bluuebunny/crossref_metadata_2025 huggingface dataset:
Mistuning Identification of Bladed Disks Using a Fundamental Mistuning Model: Part 1 — Theory
Authors: Feiner D. M. , Griffin J. H.
Published: February 2009

This paper is the first in a two-part study of identifying mistuning in bladed disks. It develops a new method of mistuning identification based on measurements of the vibratory response of the system as a whole. As a system-based method, this approach is particularly suited to integrally bladed rotors, whose blades cannot be removed for individual measurements. The method is based on a recently developed reduced order model of mistuning called the Fundamental Mistuning Model, FMM, and is applicable to isolated families of modes. Two versions of FMM system identification are presented: a basic version that requires some prior knowledge of the system’s properties, and a somewhat more complex version that determines the mistuning completely from experimental data.
Mistuning Identification of Bladed Disks Using a Fundamental Mistuning Model: Part 2 — Application
Authors: Feiner D. M. , Griffin J. H.
Published: February 2009

This paper is the second in a two-part study of identifying mistuning in bladed disks. It presents experimental validation of a new method of mistuning identification based on measurements of the vibratory response of the system as a whole. As a system based method, this approach is particularly suited to integrally bladed rotors, whose blades cannot be removed for individual measurements. The method is based on a recently developed reduced order model of mistuning called the Fundamental Mistuning Model and is applicable to isolated families of modes. Two versions of FMM system identification are applied to the experimental data: a basic version that requires some prior knowledge of the system’s properties, and a somewhat more complex version that determines the mistuning completely from experimental data.
Active On-Line Protective Tuning Adjustment Technique to Achieve Better Availability and Performance in Pre-Mix DLN Combustion
Authors: Koeneke C. , Nomura M. , Iba H. , Kawakami T. , Koga T.
Published: February 2009

Stable combustion of gas turbines is essential to ensure reliability, availability and achieve maximum component life capability. Combustor instabilities can trigger high-pressure fluctuations that are generally due to sudden changes in fuel calorific value or fuel quality, large ambient temperature swings, or sudden changes in operating load conditions. In order to protect against combustor instabilities, Mitsubishi developed an advanced monitoring and protection system known as the Advanced Combustor Pressure Fluctuation Monitoring (advanced CPFM) system. This on-line monitoring and protection system automatically tunes the air bypass valve, main and pilot fuel flows to maintain appropriate fuel/air ratio depending on the combustion chamber flame instability condition. The response to such actions successfully prevents flame out occurrence, combustion oscillation, and flame flash back under various modes while trying to maintain emissions within specified levels. This paper describes the operation and functionalities of the advanced CPFM system that has been tested at Mitsubishi’s in-house combined cycle power plant under real operating conditions.
Update on Mitsubishi G Series Gas Turbines With Over 78,000 Hours Fleet Operation
Authors: Kallianpur V. , Stacy D. , Fukuizumi Y. , Arimura H. , Uchida S.
Published: February 2009

Seven G gas turbines from Mitsubishi are in commercial operational at various combined cycle power plants since the first Mitsubishi G gas turbine was inroduced in 1997. The combined operating time on the fleet exceeds over 78,000 actual hours. Additional power plants using Mitsubishi G-series gas turbines are in advanced stages of commissioning in the U.S.A., and are expected to be in commercial operation in 2003. This paper describes operating experience of the Mitsubishi G-series gas turbines, which apply steam-cooling instead of air-cooling to cool the combustor liners. The paper discusses design enhancements that were made to the lead M501G gas turbine at Mitsubishi’s in-house combined cycle power plant facility. It also addresses the effectiveness of those enhancements from the standpoint of hot parts durability and reliability at other power plants that are in commercial operation using Mitsubishi G gas turbines.
Computation of the Statistics of Forced Response of a Mistuned Bladed Disk Assembly via Polynomial Chaos
Authors: Sinha Alok
Published: February 2009

The method of polynomial chaos has been used to analytically compute the statistics of forced response of a mistuned bladed disk assembly. The model of the bladed disk assembly considers only one mode of vibration of each blade. Mistuning phenomenon has been simulated by treating the modal stiffness of each blade as a random variable. The validity of the polynomial chaos method has been corroborated by comparison with the results from numerical simulations.
Modeling Laminar-to-Turbulent Transition in a Low-Pressure Turbine Flow Which Is Unsteady Due to Passing Wakes: Part II — Transition Path
Authors: Jiang Nan , Simon Terrence W.
Published: February 2009

Modeling of transition often is done with an algebraic model for predicting the onset and a path model for describing the evolution from the laminar state to the fully turbulent state. This paper discusses the path model. A companion paper addresses onset modeling. A predicted intermittency distribution from a model that includes the influence of wakes, as in gas turbine flows, is compared against data taken from an experiment conducted at the University of Minnesota. There is good agreement between model and experiment at the beginning of the transition process with poor agreement farther downstream. The inability of the model to capture the strong intermittent behavior caused by the wakes in the comparison case is thought to be the reason for the poor comparison of the time-averaged intermittency in the downstream portion of the transitional flow.
Casing Distortion of GE Frame 3 Gas Turbines
Authors: Mitchell Ryan D. , Bernstein Henry L. , Talley Peggy L.
Published: February 2009

