Stator vane actuator in gas turbine engine

Details Stator vane actuator in gas turbine engine Stator vane actuator in gas turbine engine

2002-07-31

2004-08-03

Look, Edward K. (Department: 3745)

Rotary kinetic fluid motors or pumps

Selectively adjustable vane or working fluid control means

Runner, shaft, or separate motor operated

C415S159000, C415S162000

Reexamination Certificate

active

06769868

ABSTRACT:

TECHNICAL FIELD
The invention concerns actuation systems which rotate stator vanes in gas turbine engines.
BACKGROUND OF THE INVENTION
The compressor in the modern axial-flow gas turbine engine is commonly equipped with variable stator vanes.
FIGS. 1 and 2
illustrate the function of the stator vanes. They are views from outside a compressor having transparent walls, looking toward the axis of rotation, and looking at the tips of the blades.
These Figures are not drawn to scale, and are not aerodynamically accurate in detail. They are presented solely to illustrate the principle of using stator vanes to change the angle-of-attack of incoming airstreams to a compressor stage located downstream of the stator vanes.
FIG. 1
illustrates two stages
3
and
6
of a compressor. Incoming air, travelling in the direction of vector
9
, is compressed by the first stage
3
. Vector
9
is drawn as horizontal on the page. However, the direction of air actually seen by the first stage
3
is the vector sum of (1) vector
9
and (2) the velocity of the stage
3
. Vector
12
represents the velocity, and vector
15
represents the vector sum.
Vector
15
represents a particular angle-of-attack at which the first stage
3
encounters the incoming air
9
. After the first stage
3
compresses the air it discharges it in a different direction, represented by vector
18
. Not only will vector
18
lie in a different direction than vector
9
, but its velocity will be greater, because of the compression process. Vector
18
does not necessarily represent an optimal angle-of-attack for the second stage
6
.
Variable stator vanes provide a solution. If variable stator guide vanes
24
are provided, as in
FIG. 2
, vector
18
of
FIG. 1
can be changed to vector
18
A of
FIG. 2
, having the correct angle-of-attack. The Inventor points out that the stator vanes
24
do not rotate along with stages
3
and
6
. They are stationary, although individual vanes may pivot, as will now be explained.
Many types of stator vanes are adjustable, in order to adjust the angle-of-attack seen by the compressor stage to which the stator vanes deliver discharge air. For example, they may pivot about axis
26
, as indicated by arrows
27
.
FIG. 3
illustrates one mechanism for adjusting the stator vanes, and
FIG. 4
illustrates many of the components of
FIG. 3
in simplified, schematic form. Axes
26
in
FIGS. 3 and 4
, namely, the axes about which stator vanes
24
pivot, correspond to axis
26
in
FIG. 2. A
lever
36
is connected to each stator vane. All levers for a given stage of stator vanes are connected to a movable ring, such as rings
39
and
42
in FIG.
3
.
FIG. 4
shows ring
39
.
Each ring is rotated about axis
45
, to thereby rotate its stage of stator vanes. A bell crank, such as bell crank
48
, rotates each ring. For example, when bell crank
48
rotates about axis
49
in
FIG. 4
, link
51
causes ring
39
to rotate about axis
45
. Crank
36
thus rotates about axis
26
, thereby rotating the stator vane
24
.
All bell cranks are constrained to move in unison, by connection to arm
54
. An actuator
60
, described below, moves the bell cranks in unison, through a linkage represented by arrow
63
in FIG.
5
.
The Inventor has identified an improvement to this type of construction.
SUMMARY OF THE INVENTION
In one form of the invention, a mechanical actuator which adjusts positions of adjustable stator vanes in a gas turbine engine occupies a sector of reduced size on the circumference of the engine, compared with the prior art.


REFERENCES:
patent: 3458118 (1969-07-01), Burge et al.
patent: 3487992 (1970-01-01), Pineda
patent: 3614253 (1971-10-01), Gaertner
patent: 3779665 (1973-12-01), Tatem et al.
patent: 3873230 (1975-03-01), Norris et al.
patent: 4295784 (1981-10-01), Manning
patent: 4409788 (1983-10-01), Nash et al.
patent: 4720237 (1988-01-01), Weiner et al.
patent: 4755104 (1988-07-01), Castro et al.
patent: 5549448 (1996-08-01), Langston

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