bluuebunny/crossref_metadata_2025_split huggingface dataset:
Turbulent mixing enhancement with a 10° chute mixer
Authors: Ahmed M.R. , Sharma S.D. 
Published: January 2007

PurposeTurbulent mixing of two co‐axial jets having a low annular to core area ratio is enhanced by employing a chute mixer, directing part of the annular stream at 10° towards the core region. Aims to present results from measurements of time‐averaged and fluctuating components of velocity under cold flow conditions.Design/methodology/approachExperiments were conducted at a bypass ratio of 0.47 which is a typical value for low bypass turbofan engines. Contours of time‐averaged velocity and streamwise and transverse turbulence intensities were obtained by making detailed measurements close to the chutes. Distributions of time‐averaged velocity and turbulence intensity were obtained at different axial locations downstream of the chute mixer. Total and static pressure measurements were also performed.FindingsThe high velocity annular stream was found to quickly diffuse after entering through the chutes and mix with the core stream due to high turbulence generation. A strong transverse turbulence component enhanced the mixing of the streams. With the aid of the chute mixer, nearly complete mixing is achieved over a length of 5 duct radii. A higher total pressure loss of about 1.38 percent is the penalty paid for the enhanced mixing.Originality/valueProvides results from experiments into the process of turbulent mixing of co‐axial jets.
Start systems for aero gas turbines
Authors: Pascoe A.G. 
Published: January 2007

PurposeThis paper is an overview of aero gas turbine engine starting systems and discusses the system design considerations and integration with other aircraft systems.Design/methodology/approachReview of a range of recent publications on the subject, aiming to provide an introduction to modern aero gas turbine engine starting systems.FindingsProvides basic information on starter types and their limitations, and why some starter types are more favoured in modern installations. The effects of altitude and temperature are discussed which may not be initially considered as variables affecting aero start systems.Originality/valueThis paper provides further information on the starting systems of modern aero gas turbines and the considerations associated with integration and efficiency.
Aerodynamic calculation of unmanned aircraft
Authors: Figat Marcin , Goetzendorf‐Grabowski Tomasz , Goraj Zdobysław 
Published: January 2007

PurposeTo provide an effective numerical method for analysis and design of aerodynamic characteristics of unmanned aerial vehicles basing on commercial package VSAERO.Design/methodology/approachCalculation was made by VSAERO package, which is based on a classical panel method enhanced on boundary layer method. Paper explains how to use efficiently VSAERO package, which utilizes advanced CAD techniques, in modern designing of unmanned aircraft.FindingsDuring aerodynamic analysis of unmanned aircraft the computing cycle is repeated many times until the required accuracy is obtained and when the best performance of an aircraft is achieved. Design process depends on the number of iterations. If the preliminary configuration (the so‐called starting design point) is well selected and the aerodynamic analysis is completed in a relatively short time, then the overall design time will be shortened.Research limitations/implicationsThe panel method is very useful tool in spite of different limitations. For example, the Reynolds number has to be sufficiently high, angles of attack and sideslip have to be small enough. Computational process is relatively fast and the accuracy depends on the geometry representation. The boundary layer included into the computational model improves the accuracy of aerodynamic calculations. This methodology is limited to subsonic and low transonic speeds.Practical implicationsA very useful source of computational information and patterns to follow, especially for engineering students and engineers dealing with aerodynamic of unmanned aviation. Surface panel geometry can be transferred from UNIGRAPHICS via IGES files or can be generated from scratch using SPING or PEP software.Originality/valueThis paper offers a practical help for designers planning to develop a new unmanned platform. VSAERO package appeared to be a very useful tool for aerodynamic calculation in the full cycle design activity. This software utilizes the panel method enhanced on a boundary layer model for determination of the fundamental aerodynamic characteristic of an arbitrary aircraft. Presented paper shows a very efficient way how to compute the aerodynamics necessary for design of a new MALE class UAV.
Electrostatic linear engine
Authors: Bolonkin Alexander 
Published: January 2007

