A rotor stage disposed within an annular fluid flowpath in a turbomachine is disclosed. The rotor stage includes outer and inner rings and a plurality of first and second airfoils. The outer and inner rings define flowpath surfaces for said flowpath. The first and second airfoils extend between the rings for transferring energy between the fluid and the rotor stage. At least one of the first airfoils surrounds means for transmitting energy across the flowpath

Hauser, Ambrose A.

Strock, William J.

NASA Technical Reports Server

United States Patent [191 [ i l l  Patent Number: 4,758,129 
Strock et al. [45] Date of Patent: Jul. 19, 1988 
[54] POWER FRAME 
[75] Inventors: 
[73] Assignee: 
[21] Appl. NO.: 
[22] Filed: 
William J. Strock, Cincinnati; 
Ambrose A. Hauser, Wyoming, both 
of Ohio 
General Electric Company, 
Cincinnati, Ohio 
739,804 
May 31, 1985 
1511 Int. (3.4 ........................... FOlD 5/06; F02C 3/04 
[52] U.S. Cl. ...................................... 415/69; 416/128; 
416/157 R; 416/231 B; 60/268 
[58] Field of Search ....................... 415/65, 66, 68, 69, 
415/77, 129, 130, 195; 416/127, 130, 157 R, 
158, 128, 231 B; 60/39.162, 268, 226.1, 262 
[561 References Cited 
U.S. PATENT DOCUMENTS 
2,314,572 3/1943 Chitz ............................... 416/130 X 
2,941,781 6/1960 Boyum ................................ 415/142 
3,075,743 1/1963 Sheets ......................... 416/231 B X 
3,467,198 9/1969 Ellinger .......................... 416/157 X 
3,924,404 12/1975 Pollert ............................. 415/130 X 
3,468,473 9/1969 Davies et al. ................... 416/157 X 
4,264,274 4/1981 Benedict ........................... 415/199.5 
4,304,522 12/1981 Newland ............................. 415/135 
4,452,566 6/1984 Karoas ............................ 415/115 X 
4,478,551 10/1984 Honeycutt, Jr. et al. .......... 415/142 
4,483,659 11/1984 Armstrong .................. 416/231 B X 
FOREIGN PATENT DOCUMENTS 
2129502 5/1984 United Kingdom .................. 60/268 
Primary Examiner-Robert E. Garrett 
Assistant Examiner-Joseph M. Pitko 
Attorney, Agent, or Firm-Derek P. Lawrence 
[571 ABSTRACT 
A rotor stage disposed within an annular fluid flowpath 
in a turbomachine is disclosed. The rotor stage includes 
outer and inner rings and a plurality of first and second 
airfoils. The outer and inner rings define flowpath sur- 
faces for said flowpath. The first and second airfoils 
extend between the rings for transferring energy be- 
tween the fluid and the rotor stage. At least one of the 
first airfoils surrounds means for transmitting energy 
across the flowpath. 
12 Claims, 1 Drawing Sheet 
https://ntrs.nasa.gov/search.jsp?R=20080012400 2019-08-30T04:03:14+00:00Z
U.S. Patent 
-q 
A6 I 
Jul. 19,1988 4,758,129 
18 
I' 
20a -
A 
1 
4,758,129 
POWER FRAME 
The invention herein described was made in the per- 
formance of work under a NASA contract and is sub- 5 
ject to the provisions of Section 305 of the National 
Aeronautics and Space Act of 1958, Public Law 85-568 
(72 Stat. 435; 42 USC 2457). 
This invention relates generally to turbomachinery 
and, more particularly, to a dual function rotor stage 10 
therein. 
BACKGROUND OF THE INVENTION 
Turbomachinery generally includes an annular flow- 
path for fluid with one or more rotor stages disposed 15 
therein. Each rotor stage typically includes a plurality 
of blades or airfoils for transferring energy between the 
fluid and the rotor stage. 
One form of a turbomachine is a gas turbine engine 
which generally includes a gas generator comprising a 20 
compressor for compressing air flowing through the 
engine, a combustor in which fuel is mixed with the 
compressed air and ignited to form a high energy gas 
stream, and a turbine which includes a rotor for driving 
the compressor. In gas turbine engines, rotor stages in 25 
the compressor transfer energy from the rotor to the air. 
