CA1069710A - Turboshaft engine - Google Patents
Turboshaft engineInfo
- Publication number
- CA1069710A CA1069710A CA296,974A CA296974A CA1069710A CA 1069710 A CA1069710 A CA 1069710A CA 296974 A CA296974 A CA 296974A CA 1069710 A CA1069710 A CA 1069710A
- Authority
- CA
- Canada
- Prior art keywords
- compressor
- rotor
- speed
- turbine
- gas generator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C3/00—Gas-turbine plants characterised by the use of combustion products as the working fluid
- F02C3/04—Gas-turbine plants characterised by the use of combustion products as the working fluid having a turbine driving a compressor
- F02C3/107—Gas-turbine plants characterised by the use of combustion products as the working fluid having a turbine driving a compressor with two or more rotors connected by power transmission
- F02C3/113—Gas-turbine plants characterised by the use of combustion products as the working fluid having a turbine driving a compressor with two or more rotors connected by power transmission with variable power transmission between rotors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C3/00—Gas-turbine plants characterised by the use of combustion products as the working fluid
- F02C3/04—Gas-turbine plants characterised by the use of combustion products as the working fluid having a turbine driving a compressor
- F02C3/06—Gas-turbine plants characterised by the use of combustion products as the working fluid having a turbine driving a compressor the compressor comprising only axial stages
- F02C3/067—Gas-turbine plants characterised by the use of combustion products as the working fluid having a turbine driving a compressor the compressor comprising only axial stages having counter-rotating rotors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
- F02C9/16—Control of working fluid flow
Abstract
TITLE
TURBOSHAFT ENGINE
INVENTORS
Marcus S. Chappell Douglas A.J. Millar ABSTRACT OF THE DISCLOSURE
An improvement in torque characteristics is provided for a turboshaft engine of the type having a compressor rotor driven by a gas generator turbine that is mechanically independent of the power turbine.
The improvement comprises a rotatable compressor stator casing which is interconnected with the power turbine rotor to allow rotation of the compressor casing in the same direction as the compressor rotor at a lower speed. At reduced output shaft speed, the relative speed between the compressor rotor blades and stator blades is increased for increased gas generator output and hence torque, while the compressor rotor speed remains constant.
TURBOSHAFT ENGINE
INVENTORS
Marcus S. Chappell Douglas A.J. Millar ABSTRACT OF THE DISCLOSURE
An improvement in torque characteristics is provided for a turboshaft engine of the type having a compressor rotor driven by a gas generator turbine that is mechanically independent of the power turbine.
The improvement comprises a rotatable compressor stator casing which is interconnected with the power turbine rotor to allow rotation of the compressor casing in the same direction as the compressor rotor at a lower speed. At reduced output shaft speed, the relative speed between the compressor rotor blades and stator blades is increased for increased gas generator output and hence torque, while the compressor rotor speed remains constant.
Description
BACKGROUND GF TIIE INVENTION
Th~s invention relates -to a turboshaf, gas turbine engine.
For many applications of turboshaft engines, it is desirable that available engine torque increase as output shaft speed decreases. This effect is obtainable to some extent with present free-power-turbine engines which provide about 200~ of design-point torque when the output shaft is stationary. However, it is desirable that torque be multiplied still further to more nearly match the power unit to its load with minimal intervening means such as gearing or torque converter.
SUMMARY OF THE INVENTION
An object of the present invention is to enhance the increase of torque of a turboshaft engine as the output shaft speed is decreased.
Another object is to provide increased torque without increase in gas generator rotor speed.
Another object is to provide an increase in gas generator output without an increase in the speed of the gas generator rotor.
Another object is to provide a gas turbine engine in which the gas generator contributes shaft power to the output shaft.
Another object is to provide flexibility of design hy distributing load between the power turbi,ne and gas generator turbine.
The present invention provides an improved turboshaft enyine comprlsing a compressor having a rotor and stator casing, a gas generator turbine having a rotor and stator, a power turhine havillg a rotor, and an OUtpll t 10~;9710 shaft connected w~th the po~er turbine rotor; said compressor rotor b~lng connected with the gas generator turbine rotor; said gas generator turbine being mechanically and aerodynamically independent of the power turbine; and said compressor stator casing being rotatably mounted and coaxial with the compressor rotor and interconnected with the power turbine rotor for allowing rotation of the compressor casing in the direction of the compressor rotor at a speed less than that of the compressor rotor.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic illustration of a turboshaft gas turbine engine in accordance with the present invention.
Figures 2 to 4 are schematic illustrations of other embodiments of the present invention incorporating various gearing configurations.
