GB2163219A

GB2163219A - Cooled turbine blade

Info

Publication number: GB2163219A
Application number: GB08132879A
Authority: GB
Inventors: Rodney John Clifford; Ian James Charters
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1981-10-31
Filing date: 1981-10-31
Publication date: 1986-02-19
Also published as: GB2163219B; US4684322A

Description

1

SPECIFICATION

Cooled turbine blade This invention, relates to cooled turbine 70 blades.

According to this invention, there is pro vided a turbine blade comprising an aerofoil body, a cooling air passage extending through the body in a helical or serpentine path such that the passage passes alternately between a first and a second region of the blade, wherein the second region is one which, dur ing operation tends to have a temperature lower than that of the first region.

The helical or serpentine configuration nof the passage makes it possible for the passage to have a high length /cross-section ratio. At the same time the length of the passage may be limited according to its length of the pas sage is limited in this way, two or more said passages may be provided in succession along the span of the blade. However, in a region requiring high heat transfer, two passages may be provided side by side or in overlap ping or intertwining relationship. It will be seen that due to the helical or serpentine configuration of a said passage, the air flow ing therethrough gives up heat at each pass through a said second region so that the heat 95 transfer capacity of the air is at least partially replenished with each such pass. Thus the invention makes it possible to transfer heat rapidly from a hot to a cooler region of the blade over the whole span thereof.

The term---blade-used herein means a blade of a turbine rotor or a blade or vane of a turbine stator.

Examples of a blade according to this inven tion will now be described with reference to 105 the accompanying drawings wherein:

Figure 1 is a chordal view of a blade showing the cores of ducts and passages through the blade.

Figure 2 is a view on the line 11-11 in Fig. 1. 110 Figure 3 is a view similar to Fig. 1 but shows a modification.

Figure 4 is a section on the line IV-IV in Fig. 3.

Figure 5 is a detail of Fig. 3 showing a 115 further modification.

Referring to Figs. 1 and 2, the blade com prises an aerofoil body 10 having a leading edge surface 11 requiring to be cooled. The body 10 includes a cooling air passage 12 which extends generally in the direction of the span of the blade but follows a helical path such that the passage 12 passes alternately between a first region 13 lying close to the surface 11 and a second relatively cooler or heat sink region 14 lying remote from the surface 11. The relatively lower temperature of the region 14 is produced or enhanced by a heat sink duct 15 extending spanwisely within the helical configuration of the passage GB 2 163 219A 1 12 but closer to the region 14 than the region 13.

In operation cooling air is supplied to the passage 12 and to the duct 15. The air passing through the passage 12 receives heat at the region 13 and gives off at least some of that heat at the region 14, the latter region being cooled by the air flowing.through the duct 15 and therefore, constituting a heat sink.

In the modification shown in Figs. 3 and 4 a first passage 1 2A extends generally in the direction of the span of the blade but follows a helical path between a first region 1 3A lying close to the surface 11 and a second region 14A lying remote from the surface 11. The passages 12A has an inlet port 12A1 in a duct 16 extending spanwisely through the body 10 and fed with cooling air for the passage 12A. The passage 1 2A extends only over a region 1 8A being a part-length of the span of the blade and has an outlet port 19 in a duct 17 or an outlet port 20 at a surface portion of the blade remote from the surface 11. A heat sink duct 1 5A may also be provided.

Further passages 1 2B, 1 2C, similar to the passage 1 2A, are provided at regions 18 B, 18C. The regions 18A, 1813, 18C lie generally in succession along the span of the blade but they may overlap, as shown between the regions 1813, 18C, where increased cooling effect is required, i.e. at relatively hotter portions of the surface 11.

At the trailing edge of the blade shown in Figs. 3, 4, passages 121), 1 2E are arranged in spanwise succession, each passage extending generally spanwisely but in serpentine configuration from an inlet port 21 in a supply duct 22 to an outlet port 23 at the trailing edge extremity 24 of the blade. Successive passes of the serpentine of each passage 121), 1 2E may lie alternately adjacent the opposite sides 1 OA, 1 OB, of the blade so as to transfer heat from the hotter side 1 OA to the cooler side 1 OB. Alternatively, Fig. 5, a heat sink duct 1513 may be provided to establish a region which is cool compared to the region more nearly adjacent the extremity 23 and where the air flowing through the serpentine passage, here denoted 1 2F, can be cooled.

Claims

1. A turbine blade comprising an aerofoil body, a cooling air passage extending through the body in a helical or serpentine path such that the passage passes alternately between a first and a second region of the blade, wherein the second region is one which, during operation tends to have a temperature lower than that of the first region.

2. A blade according to Claim 1 comprising a spanwise duct for cooling air and defin- ing said second region.

2 GB 2 163 21 9A 2

3. A blade according to Claim 2 wherein said passage is helical and said duct extends within the helix defined by said passage.

4. A blade according to Claim 2 wherein said pasage is helical and said duct extends outside the helix defined by said passage.

5. A blade according to Claim 1 comprising a spanwise duct for cooling air, at least two said passages arranged in succession along the span of the blade and each having an inlet port in said duct.

6. A blade according to Claim 1 wherein said first and second regions are defined by respective surfaces of the blade which, in operation, have different temperatures.

7. A turbine blade substantially as described herein with reference to the accompanying drawings.

Printed in the United Kingdom for Her Majesty's Stationery Office, Dd 8818935, 1986, 4235. Published at The Patent Office, 25 Southampton Buildings, London. WC2A lAY, from which copies may be obtained.