The Influence of Manufacturing Tolerances on Swirler Durability

Jet fuel flowing through the fuel injector is atomized and then mixed with high temperature compressed air flowing through the swirler to create a combustible mixture inside a gas turbine combustor. Individual geometric and flow features are carefully tuned at a component level to deliver optimum combustion performance. In a critical interface such as the fuel injector and swirler, manufacturing tolerances not only have an impact on combustor performance and operability but also on durability, as the relative position of the fuel injector to the swirler significantly impacts the swirler temperature. This paper studies the influence of manufacturing tolerances on component assembly and the resulting impact on swirler temperature. The oxidation damage mechanism of the swirler is used as a measure to assess swirler durability. A Pareto chart of the effect of manufacturing tolerances on metal temperature is used to highlight the key influencing parameters. Probability distribution associated with manufacturing tolerances is gathered with Monte Carlo simulation to guide the design.

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Fatigue–oxidation–creep damage model under axial-torsional thermo-mechanical loading

International Journal of Damage Mechanics ◽

10.1177/1056789519887217 ◽

2019 ◽

Vol 29 (5) ◽

pp. 810-830 ◽

Cited By ~ 2

Author(s):

Dao-Hang Li ◽

De-Guang Shang ◽

Jin Cui ◽

Luo-Jin Li ◽

Ling-Wan Wang ◽

...

Keyword(s):

Damage Model ◽

Creep Damage ◽

Fatigue Loading ◽

Damage Mechanism ◽

Critical Crack ◽

Critical Crack Length ◽

Mechanical Fatigue ◽

Proposed Model ◽

Oxidation Damage ◽

Creep Damage Model

A fatigue–oxidation–creep damage model that can take into account the effect of multiaxial cyclic feature on the damage mechanism is proposed under axial-torsional thermo-mechanical fatigue loading. In the proposed model, the effects of non-proportional additional hardening on fatigue, oxidation, and creep damages are considered, and the variation of oxidation damage under different high temperature loading conditions is also described. Moreover, the intergranular creep damage needs to be equivalent to the transgranular damage before accumulating with the fatigue and oxidation damages. The fatigue, oxidation, and creep damages can be expressed as the fractions of fatigue life, critical crack length, and creep rupture time, respectively, which allows the linear accumulation of different types of damages on the basis of life fraction rule. In addition, the proposed model is validated by various fatigue experimental results, including uniaxial thermo-mechanical fatigue, axial-torsional thermo-mechanical fatigue, and isothermal axial-torsional fatigue under proportional and non-proportional loadings. The results showed that the errors are within a factor of 2.

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Model Issues Regarding Modification of Fuel Injector Components to Improve the Injection Parameters of a Modern Compression Ignition Engine Powered by Biofuel

Applied Sciences ◽

10.3390/app9245479 ◽

2019 ◽

Vol 9 (24) ◽

pp. 5479 ◽

Cited By ~ 3

Author(s):

Jacek Eliasz ◽

Tomasz Osipowicz ◽

Karol Franciszek Abramek ◽

Łukasz Mozga

Keyword(s):

Combustion Process ◽

Quality Parameters ◽

Combustible Mixture ◽

Opening Angle ◽

Fuel Injector ◽

Compression Ignition Engine ◽

Injection Dose ◽

Innovative Idea ◽

Flow Turbulence ◽

Fuel Stream

This article presents a theoretical analysis of the use of spiral-elliptical ducts in the atomizer of a modern fuel injector. The parameters of the injected fuel stream can be divided into quantitative and qualitative. The quantitative parameter is the injection dose amount, and the qualitative parameter is characterized by the stream of injected fuel (width, atomization, opening angle, and range). The purpose of atomizer modification is to cause additional flow turbulence, which may affect the stream parameters and improve the combustion process of the combustible mixture in a diesel engine. The spiral-elliptical ducts discussed here could be used in engines powered by vegetable fuels. The stream of such fuels has worse quality parameters than conventional fuels, due to their higher viscosity and density. The proposal to use spiral-elliptical ducts is an innovative idea for diesel engines.