Figure 5 compares graphically the torque characteristics of a conventional free-power-turbine engine and an engine incorporatins the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to Figure 1, the turboshaft engine of the present invention includes a compressor 1 having a rotor 2 and stator casing 3, a gas generator turbine 4 connected with the compressor rotor 2, a power turbine 5, a combustor 6 and an outp~lt shaft 7. The compressor stator casing 3 is rotatably mourted and coaxial with the compressor rotor. Interconnecting the power turbine 5, the compressor stator 3 and the output shaft 7 is gearing shown in the form oE a planetary gear set 3.
In the planetary gear set ~, the power turbine rotor 5 is interconnected wit:h the sun gear 9 by means of the ~2--1069~10 shaft 10, the compressor stator casing 3 is connected with the pinion carrier 11, and the ring gear 12 is fixed.
The compressor rotor 2 and the gas generator turbine ~, which are interconnected by the shaft 13, are mounted for free rotation relative to the sha~t 10.
The gearing 8 is such that the compressor casing 3 rotates at a predetermined ratio with the output shaft 7 and in the same direction as the compressor rotor 2 but at a reduced speed. The gearing ratio is selected so that the compressor casing rotates at a speed less than that of the compressor rotor under any speed conditions of the ou-tput shaft or gas generator rotor.
In operation, the compressor rotor 2 is driven by the turbine 4 and is governed to run at predetermined conditions such as constant speed or constant turbine temperature in a conventional manner. At design conditions the power turbine 5 will be rotating at design (100~
speed and the compressor casing 3 will be rotating in the direction of the compressor rotor 2 but at a lesser speed, so that the relative speed between the compressor rotor blades and stator blades will be less than the compressor rotor speed. Under conditions of increased loading the speed of the power turbine will be reduced. At the same time the speed of the compressor casing will be reduced proportionally. Since the compressor casing rotates in the direction of the com~ essor rotor, the redwctioll o~ casing speed results in an increase in relative or aerodynamic speed of the compressor, chereby increasing gas generator output and providing increased torque and power. Maximum torque will normall be achieved when the output shaft 7 ~0697~0 is stationar~, since under such conditions the stator casing will also be stationary and the relative compressor speed will be maximum.
The present invention also allows the gas generator turbine to contribute torque and power to the output shaft without a direct mechanical connection. As the compressor rotor 2 rotates, it exerts a torque on the compressor casing 3 which is transferred to the output shaft by means of the interconnected gearing 8.
The ability to distribute load between the power turbine and gas generator turbine provides greater flexibility of design.
In Figure 1 the output shaft 7 is shown connected directly with the power turbine 5. However, for most applications, the high turbine speed must be reduced.
Referring to Figure 2, speed reduction can conveniently be achieved by interconnecting the output shaft 20 with the pinion carrier 21. With this arrangement, the output shaft speed will be equal to the speed of the compressor casing 22. In other respects the operation is identical to that shown in Figure 1.
Figure 3 illustrates another gearing arrangement which allows the output shaft speed to be chosen independ-ently of the compressor casing speed and power turbine speed.
Referring to Figure 3, the gearing 30 comprises two planetary sets 31 and 32 inccrporating a single sun gear and two ring gears engaying dual planet gears. The ring gear 33 of planet set 31 is interconnected with the compressor casing 34 while ring gear 35 is fixed.
Figure 4 shows another embodiment for an engine having a counter rotating power turbine 40 and employing 1069'710 layshaft gearing 41 for reducing the speed of the output shaf-t 42 and allowing rotation of the compressor casing 43.
As in all the previous embodiments, the gearing is chosen so that the compressor casing ~3 rotates in the same direction as the compressor rotor 44 but at reduced speed.
It will be understood that the present invention is not limited to the particular gearing arrangements illustrated or described which may be replaced by other interconnecting means which allows rotation of the compressor casing in a similar manner. Also, the present invention can be applied to other engine configurations. For example, in an engine having more than one gas generator spool, a rotatable stator casing may be used in combination with one or more compressor rotors, or additional rotatable stator casings can be added and interconnected with separate gear ratios to the output shaft.
The selection of the gearing ratio for the compressor stator casing will depend on a number of factors. Although the torque multiplication increases with higher compressor ~0 stator speeds, the speed may be limited by aerodynamic and mechanical considerations such as turbine inlet temperature, compressor efficiency and stability, and increased rotor stresses.
EXAMPLE
A comparative analysis has been made between a turboshaft engine incorporating the present invention as illustrated schematically in Figure 3 and a conventional free-power-turbine engine utilizing equivalent components.