PurposeTo suggest a new revolutionary electrostatic linear engine.Design/methodology/approachMethods of the electrostatic physic are used for research.FindingsTheory of this engine is developed and its possibilities researched.Research limitations/implicationsThis engine gives a big thrust (up 4 × 105 N/m2), uses a high voltage electricity and light wires.Practical implicationsThis engine can be used as a linear engine (accelerator), as a strong space launcher, as a high speed delivery system for space elevator, Earth‐Moon cable transport space, for an electrostatic levitation train, as a conventional high voltage rotating engine, as an electrostatic electric generator weapon (high speed gun), and so on. Theory of engine applications was developed and it shows powerful possibilities in space, transport and military industries. The projects are computed and show the good potential of the offered new concept.Originality/valueSucceeds in proposing a new revolutionary electrostatic linear engine.
Dynamic instability characteristics of a free‐free missile structure under a controlled follower force
Authors: Pradhan Sumeet , Datta P.K. 
Published: January 2007

PurposeTo study the effect of rocket mass and an intermediate mass on the critical flutter load of a free‐free beam (missile‐like structure).Design/methodology/approachA finite element model of beam considering shear deformation and rotary inertia, based on Hamilton's principle applied to non‐conservative system.FindingsSmaller geometric dimensions of the end rocket assist in the stability. Optimum positioning of the intermediate mass leads to stability.Practical implicationsThe stability of free‐free missile structures can be better understood.Originality/valueSheds new light on the effect of rocket mass and an intermediate mass on the critical flutter load of a free‐free beam.
Failure analysis of catalytic steam reformer tubes
Authors: Tawancy H.M. , Ul‐Hamid A. , Mohammed A.I. , Abbas N.M. 
Published: January 2007

PurposeTo determine if the interim use of liquid waste as a fuel in a catalytic steam reformer unit had any deleterious effect on the long‐term life of the reformer tubes.Design/methodology/approachStandard metallographic techniques were used to prepare representative samples obtained from various sections of the reformer tubes for metallurgical evaluation. Microstructural characterization was carried out in a scanning electron microscope equipped with an energy dispersive X‐ray spectrometer. Imaging and elemental analysis was used for the identification of the alloy material, corrosion products and other microstructural features.FindingsHydrogen was produced in a catalytic steam reformer by cracking methane using natural gas as a fuel. Corrosion of reformer tubes occurred when natural gas fuel was replaced with a liquid waste. Use of liquid fuel waste accelerated the rate of oxidation at the outer tube surface. However, foreign species from the fuel were not transported into the tube material. The heat‐resistant steel casting used for this application was susceptible to precipitation of Si‐stabilized Ni‐Nb Laves phase, thus reducing rupture life of the component. Voids at grain boundaries indicative of creep damage were observed.Practical implicationsAlthough, the interim use of liquid waste fuel appeared not to have damaged the tubes, it was concluded that the expected service life of the tubes may not be realized because of the susceptibility of the material to precipitation of Laves phase. An Fe‐base superalloy UNS N08810 or UNS N08811 was recommended as a replacement material for this application.Originality/valueThis paper provides an account of a failure analysis study. It identifies incorrect materials selection for a particular application and suggests better alternative along with its justification. The information is deemed useful for plant designers and engineers working in the related industry.
Silica fume – formed during the manufacture of ferrosilicon alloys – as an extender pigment in anticorrosive paints
Authors: Abu‐Ayana Y.M. , Yossef E.A.M. , El‐Sawy S.M. 
Published: January 2007

