gen * Cp = 0.14 A=<br/><br/>p 0.5 *  *  3 * SYS 1000 0.5 *1.225 *113 * 0.14<br/><br/>=<br/><br/>A  8.8 m2 D=<br/><br/>4A<br/><br/><br/><br/>D  3.4 m The Tip speed ratio d can be calculated as follow [6]:<br/><br/>d =<br/><br/>2 * n * R 60 * <br/><br/>d = 3.23 which is chosen to be d = 3.3 Where: d: Tip speed ratio n: assumed wind rotor r.p.m = 200 R: rotor radius = 1.7 m : design velocity = 11 m/s The solidity of the rotor is about 10%. For determining the lift coefficient (CL) along the blade we need the blade chord length at which station of blade the lift coefficient will be calculated, and the blade number. [8] It has been selected: d: nrot: Vr: R: S: tip speed ratio = 3.3 assumed wind rotor r.p.m =200 design velocity =11 m/s rotor radius = 1.7 m solidity of the rotor ~ 0.17<br/><br/>Z:<br/>: r: t:<br/><br/>number of blades = 3<br/>relation lift to drag = 60  = ( 0.4 ­ 1.7) m chord length ( m ).<br/><br/>CL = 60 CD<br/><br/>C LTip =<br/><br/>0.59 * 2 *  * R Z * t * ( 2 + 1)(1 -<br/><br/> ) <br/>Date: 22/12/2008 Responsible TTA Page 8/36<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Lift coefficient (CL) as function of radius :<br/><br/>CL(r ) = Z * t(<br/><br/>0.59 * 2 *  * r<br/>2 0<br/><br/>R<br/><br/>2<br/><br/>r 2 + 1)(1 -<br/><br/>0 .r) R. <br/><br/>Table (1): Lift Coefficient CLTip as a function of radius r 1.65 1.55 1.25 1.05 0.85 0.65 0.45 0.25 t 0.22 0.24 0.27 0.30 0.32 0.35 0.38 0.40 CLTip 0.833 0.80 0.74 0.52 0.42 0.33 0.25 0.18<br/><br/>From CL value the Angle of Attack (AOA)  can be taken from catalogue. The flow angle of relative wind speed to airfoil () is a function of (r), where:<br/><br/>( r ) =<br/><br/>1<br/><br/>( r )<br/><br/>from the blade twist angle , where<br/><br/> = ( r ) -  ( r )<br/>We can build the blade. The following table presents the geometry of the blade, along the radius: Table (2): The geometry of the blade and the lift coefficient a long the radius Station (m) 1.65 1.55 1.25 1.05 0.85 0.65 0.45 0.25 t (m) 0.22 0.24 0.27 0.30 0.32 0.35 0.38 0.40 Twist  (deg) 11.7 13.1 17.9 24.4 30.7 38.9 50.2 67.0 AOA  (deg) 6 5.6 4.9 2.2 1.0 0.0 -0.8 -1.5 Setting  (deg) 17.66 18.72 22.79 26.57 31.71 38.94 49.41 65.55 lift coeff. Cl 0.833 0.80 0.74 0.52 0.42 0.33 0.25 0.18<br/><br/>From the relation between Cl &amp; AOA we obtained the values of AOA for the calculated lift coefficient along the radius of the blade.<br/>D 16 Project: Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA Page 9/36 Date: 22/12/2008<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>0,9 0,85 0,8 0,75 0,7 0,65 0,6 0,55 0,5<br/><br/>CL<br/><br/>0,45 0,4 0,35 0,3 0,25 0,2 0,15 0,1 0,05 0 - 2 ,5 -2 -1,5 -1 - 0 ,5 0 0 ,5 1 1,5 2 2 ,5 3 3 ,5 4 4 ,5 5 5 ,5 6 6,5<br/><br/>AOA<br/><br/>Figure (3): The relation between Lift coefficient (CL) and Angle of Attack (AOA)<br/><br/>Rotor design of second prototype: The net power of the second wind turbine prototype will be 1000 Watt. The same procedure of first prototype is followed to design the rotor of the second one. The followings are the assumed and the calculated parameters of the second prototype: Assumed rotor speed Assumed design wind velocity Assumed generator efficiency Air density Assumed power coefficient Number of blades Calculated rotor diameter Calculated tip speed ratio 2.2.1 Rotor connected to the hub The wind turbine rotor consists of two main components: Hub and Blades. For the first prototype, the Hub is made from recycled Aluminum. It is rigid with fixed pitch as shown in figure 4. For the second prototype, the hub produced from two plates that sandwich the blades at the centre. This type of hub was chosen for simplicity in manufacturing and installation and cheaper in cost as shown in figure 5. nrot Vr Cp Z D d : 400 RPM : 9 m/s : 0.56 : 1.225 kg/m3 :0.35 :3 : 2.7 m : 6.3<br/><br/>gen <br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 10/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Figure (4): Three blade rotor assembly showing the Hub and Blades (First prototype).<br/><br/>Figure (5): Three blade rotor assembly showing the Hub and Blades (Second prototype). 2.2.2 Airfoil selection The clark Y airfoil was chosen for this wind turbine, because it has a practical shape for easy manufacturing and for easy adjusting the twist of the blade. This airfoil provides a desirable high lift coefficient. Figure 6 shows the shape of the clark Y airfoil, in this shape you can see the flat lower side, which is practical for handling.