The size and configuration of these engines was chosen to be suitable for an off-the-road vehicle application with an installed horsepower of the order of 1000, and with 106~710 a moderate turbine inlet temperature to avoid the necessity for blade cooling in a potentia]ly dusty environment. The example engine has a single multi-stage axial flow compressor dri~en at constant speed by a two stage turbine, and a single stage power turbine.
The gearing for the engine of the present invention was chosen to provide a compressor stator casing speed of 20% of the compressor rotor speed at the chosen design conditions.
Figure 5 compares the part speed torque of the example engine with that of a conventional free-power-turbine engine. Figure 5 shows a significantly greater torque amplification for the engine of the present invention.
The increased torque magnification indicates the suitability of the present invention to applications requiring high torque at part speed.
Th~s invention relates -to a turboshaf, gas turbine engine.
For many applications of turboshaft engines, it is desirable that available engine torque increase as output shaft speed decreases. This effect is obtainable to some extent with present free-power-turbine engines which provide about 200~ of design-point torque when the output shaft is stationary. However, it is desirable that torque be multiplied still further to more nearly match the power unit to its load with minimal intervening means such as gearing or torque converter.
SUMMARY OF THE INVENTION
An object of the present invention is to enhance the increase of torque of a turboshaft engine as the output shaft speed is decreased.
Another object is to provide increased torque without increase in gas generator rotor speed.
Another object is to provide an increase in gas generator output without an increase in the speed of the gas generator rotor.
Another object is to provide a gas turbine engine in which the gas generator contributes shaft power to the output shaft.
Another object is to provide flexibility of design hy distributing load between the power turbi,ne and gas generator turbine.
The present invention provides an improved turboshaft enyine comprlsing a compressor having a rotor and stator casing, a gas generator turbine having a rotor and stator, a power turhine havillg a rotor, and an OUtpll t 10~;9710 shaft connected w~th the po~er turbine rotor; said compressor rotor b~lng connected with the gas generator turbine rotor; said gas generator turbine being mechanically and aerodynamically independent of the power turbine; and said compressor stator casing being rotatably mounted and coaxial with the compressor rotor and interconnected with the power turbine rotor for allowing rotation of the compressor casing in the direction of the compressor rotor at a speed less than that of the compressor rotor.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic illustration of a turboshaft gas turbine engine in accordance with the present invention.
Figures 2 to 4 are schematic illustrations of other embodiments of the present invention incorporating various gearing configurations.
Figure 5 compares graphically the torque characteristics of a conventional free-power-turbine engine and an engine incorporatins the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to Figure 1, the turboshaft engine of the present invention includes a compressor 1 having a rotor 2 and stator casing 3, a gas generator turbine 4 connected with the compressor rotor 2, a power turbine 5, a combustor 6 and an outp~lt shaft 7. The compressor stator casing 3 is rotatably mourted and coaxial with the compressor rotor. Interconnecting the power turbine 5, the compressor stator 3 and the output shaft 7 is gearing shown in the form oE a planetary gear set 3.
In the planetary gear set ~, the power turbine rotor 5 is interconnected wit:h the sun gear 9 by means of the ~2--1069~10 shaft 10, the compressor stator casing 3 is connected with the pinion carrier 11, and the ring gear 12 is fixed.
The compressor rotor 2 and the gas generator turbine ~, which are interconnected by the shaft 13, are mounted for free rotation relative to the sha~t 10.
The gearing 8 is such that the compressor casing 3 rotates at a predetermined ratio with the output shaft 7 and in the same direction as the compressor rotor 2 but at a reduced speed. The gearing ratio is selected so that the compressor casing rotates at a speed less than that of the compressor rotor under any speed conditions of the ou-tput shaft or gas generator rotor.
In operation, the compressor rotor 2 is driven by the turbine 4 and is governed to run at predetermined conditions such as constant speed or constant turbine temperature in a conventional manner. At design conditions the power turbine 5 will be rotating at design (100~
speed and the compressor casing 3 will be rotating in the direction of the compressor rotor 2 but at a lesser speed, so that the relative speed between the compressor rotor blades and stator blades will be less than the compressor rotor speed. Under conditions of increased loading the speed of the power turbine will be reduced. At the same time the speed of the compressor casing will be reduced proportionally. Since the compressor casing rotates in the direction of the com~ essor rotor, the redwctioll o~ casing speed results in an increase in relative or aerodynamic speed of the compressor, chereby increasing gas generator output and providing increased torque and power. Maximum torque will normall be achieved when the output shaft 7 ~0697~0 is stationar~, since under such conditions the stator casing will also be stationary and the relative compressor speed will be maximum.