PurposeThis paper is concerned with the study of silica fume that arises in tonnage amounts during the manufacture of ferrosilicon alloys; this was done in order to maximize productivity and to create new market for industrial by‐product and/or waste material.Design/methodology/approachThe structure and particle shape of silica fume were identified using X‐ray diffraction and electron microscope, respectively. Standard methods were used for the identification of chemical analyses, solubility, hydrogen ion concentration, specific gravity, bulking value, oil absorption, chemical resistance and particle size. The characterized and evaluated silica fume was applied in several paint formulations. The physico‐mechanical, chemical and corrosion protective properties of the paint films were measured according to standard methods.FindingsThe silica fume under investigation was a fine lightweight fluffy amorphous powder. It has a grayish‐white color that makes it suitable for use as a filler and extender pigment in a wide variety of different fields of application; its amorphous nature favors safe use from a standpoint of industrial hygiene. It can be used as an economic pigment that possesses suitable values of specific gravity, bulking value and oil absorption. It also is inert, neutral and of an excellent chemical resistance. The material can be used successfully as an extender pigment in different paint formulations; taking into consideration that alkyd resin based paints should not be used in alkaline environments or mixed with basic pigments, or the paint film will deteriorate. Silica fume particles in the pigment mixture may offer a suitable opportunity for the voids formed by the larger particles to be occupied by smaller ones to produce a condition of maximum packing. It can be successfully used with the flaky aluminum or stainless steel anticorrosive pigments to produce a highly efficient corrosion protective film.Originality/valueThere is increasing environmental concern with regard to excessive volumes of solid waste hazards accumulation. Silica fume that arises – as a disposal material – in tonnage amounts during the manufacture of ferrosilicon alloys can find a new market in paint industry. It can be used successfully for anticorrosive paints to provide well backed paint films.
A study of carbon steels in basic pitting environments
Authors: Boucherit M.N. , Tebib D. 
Published: January 2007

PurposeAims to study the behaviour of four polycrystalline carbon steels in basic pitting solutions.Design/methodology/approachElectrochemical investigations were carried out on four steels: Fe.06C, Fe.18C, Fe.22C and Fe.43C. The analysis was made using an X‐ray fluorescence apparatus. The performance indicator was the pitting potential, which was obtained through potentiodynamic sweeping. Emphasis was placed on the influence of the pH, chlorine concentration, phase proportions in the steel and the initial electrode surface state.FindingsThe results showed that in a solution with a low chlorine concentration, the performance of the steels according to pitting corrosion resistance decreased with the increase in carbon content. By raising the chlorine concentration, the order of performance was inverted gradually, while at a high chlorine concentration, the behaviour of the steels tended to be similar. The interpretation of the results is based on the consideration of cathodic reactions on the level of the cementite phase and the difference in the local chemical properties of the solution. In neutral solutions, pitting potentials were shifted cathodically, but the main observations developed for basic solutions remained valid.Originality/valueProvides further research on pitting corrosion.
Effect of aging time and temperature on intergranular corrosion of aluminium alloys
Authors: Khoshnaw Fuad M. , Gardi Ramadhan H. 
Published: January 2007

PurposeTwo types of aluminium alloys, 2024‐T3 and 7075‐T6, having been selected, this study aims to investigate the effect of metallurgical aspects on intergranular corrosion.Design/methodology/approachTo determine and evaluate the metallurgical effects of heat treatments on corrosion behaviour of these alloys, G67 ASTM test was selected.FindingsThe results showed that with increasing the aging time in aluminium alloy type 2024‐T3 the susceptibility to intergranular corrosion increases, while in type 7075‐T6 with increasing aging time the intergranular corrosion rate remains nearly unchanged.Practical implicationsAs these results refer to precipitate the intermetallic compound phases, the amount of these phases increases with the increase of the aging time in both alloys.Originality/valueThe investigations showed that the phases that initiate in 2024‐T3 act as anode sites, while in 7075‐T6 they act as cathode sites.
Corrosion resistance of rapidly solidified Fe36Co36Zr7Si10B11 and Fe33.5Co33.5Nb7Si15B11 alloys
Authors: Santos F.S. , May J.E. , Kuri S.E. 
Published: January 2007

PurposeAmorphous and nanocrystalline FeCo‐based alloys present excellent soft magnetic properties and high Curie TC temperatures. At ambient temperatures, these alloys are subject to electrochemical corrosion, which causes degradation of their magnetic properties. This paper seeks to characterize the microstructure and evaluate the corrosion resistance of Fe36Co36Zr7Si10B11 and Fe33.5Co33.5Nb7Si15B11 alloys.Design/methodology/approachThese alloys are solidified at different cooling rates.FindingsThe corrosion resistance, which is found to depend on the microstructure, decreases as the cooling rate increases in the interval of 50‐150°C.Originality/valueBuilds on existing knowledge of the microstructure and corrosion resistance of Fe36Co36Zr7Si10B11 and Fe33.5Co33.5Nb7Si15B11 alloys.
Corrosion of zinc‐coated reinforcing bars in tropical humid marine environments
Authors: Maldonado L. , Pech‐Canul M.A. , Alhassan Safaa 
Published: January 2007