In the turbine, a rotor stage transfers energy from the 
gas stream to the rotor. Many engines further include a 
second turbine, known as a power turbine, located aft of 
the gas generator which extracts energy from the gas 30 
flow to drive a propulsor. 
In many applications, it is desirable or necessary to 
transmit energy between the inner and outer regions 
defined by the annular flowpath. In other words, it may 
be necessary to transmit energy across the flowpath. 
Transmission of energy across a flowpath typically 
occurs at non-rotating fmed struts which extend 
through the flowpath. For example, a power take-off 
from the main drive shaft of a gas turbine engine may 
pass through a fixed strut. In some applications, it may 40 
be desirable to transmit energy across the flowpath 
when a fmed strut is not available. For example, in the 
unducted fan engine such as disclosed in U.S. Patent 
Application Ser. No. 647,283 U.S. Pat. No. 
4.657,484-Wakeman, which includes a counterrotating 45 
35 
power turbine with direct drive of counterrotating ug 
ducted fan blades, energy must be transmitted across 
the flowpath in order to change the pitch of the blades. 
OBJECTS OF THE INVENTION 
It is an object of the present invention to provide a 
new and improved means of transmitting power across 
a flowpath. 
It is another object of the present invention to pro- 
vide a dual function rotor stage for a gas turbine engine. 
It is yet another object of the present invention to 
provide a new and improved power frame with in- 
creased strength. 
It is yet a further object of the present invention to 
provide new and improved means for varying the pitch 
of propeller blades. 
SUMMARY OF THE INVENTION 
The present invention is a rotor stage disposed within 
a fluid flowpath in a turbomachine. The rotor stage 
comprises a plurality of first and second airfoils and 
outer and inner rings. The first and second airfoils ex- 
tend between the rings and transfer energy between the 
50 
55 
60 
65 
fluid and the rotor stage. The outer and inner rings 
define outer and inner flowpath surfaces, respectively. 
At least one of the first airfoils surrounds means for 
transmitting energy across the flowpath. 
BRIEF DESCRIPTION OF THE DRAWINGS 
FIG. 1 is a partial longitudinal schematic view which 
substantially illustrates a preferred embodiment of the 
present invention. 
FIG. 2 is a fragmentary perspective view taken gen- 
erally in the direction of arrow 2 in FIG 1. 
DETAILED DESCRIPTION OF THE 
INVENTION 
The present invention applies generally to any turbo- 
machine. For illustrative purposes, the invention is de- 
scribed as it would be used in a gas turbine engine. One 
application of the invention, according to a preferred 
embodiment, is shown in FIG. 1. 
FIG. 1 discloses a power turbine 10 of a gas turbine 
engine. Power turbine 10 includes an annular flowpath 
12 for a fluid or gas 14. Power turbine 10 includes inner 
and. outer counterrotating rotors 16 and 18, respec- 
tively. Inner rotor 16 includes a plurality of inner blade 
rows or stages 20 which extend radially outwardly 
therefrom. Each blade row or stage 20 is effective for 
transferring energy from gas stream 14 to inner rotor 
16. Similarly, outer rotor 18 includes a plurality of outer 
blade rows or stages 22 extending radially inwardly 
therefrom. Each stage 22 is effective for transferring 
energy from gas stream 14 to outer rotor 18. 
Inner rotor 16 and outer rotor 18 are each supported 
to a non-rotating shaft 24 by suitable bearing means 26 
and 28, respectively. It will be clear that the bearing 
configuration shown is exemplary only and that numer- 
ous alternative configurations are possible and in no 
way limit the scope of the present invention. 
Rotor stage 20a comprises outer ring 30 and inner 
ring 32 which partially define outer and inner flowpath 
surfaces 34 and 36, respectively, for flowpath 12. As 
shown in FIG. 2, rotor stage 20a further comprises a 
plurality of first airfoils 38 and second airfoils 40 extend- 
ing between outer ring 30 and inner ring 32. Airfoils 38 
and 40 are effective for transferring energy from gas 
stream 14 into rotor stage 20a. In order to provide im- 
proved stiffness characteristics to rotor stage 20a, inner 
ring 32 is generally box-shaped in radial cross-section. 