The present invention also allows the gas generator turbine to contribute torque and power to the output shaft without a direct mechanical connection. As the compressor rotor 2 rotates, it exerts a torque on the compressor casing 3 which is transferred to the output shaft by means of the interconnected gearing 8.
The ability to distribute load between the power turbine and gas generator turbine provides greater flexibility of design.
In Figure 1 the output shaft 7 is shown connected directly with the power turbine 5. However, for most applications, the high turbine speed must be reduced.
Referring to Figure 2, speed reduction can conveniently be achieved by interconnecting the output shaft 20 with the pinion carrier 21. With this arrangement, the output shaft speed will be equal to the speed of the compressor casing 22. In other respects the operation is identical to that shown in Figure 1.
Figure 3 illustrates another gearing arrangement which allows the output shaft speed to be chosen independ-ently of the compressor casing speed and power turbine speed.
Referring to Figure 3, the gearing 30 comprises two planetary sets 31 and 32 inccrporating a single sun gear and two ring gears engaying dual planet gears. The ring gear 33 of planet set 31 is interconnected with the compressor casing 34 while ring gear 35 is fixed.
Figure 4 shows another embodiment for an engine having a counter rotating power turbine 40 and employing 1069'710 layshaft gearing 41 for reducing the speed of the output shaf-t 42 and allowing rotation of the compressor casing 43.
As in all the previous embodiments, the gearing is chosen so that the compressor casing ~3 rotates in the same direction as the compressor rotor 44 but at reduced speed.
It will be understood that the present invention is not limited to the particular gearing arrangements illustrated or described which may be replaced by other interconnecting means which allows rotation of the compressor casing in a similar manner. Also, the present invention can be applied to other engine configurations. For example, in an engine having more than one gas generator spool, a rotatable stator casing may be used in combination with one or more compressor rotors, or additional rotatable stator casings can be added and interconnected with separate gear ratios to the output shaft.
The selection of the gearing ratio for the compressor stator casing will depend on a number of factors. Although the torque multiplication increases with higher compressor ~0 stator speeds, the speed may be limited by aerodynamic and mechanical considerations such as turbine inlet temperature, compressor efficiency and stability, and increased rotor stresses.
EXAMPLE
A comparative analysis has been made between a turboshaft engine incorporating the present invention as illustrated schematically in Figure 3 and a conventional free-power-turbine engine utilizing equivalent components.
The size and configuration of these engines was chosen to be suitable for an off-the-road vehicle application with an installed horsepower of the order of 1000, and with 106~710 a moderate turbine inlet temperature to avoid the necessity for blade cooling in a potentia]ly dusty environment. The example engine has a single multi-stage axial flow compressor dri~en at constant speed by a two stage turbine, and a single stage power turbine.
The gearing for the engine of the present invention was chosen to provide a compressor stator casing speed of 20% of the compressor rotor speed at the chosen design conditions.
Figure 5 compares the part speed torque of the example engine with that of a conventional free-power-turbine engine. Figure 5 shows a significantly greater torque amplification for the engine of the present invention.
The increased torque magnification indicates the suitability of the present invention to applications requiring high torque at part speed.
Claims
CLAIM
A turboshaft engine comprising a compressor having a rotor and stator casing, a gas generator turbine having a rotor and stator, a power turbine having a rotor, and an output shaft connected with the power turbine rotor;
said compressor rotor being connected with the gas generator turbine rotor;
said gas generator turbine being mechanically and aerodynamically independent of the power turbine; and said compressor stator casing being rotatably mounted and coaxial with the compressor rotor and interconnected with the power turbine rotor for allowing rotation of the compressor casing in the direction of the compressor rotor at a speed less than that of the compressor rotor.
A turboshaft engine comprising a compressor having a rotor and stator casing, a gas generator turbine having a rotor and stator, a power turbine having a rotor, and an output shaft connected with the power turbine rotor;
said compressor rotor being connected with the gas generator turbine rotor;
said gas generator turbine being mechanically and aerodynamically independent of the power turbine; and said compressor stator casing being rotatably mounted and coaxial with the compressor rotor and interconnected with the power turbine rotor for allowing rotation of the compressor casing in the direction of the compressor rotor at a speed less than that of the compressor rotor.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77428077A | 1977-03-04 | 1977-03-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069710A true CA1069710A (en) | 1980-01-15 |
Family
ID=25100774
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA296,974A Expired CA1069710A (en) | 1977-03-04 | 1978-02-15 | Turboshaft engine |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1069710A (en) |
| GB (1) | GB1580528A (en) |
-
1978
- 1978-02-15 CA CA296,974A patent/CA1069710A/en not_active Expired
- 1978-03-02 GB GB831178A patent/GB1580528A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1580528A (en) | 1980-12-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |