Rotary machine

Details Rotary machine Rotary machine

1998-12-22

2001-03-20

Look, Edward K. (Department: 3745)

Rotary kinetic fluid motors or pumps

Bearing, seal, or liner between runner portion and static part

Between blade edge and static part

C415S173500, C415S174400, C415S131000

Reexamination Certificate

active

06203273

ABSTRACT:

TECHNICAL FIELD
This invention relates to a rotary machine such as a portion of a gas turbine engine having a stator assembly and a rotor assembly. More particularly, it relates in one embodiment to a compressor which has a fan rotor, which has rotor blades and stator vanes, and which has seal lands extending circumferentially with respect to the clearance between the stator assembly and the rotor assembly.
BACKGROUND OF INVENTION
Rotary machines are used to transfer energy between a flow path for working medium gases and rotating elements inside the machine. There are many examples of such machines in widely disparate fields of endeavor.
FIG. 1
shows a side elevation view of the turbofan engine
10
having an axis of rotation Ar. It is one example of a rotary machine of the gas turbine engine type. The turbofan engine is widely used for powering commercial aircraft and military aircraft.
The turbofan engine
10
has a compression section
12
, a combustion section
14
and a turbine section
16
. The compression section has an annular (core) flowpath
18
for working medium gases. The flowpath leads to the combustion section and thence to the turbine section. In addition, the compression section has an annular bypass flowpath
22
for working medium gases which conducts an annulus of flow around the core flowpath. The flow rate through the bypass duct can be many times the flow rate through the core flowpath
18
. In typical commercial turbofan engines, the flow is five (5) times or greater the flow through the core section of the engine.
The core flow path
18
extends through the engine inwardly of the bypass flowpath
22
. As the working medium gases are flowed through the engine, the gases are compressed in the compression section
12
. The compressed gases are burned with fuel in the combustion section
14
to add energy to gases and expanded through the turbine section
16
to produce power. As the gases are flowed through the turbine section, rotating elements (not shown) receive energy from the working medium gases. The energy is transferred to the compression section by compressing the incoming gases in both the core and bypass flowpaths. A portion of the energy from the turbine section
16
drives large masses of air through the bypass flowpath
22
, usually without adding energy to the gases by burning fuel with the gases. Thus, the gases produce useful thrust as they exit the engine at the rear of the engine and at the rear of the bypass duct.
FIG. 2
is a side elevation view of the engine
10
shown in FIG.
1
. The engine is partially broken away to show a portion of the interior of the compression section
28
. The engine has a low pressure rotor assembly
24
and a high pressure rotor assembly (not shown). The rotor assemblies extend axially through the engine for transferring energy from the turbine section
16
to the compression section
12
. The working medium flow path
18
extends through the rotor assemblies. A stator assembly
26
bounds the flowpath and directs the gases as the gases pass through the stages of the rotor assembles.
The compression section includes a first, low pressure compressor
28
. The turbine section
16
includes a low pressure turbine
30
. The low pressure turbine is the device used to extract energy from the working medium gases. A shaft
32
connects the turbine section to the low pressure rotor assembly
24
in the low pressure compressor. The shaft is typically called the low shaft. A bearing
34
supports the shaft. Energy is transferred via the rotatable low shaft
32
to the low pressure compressor. The shaft drives the low pressure compressor about the axis of rotation Ar at over three thousand revolutions per minute to transfer energy from the low pressure turbine to the low pressure compressor.
The compression section
12
also includes a high pressure compressor
36
. The high pressure compressor receives working medium gases from the exit of the low pressure compressor. The high pressure compressor is connected by a second (high) shaft (not shown) to a high pressure turbine. The high shaft is disposed outwardly of the shaft
32
for the low pressure compressor
28
. The high pressure compressor is driven by a high pressure turbine
38
downstream of the combustion section
14
. The hot working medium gases are then discharged to the low pressure turbine
30
and drive the low pressure turbine about the axis of rotation Ar.
The low pressure compressor
28
is often referred to as the fan-low compressor. Another example of a fan-low compressor is shown the U.S. Pat. No. 4,199,295 issued to Raffy et al. entitled “Method and Device for Reducing the Noise of Turbo Machines.” In Raffy and as shown in
FIG. 2
, the fan-low compressor has a relatively massive fan rotor disk
42
. A plurality of relatively massive fan rotor blades
44
extend radially outwardly from the fan rotor disk across the core flowpath
18
and across the by-pass flowpath
22
.
FIG. 2A
illustrates the relationship during assembly of the engine of the two main subassemblies: a first subassembly of the fan-low compressor with a fan blade
44
installed and another fan blade being installed; and, a second subassembly that comprises the rest of the engine. The fan rotor blades
44
are axially inserted into the fan rotor disk as one of the last steps of assembling the engine.
FIG. 2A
shows the engine during the method of assembly as discussed below with at least one fan blade
44
installed and with the next fan blade moving on its path of insertion into the rotor disk.
Each fan blade
44
has a root or dovetail
46
which engages a corresponding slot
48
in the fan rotor disk. Alternatively, the fan blade might be pinned to the rotor disk. The low pressure compressor also includes a drum rotor
50
which is part of the low pressure rotor assembly
24
. The drum rotor is so called because of its drum-like shape. The drum rotor extends rearwardly from the fan rotor disk.
As shown in
FIG. 3
, the drum rotor has dovetail attachment members
52
. The members adapt the rotor to receive rotor elements such as a plurality of arrays of rotor blades as represented by the rotor blades
54
,
56
,
58
,
62
,
64
, and
66
. The stator assembly
26
has an interior casing or outer case
68
which extends circumferentially about the rotor assembly. The outer case includes a flow path wall
69
for the bypass flowpath. The rotor blades extend radially outwardly across the working medium flow path
18
. Each rotor blade has a tip,
30
as represented by the tips
72
,
74
,
76
,
78
,
82
84
. An outer air seal
85
has outer air seal lands
86
which extend circumferentially about the outer case. The outer seal lands are disposed radially outwardly of the arrays of rotor blades to block the loss of working medium gases from the flowpath. These seal lands, generally called “rubstrips”, are in close proximity to the rotor assembly
24
. A plurality of arrays of stator vanes, as represented by the stator vanes
92
,
94
,
96
,
98
,
102
and
104
extend radially inwardly from the outer case into at least close proximity with the drum rotor. Each stator vane has a tip, as represented by the tip
106
.
An inner air seal
108
is disposed between the stator vanes
92
-
104
and the drum rotor
50
. Each inner air seal
108
has a seal land
112
which extends circumferentially about the tips
106
of the stator vanes. The seal land is disposed in at least close proximity to the drum rotor. The drum rotor is adapted by rotor elements, as represented by the knife edge seal elements
114
, which extend outwardly and cooperate with the seal land to form the inner air seal. The knife edge seal elements have a greater height than width and are relatively thin. The knife edge elements cut into the seal land under operative conditions as the knife edge elements move radially outwardly under operative conditions. An example of such a construction is shown in U.S. Pat. No. 4,257,753 issued to Bradley et al. entitled “Gas Turbine Engine Seal and Method for Making a Gas Turb

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