Ramamurthy Prabhakaran
Old Dominion University, USA
Title: Innovations in design, materials and manufacturing of turbine blades for jet-engines
Biography
Biography: Ramamurthy Prabhakaran
Abstract
Turbo-engines are used in land-based power generators as well as in aircraft . Th e modern turbo-engine is the product of decades of innovations in design, materials and manufacturing; and the innovations are continuing, in the never-ending quest for lighter and more effi cient turbo-engines. Among the fi ve essential parts of a turbo-engine namely the air-intake, compressor, combustion chamber, turbine and exhaust the blades of the high-pressure turbine are subjected to very high centrifugal loads and very high temperatures. Historically, the early jet engines developed in Germany and England utilized stainless steels for the turbine blades and they had a temperature limit of about 5000C. Nickel-based superalloys were developed around the Second World War. Several generations of these superalloys were the result of material innovations. Several manufacturing innovations extended the operating temperature of the superalloys: notably, directional solidifi cation to induce elongated grains, single-crystal solidifi cation and directional solidifi cation of eutectic superalloys to align the fi brous reinforcements. Th e ever-increasing demands for lighter and more effi cient turbo-engines, due to rising fuel prices, air-traffi c volume and environmental concerns, have continuously raised the turbine inlet temperature. Design innovations such as intricate cooling passages in the blades allow them to operate at temperatures well in excess of the melting point of the superalloys themselves. Ceramic coatings on the superalloy blades represent the next material innovation. Innovations in manufacturing are enabling the additive manufacturing of superalloy blades, reducing the time needed to move from the design phase to the testing phase. With the superalloy blades reaching their limit, conventional limitations of brittleness and low reliability of monolithic ceramics are sought to be overcome by innovations such as self-healing ceramics and transformation-toughened ceramics. Ceramic matrix composites are showing promise to push the turbine inlet temperature beyond the current limits. Th is presentation will summarize some of these innovations.