A study of casing distortion in General Electric MS3002 gas turbines used in the oil and gas industry revealed significant distortion for MS3002 Models C through G. The primary distortion problem was ovalization of the turbine casing, which could occur in either the horizontal or vertical directions. Malfunctioning of the water cooling system, or improper disassembly and assembly procedures can cause casing distortion. The MS3002 Models A-G gas turbines have water cooled turbine casings, and malfunctioning of their cooling water systems, regardless of distortion, is also a significant problem.
Review of Centrifugal Compressor’s Application and Development
Authors: Krain Hartmut
Published: February 2009

The paper historically describes the application and development of the centrifugal compressor from the very beginning of its introduction until today. It focuses on selected practical and theoretical examples that — to the author’s opinion — pushed the centrifugal’s standard from simple, low efficiency designs to its current high level status. The main events related with this development like the impact of the industrial revolution and the introduction of jet propulsion are pointed out. The implication of improved theoretical tools becoming available with raising computer capacity and the impetus of advanced measurement techniques on the centrifugal’s improvement are described. A considerable number of references offers the possibility to engross the thoughts.
Response of a Laminar Separation Bubble to an Impinging Wake
Authors: Gostelow J. P. , Thomas R. L.
Published: February 2009

Laminar separation and transition phenomena were investigated experimentally in the wake-disturbed flow over a 2.4 m long flat plate. A controlled diffusion pressure distribution, representative of that on a compressor blade, was imposed but with sufficiently strong loading to cause laminar separation. Boundary layer velocity traverses were performed at several longitudinal stations. Wakes were generated upstream by a single rod, parallel to the leading edge, attached to a rotating disc mounted flush in the side-wall of the working section. Data are presented in the form of velocity traces, and contours of velocity and turbulent intermittency. The results highlight the interaction between the incoming wake and the natural boundary layer, which features a long and thin laminar separation bubble; they demonstrate that wind tunnel experiments provide a good representation of boundary layer behavior under wake disturbances on turbomachinery blading. The calmed region behind the disturbance is a feature that is even stronger behind a wake interaction than behind a triggered turbulent spot. Intermittency values for the undisturbed flow in the separation bubble reattachment region are well-represented by Narasimha’s universal intermittency distribution, lending support to the use of intermittency-based predictive routines in calculations of blade boundary layers.
Tailored Structural Design and Aeromechanical Control of Axial Compressor Stall: Part II — Evaluation of Approaches
Authors: Fre´chette L. G. , McGee O. G. , Graf M. B.
Published: February 2009

A theoretical evaluation was conducted delineating how aeromechanical feedback control can be utilized to stabilize the inception of rotating stall in axial compressors. Ten aeromechanical control methodologies were quantitatively examined based on the analytical formulations presented in the first part of this paper (McGee et al, 2003a). The maximum operating range for each scheme is determined for optimized structural parameters, and the various schemes are compared. The present study shows that the most promising aeromechanical designs and controls for a class of low-speed axial compressors were the use of dynamic fluid injection. Aeromechanically incorporating variable duct geometries and dynamically re-staggered IGV and rotor blades were predicted to yield less controllability. The aeromechanical interaction of a flexible casing wall was predicted to be destabilizing, and thus should be avoided by designing sufficiently rigid structures to prevent casing ovalization or other structurally-induced variations in tip clearance. Control authority, a metric developed in the first part of this paper, provided a useful interpretation of the aeromechanical damping of the coupled system. The model predictions also show that higher spatial modes can become limiting with aeromechanical feedback, both in control of rotating stall as well as in considering the effects of lighter, less rigid structural aeroengine designs on compressor stability.
Humid Air Injection Power Augmentation Technology Has Arrived
Authors: Nakhamkin Michael , Pelini Robert , Patel Manu I.
Published: February 2009

This paper presents the latest information on Humid Air Injection (HAI) power augmentation technology for Combustion Turbine and Combined Cycle power plants. It describes: a) The summary of the latest activities on the implementation of HAI and Dry Air Injection (DAI) technologies including results of the validations tests conducted on the PG7241 (FA) combustion turbine, and findings of various CT-HAI implementation projects; b) The technical background including the latest CT-HAI and CT-DAI concepts resulting on the performance improvements and reduced emissions; and c) The novel concept for humidification of the injected air that further reduces overall capital costs by 15%.
CSGT: Final Design and Test of a Ceramic Hot Section
Authors: Jimenez Oscar , Bagheri Hamid , McClain John , Ridler Ken , Bornemisza Tibor
Published: February 2009

