Wind Turbines Take a Technical       Spin at Generating Electricity           Simulation verifies           design durabil...
D E S I G N         S T R AT E G I E S                                                                                    ...
High-Tech Wind                                                                                          Turbine           ...
D E S I G N          S T R AT E G I E S     Count on     Cascade     Engineering    B            ased in Grand Rapids, MI,...
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Wind Turbines Take a Technical Spin at Generating Electricity


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Wind Turbines Take a Technical Spin at Generating Electricity

  1. 1. Wind Turbines Take a Technical Spin at Generating Electricity Simulation verifies design durability of a new rooftop wind energy system. by Richard Peek Wind turbines convert kinetic energy into or less. Some small wind turbines are designed to be mechanical power. In use for centuries, they have installed on top of a roof and are geared to residential harnessed the power of the wind to pump water, or industrial use. grind grain and generate electricity. Cascade Engineering, a leader in plastic injec- While their popularity has peaked and ebbed tion-molded systems for the automotive, industrial over the years, interest in wind turbines to gener- and solid waste industries, is familiar with small wind ate electricity is again gaining momentum. As an turbines. Through close business collaboration with alternative to fossil fuels, wind energy is seen as a an established United Kingdom-based wind turbine viable way to produce energy while reducing global manufacturer and a global design consultancy, warming and pollution. Cascade used simulation to justify a move to an Although there are various types of wind turbines injection-molded rotor design over the existing, on the market, one type that is capturing worldwide expensive, labor-intensive carbon fiber construction. attention is known as the small wind turbine – In addition to mass production scalability, the a system with a rated capacity of 100 kilowatts (kW) molded construction presented the opportunityConcept To Reality Spring / Summer 2008 8
  2. 2. D E S I G N S T R AT E G I E S The building-to significantly reduce time-to-market and pro- is purchased from the utility. As wind speeds in- mountable SWIFTduction costs – making wind power generation crease, turbine output increases, and the amount of wind turbinesa more viable, “green” energy solution. power purchased from the utility is proportionately feature injection- decreased. When the turbine produces more power molded bladesThe Swift Solution than is needed, utilities typically institute a policy developed by Cascade Renewable Devices Swift Turbines Ltd., based in called “net metering,” where the meter turns back- Engineering.Edinburgh, Scotland, unveiled its SWIFT Rooftop wards and the customer gets a credit. All of this isWind Energy System in 2004. This building-mount- done wind turbine serves as an energy source for The SWIFT wind turbine includes three ma-domestic, community and industrial use. jor components – the rotor, the generator and the When correctly sited, it cuts up to 1.2 tons of structural support. The rotor features speciallycarbon dioxide emissions annually and reduces designed blades and a patented diffuser ring thatelectricity bills. Designed to be environmentally quietly capture the wind energy; the generator, withsustainable, it produces more energy in its lifetime control electronics, converts the mechanical energythan is incorporated in the materials and processes into electrical energy; and the support structure, orused to manufacture it. Therefore, it is designated as mast, has a special mounting system that minimizes“harm neutral.” vibration to the building. Cascade Engineering The SWIFT has a rated power output of 1.5 kW focused its expertise in plastics on developing anand can supply up to 2,000 kW per year in a good injection-molded alternative to the current carbonwind condition – about 20 percent of an average fiber rotor blades.home’s use. It is a grid-connected form of embeddedpower generation. That is, in a normal residential Building the Bladesapplication, a home is served simultaneously by the Traditionally, wind turbines generate noise as thewind turbine and a local utility. wind travels the length of the blades, which have For example, if the wind speed is not high enough curved surfaces. The SWIFT wind turbine, with itsto spin the wind turbine’s blades, there will be no five blades, is quiet. That’s because the wind turbineoutput from the turbine, and all of the needed power features an outer ring that acts as a diffuser as 9 Concept To Reality Spring / Summer 2008
  3. 3. High-Tech Wind Turbine Several characteristics make the SWIFT Wind wind travels down the blades and is dispersed along Turbine unique: • Silent operation. Patented, acoustic suppres- the ring. Noise from operation is less than 35 decibels sion aerodynamics, notably the ring diffuser, re- for all wind speeds. moves noisy, turbulent air currents at the blade Initially, Renewable Devices constructed the blades tips. Also, the direct-driven generator contains from carbon fiber. However, it is a costly material that no gear box, which means there is no mechani- poses some challenges. For example, because the carbon cal noise. fiber rotor manufacturing process is manually labor • Anti-vibration mounting brackets. For place- intensive, it can take a long time to make the blades. ment on buildings, the SWIFT mounting systems Second, there is an opportunity for error: if the carbon are scientifically designed to dampen all reso- fiber material is inadvertently laid in the wrong direc- nances that may be encountered during normal tion, it can affect the blades’ strength. Third, it is diffi- operation of the turbine. The mounting brackets cult to maintain