Showing papers on "Afterburner published in 2007"

Laser-induced Phosphorescence for Surface Thermometry in the Afterburner of an Aircraft Engine

Abstract: In the present work, surface thermometry using a method based on the spectroscopy of inorganic luminescent material was applied in the afterburner of a full-size aircraft jet engine. The technique uses laser-induced emission from thermographic phosphors for nonintrusive remote temperature diagnostics in combustion applications with high sensitivity and accuracy. A phosphor material having suitable temperature sensitivity in the expected temperature range was applied to the surface of interest in the engine afterburner. Phosphorescence radiation was generated using the forth harmonic (266 nm) from a pulsed Nd:YAG laser. The resulting signal was detected with a photomultiplier tube and phosphorescence lifetime decay curves were recorded for various engine loads, including operation of the afterburner. By analyzing the phosphorescence decay, temperature data were acquired through implementation of a regression equation extracted from well-defined calibration measurements on the phosphor used. Quantitative temperature data recorded with a repetition rate of 10 Hz are presented. The laser-induced phosphorescence technique for surface thermometry has proven its applicability in the extremely harsh environment prevailing inside and next to a jet engine operating at full load. (Less)

Ceramic-encased hot surface igniter system for jet engines

Abstract: A ceramic-encased hot surface igniter system for jet engines is presented. The advanced ceramic-encased hot surface igniter system comprises at least one electrical resistance heated element encased in a durable, thermal and mechanical shock resistant, high temperature advanced ceramic compound such as silicon nitride. The one or more advanced ceramic-encased hot surface igniter elements are mounted proximally upstream or within a combustion chamber of a jet engine enclosure or within the afterburner section of a jet propulsion engine's exhaust. The surface temperature of each ignition element's encasement being of sufficient temperature to cause the ignition of a gaseous, atomized, or liquid fuel.

Device for mounting an air-flow dividing wall in a turbojet engine afterburner

Abstract: A device for mounting a dividing wall for separating the main air stream and the bypass air in a bypass turbojet engine afterburner is disclosed. The device includes an attachment unit which attaches the upstream end of the wall to a guide vane casing and a supporting unit which supports the downstream end of the wall provided on flame holder arms of the afterburner radially on the inside of the dividing wall.

Purged flameholder fuel shield

Abstract: A fuel shield (68) is configured for use in the afterburner (34) of a turbofan aircraft engine (10). The shield (68) includes wings (72,74) obliquely joined together at a nose (76) to conform with the leading edge region (52) of a flameholder vane (42). A hood (78) is joined to the wings (72,74) and extends obliquely therefrom to conform with a supporting outer shell (44) of the flameholder (34).

Fuel cell system and method for influencing the thermal and temperature budget of a fuel cell stack

Abstract: The invention relates to a fuel cell system having a fuel cell stack (10), an afterburner (12) for burning off gas emerging from the fuel cell stack, and a heat exchanger (16) which is arranged in an off-gas passage (14) from the afterburner and in which cathode supply air (18) to be supplied to the fuel cell stack can be heated. The invention provides for the capability to supply cathode supply air (20) to the fuel cell stack (10) without previously having been heated in the heat exchanger (16), and for the capability to use the total amount of cathode supply air supplied as well as the ratio of the component of the cathode supply air (18, 20) that has been heated in the heat exchanger and of that which has not been heated in the heat exchanger to influence the thermal and temperature budget of the fuel cell stack (10). The invention also relates to a method for influencing the thermal and temperature budget of a fuel cell stack.

Preheating arrangement in a fuel cell apparatus

Abstract: The present invention relates to a preheating arrangement in a fuel cell apparatus, the fuel cell apparatus comprising at least a fuel cell unit (6) having an anode side (7) and a cathode side (8) with an electrolyte (9) therebetween, the fuel cell apparatus having at least a fuel inlet (1) to the anode side (7) and an oxygen-containing air inlet (11) to the cathode side (8) as well as a sulphur removal unit (3) and a fuel modifying unit (4) and an afterburner (14) for combusting the exhaust gases from the anode and/or cathode side. According to the invention, the afterburner (14) is provided with a separate fuel inlet channel (24) for introducing fuel to the afterburner (14) during the start-up phase of the fuel cell apparatus and that at least a part of the exhaust gases formed in the combustion of the separately fed fuel is arranged to be directed from the afterburner (14) for heating at least the sulphur removal unit (3) and/or the fuel modifying unit (4) during the start-up phase. The outlet channels (27') (29') are provided with heat exchangers (31) and adjustment means (30) for adjusting the exhaust gas flow rate.