The Ceramic Stationary Gas Turbine (CSGT) Development Program was performed under the sponsorship of the United States Department of Energy (DOE), Office of Industrial Technologies (OIT). The goal was to improve the performance (fuel efficiency, output power, and exhaust emissions) of stationary gas turbines in cogeneration through the selective replacement of hot section metallic components with ceramic components. The team was headed by Solar Turbines Incorporated and supported by ceramic component suppliers and national research institutes. The team performed a detailed engine and component design, fabrication, and field-testing of ceramic components. This program culminated in an engine test at 1121°C (2050°F) TRIT. This was a major challenge in that the engine ran with a continuous fiber reinforced ceramic composite liner (CFCC) and with silicon nitride (Si3N4) stage one ceramic blades and nozzles. The design and testing of all three components will be discussed in this paper, with emphasis on the ceramic nozzles. Another test that will be discussed in this paper is a heavily instrumented engine test that took place prior to the test mentioned above. This instrumented engine test was performed in order to better understand the temperature effects between the ceramic and metallic component interfaces. The results from this were then used to correlate the analytical model with test data. This led to additional design changes to the outer and inner shroud ceramic / metallic interfaces, as well as ceramic nozzles, fabricated from Kyocera SN 282 silicon nitride material. These nozzle changes were then engine tested successfully for a total of 100 hours at full load [1010°C (1850°F) TRIT and 100% speed]. During the engine test, the firing temperature was increased to 1121°C (2050°F) TRIT for an adequate duration to ensure meaningful performance data were gathered.
Two Years of Operational Experience With Gas Turbine Inlet Fogging at Reliance Cogeneration Facilities
Authors: Mishra P. K. , Misra B. K. , Dighe Ajay , Chaker Mustapha , Meher-Homji Cyrus B.
Published: February 2009

The design, installation, commissioning, operation and maintenance experiences of a fogging system for 5 GE Frame 6B gas turbines in cogeneration service are described in this paper. The pilot project was initiated in October 2000 on one GT and based on the encouraging results, fogging based inlet air cooling has been incorporated on an additional 4 gas turbines. The paper provides a description of the cogeneration plant and the underlying need for inlet fogging. The paper also shows how the inlet fogging was instrumental in boosting power and improving heat rate for the cogeneration cycle. Modifications done in the control logic to operate the fogging based inlet-cooling system on part load operation of gas turbines are also provided.
LPG Fueled Engine Under Kuwait Summer Climate
Authors: Alasfour Fuad N. , Abdulraheem Hassan K.
Published: February 2009

The purpose of this research is to investigate the effect of using LPG (liquefied petroleum gas) fuel on the performance of spark ignition engine under summer climate. A Hydra single-cylinder, spark ignition, water cooled engine was tested under elevated inlet air temperature. The effect of preheating inlet air from 25 to 60 °C to simulate Kuwait summer climate was investigated. Engine performance and the level of CO and CO2 emissions were measured experimentally using a gaseous Hydra research engine. The engine was fueled with local, commercial LPG. Several parameters were varied during the experimental work: fuel/air equivalence ratio, engine load and engine speed. The goal of this research was to investigate and simulate the effect of elevated inlet air temperature on the performance of car engine during summer season in Kuwait. The local LPG fuel is composed of 25% propane, 23% Iso-butane and 52% n-butane. Results show that the engine performance curves (brake power, brake specific fuel consumption and mechanical efficiency) have lower performance effect when inlet air temperature preheated from 25 to 60 °C, where the engine brake power dropped by 8% at equivalence ratio of 0.8. Carbon monoxide emission increased as inlet air preheated except at fuel air equivalence ratio less than 0.78. The present research provides a quantitative comparison of engine performance and CO and CO2 emissions between engine running at ambient and elevated inlet air temperature. Although there is a slight drop in the engine performance with heated inlet air, there is good reduction in the level of CO2.
Oxidation of Biodiesel Fuels for Improved Lubricity
Authors: Wain Kimberly S. , Perez Joseph M.
Published: February 2009

Diesel engine emissions are a source of environmental concern. The use of vegetable oil based fuels, called biodiesels, lowers particulate emissions due to the increased oxygen content of the fuel. This study aims to further increase the oxygen content of biodiesel by oxidizing the fuel, analyzing the resulting product, and determining if favorable lubricity qualities result. Oxidation is performed in a non-catalytic vapor phase reactor at temperatures between 300–400°C. The product is characterized using various analyses including sulfuric acid solubility, density, gas chromatography, bomb calorimetry, and lubricity. Optimum blend ratios of the oxidized fuels in a low sulfur diesel fuel to obtain maximum lubricity are determined.
Experimental Investigation and Numerical Modeling of Spray Combustion and Emission in a Diesel Engine
Authors: Cheng Xiao-Bei , Huang Rong-Hua , Zhi Wang , Zhu Mei-Lin
Published: February 2009

