Two-spool auxiliary power unit and control means

Claim 2

A gas turbine engine comprising: a. casing means forming a rotor chamber, a bleed air chamber, and a combustion air chamber; b. rotor means in said rotor chamber having dual independently rotatable spools, each spool having a compressor impeller and turbine means for driving the same; c. means in said casing for separating the output of the compressor impeller of one spool into two parts and directing one part to the bleed air chamber and the balance to the inlet of the compressor of the other spool, the latter discharging into said combustion air chamber; d. combustor means in said combustion air chamber for mixing and burning fuel with air supplied thereto to produce hot gases; e. nozzle means for directing the hot gases to the turbine means on said sPools to impart rotary motion thereto; f. power shaft extraction means having a shaft in driving engagement with said other spool; and g. means for varying the speed of rotation of said one spool to change the rate of flow of bleed air into said chamber while maintaining the speed of rotation of said other spool substantially constant, and thereby maintaining the speed of rotation of said shaft substantially constant.

Claim 3

The gas turbine engine of claim 1 in which said nozzle means includes adjustable vane means and said means for varying the speed of rotation of said one spool includes means for adjusting the position of said vane means to change selectively the power imparted to the turbine blades of said one spool.

Claim 4

The gas turbine engine of claim 1 in which the compressor impeller of said one spool is of the axial type and the compressor impeller of said other spool is of the centrifugal type.

Claim 5

The gas turbine of claim 3 in which the axial-type compressor impeller is upstream of the centrifugal-type compressor impeller.

Claim 6

The gas turbine engine of claim 1 in which said means for varying includes control means for said engine, said control means having portions responsive to signals from independent sources to cause said other spool to operate at substantially constant speed and said one spool to operate at variable speeds required to supply predetermined volumes of air to said bleed air chamber.

Claim 7

The gas turbine engine of claim 3 in which said means for varying includes control means for varying the rate of operation of the spool having the axial compressor and maintaining constant the rate of operation of the other spool.

Claim 8

The gas turbine engine of claim 6 in which a control system is provided having means responsive to the demands of pneumatic power utilizing means to actuate the means for varying the rate of operation of the spool having the axial compressor.

Claim 9

The gas turbine engine of claim 7 in which the control system is provided with means responsive in part to the rate of operation of said other spool to govern the supply of fuel to the engine.

Claim 10

The gas turbine engine of claim 2 in which fluid pressure responsive means are provided to actuate said adjustable vane means and means are also provided for controlling the application of fluid pressure to said fluid pressure responsive means in accordance with demands for pneumatic power by means utilizing the same.

Claim 11

The gas turbine engine of claim 6 in which said control means has a fuel control means operative to govern the total power developed to operate said turbine means, and means for regulating the division of power between the turbine means for said spools to maintain constant the rate of operation of one spool and vary the rate of operation of the spool which drives the axial compressor in accordance with the demands of means utilizing the air directed to the bleed air chamber.

Claim 12

The gas turbine engine of claim 5 in which said control means has adjustable means for varying the admission of air to one of said compressor impellers.

Claim 13

In an environmental control system, the combination comprising: a. an auxiliary power unit having means for separately delivering shaft power and pneumatic power, said power unit including a gas turbine engine having a plurality of spools, a first one of said spools being operated at a constant speed to provide said shaft power and a second one of said spools being operated at a variable speed to provide said pneumatic power at variable pressure and quantities; and b. control means for said power unit operable, in response to changing requirements of a region utilizing said pneumatic power, to adjust the operation of said second spool to vary the pressure and quantity of pneumatic power delivered while maintaining the speed of said first spool substantially constant.

Claim 14

In an environmental control system, the combination comprising: a. an auxiliary power unit having means for separately delivering shaft power and pneumatic power, said power unit including a gas turbine engine having a plurality of spools, a first one of said spools being operated at a constant speed to provide said shaft power and a second one of said spools being operated at a variable speed to provide said pneumatic power at variable pressure and quantities; and b. control means for said power unit operable, in response to changing requirements of a region utilizing said pneumatic power, to adjust the operation of said second spool to vary the pressure and quantity of pneumatic power delivered while maintaining the speed of said first spool substantially constant.

Claim 15

A gas turbine engine comprising: a first means forming a casing having an air inlet at one end, an exhaust gas outlet at the othEr end, said first means also forming an annular passage extending from the air inlet to the gas outlet; first and second spool assemblies supported for rotation in said casing in concentrically arranged relation, the first spool assembly having a plurality of axial compressor blades projecting into said annular passage and a first set of turbine blades extending into said annular passage, the second spool assembly having a centrifugal compressor rotor with the inlet thereof communicating with the annular passage downstream from said axial compressor blades and a second set of turbine blades projecting into said annular pasage in advance of the turbine blades of said first spool assembly; a bleed air discharge passage communicating with said annular passage between said axial compressor blades and said centrifugal compressor rotor inlet; burner means communicating with said annular passage for increasing the temperature and pressure of gases in said annular passage between said centrifugal compressor and said second set of turbine blades; shaft power extraction means having a rotary shaft and including means coupling said rotary shaft to said second spool assembly for rotation therewith; and adjusting means in said annular passage upstream from said first set of turbine blades for varying the torque applied to said first spool assembly by said turbine blades by gases flowing in said annular passage, said adjusting means operating to change the rate of flow of said bleed air through said discharge passage without changing the speed of rotation of said second spool and thereby maintaining the speed of said shaft substantially constant.

Claim 16

A gas turbine engine comprising: a first means forming a casing having an air inlet at one end, an exhaust gas outlet at the othEr end, said first means also forming an annular passage extending from the air inlet to the gas outlet; first and second spool assemblies supported for rotation in said casing in concentrically arranged relation, the first spool assembly having a plurality of axial compressor blades projecting into said annular passage and a first set of turbine blades extending into said annular passage, the second spool assembly having a centrifugal compressor rotor with the inlet thereof communicating with the annular passage downstream from said axial compressor blades and a second set of turbine blades projecting into said annular pasage in advance of the turbine blades of said first spool assembly; a bleed air discharge passage communicating with said annular passage between said axial compressor blades and said centrifugal compressor rotor inlet; burner means communicating with said annular passage for increasing the temperature and pressure of gases in said annular passage between said centrifugal compressor and said second set of turbine blades; shaft power extraction means having a rotary shaft and including means coupling said rotary shaft to said second spool assembly for rotation therewith; and adjusting means in said annular passage upstream from said first set of turbine blades for varying the torque applied to said first spool assembly by said turbine blades by gases flowing in said annular passage, said adjusting means operating to change the rate of flow of said bleed air through said discharge passage without changing the speed of rotation of said second spool and thereby maintaining the speed of said shaft substantially constant.

Claim 17

A gas turbine engine according to claim 13 wherein said adjusting means includes vanes positioned in said annular passage adjacent said first set of turbine blades, and includes means for selectively changing the position of said vanes to change the power imparted to said first spool assembly by gases flowing in said annular passage.

Claim 18

The gas turbine engine according to claim 13 including control means responsive to demand for bleed air for operating said adjusting means to increase the speed of said first spool assembly when a higher rate of flow of bleed air is required and to decrease the speed of rotation of said first spool assembly when less bleed air is required, said control means maintaining the speed of rotation of said second spool assembly substantially constant.