United Technologies Corporation

George D Lewis

James H Shadowen

Norman W Mangum, Jr

James P Rusnak

Gary D Garrison

Paul L Russell

Jeffrey Stettler

An improved combustor for a gas turbine engine is disclosed. Techniques for reducing the level of noxious pollutants emitted by the combustor are developed. In one embodiment, a combination of serpentine geometried, fuel-mixing tubes discharging to the radially outward area of the combustor and an axially oriented, fuel-mixing tube near the center of the combustor are adapted to generate a strong centrifugal force field within the combustor. The force field promotes rapid mixing and combustion within the chamber to reduce both the magnitude of the combustor temperature and the period of exposure of the medium gases to that temperature. In accordance with the method taught, the fuel air ratio in the serpentine mixing tubes is maintained within the range of 0.035 to 0.05 and the fuel air ratio in the axial mixing tube is maintained at a value less than 0.05.

Method and apparatus for reducing nitrous oxide emissions from combustors

An improved combustor for a gas turbine engine is disclosed. Techniques for reducing the level of noxious pollutants emitted by the combustor are developed. In one embodiment, a combination of serpentine geometried, fuel-mixing tubes discharging to the radially outward area of the combustor and an axially oriented, fuel-mixing tube near the center of the combustor are adapted to generate a strong centrifugal force field within the combustor. The tube near the center of the combustor has a convergent section at the upstream end thereof and a divergent section at the downstream end thereof. Fuel supply means is adapted to discharge fuel into the convergent section of the tube. Vaporization of the fuel in the tube is aided by maintaining a differential axial velocity over the length of the tube. The force field promotes rapid mixing and combustion within the chamber to reduce both the magnitude of the combustor temperature and the period of exposure of the medium gases to that temperature. In accordance with a method taught, the fuel/air ratio in the serpentine mixing tubes is maintained within the range of fifty to seventy-five percent (50 to 75%) of the stoichiometric fuel/air ratio for the fuel employed and the fuel/air ratio in the axial mixing tube is maintained at a value less than seventy-five percent (75%) of the stoichiometric fuel/air ratio for the fuel employed.

A thrust augmentor for a turbofan, gas turbine engine is disclosed. Techniques for mixing and burning dissimilar density gases in a thrust augmentor are developed. In accordance with one specific teaching the flame front in a swirl augmentor is stabilized by a continuously operative pilot burner. The pilot burner is positioned in the radially outward portion of the augmentor. The pilot burner employs fuel premixing techniques and is adapted to operate at low inlet pressure levels.

Thrust augmentor

In order to maintain local flame temperatures in a gas turbine engine combustor lower than 3200.degree. F. to prevent excessive formation of nitrogen oxides and above 2500.degree. F. to prevent excessive carbon monoxide formation and flameout, it is desirable to measure the flame temperature at a number of points within the combustor. Appropriate volumes of cool air entering the burner and hot gas in the flame vicinity are withdrawn and mixed to produce a gas mixture at a temperature low enough to be measured by conventional means such as thermocouples. The volume of each gas withdrawn is controlled by flow through a choked orifice. The pressure differential between the combustor pressure and ambient pressure is used to choke the flow control orifices.

Combustion temperature control

An annular ram burner has a movable wall adjacent the flameholder to provide a large variation in area change at the flameholder plane. The movable wall comprises a number of flaps mounted around the ram burner. While a ram burner is shown a fan duct burner can also be used. The flaps are attached to an actuator mechanism through a linkage system which allows the wall to be moved rapidly and to be simply controlled by an engine control device, substantially in the same manner that the variable area exhaust nozzle is controlled. The flaps further are provided with a liner so that cooling air is directed therethrough to an annular liner around the combustion chamber.

Variable area flameholder duct

A reaction chamber in which nitrous oxide is decomposed, with liquid nitrous oxide delivered through an injector system to produce a swirling two-phase flow counter to the flow of the gases produced by decomposition, this counter flow being discharged from the injector system in a direction opposite to the flow of gases through and from the chamber.

Nitrous oxide decomposition reactor

A device for increasing combustion stability in a combustion chamber wherein the combustion chamber has a plurality of openings or apertures in the wall thereof, with each aperture having a swirl device therein to swirl gases passing through the apertures in either direction. A solid cylindrical wall extends around said combustion chamber to form a backing volume therebetween.

Growing community of inventors

North Palm Beach, FL, United States of America

George D Lewis