An improved multi-dimensional CFD code has been employed to simulate the spray, combustion and pollution formation process within a diesel engine cylinder. The computational results are compared with experimental data from an optical high-speed research engine equipped with a high-pressure injection system. Several spray sub-models have been implemented into the code, and their influence on the predicted droplet characteristic was evaluated. These models account for liquid core atomization, droplet secondary breakup, spray/wall interaction, droplet turbulent dispersion and evaporation. These models improve the prediction of the droplet sizes within a diesel spray and provides a more accurate initial condition for the evaporation, combustion models. The combustion sub-model employed has two components: one for predicting auto-ignition and one for computing the subsequent combustion of the ignited gas. Thermal NOx formation is calculated according to the extended Zeldovich mechanism, which gives the NOx formation as a function of temperature and O, H and OH radical concentrations. Soot formation process adopted in present study is modeled according to a hybrid chemical kinetics/turbulent mixing controlled rate expression. For the engine configurations and operating conditions considered, in most case the calculated cylinder averaged results show good agreement between measured and global pressure, heat release rate and emission data, but in some case they have limitations. Discrepancies are highlighted and possible reasons suggested. The major influences of the injection timing and combustion chamber geometry on the pollutant formation processes have been identified. The calculated results provide a detailed insight into the processes governing combustion and pollutant formation in spray flames under diesel engine conditions. The good agreement indicates that computer models are available for use by the engine industry to provide directions for engine design.
Development of a Transient CFD Model of an SI Fuel Injector
Authors: Hii Wilson W. S. , Michalek Donna J.
Published: February 2009

As the use of fuel injection in spark ignition engines has increased, continuous refinements in the design of fuel injectors are needed in order to obtain lower engine emissions and increased performance. In this endeavor, computational fluid dynamics (CFD) has been used as a means of gaining an understanding of the flow through the injector, and also as a valuable tool in the design process. Most CFD models constructed to study injector flow utilize the standard k-ε turbulence model and perform steady state calculations with the fuel injector needle held in a fixed position. The objectives of this research were to determine the appropriate turbulence model for this flow situation and the accuracy of using a steady state analysis to simulate the transient flow in an operational fuel injector. An evaluation of three turbulence models was performed. The standard k-ε, along with the Renormalisation Group (RNG) and the Chen modifications of the k-ε scheme were used to obtain steady state flow results for a fuel injector in the fully open position. Star-CD was used to perform the simulations of two fuel injectors containing Ford compound nozzles, which are specifically designed to generate turbulent flow just upstream of the injector exit. This comparison resulted in the determination of an appropriate turbulence model, which was then used in a transient CFD simulation of the injector. In addition to the transient simulation, which modeled the opening and closing processes, four steady state simulations were performed at different needle lift positions. The results obtained from these steady state simulations were compared to those from the transient simulation at the same needle lift positions. In all cases, the flow properties used for the comparisons were the fluid velocity, the turbulent kinetic energy, and the turbulent dissipation in the nozzle exit plane. This location was chosen because of its influence on the spray dispersion and droplet size distribution produced by the injector. From the turbulence model study it was determined that the Renormalisation group and Chen’s modifications schemes were preferred over the standard k-ε scheme for predicting the turbulent flow properties. Comparisons between the transient and steady state simulation results clearly illustrated that the rapid movement of the pintle needle during the opening and closing processes greatly influences the flow at the injector exit. From these observations, it was determined that a fuel injector can operate entirely within the transient mode. Therefore, it was concluded that a transient simulation is the preferred method to use for injector analysis.
A Model for Droplet Vaporization for Use in Gasoline and HCCI Engine Applications
Authors: Ra Youngchul , Reitz Rolf D.
Published: February 2009

A model for unsteady droplet vaporization is presented that considers the droplet temperature range from flash-boiling conditions to normal evaporation. The theory of continuous thermodynamics was used to model the properties and compositions of multi-component fuels such as gasoline. In order to model the change of evaporation rate from normal to boiling conditions more realistically, an unsteady internal heat flux model and a new model for the determination of the droplet surface temperature is proposed. An explicit form of the equation to determine the heat flux from the surrounding gas mixture to the droplet-gas interface was obtained from an approximate solution of the quasi-steady energy equation for the surrounding gas mixture, with the inter-diffusion of fuel vapor and the surrounding gas taken into account. The model was applied to calculate evaporation processes of droplets for various ambient temperatures and droplet temperatures.
An Experimental Optimisation of a Spark Ignition Engine Fuel Injector to Reduce the Total Hydrocarbon Emissions During Cold Start Conditions
Authors: Cardone M. , Cioffi V. , De Fenzo A. , De Marino C. , Senatore A. , Torella E.
Published: February 2009

