MULTI-INSERT DESIGN IN SINGLE NOZZLE CAVITY FOR COOLING GAS TURBINE AIRFOILS
Publication Date: 2012-Dec-31
The IP.com Prior Art Database
This invention proposes a multi-insert design in a single nozzle cavity for efficient cooling of gas turbine airfoils. In the proposed design, two or more impingement inserts are fitted into a single nozzle cavity sequentially through a restricted cavity inlet port. The insert after being positioned inside the cavity, is pushed axially downstream to occupy the cavity space completely thereby minimizing the pin-bank or turbulator region. The proposed design improves overall nozzle cooling capacity and minimizes film cooling usage thereby improving engine efficiency and reducing emission level remarkably. Since the design only requires changes to the insert and pin-bank, quick implementation at low cost is achieved. The multi-insert design can also be used as retrofit to existing gas turbine nozzles.
This invention relates to a multi-insert design in a single cavity of nozzle for efficient cooling of gas turbine airfoils. Cooling of the turbine airfoils by a combination of impingement cooling and film cooling is a well-known technique and the prior cooling systems employ only one insert in a single nozzle cavity. Some known cooling systems for turbine nozzles employ near wall cooling (US 5993156, US7198458) and serpentine cooling (US6955523). The conventional nozzle airfoil cooling system has an impingement cooling region upstream, a pin-bank or turbulator region in the middle and a cooling hole region at the trailing edge. The pin-bank or turbulator region has very low cooling capacity compared to that of the impingement cooling region. Hence strong film cooling is employed to protect this weak cooling region which in turn lowers the engine efficiency as well as the NOX emission margin. To overcome the above drawbacks, an improved cooling system is proposed in which multiple inserts are provided in a single nozzle cavity.
BRIEF DESCRIPTION OF DRAWINGS
Multi-insert design in a single nozzle cavity for improved cooling of gas turbine airfoils is described further with reference to the following drawing in which:
Figure 1 shows the conventional nozzle-insert design used for cooling gas turbine airfoils.
Figure 2 shows the proposed multi-insert design for efficient cooling of gas turbine airfoils according to one embodiment of the invention.
This invention proposes a multi-insert design in a single nozzle cavity for efficient cooling of gas turbine airfoils. In a prior design as shown in Fig. 1, a large area of pin-bank region is used since the impingement insert cannot fully extend towards the trailing edge of the turbine airfoil due to the nozzle platform and outer rail design restrictions. In the proposed design as shown in Fig. 2, two or more impingem...