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ME 307 Machine Design (161) Term Project Due Jan 01, 2017

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King Fahd University of Petroleum & Minerals College of Engineering Sciences

Mechanical Engineering Department First Semester 2016/2017 (161)

ME 307 Machine Design I Assigned: Sunday Dec 11, 2016

Term Project Due: Sunday Jan 01, 2017

Project group: 2-3 students

Introduction Wind turbine such as the one shown if Fig. 1a is called Horizontal Axis Wind Turbine (HAWT). Depending on their power output capacity, the size of wind turbines can reach to an enormous size (try to find the person who is standing in Fig. 1b) as shown in Fig. 1b.

Figure 1. Horizontal axis wind turbine. (a) wind turbine farm (b) wind turbine sizes.

The Nacelle is a cover housing that houses all the generating components in a wind turbine, including the gear box, low- and high-speed shafts, generator, controller, and brake assembly as shown in Fig. 2a. The Rotor consists of the blades and hub. The hub is connected to the low speed shaft as shown in Fig. 2b. The yaw system of wind turbines is the component responsible for the orientation of the wind turbine rotor towards the wind as illustrated in Fig. 2c.

(b)(a)

ME 307 Machine Design (161) Term Project Due Jan 01, 2017

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Figure 2. Wind turbine. (a) Nacelle’s components, (b) Hub connection to the low speed shaft, (c) Yaw system.

Design Problem The specifications for the horizontal wind turbine to be designed are:

Rated Power 5 MW Rotor configuration 3 blades Rotor diameter 126 m Hub Height 90 m Rated wind speed 11.4 m/s Rated rotor speed 12.1 rpm Rotor mass 110,000 kg Nacelle mass 240,000 kg Tower mass 347,460 kg Low speed shaft length 5.5 m Distance from the hub center to the yaw axis 5.0 m Distance from the hub center to the main bearing 1.9 m Rated generator speed 1173.7 rpm Gearbox ratio 97:1 Rated generator torque 43,093 N.m Rotor torque 3.95 MN.m

Wind turbines are usually subjected to different loadings due to different sources. However, you are requested to consider the forces and moments illustrated in Fig. 3.

(a) (b)

(c)

low speed shaft

ME 307 Machine Design (161) Term Project Due Jan 01, 2017

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Figure 3. Forces and moments acting in horizontal wind turbine.

Given the loads below, you are request to design the low speed shaft and the tower of a horizontal axis wind turbine. Load Maximum Minimum 𝑀"#: Out-of-plane blade root moment 7.0 MN.m 3.0 MN.m 𝑀$#: In-plane blade root moment 6.0 MN.m 2.0 MN.m 𝑀%&': x-direction moment at the tower base 1.5 MN.m 0.7 MN.m 𝑀%&(: z-direction moment at the tower base 40 MN.m 20 MN.m 𝑀)*&: Yaw moment at the nacelle yaw bearing 1.0 MN.m -1.0 MN.m 𝐹%,: Thrust force resulting from drag 1.0 MN 0.0

Report Requirements: Tasks Marks Hint 1) Layout for low speed shaft 7 a) Bearings should be able to

withstand thrust force. b) Shaft is connected to the gearbox

by spur gear with pressure angle of 20°.

c) Assume that the pitch (nominal) diameter of the spur gear connected to the gearbox is 6 times the diameter of the shaft.

2) Layout for the tower 5

x

y

z !"#$!%&

!'&!()) *+,

*+$-

*+$. !+$.

!+$-

/0#1

!%&: Out-of-plane blade root moment !'&: In-plane blade root moment

!()): Low speed shaft torque !+$-: x-direction moment at the tower base !+$.: z-direction moment at the tower base

*+$.: z-direction force at the tower base *+$-: x-direction force at the tower base *+,: Thrust force resulting from drag /0#1 : Weight of nacelle

!"#$: Yaw moment at the nacelle yaw bearing /2%

/+$

/2%: Weight of rotor /+$: Weight of tower

ME 307 Machine Design (161) Term Project Due Jan 01, 2017

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3) Draw FBD for low speed shaft 4 4) Draw FBD for the tower 4 5) Determine all forces and reactions in

the low speed shaft 5

You can use MDSolid: http://www.mdsolids.com/download.htm

6) Determine all forces and reactions in the tower

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7) Draw the shear force and bending moment and torque diagrams for the low speed shaft

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8) Draw the shear force and bending moment and torque diagram for the tower

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9) Determine the critical locations in the low speed shaft for stress design

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10) Determine the critical locations in the tower for stress design

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11) Determine critical diameters of the low speed shaft based on fatigue and static stresses at the critical locations.

15 Minimum design factor is 1.5

12) Determine critical diameters of the tower based on fatigue and static stresses at the critical locations.

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13) Check the deflection at the critical locations in the low speed shaft. Check recommended limits in Table 7–2 and comment on your results.

4 You can use MDSolid You can use MDSolid

14) Check the deflection at the critical locations in the tower. Check recommended limits in Table 7–2 and comment on your results.

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15) If any of the deflections exceed the recommended limits, make appropriate changes to bring them all within the limits.

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16) What do you think of your design? 3 a) Are your dimensions reasonable? b) Can you find the material in the

market? c) Is your design manufactural?

17) Use SolidWorks to draw the low speed shaft and the tower to scale and showing all proposed dimensions. Suggest better materials that may improve the deflection without changing the overall dimensions.

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18) Bill of material, number and types of each component (i.e. shaft, keys, retaining rigs, bearings and gears).

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19) Reference any source you used in this project. (Internet sites, books, notes, etc.).

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ME 307 Machine Design (161) Term Project Due Jan 01, 2017

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Report Format:

1. Cover page 2. Task distribution (List the tasks done by each member) 3. Final design results (Show all detailed results) 4. Appendix (If any, show design iterations)

Take note of the followings:

I. Make any other dimensional decisions necessary to specify all diameters and axial dimensions.

II. You are designing a shaft and a tower for huge wind turbine with a rotor diameter of 120m. The Airbus A380, the world's largest commercial aircraft, has a wingspan of 79.75 m only!

III. A 2 MW wind turbine roughly costs $3-$4 million installed. IV. A typical low speed shaft for a wind turbine is shown in Fig. 4.

Figure 4. Typical low speed shaft of wind turbine.

V. Useful resources about the wind turbines:

Ø How wind turbines work: http://www.energy.gov/eere/wind/animation-how-wind-turbine-works

Ø The inside of a wind turbine

http://www.energy.gov/eere/wind/inside-wind-turbine-0