A blade is provided and includes a platform and a root configured to be connected to a blade carrier. Airfoil portions extend from opposite sides of the platform. Each airfoil portion defines an operating surface being the surface facing the other airfoil portion. An operating surface of one of the airfoil portions defines a suction side and the other operating surface of the other airfoil portion defines a pressure side.
1. A blade comprising:
a platform; and
at least one root configured to be connected to a blade carrier,
wherein airfoil portions extend from opposite circumferential sides of the platform, each airfoil portion defining an operating surface being a surface facing the other airfoil portion,
wherein an operating surface of one of the airfoil portions defines a suction side and the other operating surface of the other airfoil portion defines a pressure side,
wherein, when assembled, the two airfoils portions of the blade and another blade adjacent thereto and connected to each other together define an airfoil, and
wherein the airfoil portions each extend to a trailing edge of the airfoil and define a gap between a facing edge at the corresponding trailing edge, respectively, the gap extending the length of the trailing edge of the airfoil.
2. The blade as claimed in claim 1 , further comprising:
a shroud connected at ends of the airfoil portions, wherein the platform with the airfoil portions and the shroud define a closed channel.
3. The blade as claimed in claim 1 , wherein a surface of each airfoil portion opposite the operating surface defines an inner surface of the airfoil that, when a number of blades are assembled on the blade carrier, is defined by two adjacent airfoil portions.
4. The blade as claimed in claim 3 , wherein the inner surface of at least one of the airfoil portions has heat transfer enhancers arranged to increase thermal exchanges.
5. The blade as claimed in claim 3 , wherein the inner surface of at least one of the airfoil portions comprises spacers, and
wherein when a number of blades are assembled on the blade carrier, the spacers are interposed between two adjacent airfoil portions.
6. The blade as claimed in claim 2 , wherein at least one of the airfoil portions, the platform and the shroud has through holes arranged to let cooling air to pass therethrough.
7. The blade as claimed in claim 1 , wherein the blade is assembled onto the blade carrier adjacent to other blades, and
wherein the airfoil portion with the operating surface defining a pressure side of the blade is connected to the airfoil portion with the operating surface defining a suction side of an adjacent blade.
8. The blade as claimed in claim 1 , wherein a chamber is defined between adjacent airfoil portions.
9. The blade as claimed in claim 8 , further comprising
a tubular insert having an end inside of the chamber and an opposite end outside of the chamber in the region of the roots of the blades.
10. The blade as claimed in claim 9 , wherein the tubular insert comprises a number of calibrated through holes arranged to control the cooling air entering the chamber.
11. The blade as claimed in claim 9 , wherein the platform has a hole to let the tubular insert pass through.
12. The blade as claimed in claim 2 , further comprising:
seals provided at least one of: at side borders of the platform and at side borders of the shroud.
13. The blade as claimed in claim 2 , further comprising:
a seal at the shroud.
14. The blade as claimed in claim 1 , wherein the blade is a rotor blade or a guide vane.