This application relates to a fuel injection apparatus and method for use in a gas turbine engine, where both bluff body injectors, and swirler injectors are utilized in stages.
Gas turbine engines are known, and typically include a compressor compressing air and delivering the air to be mixed with fuel in a combustion chamber, and then ignited. The amount and ratio of fuel and air which are mixed and ignited vary. At low power, a fuel/air ratio is low, and at higher power, such as take-off and cruise, the fuel/air ratio is higher. It is known to control a group of injectors in stages, with some injectors not being utilized during low power operation, and then utilized at higher power operation.
Fuel injectors are known which utilize a swirler concept. In a swirler concept, the fuel is injected into a swirling chamber, and mixed with air prior to combustion.
Another type of injector is a so-called bluff body injector, which directly injects fuel into a combustion chamber.
A fuel injection array for a gas turbine engine includes a plurality of bluff body injectors and a plurality of swirler injectors. A control operates the plurality of bluff body injectors and swirler injectors such that bluff body injectors are utilized without all of the swirler injectors at least at low power operation. The swirler injectors are utilized at higher power operation.
These and other features of the present invention can be best understood from the following specification and drawings, of which the following is a brief description.
A gas turbine engine 10, such as a turbofan gas turbine engine, circumferentially disposed about an engine centerline, or axial centerline axis 12 is shown in
Swirlers are generally known, and one such device is shown in
Fuel is injected outwardly through ports 58 and into the air flow 52 creating a portion of well mixed zone 100. The flame is held in the zones 86 and 84 which are relatively low velocity regions of the flame.
The swirler 42 is shown creating the other portion of well mixed fuel/air zone 100. The flame is held in zones 82 from the injected fuel 80.
Returning to
The injector array 40 is utilized in stages. Under low power operation, a first stage defined by the pilot openings 56 is utilized in combination with a second stage which is defined by the flow through the ports 58. Thus, at idle, taxi, or sub-cruise operation, fuel is blocked through the swirlers 42 by the control 300.
At take-off and cruise, a third stage is utilized in combination with the first two stages. The third stage includes the swirlers 42.
The bluff body injector is particularly advantageous at lower power operation, as it provides the stable and reliable flame. A swirler is not as efficient at lower volume flow.
On the other hand, using the several types of injectors at higher power provides benefits in that the swirlers provide excellent mixing. Further, the second stage injection would also provide good mixing. The use of the several distinct types of injection results in an overall combustion pattern that is not a coherent structure. If only a single type of injector is utilized, then the resultant combustion could act as a coherent structure, and result in an audio tone, which would be undesirable.
As can be appreciated from
The use of the bluff body injector, and in particular the pilot opening ensures efficient and reliable combustion at the lower power operations On the other hand, the use of the swirler injectors at higher power operation ensure reduced smoke, or NOx emissions.
At lower power operation, the amount of fuel flow in stage 2 is much greater than the amount of fuel flow from stage 1. At mid to high power operation, the amount of fuel flow from stage 3 can be optimized for emissions and combustion dynamics. The amount of fuel flow from stage 1.
Although embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
This invention was made with government support under Contract No. NNC08CA92C by NASA. The Government has certain rights in this invention.