<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 11/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>The shape of Clark Y<br/><br/>Figure (6): The shape of the clark Y airfoil The characteristics of this airfoil are suitable for use in wind turbine according to the suitable Reynolds number, which affects airfoil lift and drag behavior. The characteristics of particular airfoil are lift, drag, and the pitching moment. Figure 7 shows the lift coefficient as a function of angle of attack  for this airfoil:<br/><br/>Figure (7): Profile data from reference [6] 2.2.3 Determination of blade data The design and construction of a sophisticated wind turbine blade requires enormous amounts of data. Most important are those describing the geometry and structural characteristics such as length, thickness distribution, chord length distribution, twist, blade root,......,etc. The rated electric power of a wind turbine required a geometry of the blade which will be determined as described in table 3 for the first prototype. The geometry of the blade is completely defined which will allow the determination of the blade loads and other aerodynamic characteristics.<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 12/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Table (3): Blade geometry Station (m) 1.65 1.55 1.25 1.05 0.85 0.65 0.45 0.25 2.2.4 Blade root The blade root for the first prototype is the heaviest and thickest part of the blade because it carries the blade structure as shown in figure 4. It is the junction point between the blade body and the hub. The root has to take maximum moments and torques transmitted by aerodynamic forces through the blade to the rotor shaft and therefore stresses and strains will be concentrated in the root area. For the second prototype the root is simple as shown in figure 5. The evaluation of the ultimate strength and fatigue characteristics of a rotor blade is based on a static proof test [3]. The static proof load is derived from the assumption of an extreme thrust load of 300 N/m2 swept area. This load is equally shared among the blades and distributed in triangular pattern with zero at the rotor with a swept area of 8 m2 should withstand and extreme load of 0.8 KN. The blade should withstand this load without sustaining any damage. On fatigue, the certification criteria [4] states that at a load factor of 0.5 (150 N/m2 * swept area / number of blades), the measured strain for GRP must be less than 0.2% (2000 micro strains) in the side of the blade under compression and less than 0.3% (3000 micro strains) in the side of the blade in tension. Therefore, we have two load cases: Load case 1: 300 N/m2  0.8 KN/Blade Load case 2: 150 N/m2  0.4 KN/Blade Figure 8 below shows the load case 1 and associated moments. Twist (deg.) 11.7 13.1 17.9 24.4 30.7 38.9 50.2 67.0 Chord (mm) 240 260 290 320 340 370 400 420<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 13/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Figure (8): Load case 1 and associated moments From the rotor dimensions and load distribution, the moment acting on the blade root is the sum of the areas marked A2 and A3, where the concentrated load can have variable values according to the linear curve shown when moved from point to another along the blade length. Using similar triangles yields: 0.8/106 = y/0.2  y = 0.1 KN A1 = 0.1 KN *<br/><br/>0.2 = 0.01 2<br/><br/>A2 = 0.1 KN * 1.4 m = 0.14 A3 = 0.8 - (0.01 + 0.14) = 0.65, hence, M root = (0.14 * 0.7) + (0.65 * 2/3 *1.4) = 1.89 Nm From Hook's law, the stress within the root section is :<br/><br/> root = root * E root<br/>where E = 30 Gpa in the modules of elasticity for GRP, and with a strain limit of 0.3 % in tension and allowing only half of this amount (0.15%) which is equivalent to a safety factor of 2, we get : = (0.15% /100) * 30 * 109 N/m2 = 4.5 * 107 N/m2 = M root + r root/I root where, I root = /64 * (do4 - di4) is the cross sectional moment of inertia, and root do = root outer diameter = 0.095 m di = root inner diameter = 0.050 m droot = the distance from the cross section center to the outer most fiber, which is do/2. Therefore,  root = (32 * M root * do) / (do 4 - di 4)<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 14/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>The important criteria is avoiding sudden changes in geometry and keeping the Glass Fiber continuous from root to tip. Therefore, the flange is designed as a sandwich structure between steel ring and Hub flange see figure 9.