bluuebunny/crossref_metadata_2025 huggingface dataset:
On Line Compressor Washing on Large Frame 9-FA Gas Turbines: Erosion on R0 Compressor Blade Leading Edge — Field Performance With a Novel On Line Wash System
Authors: Oosting Jos , Boonstra Klaas , de Haan Annemarie , van der Vecht Dick , Stalder Jean-Pierre , Eicher Urs
Published: March 2009

On line compressor washing is an established practice amid gas turbine operators. Among these operators is the Netherlands Division of Electrabel who is operating at Eemshaven 5 x GE Frame 9-FA units since 1995. The plant operator used to perform routinely a daily on line wash and a single off line wash every year at shut down of the units for the annual inspection or maintenance outage. The on line water wash (OLWW) systems installed on these 5 engines are of the Turbotect Mk1 nozzle design and were originally procured and supplied by the OEM. To our knowledge, all other manufactured gas turbines in the 7/9-FA fleet are equipped with the OEMs’ own engineered OLWW nozzle systems. The OLWW regime of washing was reduced in June 2001 upon receipt of a recommendation by the OEM to inspect the first stages of the compressor for erosion marks. This recommendation was issued because some events have lead to investigation on erosion issues which materialized in the R0 (first stage rotor) compressor blades in some engines of the 7/9-FA fleet operating with the OEM OLWW system and resulting from frequent compressor wash routine, and/or from water ingestion used in power augmentation. Likewise, during the same time, some gas turbines at Eemscentrale had undergone their first major overhaul which allowed the compressor first row blading to be examined for signs of erosion. It was found that only minor erosion at the R0 blade leading edge had occurred over more than seven years of operation, during which period a daily on line wash had been performed. However, because of the erosion concerns among the 7/9-FA fleet and the OEM-recommended frequent inspections and measures to mitigate the rate of erosion due to droplet impingement, Electrabel investigated independently for a way of further reducing the erosion rate while maintaining on line washing over the lifetime of the gas turbine and improving the cleaning efficiency. To this effect, the OLWW system on unit EC-6 was upgraded in June 2004 with a new on line nozzle system specifically developed for use in large gas turbines. This paper presents the investigation results after some 24 months of operation and routine on line compressor washing. The Turbotect Mk3 OLWW nozzle system demonstrated and confirmed that it is contributing to mitigate the erosion risk on the R0 compressor blade leading edge, and in turn to decrease the number of blending operations over the life time of the R0 compressor blades. This nozzle designed for on line compressor cleaning of large gas turbines achieved a substantially improved cleaning effectiveness, respectively a lower rate in power degradation, by approx. 30 to 40% as compared to the current in use Mk1 OLWW nozzle system.
Flame Structure and Stabilization Mechanisms in a Stagnation Point Reverse Flow Combustor
Authors: Bobba Mohan K. , Gopalakrishnan Priya , Periagaram Karthik , Seitzman Jerry M.
Published: March 2009

A novel combustor design, referred to as a Stagnation Point Reverse Flow (SPRF) combustor, was recently developed to overcome the stability issues encountered with most lean premixed combustion systems. The SPRF combustor is able to operate stably at very lean fuel-air mixtures with low NOx emissions. The reverse flow configuration causes the flow to stagnate and hot products to reverse and leave the combustor. The highly turbulent stagnation zone and internal recirculation of hot product gases facilitates robust flame stabilization in the SPRF combustor at very lean conditions over a range of loadings. Various optical diagnostic techniques are employed to investigate the flame characteristics of a SPRF combustor operating with premixed natural gas and air at atmospheric pressure. These include simultaneous Planar Laser-Induced Fluorescence (PLIF) imaging of OH radicals, chemiluminescence imaging, Spontaneous Raman Scattering. The results indicate that the combustor has two stabilization regions, with the primary region downstream of the injector where there are low average velocities and high turbulence levels where most of the heat release occurs. High turbulence level in the shear layers lead to increased product recirculation levels, elevating the reaction rates and thereby, the combustor stability. The effect of product entrainment on the chemical timescales and the flame structure is quantified using simple reactor models. Turbulent flame structure analysis indicates that the flame is primarily in the thin reaction zones regime throughout the combustor. The flame tends to become more flamelet like, however, for increasing distance from the injector.
On the Response of a Strongly Diffusing Flow to Propagating Wakes
Authors: Gostelow J. P. , Thomas R. L. , Adebayo D. S.
Published: March 2009

