Aircraft vapour trail control system

Patent metadata

Field	Value
Publication number	US-2016376918-A1
Application number	US-201615163318-A
Country	US
Kind code	A1
Filing date	May 24, 2016
Priority date	Jun 22, 2015
Publication date	Dec 29, 2016
Grant date	—

Abstract

The invention concerns an aircraft propulsion system having an engine core within which fuel is combusted to produce an exhaust containing water produced from the combustion of fuel, at least one propulsive fan for generating a mass flow of air which mixes with the exhaust of the engine core, and one or more sensor arranged to sense a condition indicative of vapour trail formation by the exhaust flow from the engine; and a controller arranged to control the ratio of the mass flow of water in the exhaust to the mass flow of air propulsed by the propulsive fan such that the ratio is reduced upon sensing of said condition by the one or more sensor.

First claim

1 . A method of operating an aircraft propulsion system having an engine with an engine core, and at least one propulsive fan for generating a mass flow of air, wherein:
fuel is combusted in the engine core to generate an exhaust flow containing water produced by combustion of fuel; the propulsive fan is rotated at a velocity that generates a mass flow of air;
the method comprising the steps of monitoring conditions indicative of contrail formation and increasing the ratio of the mass flow of air generated by the propulsive fan to the mass of water in the exhaust flow when the conditions.

2 . A method according to claim 1 , wherein upon sensing conditions indicative of contrail formation the ratio of the mass flow of air generated by the propulsive fan to the mass of water in the exhaust flow is increased by reducing the mass of water produced in the core.

3 . A method according to claim 1 , wherein the ratio is increased by increasing the mass flow of air generated by the propulsive fan.

4 . A method according to claim 3 , wherein the propulsive fan is coaxially located with the engine core the mass flow of the air generated by the propulsive fan mixing with the engine core exhaust.

5 . A method according to claim 4 , wherein the fan is bounded by a duct, the duct defining an annular nozzle at its downstream end which directs the flow of air bypassing the core towards the exhaust.

6 . A method according to claim 5 , wherein upon sensing conditions indicative of contrail formation the ratio of the mass flow of air generated by the propulsive fan to the mass of water in the exhaust flow is increased by increasing the rotational velocity of the propulsive fan to increase the mass flow of air generated.

7 . A method according to claim 6 , wherein the propulsive fan is connected to an electrical network which supplies additional drive energy to increase the rotational velocity of the propulsive fan.

8 . A method according to claim 2 , wherein the mass of water produced in the core is reduced by lowering the fuel burn in the engine core to reduce thrust generated by the engine core, wherein the reduced thrust is mitigated by increasing thrust generated by one or more further propulsive units.

9 . A method according to claim 8 , wherein the further propulsive units are electrically driven fans connected to an electrical power supply via an electrical network, wherein upon sensing conditions indicative of contrail formation power, or increased power, is supplied to the further propulsive units from the electrical power supply.

10 . A method according to claim 9 , wherein the electrical power supply is a battery charged by the engine.

11 . An aircraft propulsion system comprising:
an engine having an engine core within which fuel is combusted to produce an exhaust containing water produced from the combustion of the fuel, at least one propulsive fan for generating a mass flow of air; one or more sensor arranged to sense a condition indicative of vapour trail formation by the exhaust flow from the engine; and a controller arranged to control the ratio of the mass of water in the exhaust to the mass of air propulsed by the propulsive fan such that the ratio is reduced upon sensing of said condition by the one or more sensor.

12 . An aircraft propulsion system according to claim 11 , wherein upon sensing of said condition by the one or more sensor the rotational velocity of one or more of the at least one propulsive fan is increased.

13 . An aircraft propulsion system according to claim 11 , wherein one of the at least one propulsive units is coaxial with the engine core.

14 . An aircraft propulsion system according to claim 13 , wherein the coaxial propulsive unit is located within a duct having an annular flow opening downstream of the fan.

15 . An aircraft propulsion system according to claim 14 , wherein the flow opening comprises a portion of a bypass duct of the engine.

16 . An aircraft propulsion system according to claim 11 , wherein at least one of the propulsive fans is connected to the engine via an electrical network.

17 . An aircraft propulsion system according to claim 16 , wherein the electrical network comprises at least one electrical storage unit that can supply electrical energy to the at least one propulsive fan via the electrical network to effect rotation of the propulsive fan.

18 . An aircraft propulsion system according to claim 18 , wherein the controller is arranged to suppress contrail formation only when ambient air is supersaturated with respect to ice and/or when ambient light is below a predetermined threshold level.

19 . An aircraft propulsion system according to claim 11 , comprising an altitude sensor and the controller is arranged to reduce the ratio of the mass of water in the exhaust to the mass of air propulsed by the propulsive fan only at an altitude above a predetermined threshold and/or within a predetermined altitude range.

20 . An aircraft propulsion system according to claim 11 , wherein the one or more sensor comprises a receiver for receiving an electromagnetic or acoustic reflection and/or emission from a contrail downstream of the engine.

Assignees

• Rolls Royce Plc

Inventors

• Swann Peter
• Rolt Andrew M
• Fletcher Paul

Classifications

• B64D27/31

  within, or attached to, wings · CPC title

• B64D35/023

  of series-parallel type · CPC title

• B64D31/18

  for hybrid-electric power plants · CPC title

• B64D27/33

  Hybrid electric aircraft · CPC title

• F05D2270/306

  Mass flow · CPC title