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Elementary Computer Modeling Applied to TWA800 Fuel Tank Forensic Issues

Volume 6: 18th Computers in Engineering Conference ◽

10.1115/detc98/cie-6021 ◽

1998 ◽

Author(s):

Floyd A. Wyczalek

Keyword(s):

Jet Fuel ◽

Combustible Mixture ◽

Scientific Data ◽

Fuel Tank ◽

Critical Conditions ◽

Jet Fuels ◽

Potential Hazard ◽

Minimum Ignition Energy ◽

Aircraft Fuel ◽

Fuel Tanks

Abstract The specific mission was to identify the conditions of atmospheric pressure and ambient temperature under which a so-called empty-Boeing model 747-131 fixed wing jet aircraft center wing tank (CWT), containing a residual fuel loading of about 3 kg/m3, less than 100 gallons of aviation kerosene (JetA Athens refinery commercial jet fuel), could form hazardous air/fuel mixtures. The issues are limited to explosion safety concerns relating to certificated fixed wing jet aircraft in regularly scheduled commercial passenger service. It is certain that a combustible mixture does not exist in a fuel tank containing Jet-A type fuel at ambient temperatures below 38°C (100°F), which is the lean limit flash point (LFP) for commercial jet fuel at sea level. Never the less, although not included in this paper, the original study reported by Wyczalek and Suh (1997), identified six highly unlikely, but rationally possible critical conditions which can occur in a combination which may permit a combustible mixture to exist within a jet aircraft fuel tank and pose a potential hazard. The scope of this paper is limited to mathematical modeling concerns related to fixed wing jet aircraft fuel tanks and commercial jet fuels combustible air-fuel mixture ratios. It was further limited to a historical review of the scientific literature in the public domain from 1950 to the present time, which defined the thermodynamic and minimum ignition energy properties of aviation gasoline and commercial jet fuels; and, to comparisons with new thermodynamic data for JetA Athens flight test samples, released by the National Transportation Safety Board (NTSB) during public hearings on the TWA800 event in Baltimore, Maryland in December 1997. The original work reported by Wyczalek and Suh (1997) conclusively demonstrated that the USAF Wright Air Development Center and the US Bureau of Mines conducted and published comprehensive evaluations of the potential hazards relating to jet aircraft fuel tanks as early as 1952. This historical scientific data and the mathematical models for the new jetA and Athens refinery jetA in this paper, are relevant to pending TWA800 related litigation, and to the future implementation of NTSB recommendations resulting from the TWA800 event.

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Flow and Spray Characteristics of a Lean Fuel Injection Module With Radial Swirlers

Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/2000-gt-0118 ◽

2000 ◽

Cited By ~ 1

Author(s):

Woo Seok Seol ◽

Yeoung Min Han ◽

Dae Sung Lee

Keyword(s):

Fuel Injection ◽

Reverse Flow ◽

Jet Fuel ◽

Fuel Injector ◽

Flow Zone ◽

Mixing Rate ◽

Spray Characteristics ◽

Injection Point ◽

Size Number ◽

Lean Fuel

Lean fuel modules are sometimes employed to reduce NOx emissions in aero-engine combustors. With a lean fuel module whose AFR is larger than the stoichiometric AFR, the bulk AFR remains larger than the stoichiometric AFR throughout the combustor, and hence the peak NOx producing regime can be avoided. In addition, by introducing a large amount of air at the fuel injection point and increasing the mixing rate, the existing time of local stoichiometric pockets can be reduced. In the present study, flow and spray characteristics of a 21AFR lean fuel module, which consists of a pressure jet fuel injector and radial air swirlers, are measured by an adaptive Phase/Doppler technique. Gas phase velocity field, and distributions of droplet size, number density, and liquid phase volume flux are presented for co-swirl and counter-swirl lean modules. The present study reveals that a strong reverse flow zone is formed by the lean fuel module with radial swirlers. The shape of the reverse flow zone and the reverse flow velocity depend on the swirl direction significantly. The lean fuel module with radial swirlers provides effective atomization, and the SMD distribution near the module exit is quite uniform. The swirl direction has significant effects on the spray characteristics, too.

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Effect of GTL-Like Jet Fuel Composition on GT Engine Altitude Ignition Performance: Part I—Combustor Operability

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2011-45487 ◽

2011 ◽

Cited By ~ 11

Author(s):

Darren Fyffe ◽

John Moran ◽

Kumaran Kannaiyan ◽

Reza Sadr ◽

Ali Al-Sharshani

Keyword(s):