Engine exhaust emission limits have been subject to increasingly severe controls during the last few years. This has led to the need for a suitably structured systemic approach to the problem of exhaust gas treatment, instead of just focusing on improving catalytic converters efficiency, in other words, it has become increasingly more productive, and necessary, to carry out “global” optimization of the chemical conversion process generally present when gases are burnt, along with activities aimed directly at reduce the cause of their creation, acting on the engine geometric and operating parameters. This work was aimed at an operating experimental analysis of alternative fuel injection systems to optimize their use in order to reduce exhaust emissions in spark ignition engines, especially during cold starts in low temperature conditions.
Analysis of a 6 Cylinder Turbocharged HCCI Engine Using a Detailed Kinetic Mechanism
Authors: Cantore Giuseppe , Montorsi Luca , Mauss Fabian , Amne´us Per , Erlandsson Olof , Johansson Bengt , Morel Thomas
Published: February 2009

When analyzing HCCI combustion engine behavior, the integration of experimental tests and numerical simulations is crucial. Investigations of possible engine control strategies as a function of the different operating conditions have to take the behavior of the whole HCCI engine into account, including the effects both of the combustion process and of complex devices. Therefore the numerical simulation code must be able both to model accurately the gas-dynamic of the system and to evaluate the combustion chemical kinetics. This paper focuses on the coupling between the commercial one-dimensional fluid-dynamic GT-Power Code and our in-house detailed chemical kinetic Ignition Code. An interface has been developed in order to exchange information between the two codes: the Ignition Code considers as boundary conditions the GT-Power Code values provided for the gas composition at IVC and the pressure and temperature at every time step and passes back to GT-Power the burnt fuel fraction and stores in an external file the in cylinder gas composition. Thus the whole engine cycle can be accurately simulated, estimating the interactions between the gas-dynamics phenomena along the intake and exhaust pipes and through the valves, and the chemical processes occurring during the closed valves period. This tool makes it possible to analyze the engine behavior under duty cycle operating conditions, and therefore it represents a useful support to the experimental measurements, reducing the number of tests required to assess the proper engine control strategies.
Experimental Data Extrapolation by Using V Order Logarithmic Polynomials
Authors: Lanzafame R. , Messina M.
Published: February 2009

In this work, the authors consider the possibility to extrapolate experimental data on fuels specific heat at constant pressure, beyond the range of temperature investigated in the experimental measurements. With a proper extrapolation it is possible to avoid the necessary but empirical linear extrapolation, often used by CFD programs. Mathematical functions obtained from fitting experimental data are very useful when computational models on ICE are implemented. To obtain reliable results from these models, a great precision is required to the mathematical functions. In this work a new polynomial, used in order to fit experimental data on gases properties at low pressure, is presented. The new mathematical function presented has the functional form of a fifth order Logarithmic Polynomial, and it is evaluated through the least squares method, on the basis of experimental thermodynamic data found in literature. This new function presents three great advantage in respect to traditional polynomials used in literature: 1) it offers a great fitting precision (correlation factor R2 greater than 0.99); 2) it is able to cover wide range of temperature with a single polynomial; 3) it gives the possibility to extrapolate data beyond experimental temperature range.
Development of a Long Duration Capacitive Discharge Ignition System
Authors: Brooks Keith , Lepley Joe
Published: February 2009

The development and testing of a new long secondary duration capacitor discharge ignition system is described. Results obtained on a large-bore, slow speed, 2-stroke test engine are described and compared to the results obtained by a commercially available capacitor discharge (CD) single-strike and double-strike ignition system. These tests are conducted under rated full load conditions and high boost lean operation. Engine emissions, fuel consumption, and misfire rates are analyzed and compared in order to determine if such a product merits commercialization. It has been previously demonstrated that multi-strike ignition systems (four strikes per compression stroke) can offer significant reductions in emissions and misfire rate in large-bore slow speed engines field retrofitted to increased boost lean operation for much lower costs than physical modifications to the heads to accommodate prechambers and fuel systems modifications. The work described here utilizes single and double-strike systems (two strikes per compression stroke) with lower energy than previous tests and lower total cost. The extended spark system tested is a proprietary development capacitor discharge system offering the benefits of capacitor discharge design with extremely long duration.
Influence of Nucleate Boiling on the Design of Automotive Cooling Systems
Authors: Strepek Steve , Winterton Richard H. S. , Wiseman Marc , Nelson Chris
Published: February 2009

With higher power ratings in automotive cooling systems the correct calculation of the heat transfer coefficient when nucleate boiling is occurring has become important. In accounting for the enhanced cooling that nucleate boiling provides, analysts can achieve two goals: more accurate metal temperature prediction at local hot spots; and an assessment of the probability that catastrophic film boiling will occur. Two correlations examined: the classic Chen correlation and the more recent Liu and Winterton correlation. The method of extending the correlations to mixtures is explained. Predictions are presented for the 50:50 mixture of water and ethylene glycol, and compared with literature data. The method of incorporating these correlations into engine CAE analysis is explained and demonstrated. The paper also considers the effect of nucleate boiling on vapor production, leading to vapor blanketing and the critical heat flux. A method of estimating critical heat flux for the mixture is described.
Engine Failure Experience Improves the Product
Authors: Dexter Stephen G. , Rasser Michael W.
Published: February 2009