consistency from product to product. feature integrated anti-vibration technology that ensures that no discernable vibration is transmit- What Renewable Devices needed was a more ted to the structure. cost-effective rotor. The company found just such a • Mechanical/electronic furling. As the wind solution in an injection-molded rotor with thermal increases past a certain speed, the turbine starts plastic blades that Cascade Engineering developed. to furl, or turn itself out of the wind. Even when it The Cascade Engineering team made slight changes is not pointing directly at the airflow, the SWIFT’s to the original outer envelope of the rotor. Most of the rotor enables it to operate efficiently, regulating design effort focused on adding internal ribbing and the energy taken from the wind and, consequently, On behalf of Cascade other geometric features that would provide strength to the electricity generated. An electronic furling Engineering, Altair the rotor while also reducing stress. A key objective was system copes with the extra strong gusts of ProductDesign, to create as stiff a structure as possible. wind by regulating the rotational speed of the a global design Cascade worked to meet engineering standards set rotor, thus keeping power generation at its consultancy and optimal level. forth by the International Electrotechnical Commission. division of Altair • Electronic braking. An automatic electronic The IEC 61400-2 Small Wind Turbine Safety standard Engineering, Inc., brake activates in the event of extreme wind applies to wind turbine generator systems with swept speed, and no power is generated. employed Altair areas of less than 40 m2. HyperWorks to evaluate the Engineering, Inc., to provide design direction, fluid and structural performance of Simulation Savvy through simulation, to successfully develop a thermal the wind turbine’s As part of the development process, Cascade plastic rotor replacement. It was important to thermal plastic Engineering collaborated with Altair ProductDesign, understand how the injection-molded rotor com- rotor blades. a global design consultancy and division of Altair pared with the original carbon fiber design.Concept To Reality Spring / Summer 2008 10
  4. 4. D E S I G N S T R AT E G I E S Count on Cascade Engineering B ased in Grand Rapids, MI, Cascade Engineering is a leader in the development, engineering and manufacturing of plastics solutions for multiple industries, including the to municipal governments including the City of Rochester, automotive, industrial and solid waste markets. The company NY, and others. Cascade steps up to the challenge, devises is a strong advocate for “sustainable” business practices that innovative solutions and produces results. emphasize the key role business can play in building financial, For the City of Rochester, for example, Cascade developed social and ecological capital. a tamper-proof bar code tracking system for 70,000 waste Fred P. Keller is chairman and CEO of Cascade Engineering. containers. Each container included a permanent, in-molded Under his leadership, the company has grown from a small bar code, allowing the Department of Environmental Services injection-molding operation with six employees into a complex to assign waste containers to specific addresses.The city manufacturing organization with 1,200 employees, 13 facilities expects to save up to $200,000 per year in container worldwide and annual sales of $300 million. replacement and dumping costs as well as improve Cascade serves a diverse customer base ranging from auto operational efficiency. manufacturers such as Ford Motor Company, Chrysler, GM and Honda, to office furniture manufacturer Herman Miller, Inc., For more information about Cascade Engineering, visit or check 05 on the reply card. Altair aerospace engineers, with deep domain to committing to hard tooling. Cascade and Altairexpertise in air flow, employed Altair HyperWorks engineers leveraged HyperWorks to understandenterprise CAE solution to comparatively evaluate the influence of radii changes and modified designthe fluid and structural performance of the thermal features including rib number and placement, sizingplastic design against the baseline and IEC 61400-2 and box sections.requirements. This information was used to providecritical design direction to successfully develop the Blowing into Productionmolded replacement. By implementing simulation technology, The injection-molded results returned similar Cascade confidently went straight into productionstress areas as found on the carbon fiber design. tooling, avoiding the time and cost associated withDeflections were reasonable. The challenge, how- pre-production tooling. In addition, by moving fromever, was to get the thermal plastic design stresses a carbon fiber to injection-molded design, overalllow enough to meet fatigue and yaw specifications cost savings were the standard. In an agreement with Renewable Devices, The tensile strength of carbon fiber is higher Cascade Engineering now will supply injection-than a thermoplastic material. Engineers needed to molded rotors for the SWIFT Wind Turbine on areduce the stress level in the thermoplastic rotor to worldwide basis. What’s more, Cascade has Northacceptable levels for the material. The advantage American distribution rights to the wind turbine,with the thermoplastic rotor is that engineers had which will be introduced in September 2008.more design freedom to introduce geometry insidethe blades and to the outer diffuser. This allowed theopportunity to reduce the stress to levels under the Richard Peek is Engineering Manager, Cascade Engineering,limits of the material. Grand Rapids, MI. To ensure the thermal plastic design would meetthe in-service requirements customers have come to For more information about the SWIFT Wind Turbineexpect, a detailed design study was performed prior and HyperWorks, visit or check 03 or 04 on the reply 11 Concept To Reality Spring / Summer 2008