<br/><br/>Figure (9): Blade root structure 2.2.5 Blade geometry The blade geometry has two different views; Flapwise and Edgewise. The Flapwise view of the blade in figure 10 shows the root region and the working region. The working region is the portion of the blade which has the actual airfoil cross section, and the root region is the portion which compensates geometry between the airfoil profile and the completely circular section at the connection flange, and therefore has no contribution to power generator.<br/><br/>Figure (10): Chord length distribution along the blade in millimeters. In order to simplify manufacturing process, the blade shape has to be designed with minimum efficiency losses related to theoretical optimum. For a streamlined body with the dimensions already calculated and defined for the length, root, and tip, the best proportions for the blade would be when the chord at the beginning of the working region is 0.38 m and at the tip is 0.22 m see figure (9). In figure 11 we can see the different views of the blade of the first prototype; Edgewise, and Flapwise. The edgewise defines the blade thickness distribution, and the flapwise defines the chord length distribution of the selected airfoil.<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 15/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>For the rigidity purposes the thickest portion of the blade must be the root, and viewing the blade from the edgewise position, one concludes that the blade must be tapered down from root to tip.<br/><br/>Figure (11): Viewing rotor blade geometry 2.2.6 Blade twist The twist of a wind turbine blade is defined in terms of the chord line. It is a synonym for the pitch angle; however the twist defines the pitch settings at each station along the blade according to local flow conditions. Looking at the velocity triangle in figure 12, the relative wind speed  is the vectorial sum of the rotational speed (Vu) and the free wind stream (Vw).<br/><br/>Figure (12): Velocity at a blade element at radius<br/><br/> = Vu2 + Vw2<br/>then  =<br/><br/>Vw Vu<br/><br/>The pitch angle () is large near the root (where speeds are low), and small at the tip (where speeds are high).<br/>D 16 Project: Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA Page 16/36 Date: 22/12/2008<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Here is a decision point, one has either to fix the rotational speed of the rotor and search for optimum twist, or fix the twist and find the best rotational speed for the machine. The first choice has been taken.<br/><br/>3. Safety Device<br/>The safety system must perform two functions:<br/><br/>1. Limit the axial thrust forces on the rotor.<br/><br/>At high wind speeds the bending moment on the blades becomes too high and eventually they will break.<br/><br/>2. Limit the rotational speed of the rotor.<br/>-<br/><br/>High rotational speeds lead to the following phenomena: High centrifugal forces, resulting in high tensile forces in the blades. Finally one of the blades will be launched as a projectile, leaving behind an unbalanced wind machine with an extremely short lifetime. A combination of high rotor speed and sudden directional changes of the rotor head gives rise to high gyroscopic moments, i.e. high bending moments in the blades and rotor shaft. High tip speeds can induce dangerous aero-elastic behavior, called &quot;flutter&quot;. This is a combination of severe torsion and bending vibrations in the blades. In the case of water pumping windmill the high pump frequencies lead to a sharp increase of the shock forces, carried to the bearings and the crank mechanism via the pump rod. They are caused by acceleration forces and extra shock forces due to delayed closure of the valves of the piston pump.