WIND TURBINE GEARBOX CASE STUDY

TEAM NUNCHUCKS Shyamal Satodia

Varun Kumar Dillip Lakshmipathy Raphael Noel Roche

PROBLEM STATEMENT To design the power transmission for a

windmill given the gearbox specifications and other input and output constraints.

CONSTRAINTS Max power to be delivered – 1700Kw Steady state power to be delivered – 1600Kw Input speed- 16 rpm Output speed- 1800 rpm Speed ratio- 111.2 Input shaft size and configuration-510mm Output shaft size and configuration-120mm Max weight allowed – 16000kg Power efficiency – 97% Max cost - $150k Production numbers – 1000/year Life – 20 years

PROPOSED LAYOUT Two planetary gear sets followed by a

parallel spur gear set. The ring gears of both the planetary sets

were fixed.

View of transmission Assembly Layout (Front

side)

A view of the Transmission Assembly (Rear side)

PROPOSED LAYOUT

View of transmission Assembly Layout (Front

side)

A view of the Transmission Assembly (Rear side)

PROPOSED LAYOUT

View of transmission Assembly Layout (without

ring gear)

View of the Transmission Assembly (without ring gear)

PROPOSED LAYOUT

GEARS

SHAFT DESIGN

Alternating von Misses stress Midrange von Misses stress Factor of safety of the shafts are calculated based on the following Goodman equation

Where, alternating bending stress ( Mean bending stress ( Alternating torsion Mean torsion (

SHAFTS

Shaft material : Alloy steel ASTM A514Shafts are assumed to be surface hardened and have reliability of 99%.The carrier of the second planetary gear is a floating member.

FACTOR OF SAFETY OF ALL THE SHAFTS:Shaft number

Shaft diameter

Factor of safety

Shaft 1 510mm 1.486Shaft 2 400mm 1.582Shaft 3 300mm 1.749Shaft 4 120mm 1.896

Shaft number

Maximum deflection(ymax),m

Shaft 1 1.729E-4Shaft 2 1.037E-4Shaft 3 1.571E-4Shaft 4 1.467E-4

Deflections of all the shafts

The maximum deflection of the shafts are within the safe limit.

Bending moment diagram of shaft 1

Bending moment diagram of shaft 3

Bending moment diagram of shaft 4

BEARINGS We have four bearings in the whole

transmission Using the force at each of these points, the

desired life, the speed of the corresponding shaft; the catalog rating life can be determined.

Depending on the C10 values the bearings were selected from the SKF catalog.

Bearing 2 Bearing 4Bearing 3

Bearing no.

Bearing type

Bearing designati

on

Outer diameter

Bore

Bearing 1 Cylindrical roller- 4

row

BC4B 319411

680 500

Bearing 2 Cylindrical roller- 1

row

NNU 4180 M/W33

680 250

Bearing 3 Cylindrical roller 4 row

314484 D 420 300

Bearing 4 Cylindrical roller Thrust bearing

K 89424 M 250 78

KEYWAYS We use keys for the two sun gears and the

two spur gears of the last stage The width and the depth of key can be got

from the catalog and depends on the size of the shaft

The length of the key can be determined from the Modified Goodman equation.Key no. Width of

key Height of

keyDepth of keyway

Length of key

Key 1 0.09 0.045 0.0174 0.354Key 2 0.07 0.036 0.0144 0.256Key 3 0.07 0.036 0.0144 0.320Key 4 0.032 0.018 0.0074 0.260

SIMULATION RESULTSShaft 03

Stress Distribution

Shaft Deformation

SIMULATION RESULTS

Output shaft

Stress Distribution

Shaft Deformation

SIMULATION RESULTS

Sun and Planet Gears

DRAWINGS

Sun gear

DRAWINGS

Shaft 03

REFERENCES Budynas, R. G., & Nisbett, J. (2011).

Shigley's Mechanical Engineering Design. New York: McGraw Hill.

Norton, R. L. (2005). Machine Design: An Integrated Approach. Prentice Hall.

Beardmore,Roy.Epicyclic Gears N.p.,n.d.Web Nov.2014

SFB bearing website http://www.skf.com/us/products/bearings-units-housings/product-tables/index.html

AGMA – Design Manual for Enclosed Epicyclic Gear drives.

THANK YOU!!