There are the inevitable occasions when something goes wrong despite the great care taken when engines are designed, built, operated and serviced. Failures can lead at best to some cost and inconvenience or at the worst to a totally destroyed engine. The cost of repairs, followed sometimes by many weeks of down time, can be enormous. In addition there is the critical question of safety and the risk of injury to personnel. By analyzing failures and their causes a lot of experience can be gained and used to the benefit of all. This experience can improve future products. The paper describes some failures which have been experienced by the authors and shows how an analysis of the evidence has identified the root cause. We show how the knowledge gained improves our ability to predict engine behavior and the stress field in the components concerned. The paper goes on to describe what measures can be taken to improve the product and to prevent the circumstances from happening again. The use of Failure Mode and Effect Analysis (FMEA) is described because experience gained from failures can make this an extremely powerful tool when used during the design process.
New Bearing Materials for Large Engines and Compressors
Authors: Mergen Robert , Walker Rick , Putz Michael
Published: February 2009

A new concept for bimetal bearings combining the development of a new bearing alloy and the bearing type design as a composition of different layers is presented. The goal was to reach the performance of typical trimetal bearings by the economical solution of a bimetal bearing design. An intensive study of performance shortages of today’s conventional bimetal bearings as well as a scope of future bearing performance needs headed the performance description of the newly developed bearing type. Metallurgical and technological options given in the publication were used to reach the design criteria. The development resulted in an aluminum bearing alloy with increased tribological and mechanical properties including a special bearing type design with a high strength bonding layer. The roll bonding procedure was adapted to produce the steel aluminum strips. As an important part of the development, resistance against corrosion and cavitation were taken into consideration. The reported results from test rigs and field tests in different engines demonstrate that the original expectations have been fully achieved. Hence, the economical advantage of bimetal bearings versus trimetal design can be realized.
A New Approach to Fit Bearing Performance to Advanced Gas Engine Technology
Authors: Rumpf Thomas , Humer Johannes , Schneiderbauer Elisabeth , Putz Michael
Published: February 2009

Gas engines get an increasing market share compared to four stroke engines, especially in the field of energy systems. Under these special firing conditions engine components are stressed differently than in traditional diesel engines. This particularly is the case for bearings. In order to supplement the knowledge base for bearing performance under these aggravated conditions, special test methods have been developed to find out reasons for premature bearing failure characteristics. In combination with experience from the long term behavior of different bearing types in different gas engine applications, this data allows the development of improved bearing materials as well as bearing designs. Using this knowledge in combination with advanced simulation tools, a bearing supplier can offer assistance to select adequate bearing designs, give a life time prediction and in case of unexpected phenomena, redesign recommendations. The paper presents reasons and influences for life time limitations as well as different risk factors for available bearing types and situations. Based on field experience and data from the advanced bearing test procedures, values for bearing performance are given. Data for hydrodynamic performance, tribological properties and emergency running behavior, cavitation resistance, wear resistance and last, but not least corrosion resistance against active sulfur and halogens will be given for traditional and newly developed bearing materials. A short view into the future will finish the presentation.
Numerical Investigation of the Effects of Axial Cylinder Bore Profiles on Piston Ring Radial Dynamics
Authors: Piao Y. , Gulwadi S. D.
Published: February 2009

The role of cylinder bore shapes in engine performance has been the subject of several studies in recent years. In particular, the influence of bore distortion on oil consumption under high speed conditions has generated significant interest. In this paper, the effect of an axial bore profile on radial dynamics of a ring is investigated. Radial ring motions within grooves due to the axial bore profile can generate significant inertial effects and also have an impact on ring end-gap sizes and lubrication conditions at the ring-liner interfaces. The magnitude of such effects is dependent on the ring-pack configuration, engine operating conditions (speed and load) and axial bore profile details. These issues are investigated in this study due to their implication on engine oil consumption, friction and blow-by. The authors have developed an analytical expression to account for the effects of radial ring inertia due to an axial bore profile for implementation in a piston ring–pack simulation tool RINGPAK. Simulation results from a gasoline engine study are presented to illustrate the effects of engine speeds, ring tensions and characteristics of axial bore profiles on ring radial dynamics and ring-liner lubrication. Relevant qualitative comparisons are made to experimental measurements available in the literature.
Study of High Load Operation Limit Expansion for Gasoline Compression Ignition Engines
Authors: Yoshizawa Koudai , Teraji Atsushi , Miyakubo Hiroshi , Yamaguchi Koichi , Urushihara Tomonori
Published: February 2009