<br/><br/>-<br/><br/>-<br/><br/>-<br/><br/>The safety systems can act either on the rotor as a whole or on each of the blades. We have employed the first one. The protective device against strong winds or over speed of the rotor is realized through the forced rotor head side wards in order to catch less wind above a certain wind speed. The wind rotor can be pushed out of the wind with a vane attached to the head of the wind turbine. The aerodynamic forces on the vane exert a moment around the vertical axis which is balanced by the moment of the aerodynamic forces on the rotor. With increasing wind speed, the aerodynamic forces on the rotor increase, turning the rotor further of the wind. Figure 13 shows the safety device.<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 17/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Figure (13): Shows the safety device angle between the tow main and auxiliary vane.<br/><br/>4. Manufacturing<br/>4.1 4.1.1 Manufacturing the GRP Blades Stage 1 : Manufacturing the model A full scale exact geometry blade model will be made from wood. The first step in making the model is to divide the blade length into a number of intervals keeping in mind that the data available is for the outer 1.4 meters of the blade as shown in figure 10. There we have 7 stations and the 0.2 m root section will be streamlined from circular flange to the first section where the actual airfoil starts. For the seven stations mentioned there, the seven sections will be produced from 20 mm thick white wood. The perimeter of each section will be reduced by 10 mm to allow for installation of 15 X 15 mm cross section wood sticks as shown in figure 14. These sticks when stacked next to each other and bonded to the seven airfoil sections using binding resin for wood and hidden nails, will form the skin of the blade which can be later shaped and smoothed and finally sanded to a very fine finish. Then, wood sealant is applied in order to protect the wooden model from the atmosphere's moisture. The twist distribution given in section (2.2) is incorporated in the blade model by fixing the sections at their respective stations as shown in figure 15.<br/><br/>Figure (14) :Airfoil section cut from wood and reduced to allow for skin segments build-up.<br/>D 16 Project: Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED<br/><br/>Figure (15): Method of fixing the airfoil sections in their respective distribution<br/>Date: 22/12/2008<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/>Responsible TTA<br/><br/>Page 18/36<br/><br/><br/>After all segments are installed and all finishing has been done, the completed full scale (1.7 m) rotor blade wooden model is shown in figure 16.<br/><br/>Figure (16): Blade model 1.7 m long made from wood 4.1.2 Stage 2 : Manufacturing the mold The mold will be made from GRP and consists of two parts; upper and lower halves which are then strengthened using lateral rip stiffeners. The wooden model is prepared first by waxing it with a special separation agent (non - stick) which builds up a thin film between the wooden model and the GRP mold layers. The first layer of the mold caviling is a one millimeter thick gel coat mixed with a hardening epoxy to form a tough internal mold surface. After the hardening period of the gel coat, successive layers of glass fiber laminates soaked in polyester resin are laid on the wooden model to take its exact shape. After the curing period of the first mold half, it is pulled off the model and cleaned up from all extra materials especially around the edges. The second mold half is also made in similar fashion and the two halves are then assembled on the wooden model and any extra material will be removed until complete fitness on the model is achieved for the two halves combined. The two mold halves are then strengthened using lateral rips made from wood and covered with GRP in addition to installing a steel frame to insure extra strength and ease of handling. Figure 17 shows the mold that was manufactured from GRP for the second prototype.