Turbine blade

Turbine blade from a Turbo-Union RB199 jet engine. This is a blade with an outer shroud which prevents gas leaking round the blade tip in which case it wouldn't contribute to the force on the aerofoil. The platform at the base of the aerofoil forms a continuous annulus ring which, together with cooling-air cavity purge flow prevents hot gas leakage onto the turbine discs. The short extension, or shank, between the platform and fir-tree fixing in the disc allows space for cooling-air entry to blade, may control blade vibration modes and heat transfer to disc rim.[1]
The turbine blades have a golden colour in this engine cutaway.

A turbine blade is a radial aerofoil mounted in the rim of a turbine disc and which produces a tangential force which rotates a turbine rotor.[2] Each turbine disc has many blades.[3] As such they are used in gas turbine engines and steam turbines. The blades are responsible for extracting energy from the high temperature, high pressure gas produced by the combustor. The turbine blades are often the limiting component of gas turbines.[4] To survive in this difficult environment, turbine blades often use exotic materials like superalloys and many different methods of cooling that can be categorized as internal and external cooling,[5][6][7] and thermal barrier coatings. Blade fatigue is a major source of failure in steam turbines and gas turbines. Fatigue is caused by the stress induced by vibration and resonance within the operating range of machinery. To protect blades from these high dynamic stresses, friction dampers are used.[8]

Blades of wind turbines and water turbines are designed to operate in different conditions, which typically involve lower rotational speeds and temperatures.

  1. ^ "Nomenclature of Cooled Axial Turbine Blade – Turbomachinery Aerodynamic Design".
  2. ^ The Cambridge Aerospace Dictionary, Bill Gunston,ISBN 0 511 33833 3
  3. ^ https://patents.google.com/patent/US2929755A/
  4. ^ Boyce, p. 368.
  5. ^ Acharya, Sumanta; Kanani, Yousef (2017-01-01), Sparrow, Ephraim M.; Abraham, John P.; Gorman, John M. (eds.), "Chapter Three - Advances in Film Cooling Heat Transfer", Advances in Heat Transfer, vol. 49, Elsevier, pp. 91–156, doi:10.1016/bs.aiht.2017.10.001, retrieved 2019-08-30
  6. ^ Goldstein, Richard J. (1971-01-01), "Film Cooling", in Irvine, Thomas F.; Hartnett, James P. (eds.), Advances in Heat Transfer Volume 7, vol. 7, Elsevier, pp. 321–379, doi:10.1016/s0065-2717(08)70020-0, ISBN 9780120200078, retrieved 2019-08-30
  7. ^ Bogard, D. G.; Thole, K. A. (2006-03-01). "Gas Turbine Film Cooling" (PDF). Journal of Propulsion and Power. 22 (2): 249–270. doi:10.2514/1.18034. S2CID 54063370. Archived from the original (PDF) on 2019-03-07.
  8. ^ Bhagi LK, Rastogi V, Gupta P (2017). "Study of corrosive fatigue and life enhancement of low pressure steam turbine blade using friction dampers". Journal of Mechanical Science and Technology. 31: 17–27. doi:10.1007/s12206-016-1203-5. S2CID 115023151.