In this research, combustion characteristics of gasoline compression ignition engines have been analyzed numerically and experimentally with the aim of expanding the high load operation limit. The mechanism limiting high load operation under homogeneous charge compression ignition (HCCI) combustion was clarified. It was confirmed that retarding the combustion timing from top dead center (TDC) is an effective way to prevent knocking. However, with retarded combustion, combustion timing is substantially influenced by cycle-to-cycle variation of in-cylinder conditions. Therefore, an ignition timing control method is required to achieve stable retarded combustion. Using numerical analysis, it was found that ignition timing control could be achieved by creating a fuel-rich zone at the center of the cylinder. The fuel-rich zone works as an ignition source to ignite the surrounding fuel-lean zone. In this way, combustion consists of two separate auto-ignitions and is thus called two-step combustion. In the simulation, the high load operation limit was expanded using two-step combustion. An engine system identical to a direct-injection gasoline (DIG) engine was then used to demonstrate two-step combustion experimentally. An air-fuel distribution was created by splitting fuel injection into first and second injections. The spark plug was used to ignite the first combustion. This combustion process might better be called spark-ignited compression ignition combustion (SI-CI combustion). Using the spark plug, stable two-step combustion was achieved, thereby demonstrating a means of expanding the operation limit of gasoline compression ignition engines toward a higher load range.
Hydrogen Fuelled Spark-Ignition Engines: Predictive and Experimental Performance
Authors: Li Hailin , Karim Ghazi A.
Published: February 2009

Hydrogen is well recognized as a suitable fuel for spark-ignition engine applications that has many unique attractive features and limitations. It is a fuel that can continue potentially to meet the ever increasingly stringent regulations for exhaust and greenhouse gas emissions. The application of hydrogen as an engine fuel has been tried over many decades by numerous investigators with varying degrees of success. The performance data reported often tend not to display consistent agreement between the various investigators mainly because of the wide differences in engine type, size, operating conditions used and the differing criteria employed to judge whether knock is taking place or not. With the ever-increasing interest in hydrogen as an engine fuel, there is a need to be able to model extensively various features of the performance of spark ignition (S.I.) hydrogen engines so as to investigate and compare reliably the performance of widely different engines under a wide variety of operating conditions. The paper employs a quasi-dimensional two-zone model for the operation of S.I. engines when fuelled with hydrogen. In this approach, the engine combustion chamber at any instant of time during combustion is considered to be divided into two temporally varying zones: a burned zone and an unburned zone. The model incorporates a detailed chemical kinetic model scheme of 30 reaction steps and 12 species, to simulate the oxidation reactions of hydrogen in air. A knock prediction model, developed previously for S.I. methane-hydrogen fuelled engine applications (Shrestha and Karim 1999(a) and 1999(b)) was extended to consider operation on hydrogen. The effects of changes in operating conditions, including a very wide range of variations in equivalence ratio on the onset of knock and its intensity, combustion duration, power, efficiency and operational limits were investigated. The results of this predictive approach were shown to validate well against corresponding experimental results of our own and those of others, obtained mostly in a variable compression ratio CFR engine. On this basis, the effects of changes in some of the key operational engine variables, such as compression ratio, intake temperature and spark timing are presented and discussed. Some guidelines for superior knock free-operation of engines on hydrogen are made also.
Reducing Locomotive Idle Fuel Consumption and Exhaust Emissions by Applying an Auxiliary Power Unit (APU)
Authors: Biess Larry , Stewart Ted , Miller David , Fritz Steven
Published: February 2009

This paper documents results of fuel consumption and exhaust emission tests performed on a 1,500 kW EMD GP38-2 locomotive equipped with an auxiliary power unit (APU) designed to minimize main engine idling time by providing stand-by services normally provided by the main EMD 16-645-E engine at idle. The purpose of these tests was to perform an evaluation of the exhaust emissions and fuel consumption of both the EMD 16-645-E engine and the APU. The APU diesel engine was a 2.0L, 4-cylinder, turbocharged, Kubota model V2003-TEBG rated at 30.6 kW. The APU was tested using an external load box over a range of load conditions, ranging from unloaded (0 kW) through 16 kW, which was the maximum APU load expected as installed in the locomotive. Fuel consumption and exhaust emissions are compared between an idling EMD 16-645-E engine and the APU engine at a “typical” stand-by condition with the coolant and lubricating oil heaters operating and the locomotive control cab air conditioner turned off. Test results showed that the APU fuel consumption and exhaust emissions are dramatically lower than the idling EMD locomotive engine. Because the APU is designed to automatically start and stop as a function of the locomotive water temperature, and therefore operates only a portion of the time that the EMD engine would otherwise be idling. Reductions in fuel consumption and exhaust emissions over an extended period of time would be even more dramatic.
Diesel Engine Crankshaft Rotational Speed Fluctuation Analysis
Authors: Kimura Jouji , Yamashita Takashi
Published: February 2009

