Rotary kinetic fluid motors or pumps – With diversely oriented inlet or additional inlet for...
Patent
1993-09-23
1995-04-18
Look, Edward K.
Rotary kinetic fluid motors or pumps
With diversely oriented inlet or additional inlet for...
415115, F04D 3100
Patent
active
054073200
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a turbine casing and is particularly concerned with the cooling of such a casing.
The turbine of a gas turbine engine typically comprises a circular cross-section casing which encloses axially alternate annular arrays of aerofoil blades and vanes. During the operation of the engine, hot gases exhausted from the engine combustion equipment are passed through the turbine in order to provide rotation of the annular arrays of turbine blades.
DESCRIPTION OF THE PRIOR ART
Since the gases are very hot, they naturally provide some degree of heating of the turbine casing. In order to permit the casing to withstand this heating, it is usual to manufacture the casing from a high temperature resistant alloy. However, notwithstanding this, the casing can reach undesirably high temperatures, thereby making it necessary to provide cooling. One way of achieving such cooling is by the provision of cooling air manifolds around the exterior surface of the casing. Apertures in the manifolds direct a flow of cooling air on to the casing surface.
While such cooling air manifolds can be effective in providing casing cooling, they tend to be complicated and costly to produce. Moreover, their positioning adjacent the casing has to be accurate to ensure that the desired degree of cooling is achieved.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a turbine casing cooling system which is simple.
According to the present invention, a turbine casing is at least partially enclosed by a cowling so that a gap is defined between them for the flow of a cooling air, the magnitude of said gap varying in proportion to the local cooling requirements of said turbine casing so that local velocity variations in each flow of cooling air is facilitated.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a sectioned side view of the upper half of a ducted fan gas turbine engine have a turbine casing in accordance with the present invention;
FIG. 2 is a sectioned side view, on an enlarged scale, of a portion of the turbine casing of the ducted fan gas turbine engine shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, a ducted fan gas turbine engine generally indicated at 10 comprises, in axial flow series, an air intake 11, a propulsive fan 12, an intermediate pressure compressor 13, a high pressure compressor 14, combustion equipment 15, a high pressure turbine 16, an intermediate pressure turbine 17, a low pressure turbine 18 and an exhaust nozzle 19.
The gas turbine engine 10 works in the conventional manner so that air entering the intake 11 is accelerated by the fan 12 to produce two air flows: a first air flow into the intermediate pressure compressor 13 and a second flow which provides propulsive thrust. The intermediate pressure compressor 13 compresses the air flow directed into it before delivering that air to the high pressure compressor 14 where further compression takes place.
The compressed air exhausted from the high pressure compressor 14 is directed into the combustion equipment 15 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive, the high, intermediate and low pressure turbines 16, 17 and 18 before being exhausted through the nozzle 19 to provide additional propulsive thrust. The high, intermediate and low pressure turbines 16, 17 and 18 respectively drive the high and intermediate pressure compressors 14 and 13 and the fan 12 by suitable interconnecting shafts.
A portion of the casing 20 of the low pressure turbine 18 can be seen in greater detail if reference is now made to FIG. 2. The casing 20 is of generally frustoconical configuration and is provided with an annular flange 21 at its upstream end for attachment to a corresponding flange 22 provided on the downstream end of the casing of the intermediate pressure t
REFERENCES:
patent: 2445661 (1948-07-01), Constant et al.
patent: 2639579 (1953-03-01), Willgoos
patent: 2759700 (1956-08-01), Wheatley
patent: 2783965 (1957-03-01), Birmann
patent: 5100291 (1992-03-01), Glover
patent: 5152666 (1992-10-01), Stripinis et al.
Look Edward K.
Rolls-Royce PLC
Sgantzos Mark
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