Stove with dry distillation gas afterburner, and afterburner

Abstract: PROBLEM TO BE SOLVED: To provide an extremely marketable innovative stove with a dry distillation gas afterburner that is compact for footprint reduction and streamlines combustion in the stove, and such an afterburner. SOLUTION: An afterburning furnace 2 is disposed over a gasification stove furnace 1, and both furnaces 1 and 2 are interconnected via a gas passage 7 having a smaller inside diameter than the furnaces 1 and 2. A gas burner, electric heater or kerosene burner is disposed to promote combustion in the afterburning furnace 2. Inflammable gas generated by dry distillation gasification of firewood or solid fuel in the gasification stove furnace 1 is introduced via the communication part 7 into the afterburning furnace 2, which provides afterburning. COPYRIGHT: (C)2007,JPO&INPIT

Simulation of a lean direct injection combustor for the next high speed civil transport (HSCT) vehicle combustion systems

Abstract: 1. Motivation and objectives Designing commercially viable propulsion systems for supersonic aircraft is a major challenge. All modern combustors must balance the need for stability and performance with the goals of efficiency and cleanliness. These competingdemands, however, are exacerbated in supersonic situations where the operating conditions are much more severe. Supersonic transport aircrafts usually fly in the stratosphere, at cruising altitudes around 60,000 65,000 ft. The engine emissions produced at such high altitude contribute to depleting the ozone layer. In addition, the high fuel consumption increases the overall cost of operation. For example, the Concorde was powered by turbojet engines that made use of afterburner, a very inefficient combustion system. Next-generation high speed civil transport (HSCT) vehicles will likely be based on low-bypass turbofan, afterburner-free technology. In addition to the foregoing improvements, if the engine emission characteristics and performance are further enhanced, supersonic vehicles may become part of the world’s air transportation system.

Fuel cell system with means for preheating cathode air

Abstract: The system has a heat exchanger (12), via which cathode inlet air is supplied to a fuel cell or a fuel cell stack (14). A heat exchanger (18) is provided, via which the cathode inlet air is supplied from the heat exchanger (12) to the fuel cell or the fuel cell stack and via which the afterburner exhaust gas is supplied to the heat exchanger (12) so as to form the mixture, to enable heat exchange between the afterburner exhaust gas and the cathode inlet air using the heat exchanger (18).

Method and system for operating a high-temperature fuel cell

Abstract: The invention relates to a method and a system for operating a high-temperature fuel cell. The system comprises at least one fuel cell, a reformer, an afterburner and a heat exchanger. The aim of the invention is to increase the overall efficiency of high-temperature fuel cells. For this purpose, fresh air supplied to the fuel cell(s) on the cathode side is heated in several steps by means of a high-temperature heat exchanger with heat from post-combustion and from the heated air carried away from the fuel cell on the cathode side.

Energy conversion system for solid biomass used in block heating power plant, has turbine combustion chamber that is heated using gas turbine and compressor for burning solid biomass provided inside reactor

Abstract: The system includes a reactor (1) with waste injection sluice (3) for solid biomass, and gas turbine (19) and compressor (20) for generating heat inside a turbine combustion chamber (14). The solid biomass is heated inside the combustion chamber in predetermined burning time necessary to perform burning process that produces weak gases. The combustion chamber is formed with one or more afterburner openings (15) for releasing pollutant or for releasing better energy output.

Performance and Combustion Analysis of a Micro Gas Turbine-Solid Oxide Fuel Cell Hybrid System

Abstract: An integrated methodology aims at estimation of the actual possibility of operating an hybrid system based on a solid oxide fuel cell and a micro gas turbine, by paying special attention to the adaptation of the rotating and stationary components to the off-design conditions. The method leads to the definition of the operating space of the hybrid system, thus allowing detection of optimal choices for an efficient part-load operation. The computational fluid dynamics (CFD)-based analysis of the combustion chamber is addressed to the verification of the response of this component when employed as an afterburner of the residual species from the fuel cell.