Each of first airfoils 38 and second airfoils 40 defines 
an average chord length. The term “chord length” is 
well-known in the art and is a measure of a distance 
between the leading and trailing edge of a blade. As 
shown in FIG. 2, first airfoils 38 have a chord length 
which is greater than the chord length of second airfoils 
40. Generally, the number of first airfoils 38 will be 
relatively small compared to the number of second 
airfoils 40. Thus, between any two adjacent first airfoils 
38 there will be a plurality of second airfoils 40. 
According to another feature of the present inven- 
tion, at least one of first airfoils 38 encloses transmitting 
means 42 for transmitting energy across flowpath 12. 
Transmitting means 42 is shown schematically as an 
arrow in FIG. 2. According to one embodiment of the 
present invention, transmitting means 42 may include a 
conduit for hydraulic fluid. According to another form 
of the present invention, transmitting means 42 may 
include a shaft rotatable about its axis. In yet another 
form of the present invention, transmitting means 42 
may include induction means for carrying electricity 
4.758,129 
3 
therethrough. In each embodiment, transmitting means 
42 are surrounded by first airfoil 38 and operate inde- 
pendently thereof. 
According to the embodiment shown in FIG. 1, 
power turbine 10 is effective for driving counterrotat- 
ing propellers 44 and 46. Each propeller 44 and 46 in- 
cludes pitch changing means 48 and 50, respectively, for 
varying the pitch of the propeller blades. The energy 
for actuating the propeller blades will be received by 
pitch changing means 48 and 50 from transmitting 
means 42. 
In operation, rotor stages 20 and 22 extract energy 
from gas stream 14. Inner stages 20 drive inner drum 
rotor 16 which is connected to inner ring 32 of first 
rotor stage 20a. The energy in inner rotor 16 is thereby 
transferred to outer ring 30 and then to propeller 44 for 
providing a propulsive force. Similarly, outer stages 22 
drive outer drum rotor 18 which transfers the rotational 
energy to propeller 46. 
Rotor stage 20a is configured so as to increase the 
energy that rotor stage 20a may extract from gas stream 
14. First airfoils 38 must have a relatively large chord 
length for the strength necessary to carry the rotor load 
and in order to allow sufficient room for the passage 
therethrough of transmitting means 42. Second airfoils 
40 have a somewhat shorter chord length for reduced 
weight while maintaining good energy extraction from 
the fluid. 
The energy required to change the pitch of the blades 
on propeller 44 may be transmitted from non-rotating 
shaft 24. After passing over the non-rotatindrotating 
interface 52 (such as through a slip ring or bearing con- 
5 
10 
15 
20 
25 
30 
figuration), the energy will be transmitted by way of 
transmitting means 42 through first airfoil 38 to pitch 35 
changing means 48. Pitch changing means 48 may con- 
vert this energy to a mechanical torque for varying the 
pitch of the blades of propeller 44. In a similar manner, 
energy for changing the pitch of the blades of propeller 
46 may pass non-rotatindrotating interface 54 and-4  
thence transmitted through a first airfoil 38 on rotor 
stage 22a 
It will be clear to those skilled in the art that the 
present invention is not limited to the specific embodi- 
ments described and illustrated herein. Nor is the inven- 45 
tion limited to rotor stages for turbines. Rather, the 
invention applies equally to rotor stages for compres- 
sors and fans of gas turbine engines. In addition, it ap- 
plies equally to related structures in any turbomachine. 
It will be understood that the dimensions and the 
proportional and structural relationships shown in the 
drawings are illustrated by way of example only, and 
these illustrations are not to be taken as the actual di- 
mensions or proportional structural relationships used 55  
in the rotor stage of the present invention. 