<br/><br/>Figure (17): Blades mold made from GRP<br/>D 16 Project: Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA Page 19/36 Date: 22/12/2008<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>4.1.3<br/><br/>Stage 3 : Manufacturing the blade The blade is made of two shell halves and a D-spar. Each shell is fabricated in its respective mold half (i. E. upper lower)by applying a one millimeter thick white color gelcoat and an exact number of fiberglass laminates of different fiber orientations inside the mold cavity and saluting each layer with polyester resin. This process is continued until the required blade shell thickness and thickness distribution along the blade is reached. As was mentioned earlier, the blade shell will be thicker at the root and thins out linearly towards tip. The two blade shells will be joined and glued together at the leading and trailing edges and therefore some means must be provided to allow enough area for adhesions as shown in figure18. The spar is molded and cured in a separate and simple D-mold but carefully tapered down to fill exactly the allocated space and length.<br/><br/>Figure (18): Cross section of upper and lower shell construction and area for adhesion allowance The spar will be fitted to the lower shell and the upper shell is then glued to it along the designated areas. The blade mold can be used as apprising device to house the blade parts until totally cured for a period of 24 hours. After curing, the blade is taken out of the mold and cleaned from extra materials at the edges. Figure 19 shows how the manufacturing process is carried out.<br/><br/>Figure (19): Manufacturing the blades<br/>D 16 Project: Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA Page 20/36 Date: 22/12/2008<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>4.2<br/><br/>Manufacturing of Hub The decision was to use the recycled Aluminum Alloys. The manufacturing of the hub which is of the prime objectives of this system is divided in three integrated steps: The model, the mold and the sand casting hub. The mechanical and the physical properties of the chemical composition of AlZnMg3Cu1 for high mechanical strength were chosen from &quot;Product Guide&quot;, Thyssen (see table 4). Table (4): The mechanical and physical properties of the shown chemicals Zn 4.3 - 5.2 Mg 2.6 - 3.6 Cu 0.5 - 1.0 Cr 0.1 - 0.3 Mn 0.1 - 0.4 Fe 0.5 Si 0.25 Autre 0.35<br/><br/>To match the above mentioned Alloy with the recycled one, in a way to get the mechanical properties, the used recycled Aluminum Alloys was at Royal Scientific Society selected and we got the following chemical compositions shown in table 5: Table (5): The mechanical and physical properties of the shown chemicals Hardness BMN 80 73 85.5 Batch No. 1 2 3 Al 84.13 85.35 89.49 Si 9.13 8.62 6.4 Fe 0.17 0.80 0.39 Cu 2.46 2.54 1.72 Mg 0.11 0.22 0.59 Cr 0.19 0.15 ___ Ni 0.44 0.67 0.49 Mn 0.20 ___ 0.07 Zn 2.90 1.58 0.78 Autre 0.08 0.07 0.06<br/><br/>Figure 20 shows two photos, one for the hub that was manufactured for the first prototype the second is for the second prototype.<br/><br/>Figure (20): The Aluminum hub for the first prototype and the triangular plated for the second prototype. 4.3 Manufacturing the turn-table The turn table was manufactured from Aluminum Alloys too. The same procedure of the hub manufacturing was followed. The turn table is used to connect the generator with the vane. It also connects them to the tower. It houses the slip rings and the brushes that transfer the produced electricity to the cable which is connected to the batteries. Figure 21 shows the manufactured turn table.<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 21/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Table (21): The manufactured turn Table<br/><br/>5. Tower<br/>The tower of the first prototype is a three-legged (tripod) exponentially shaped truss made of galvanized piping. The height of the tower is 6m. For strength requirements, the three legs were chosen to rest on the perimeter of 1116 mm diameter circle. At the top however, a 300 mm circle was chosen to tie the centers of the three tower legs at the top. Figure 22 and figure 23 show the tower legs geometry. Therefore, the exponent of the leg shape function will be found as follows: X = R * Exp (-a*Y) where: X = distance of leg coordination from centre and it is 0.558 m at the base and 0.15 m at the top. R = 0.558 m is the leg coordinates from centre at zero height. a = shape exponent (constant) Y = tower height (0 - 6 m) So, at Y = 6 m, X = 0.15 m, then 0.150 = 0.558 * Exp (-a *6) This exponent is used in a computer program to calculate the coordinates of the tower legs [7]. A medium thickness 1 - inch galvanized steel pipes are chosen for the three legs and ¾ inch for the cross members for the remaining four sections.