Gas Turbine ◽

Alternative Fuels ◽

Carbon Number ◽

Jet Fuel ◽

Flame Stability ◽

Ignition Process ◽

Fuel Injector ◽

Simulated Altitude ◽

Number Range ◽

The Past

The current fuel used in aviation turbines is kerosene, and is tightly controlled to a well defined specification. The past 50 years of simultaneous development between the aviation turbine and kerosene jet fuel has led to the fuel specification. The design of the combustion system has also been developed with this fuel chemistry and specification. In the past 5 years, there has been a ground swell of interest in alternative fuels for aviation, where the fuels can be made from a variety of feedstocks and processes. The chemistry and composition of species within future alternative fuels will change from the current kerosene jet fuel specifications; therefore research has been carried out looking at the effects of some of the fundamental component species that will be found in potential future fuels. The gas turbine combustion ignition and stability characteristics were studied while fuelled by a series of gas-to-liquid (GTL) Synthetic Paraffinic Kerosene (SPK)-type fuels by measurement of the successful ignition and flame stability regimes at realistic altitude temperatures and pressures. The combustor under test was a multi-sector representation of an advanced gas turbine combustor and fuel injector. Tests were conducted on the Rolls-Royce plc TRL3 (Technology Readiness Level) sub-atmospheric altitude ignition facility in Derby, UK. The facility was operated at simulated altitude conditions of 6 and 8 psi combustor inlet pressure with corresponding air and fuel temperatures to represent combustor conditions following flame-out during high altitude cruise. The GTL SPK-type fuels were selected to generate a pseudo-Design of Experiments (DoE) matrix in which the iso- to normal-paraffin ratio, cyclic paraffin content, and carbon number range were varied to isolate the effects of each. Tests were conducted at combinations of air mass flow rate and fuel-air ratio necessary to map the regimes of successful ignition and flame stability. All fuels indicated little or no deterioration to the weak boundary of the ignition regime, nor the weak extinction limits, within the scatter of the experimental method. Evidence was found that a commercial GTL SPK, as well as one of the DoE blends, may have greater ignition performance at simulated altitude conditions. Further testing at higher TRL levels is recommended to confirm this finding. The test programme was supported by DLR, German Aerospace Centre, through high-speed diagnostic imaging of the ignition process, including OH* and CH* chemi-luminescence measurements, which is the subject of a separate complementary paper.

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Computational Study on the Effect of Local Expansion and Contraction Upon Surface Deposition in a Heated Fuel Injector

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2011-46265 ◽

2011 ◽

Cited By ~ 1

Author(s):

Ehsan Alborzi ◽

Renato Piazzolla ◽

Christopher Wilson

Keyword(s):

Fuel Injection ◽

Computational Study ◽

Fluid Dynamic ◽

Jet Fuel ◽

Injection System ◽

Data Sampling ◽

Fuel Injector ◽

Chemical Kinetic Model ◽

Surface Deposition ◽

Local Expansion

A preliminary numerical analysis was carried out to examine the effect of local expansion and contraction on surface deposition rate for two series of geometries. These geometries correspond to the new geometrical features found in jet fuel injection system. For this simulation, commercial computational fluid dynamic package, Fluent 6.3.26, was used. Fluid flow, energy, and turbulence equations were solved coupled with a pseudo-detailed chemical kinetic model for jet fuel thermal degradation and the subsequent surface deposition sub model. The model results indicate that the highest deposition rates occur at intermediate expansion ratios and for a bigger inlet diameter due to a lower convective heat transfer. It was also shown that high expansion ratios are recommended to be used for short injector lengths. These simulated results are used for the experimental work in progress. The most susceptible locations to surface deposition are those with the highest rates; these are the best indicative points for data sampling.

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Elemental mass loss in silicate minerals during x-ray analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177155 ◽

1990 ◽

Vol 48 (4) ◽

pp. 804-805

Author(s):

P.E. Champness ◽

R.W. Devenish

Keyword(s):

Mass Loss ◽

Current Density ◽

Damage Mechanism ◽

Beam Current ◽

Single Chain ◽

Plagioclase Feldspar ◽

X Ray ◽

Alkali Ions ◽

Structural Order ◽

Sheet Silicate

It has long been recognised that silicates can suffer extensive beam damage in electron-beam instruments. The predominant damage mechanism is radiolysis. For instance, damage in quartz, SiO2, results in loss of structural order without mass loss whereas feldspars (framework silicates containing Ca, Na, K) suffer loss of structural order with accompanying mass loss. In the latter case, the alkali ions, particularly Na, are found to migrate away from the area of the beam. The aim of the present study was to investigate the loss of various elements from the common silicate structures during electron irradiation at 100 kV over a range of current densities of 104 - 109 A m−2. (The current density is defined in terms of 50% of total current in the FWHM probe). The silicates so far ivestigated are:- olivine [(Mg, Fe)SiO4], a structure that has isolated Si-O tetrahedra, garnet [(Mg, Ca, Fe)3Al2Si3AO12 another silicate with isolated tetrahedra, pyroxene [-Ca(Mg, Fe)Si2O6 a single-chain silicate; mica [margarite, -Ca2Al4Si4Al4O2O(OH)4], a sheet silicate, and plagioclase feldspar [-NaCaAl3Si5O16]. Ion- thinned samples of each mineral were examined in a VG Microscopes UHV HB501 field- emission STEM. The beam current used was typically - 0.5 nA and the current density was varied by defocussing the electron probe. Energy-dispersive X-ray spectra were collected every 10 seconds for a total of 200 seconds using a Link Systems windowless detector. The thickness of the samples in the area of analysis was normally 50-150 nm.

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