Uso del Modelo Lineal de un Turboventilador al Análisis de su Funcionamiento con Poscombustión

Abstract: The purpose of the presented work was a comparison of an efficiency of Mechanical Flame Holders system and Aerodynamic Flame Holders system for turbofan engine afterburner. The linear mathematical model of the turbofan engine was developed to analyze an influence of air compressor-bleeding for Aerodynamic Flame Holders system on the turbofan engine characteristics. An evaluation criterion was proposed to compare an efficiency of Mechanical and Aerodynamic systems. An influence of differrent parameters on this criterion was analyzed. The factors that cause pressure loss accretion during afterburner down-time, increase the region where the use of Aerodynamic Flame Holders system is preferable in comparison with Mechanical Flame Holders system. It may be concluded that this system can be recommended as moderate thrust augmentation reserve unit for use in emergency operation (insufficient take-off distance, engine failure) or in short- time operation (to break the sound barrier, to reach the most height, take-off).

Fuel cell system with device for cathode inlet air preheating

Abstract: The invention relates to a fuel cell system including a first heat exchanger via which cathode feed air can be supplied to a fuel cell or fuel cell stack and to which a mixture of afterburner exhaust gas of an afterburner and cathode exhaust air having materialized in the fuel cell or fuel cell stack can be supplied for heat exchange between the cathode feed air and the mixture via the first heat exchanger. In accordance with the invention it is provided for that a second heat exchanger is provided via which the cathode feed air can be supplied from the first heat exchanger to the fuel cell or fuel cell stack and via which the afterburner exhaust gas can be supplied to the first heat exchanger to form the mixture, in thus achieving a heat exchange between the afterburner exhaust gas and the cathode feed air.

Surface Thermometry using Laser-induced Phosphorescence Applied in the Afterburner of an Aircraft Turbofan Engine

Abstract: In the present work surface thermometry using a method based on the spectroscopy of inorganic luminescent material has been applied in a full-size aircraft jet engine. The technique utilizes laser-induced emission from thermographic phosphors for, non-intrusive, remote temperature diagnostics in combustion applications with high sensitivity and accuracy. In the present application the laser-induced phosphorescence technique has proven its applicability even in the extremely harsh environment prevailing next to a jet engine operating at full load. The measurement object, Volvo RM12, is based on the General Electric F404 engine, from which it has been developed to meet single-engine operating criteria and achieve higher performance. A phosphor material having suitable temperature sensitivity in the expected temperature range was applied to the surface of interest on the flameholder of the engine afterburner. Phosphorescence radiation was generated using the forth harmonic (266 nm) from a pulsed Nd:YAG laser as an excitation source. The resulting signal was detected with a photo multiple tube (PMT). Phosphorescence lifetime decay curves were recorded at various load of the engine, including use of the afterburner. By analyzing the lifetime decay, the temperature data was acquired through implementation of a regression equation extracted from well-defined calibration measurements on the phosphor used.

Combustion Instability Screech In Gas Turbine Afterburner

Abstract: Gas turbine reheat thrust augmenters known as afterburners are used to provide additional thrust during emergencies, take off, combat, and in supersonic flight of high-performance aircrafts. During the course of reheat development, the most persistent trouble has been the onset of high frequency combustion instability, also known as screech, invariably followed by rapid mechanical failure. The coupling of acoustic pressure upstream of the flame stabilizer with in-phase heat-release downstream, results in combustion instability by which the amplitude at various resonant modes — longitudinal (buzz — low frequency), tangential or radial (screech — high frequency) – amplifies leading to deterioration of the afterburner components. Various researchers in early 1950s have performed extensive testing on straight jet afterburners, to identify screech frequencies. Theoretical and experimental work at test rig level has been reported in the case of buzz to validate the heat release combustion models. In this work, focus is given to study the high frequency tangential combustion instability by vibro-acoustic software and the tests are conducted on the scaled bypass flow afterburner for confirmation of predicted screech frequencies. The wave equation for the afterburner is solved taking the appropriate geometry of the afterburner and taking into account the factors affecting the stability. Nozzle of the afterburner is taken into account by using the nozzle admittance condition derived for a choked nozzle. Screech liner admittance boundary condition is imposed and the effect on acoustic attenuation is studied. A new combustion model has been proposed for obtaining the heat release rate response function to acoustic oscillations. Acoustic wave – flame interactions involve unsteady kinetic, fluid mechanic and acoustic processes over a large range of time scales. Three types of flow disturbances exist such as : vortical, entropy, and acoustic. In a homogeneous, uniform flow, these three disturbance modes propagate independently in the linear approximation. Unsteady heat release also generates entropy and vorticity disturbances. Since flow is not accelerated in the region of uniform area duct, vortical and entropy disturbances are treated as in significant, as these disturbances are convected out into atmosphere like an open-ended tube, but these are considered in deriving the nozzle admittance condition. Heat release fluctuations that arise due to fluctuating pressure and temperature are taken into consideration. The aim is to provide results on how flames respond to pressure disturbances of different amplitudes and characterised by different length scales. The development of the theory is based on large activation energy asymptotics. One-dimensional conservation equations are used for obtaining the response function for the heat release rate assuming the laminar flamelet model to be valid. The estimates are compared with the published data and deviations are discussed. The normalized acoustic pressure variation in the afterburner is predicted…