Numerous modifications, variations, and full and 
partial equivalents can now be undertaken without de- 
parting from the invention as limited only by the spirit 
What is desired to be secured by Letters Patent of the 
What is claimed is: 
1. In a turbomachine including an annular flowpath 
for a fluid, a rotor stage disposed within said flowpath 65 
comprising: 
outer and inner rings defining outer and inner flow- 
50 
and scope of the appended claims. 60 
United States is the following. 
path surfaces, respectively; and 
4 
a plurality of first and second airfoils extending be- 
tween said rings for transferring energy between 
said fluid and said rotor stage; 
wherein at least one of said first airfoils surrounds 
means for transmitting energy across said flow- 
path; 
and wherein at least two of said second airfoils are 
located between adjacent first airfoils. 
2. A rotor stage, as recited in claim 1, wherein each of 
said first and second airfoils define an average first and 
second chord length, respectively, and wherein said 
first chord length is greater than said second chord 
length. 
3. A rotor stage, as recited in claim 1, wherein said 
inner ring is generally box-shaped in radial cross-sec- 
tion. 
4. A rotor stage, as recited in claim 1, wherein said 
rotor stage is disposed within a turbine of said turboma- 
chine. 
5. In a counterrotating power turbine of a gas turbine 
engine including an annular flowpath for receiving a 
high energy gas stream, an improvement comprising: 
a first rotor stage disposed within said flowpath in- 
outer and inner rings defining outer and inner flow- 
path surfaces, respectively; and 
a plurality of first and second airfoils for extracting 
energy from said gas stream, at least two of said 
second airfoils being located between adjacent 
first airfoils; and 
first transmitting means for transmitting energy 
across said flowpath, wherein at least one of said 
first airfoils surrounds said first transmitting 
means. 
6. An improvement, as recited in claim 5, wherein 
each of said first and second airfoils defines an average 
first and second chord length, respectively, and 
wherein said first chord length is greater than said sec- 
ond chord length. 
7. An improvement, as recited in claim 5, wherein 
said inner ring is generally box-shaped in radial cross- 
section. 
8. An improvement, as recited in claim 5, further 
comprising: 
an inner rotor including a plurality of inner blade 
rows extending radially outwardly therefrom for 
transferring energy from said gas stream to said 
inner rotor; 
wherein said inner ring of said power turbine is con- 
nected to said inner rotor so that energy is trans- 
ferred from said inner rotor to said outer ring. 
9. An improvement, as recited in claim 8, further 
first and second counterrotating propellers wherein 
said first propeller is driven by said inner rotor. 
10. An improvement, as recited in claim 9, wherein 
said first propeller has a plurality of variable pitch first 
propeller blades and wherein said first transmitting 
means is effective for varying the pitch of said first 
propeller blades. 
11. An improvement, as recited in claim 10, further 
comprising: 
a second rotor stage disposed within said flowpath 
including: 
outer and inner rings defining outer and inner flow- 
path surfaces, respectively; and 
a plurality of first and second airfoils extending 
between said outer and inner rings for extracting 
cluding: 
comprising: 
5 
4,758,129 
6 
energy from said gas stream, at least two of said 
second airfoils being located between adjacent 
first airfoils: 
12. In a turbine of a gas turbine engine including an 
annular flowpath for a fluid, a rotor stage disposed 
within said flowDath comDrisine: 
second transmitting means for transmitting energy 
across said flowpath, wherein at least one of said 5 
first airfoils of said rotor stage surrounds said sec- 
ond transmitting means; and 
an outer rotor including a plurality of outer blade 
rows extending radially inwardly therefrom for 
transferring energy from said gas stream to said 10 
outer rotor; 
wherein said second propeller has a plurality of vari- 
able pitch second propeller blades and wherein said 
second transmission means is effective for varying 
the pitch of said second propeller blades. 15 
20 
25 
30 
35 
40 
L 1  
outer and inner rings defining outer and inner flow- 
path surfaces, respectively; and 
a plurality of first and second airfoils extending be- 
tween said rings and rigidly connected thereto for 
transferring energy from said fluid to said rotor 
stage; 
wherein at .least one of said first airfoils surrounds 
means for transmitting energy across said flow- 
and wherein at least two of said second airfoils are 
path, 
located between adjacent first airfoils. * * * * *  
45 
50 
55 
60 
65 


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