PurposeReinforcing steel bars in concrete structures exposed to tropical marine atmospheres experience very high corrosion rates due to several environmental factors. The aim of this research was mainly to elucidate if zinc‐coated rebars may delay the onset of corrosion and/or extend the service life of infrastructure in the tropics, as the approach is promising in other atmospheres.Design/methodology/approachHot‐dip zinc‐coated and plain steel rebars were embedded in concrete cylinders made with local aggregates and having four different water‐to‐cement ratios. Samples were exposed during 24 months at the marine breeze in a coastal site in the Gulf of Mexico. The corrosion behaviour of zinc‐coated and uncoated rebars was monitored by means of corrosion potential and linear polarization resistance techniques. Also, carbonation penetration and the chloride ingress were measured and correlated with the corrosion behaviour.FindingsOnly under the worst case conditions (concrete with 0.7 w/c ratio) did galvanized steel experience corrosion initiation. It was shown to resist higher chloride levels than uncoated steel and extended the onset of corrosion.Originality/ValueThe effectiveness of the zinc‐coated bar for corrosion control is controversial and its use mainly is supported by accelerated tests or application in cold or subtropical environments. This research showed the corrosion behaviour in an extremely corrosive tropical zone.
Rapid method for corrosion protection determination of VCI films
Authors: Valdez S.B. , Zlatev R.K. , Schorr W.M. , Rosas G.N. , Dobrev Ts. , Monev M. , Krastev I. 
Published: January 2007

PurposeTo develop and test a rapid method for evaluation of the corrosion protection (CP) of carbon steel (CS) by vapour corrosion inhibitors (VCI) films.Design/methodology/approachThe determination of the CP by VCI on CSs is commonly carried out in a chamber applying neutral salt spray (NSS) and usually it takes many days. The common disadvantage of the various rapid methods created until now is the need of special laboratory equipment making their application complicated and inconvenient for field tests. The method for CP measurement of VCI films on CS described in this study is based on measurement of the height of the anodic peak under galvanostatic condition applied earlier on other types of films and coatings. By means of a calibration plot: peak height (V) vs NSS protection time (s), CP of VCI films on CS specimens expressed in hours NSS is determined in a few seconds without using an NSS chamber. Measurements of CP by VCI films under field conditions are performed applying a hand held tester.FindingsTwo groups of CS UNS G10180 steel specimens with increasing thickness of VCI films were studied – one in an NSS chamber and the second by the application of a corrosion tester. The correlation between the results obtained for the two groups of specimens was found and a calibration plot was made.Practical implicationsBased on this method, a special corrosion tester was developed, able to measure under field conditions as well.Originality/valueThe method subject of the paper is a further development of a galvanostatic method developed by the authors for CP evaluation of chromate films of Zn and Cd coatings. The method was modified according to the properties of VCI films
Accelerated cyclic corrosion testing of structural steels and its application to assess steel bridge coatings
Authors: Itoh Yoshito , Kim In‐Tae 
Published: January 2007