Crankshafts drive many accessories such as fuel injection pumps, camshafts, oil- and water pumps, compressors, fans, alternators etc. by using either gears or belts. Since crankshaft rotational speed fluctuates and engine accessories have moments of inertia, belts slip on pulleys and gears hit other gears, which results in noise and wear. This paper describes the mechanism of the rotational speed fluctuations of crankshafts by separating rotational speed fluctuations into those for a rigid and those for a torsional crankshaft for a V-type six-, eight- and ten-cylinder diesel engine. After that, crankshaft rotational speed fluctuations at crankshaft locations are discussed.
Influence of Front Driven Equipment on Viscous Damper and System Behaviour
Authors: Denny Donna I. , Scekic Vladimir
Published: February 2009

Driving a generator, a hydraulic pump or another piece of equipment off the front of an engine is commonplace in industrial and marine applications. The (front-driven) equipment is sometimes an afterthought, a retrofit applied without due attention and proper analysis. How risky can this be? Additional equipment will, as a minimum, change the natural frequencies of the system. Adding another natural frequency that can be excited within the operating range of the system is quite common. In addition to this, if the added equipment is of substantial moment of inertia and connected to the damper rigidly enough, it may change the damper behaviour to the point of endangering the engine crankshaft. What should we know and which analysis should be completed before the decision is made to “just drive that PTO off the front of the main engine”?
Direct Water Injection to Improve Diesel Spray Combustion
Authors: Takasaki Koji , Takaishi Tatsuo , Ishida Hiroyuki , Tayama Keijirou
Published: February 2009

Now, it is essential to apply some measures for NOx reduction to low-speed diesel engines emitting much more NOx than high-speed engines. At the same time PM emission must be reduced especially when bunker fuel or heavy fuel is burned. This paper describes the applications of SFWI (Stratified Fuel Water Injection) system and DWI (Direct Water Injection) system to large sized diesel engines to reduce NOx and PM emission. SFWI system makes it possible to inject water during fuel injection from the same nozzle hole without mixing the liquids. DWI system injects water with high injection pressure from the other injection hole than the fuel injection hole into the combustion chamber directly. For testing both the systems, a 2-stroke-cycle low-speed test engine was used.
Performance Characteristics of a Diesel Engine Fueled With Avio-Kerosene
Authors: Chiatti Giancarlo , Chiavola Ornella
Published: February 2009

A comparative series of experimental tests has been performed on a 4-stroke multi cylinder indirect injection diesel engine fueled with diesel oil, pure gas-turbine fuel and gas-turbine fuel with additives. The engine has been equipped aimed at monitoring both the overall performances and the variation with time of the pressure in the pre-combustion chamber. Some key parameters have been investigated at different engine speeds and loads (ignition delay, pressure rise in the pre-combustion chamber, power output, specific fuel consumption, exhaust gas temperature) and discussed results are presented.
Study on the Relationship Between Combustion Characteristics and Properties of Marine Heavy Fuel Oil
Authors: Hashimoto Takaaki , Sasaki Senichi
Published: February 2009

The combustion characteristics (ignition delay and combustion period in this paper) of marine heavy fuel oil are affected by many factors such as density, carbon residue, asphaltene, aromaticity and carbon/hydrogen (C/H) ratio. When investigating the causes of operational problems in diesel engines, what properties should we check to find whether the main causes of the problems are related to fuel oil or not? What is the threshold of ignition delay and combustion period of fuel oil? The authors studied these topics using a combustion test apparatus called FIA 100, and arrived at the following conclusions: 1. The aromaticity index (CCAI) and the C/H ratio have good correlation with the combustion characteristics of marine fuel oil. These factors cannot be ignored during troubleshooting. 2. The carbon residue and asphaltene in fuel oil have no correlation with ignition delay, but have some correlation with the combustion period. 3. There is practically no correlation between the average molecular weight of fuel oil, and both ignition delay and combustion period. 4. Tentative threshold values of ignition delay and combustion period can be set for fuel oils of poor quality (flame retardation).
Combustion Analysis of a Natural Gas Engine
Authors: Soylu Seref
Published: February 2009

A two-zone thermodynamic model was developed for a spark ignition natural gas engine. The model was used to calculate instantaneous mass burning rate and thermodynamic state of burned and unburned zones of the combustion chamber content. Cylinder pressure data was collected at various engine operating conditions. Natural gas and natural gas–propane mixtures were used as engine fuel. From the burning rate analysis various combustion characteristics, such as flame initiation period (FIP) and flame propagation period (FPP) were calculated at various engine operating conditions. It was observed that both the FIP and FPP decrease with increasing equivalence ratio for lean mixtures. While the retarded timing decreases the FIP, the FPP has a tendency to increase. Addition of propane to natural gas reduces the FPP although the FIP is not affected. Unburned and burned gas temperatures are significantly raised with increase in equivalence ratio. However, ignition timing and propane fraction do not influence the temperatures as much as equivalence ratio does.