<br/><br/>Figure (22): Tower legs geometry<br/>D 16 Project: Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED<br/><br/>Figure (23): Sketch of first prototype tower<br/>Date: 22/12/2008 Responsible TTA Page 22/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>The tower of the second prototype of wind turbine is a 10 m tubular mast which is hinged at the base as shown in figure 24. The mast is supported by four guy wires. It is suppose to withstand storm condition of 40 m/s winds.<br/><br/>Figure (24): Sketch of second prototype tower<br/><br/>6. Testing Results<br/>The wind turbine was installed at the testing station which belongs to NERC. It is located about 170 Km South of Amman in a village called Jurf El Daraweesh. The testing period was about a month. The recorded wind speed at the site during the testing period didn't exceed 10 m/s. Figure 25 shows the turbine at the testing station.<br/><br/>Figure (25): The 1 KW wind turbine at the testing station Table 6 presents the recorded average wind speed and the average produce power. Figure 26 shows the power curve obtained during the testing period. As shown in the figure, the power produced at the rated wind speed ­ 9 m/s ­ for this prototype was 978.8 watts. The vane is expected to act for the safety of the turbine and furl at about 12 m/s. then the produced power will be declining. The turbine is not expected to stop completely. It will continue producing power.<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 23/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>. Table (6): Testing results Average wind speed (m/s) 3 4 5 6 7 8 9 10 Average produced power (W) 112.5 166.7 241.3 342.5 483.2 691.6 978.8 1182.8<br/><br/>Power Curve<br/>1300 1200 1100 1000 900 800 Power (w) 700 600 500 400 300 200 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Wind Speed (m/s)<br/><br/>Figure (26): The power curve for the second prototype of the 1 KW wind turbine<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 24/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>References:<br/>[1] Jensen, P. H., &quot;Development of Wind Farms After Cutting Tax Incentives&quot;, Proceedings of the Fourth Arab International Solar Energy Conference, Royal Scientific Society, Amman, Jordan, November 1993. MEMR (Ministry of Energy and Mineral Resources) and JEA (Jordan Electricity Authority), &quot;Final Report, Wind Energy Project in Jordan&quot;, Amman, Jordan, May 1989. Jensen, P. H., &quot;Static Test of Wind Turbine Blades&quot;, &quot;Test Station For Windmills, Riso National Laboratory, Roskilde, Denmark, April 1986. Jensen, P. H., Krogsgaard, J., Lundsager, P., Rasmussen, F., &quot;Fatigue Testing of Wind Turbine Blades&quot;, &quot;EWEA conferences and Exhibition, Rome, Italy, October 1986. Technical Concept of the Functional Model MWPs-B, I. A. SALEH, Royal Scientific Society, July 1990. Miley, S. J., &quot; A Catalog of Low Renolds Number Airfoil data for Wind Turbine Applications&quot; USDOE, Wind Energy Tech. Division, REP-3387, Uc ­ 60, February 1982. Lysen, E. H., &quot;Introduction to Wind Energy&quot;, 2nd Ed., CWD 82 ­ 1, Amersfort, The Netherlands, May 1983. Hennchen, N., &quot;Strom aus der Luft&quot;, Buchheim : IDEA, 1982.<br/><br/>[2] [3] [4] [5] [6]<br/><br/>[7] [8]<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 25/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Annex (1): Technical Drawings of the wind turbine components<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 26/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 27/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 28/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 29/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 30/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 31/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 32/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 33/36<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Lay out of concrete base of tubular mast and guy wires<br/>D 16 Project: Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA Page 34/36 Date: 22/12/2008<br/><br/>Work Package: 3- Developing Appropriate Technologies<br/><br/><br/>Base of tubular mast<br/><br/>Base of guy wires<br/><br/>D 16 Project:<br/><br/>Deliverable: Two Wind Turbine Prototypes 1 KW CRESMED Responsible TTA<br/><br/>Date: 22/12/2008 Page 35/36<br/><br/>Work Package: 3- Developing Appropriate Technologies