PurposeThe purpose of this study was to determine correlation between an accelerated cyclic corrosion test (S6‐cycle test) specified in Japanese Industrial Standards K5621 and field exposure tests, and to open up applications of the accelerated tests in various regional environments.Design/methodology/approachThe S6‐cycle corrosion test was carried out on structural steels for 30, 60, 90, 120 and 150 days and metal coating films for 100, 200 and 300 days. Comparing the weight loss of the steels with 1‐, 3‐, 5‐ and 9‐year field exposure test data at 31 sites in Japan. Correlation of the S6‐cycle tests to the field exposure tests was determined by acceleration coefficients.FindingsThe correlation between the S6‐cycle test and the field test on uncoated structural steels can be determined by acceleration coefficients based on flying salt amount. The coefficients were applicable for durability prediction of uncoated, zinc hot‐dip galvanized and painted steels.Research limitations/implicationsIn determination of the accelerated coefficients, only the flying salt amount was considered. Others factors such as temperature and humidity will be considered in future work.Practical implicationsUsing the S6‐cycle corrosion test and its accelerated coefficients, the thickness loss of uncoated structural steels and zinc hot‐dip galvanizing is predictable in a short time. Corrosion degradation of coated steels is also predictable approximately.Originality/valueThis paper contributes to open up the application of accelerated cyclic corrosion test to evaluating corrosion resistance of steel bridge members.
Effect of molybdate coating for white rusting resistance on galvanized steel
Authors: Rout T.K. , Bandyopadhyay N. 
Published: January 2007

PurposeChromium based conversion coatings have been used widely to delay the formation of white rust on galvanized steel sheets. As chromium is carcinogenic, an alternative chromium‐free conversion coating was developed for use on galvanized steel surfaces to delay the onset of white rusting. This paper seeks to address this issue.Design/methodology/approachThe molybdate coating was produced on galvanized steel surface by dipping in a phosphate solution bath using Na2MoO4 as a corrosion inhibitor.FindingsThe cyclic polarization tests conducted on molybdates‐treated samples showed a wider potential band in 3.5 per cent NaCl solution, indicating that the coating is passivating in nature. The polarization (Rp) of both treated and untreated samples was evaluated in 3.5 per cent NaCl solution by electrochemical impedance spectroscopy (EIS) technique. It was observed that the polarization resistance (Rp) of molybdate treated galvanized sample is 2.3 times higher compared with the untreated one. The improved corrosion resistance also was evident from the simulated salt spray test results where the treated sample showed a five times improvement over the untreated sample.Research limitations/implicationsThe corrosion resistance of inorganic‐based chromium‐free conversion coatings has not been equivalent to that of chromium based conversion coatings. A chromium‐free conversion coating with enhanced corrosion performance by using water reducible polymer will be described in a future paper.Practical implicationsThe developed chromium‐free passivation solution has been implemented for galvanized tube passivation. It is one of the best alternative chromium‐free chemicals for the prevention of white rust formation on galvanized materials during transit and storage.Originality/valueThis paper describes a new coating system for the galvanized material which will provide a significant improvement to white rusting resistance for the galvanizing industry.
Electrochemical noise analysis for estimation of corrosion rate of carbon steel in crude oil
Authors: Ghassem Mahjani Mohammad , Neshati Jaber , Parvaneh Masiha Hashem , Jafarian Majid 
Published: January 2007

PurposeThis paper aims to estimate the corrosion rate of the carbon steel in crude oil using the electrochemical noise (EN) analysis technique.Design/methodology/approachEN measurements and electrochemical impedance (EIS) spectroscopy were employed to study the corrosion behaviour of carbon steel in crude oil and the optimum conditions of the noise analysis for estimating corrosion rate of the carbon steel are discussed. The time series noise patterns were transformed into frequency domains by fast Fourier transformation, and then their power spectrum densities (PSDs) at a frequency were determined to be compared with the corrosion rate.FindingsThe PSDs of the potential and of the current varied with changing of rotation rate of electrode and immersion time. Square roots of the PSDs for the potential difference and for the currents were in positive and almost linear correlation with the corrosion rate obtained from EIS plots. In addition, the spectral noise was negatively and linearly correlated with the corrosion rate. The relationship between the corrosion rate and the spectral noise resistance was better at lower frequencies.Research limitations/implicationsIt is suggested that this research is carried out for crude oils with other physical and chemical characteristics.Practical implicationsThe PSD value at 3 mHz from the noise of the current and the spectral noise resistance at the same frequency are the optimum conditions for estimating corrosion rate in this research.Originality/valueThis paper arguably fills a gap in the current understanding of the interactions between corrosive species commonly found in crude feedstocks and process streams.