A turbine and its components
A turbine is a mechanical device that extracts energy from a fluid flow and converts it into usable work. When paired with a generator or a generating thrust, this work is critical in the generation of electricity. The turbine is made up of the rotor assembly, which is the drum or shaft with blades attached (Advameg, n.p.). The fluid travels across the blades, allowing them to move and give rotational energy to the rotor. Wind turbines and gas turbines are examples of turbines. These windmills are constructed of materials that can withstand extreme temperatures. For instance, a typical wind turbine is comprised of 89.1% of steel, 1.6 percent of copper, 5.8 percent fiberglass, 1.1 percent adhesives, and 0.8 percent aluminum (Advameg, n.p.). Other materials include 1.3 percent concrete that is comprised of water, cement, steel reinforcement, and aggregates. The turbine also has 0.4 percent core materials that primarily has wood, plastic, and foam.
The components of a turbine
The primary raw materials in a turbine are the tower, the nacelle and rotor blades. The tower can either be a steel lattice tower that is similar to the electrical towers or the steel tubular tower with an internal ladder to the nacelle (Wilburn, 2-4). These towers are made of steel that is coated with a zinc alloy for protection. However, the steel may be painted instead of being coated (Ikpe et al., 2). The nacelle is a hollow and durable shell containing inner workings of the wind turbine. The nacelle is made up of the fiberglass. This nacelle is comprised of the gearbox and the drive shaft. Moreover, it has a blade pitch control the yaw drive and the hydraulic system which controls the blades’ angle (Wilburn, 9-10). The generator and electric controls are the standard equipment of the turbine, and their principal components are copper and steel.
The use of materials in turbine blades
The diverse use of materials and most experimentation with new materials occur with the blades. The blades have fiberglass as the most dominant material and have a hollow core. Other materials include aluminum and woods (Dowson et al., 191. The wooden blades are solid, but most of them are comprised of skin surrounding the core. If the core is not hollow, it may be filled with a lightweight substance such as balsa wood or plastic foam or honeycomb. Any typical fiberglass blade is approximately 15 meters in length and can weigh about 2,500 pounds. Turbines particularly wind turbines have a utility box that converts the wind energy into electricity and is located at the tower's base (Advameg, n.p.). Some cables help in connecting the nacelle to the utility box while the rest connect the whole turbine to the nearest turbines and a transformer.
Properties of different turbine materials
Copper
Copper has one of the best electrical conductivity. Current easily flows through copper because of its small electrical resistance without any loss of energy. The main features of this metal that make it useful is that it has corrosion resistance, good electrical conductivity, easy to alloy and tough.
Wood
Wood is comprised of lignin and cellulose. Wood is applied in engineering as a common construction material because of its low density and the rather low stiffness that makes it difficult to limit the deflections for the large rotor blades. Notably, the wood materials with all aligned cellulose fibers in the primary load-bearing directions can be close to the maximum possible performance for wood (Babu et al., 4). Moreover, wood is a natural material and is environmentally attractive but can be difficult to obtain in high quality and reproducible which is a requirement for economical and stable manufacturing of the rotor blades.
Steel
Steel is an alloy of carbon and iron. Previously turbines were designed with the heavier steel blades or nickel alloy steels that contain higher inertia. The higher inertia buffered the changes in the rotation speed, therefore, made power output more stable (Babu et al., 4). The nickel alloy lessens distortion in lowering and quenching the critical temperatures of steel while widening the range of successful heat treatment. The nickel alloy possesses good corrosion and the oxidation resistance. Initially, the alloy steel was preferred as the optimum choice for blade fabrication but was abandoned following its low fatigue level and high weight.
Aluminium
Aluminium is a silvery white metal that has a density of around a third of the steel density. The metal was introduced because it was only implemented in the testing situations because of its lower fatigue level than steel. The metal is a good conductor of heat and ductile. Additionally, it has a low price metal and good reliability and low tensile strength. It also has lightweight but less stiff and weaker than steel.
Fibers
The matrix materials and fibers such as the epoxies, vinyl esters, and polyesters are combined into the composites. The composites have excellent properties such as thermal, chemical and mechanical properties. The glass fibers are amorphous and have isotropic properties. Most of the glass-reinforced materials are made of electrical glass that has good mechanical and electrical properties and has high heat resistance (Babu et al., 4). The E-glass is available as milled fiber, chopped fiber, continuous roving, woven fabric, woven roving, and reinforcing mat. The glass fibers for the composites also have good properties such as high strength, moderate stiffness, high strength, and moderate density.
Carbon fibers
The carbon fibers contain nearly pure carbon that forms a crystallographic lattice that has a hexagonal shape called graphite. The carbon fibers have increasingly gained interest following the requirements presented by the decreasing price of carbon fibers and the ever-larger rotor blades (Babu et al., 4). The carbon fibers for the composites have an excellent combination of high strength, high stiffness, low density, and light weight.
Aramid fibers
The aromatic polyamides are characterized by excellent thermal and environmental stability, dynamic and static fatigue resistance, and impact resistance. Aramid fibers contain the highest specific tensile strength (the strength/density ratio) of any continuous-filament yarn available commercially (Babu et al., 4). The aramid composites reinforced with thermoplastic have excellent wear resistance. Moreover, these fibers have low or very low densities.
Conclusion
Conclusively, the material selection for turbines blade is an integral step in any design process in engineering. Characteristics such as high stiffness, long fatigue life, and low density among the carbon fibers are critical aspects (Muktinutalapati, 293). The engineering decision-making process, therefore, includes acknowledging the material properties. The quality and cost of the materials are necessary to ensure efficiency of the manufacturing processes. Most importantly, the chemical, thermal, and mechanical properties are very critical (Muktinutalapati, 293). Moreover, these materials need to be reliable, should safely perform their function, readily available, and in large quantities. Ultimately, the physical attributes such as weight, size, configuration, and appearance are also paramount.
Work Cited
Advameg. Wind Turbine. Advameg Inc. 2017. http://www.madehow.com/Volume-1/Wind-Turbine.html
Babu Suresh, Raju Subba, Reddy Srinivasa and Rao Nageswara. The Material Selection for Typical Wind Turbine Blades Using a Madm Approach & Analysis of Blades. Pp. 1-12. 2006.
Dowson Philip, Bauer Derrick and Laney Scot. Selection of Materials and Material Related Processes for Centrifugal Compressors and Steam Turbines in the Oil and Petrochemical Industry. Pp. 191-198. 2008.
Ikpe Aniekan E., Owunna Ikechukwu, Patrick Ebunilo, Ememobong Ikpe. Material Selection for High Pressure (HP) Turbine Blade of Conventional Turbojet Engines. American Journal of Mechanical and Industrial Engineering. Vol. 1, No. 1, 2016, pp. 1-9.
Muktinutalapati, Nageswara. Materials for Gas Turbines- An Overview. VIT University of India. Pp. 294-310. 2011.
Wilburn, David. Wind Energy in the United States and Materials Required for the Land-Based Wind Turbine Industry from 2010 Through 2030. USGS. Pp. 1-16. 2011.