Afterburner for gas from gasification plant

Abstract: The present invention relates to an afterburner for gas from a gasification plant. The afterburner provides an optimal mixture of combustible gas and air, permitting an optimal reaction between the 02 in the air and the gas and creating a mixture ratio that enables the load on a burner to be regulated without altering the mixture ratio between air and gas. This offers the possibility of optimal combustion even during regulation of the burner, over the whole of the relevant regulating range. The result is extremely good combustion and reduced emissions of 02, CO and NOx.

Fuel cell system comprising a reformer and an afterburner

Abstract: The invention relates to a fuel cell system (10) which comprises a reformer (12) having an oxidation zone (48) to which stored fuel can be supplied by means of a fuel supply device (50) for reaction with an oxidant; and an afterburner (36) having an oxidation zone (60) to which stored fuel can be supplied by means of a fuel supply device (62) for reaction with an oxidant. The invention is characterized in that the fuel supply device (50) of the reformer (12) and the fuel supply device (62) of the afterburner (36) are adapted to supply fuel in such a manner that the fuel supplied by the fuel supply device (50) of the reformer differs from the fuel supplied by the fuel supply device (62) of the afterburner (36) with respect to the type of fuel and/or its state of aggregation and/or the temperature at which it is supplied. The invention also relates to a motor vehicle comprising said fuel cell system and to a method for operating said fuel cell system.

Steady State Processes Analysis of Aero-engine Main Fuel Control System

Abstract: The fuel system of aero engine is used to supply fuel to the main combustion and the afterburner. Digital electronic control has been the main development direction of aero-propulsion control system. The principle of the aero-engine fuel system is analyzed. Aimed at differ revolution, the steady-state is studied and the close-loop control law of fuel and staff are given.

Method for determining an anode performance in a fuel cell system

Abstract: The invention relates to a method for determining an anode performance of a fuel cell or a fuel cell stack (20). The invention is characterized in that the anode performance is determined by measuring at least one current of the fuel cell or the fuel cell stack (20), an air volume flow supplied to an afterburner (24), no fuel being fed during measuring, an excess-air coefficient of a reformer gas and an oxygen volume content in an afterburner gas.

A combustion device

Abstract: A combustion device, such as an afterburner 4 for a gas turbine engine, comprises primary and secondary fuel delivery means 12, 20 Pressure fluctuations in the afterburner 4 are damped by reducing the supply of fuel through the primary fuel delivery means 12 during pressure peaks This is achieved by means of a spill valve 18, controlled by a controller 22 in response to pressure in the afterburner 4 as sensed by a transducer 24 The spill valve 18 diverts a proportion of the fuel to the secondary fuel delivery means 20 The secondary fuel delivery means 20 is positioned upstream of the primary fuel delivery means 12 by a distance X, such that the secondary fuel delivery means serves to supply additional fuel to the combustion zone 26 during pressure troughs

Comments on the Quantum Afterburner

Abstract: A process has been proposed to increase the efficiency of an ideal Otto cycle via a quantum heat engine that has no cooler reservoir We show that such a process is not feasible

Method for determining an anode conversion degree in a fuel cell system

Abstract: The invention relates to a method for diagnosing an anode conversion degree of a fuel cell or a fuel cell stack (20). In accordance with the invention it is provided for that diagnosing the anode conversion degree is performed by measuring at least one current of the fuel cell or of the fuel cell stack (20), an air volume flow fed to an afterburner (24), receiving no fuel supply at the time of measurement, an air ratio of a reformer gas and an oxygen volume proportion in an afterburner exhaust gas.