Further evidence on the similarities between transition and separation phenomena occurring in turbomachinery and wind tunnel flows is provided by measurements on a large scale flat plate under a strong adverse pressure gradient. The flat plate has a long laminar separation bubble and is subjected to a range of disturbances with triggering caused by injection of a transverse jet and subsequently by wakes generated by rods moving transversely upstream of the leading edge. Wakes were originally presented individually. Each individual wake provoked a vigorous turbulent patch, resulting in the instantaneous collapse of the separation bubble. This was followed by a very strong, and stable, calmed region. Following the lead given by the experiments of Gutmark and Blackwelder on triggered turbulent spots, wakes were then presented in pairs at different wake spacing intervals. In this way wake interaction effects could be investigated in more detail. As in the work on triggered turbulent spots the spacing between impinging wakes was systematically varied; it was found that for close wake spacings the calmed region acted to suppress the turbulence in the following turbulent patch. To investigate whether this phenomenon was a recurring one, or whether the flow then reverted back to its unperturbed state, the experiments were repeated with three and four rods instead of two. This has the potential for making available a wide range of variables including direction and speed of rod rotation. It was found that the subsequent wakes were also suppressed by the calming effect. It may be anticipated that this repeating situation is present in a turbomachine, resulting in hidden benefits for blade count and efficiency. There may also conceivably be blade loading advantages whilst retaining favorable heat transfer conditions in high pressure turbines or stall margin in axial compressors. The inherent and prospective benefits of the calming effect therefore need to be understood thoroughly and new opportunities exploited where this is feasible.
Slow Speed Vibration Signal Analysis: If You Can’t Do It Slow, You Can’t Do It Fast
Authors: Maalouf Mel G.
Published: March 2009

For many people, the interpretation of vibration signals for a machine at running speed is complicated and foreign, and is considered an art in many circles. Interpreting the rich characteristics of the raw signals during run-up and coast down requires even more skill and experience. For some, interpreting the signals at slow speeds (sometimes called slow roll speeds) is so difficult that the signals are often ignored and discredited as not useful data. This paper will communicate the author’s experience in using this valuable, yet sometimes difficult, data to correlate and corroborate with high-speed data. This data and interpretation are used to understand the dynamic behavior of the machine while the forces on the rotor are driving the response characteristics at run up, full speed and coast down. In the sports arena, good coaches often say that if you cannot execute skills in slow motion, you likely won’t be able to execute them at normal speeds and absolutely not in high-pressure game situations. This is also true for vibration diagnostics: if you don’t do correct slow speed analysis, full speed and transient (startup and coast down) analysis may be misleading or just wrong. In this instance, the analyses and diagnostic calls that were made by using slow speed signal analysis include: Selecting Slow Roll Values, Shaft Surface Quality, Direction of Rotation, Rotor Bow (Gravity), Rotor Bow (Thermal), Locked up Coupling, Non-Concentric Coupling, Reverse Rotation. This paper will describe the methodologies for collecting data and the analysis of the data to make the above calls on specific examples experienced by the author and his colleagues.
Commercial Demonstration of Un-Cooled Pressure Sensor for Gas-Turbine Engine Monitoring
Authors: Palmer Matthew E. , Davis Matthew A. , Fielder Robert S.
Published: March 2009

An un-cooled fiber-optic sensor has been developed for the purpose of gas turbine engine health monitoring. These sensors were developed over the course of 2 SBIR and 1 STTR Phase II’s, each contributing to an advancement in the sensor’s development. Real time direct monitoring of combustion pressure within aircraft turbines will enable more efficient, lower emission designs, through active control of the fuel supply. Sensor prototypes have been demonstrated to operate at greater than 1922°F (1050°C) and 500psig in laboratory experimentation. A co-located measurement system enabled the team to calibrate an alpha prototype sensor over a range of 70°F to 1840°F (20–1000°C) and 0-500psig with an error less than 0.37% Full Scale (FS) over the entire sensor calibration envelope. Previous iterations of this sensor were prototyped and installed into an operating, specially modified, aerospace gas turbine engine immediately after the 1st stage turbine. In this engine the alpha fiber-optic sensor measured dynamic pressures of +/- 0.5 psi while exposed to a maximum temperature of 932.9°F (500.5°C) and a maximum static pressure of 15.4 psig during operation. Finally, another alpha prototype was demonstrated in field trials at a customer facility in two combustors. During these trials the sensor usefully captured hum and rumble oscillations while measuring pressures reasonably accurately at temperatures up to 1652°F (900°C).
Optimum Operation of Externally-Fired Microturbine in Combined Heat and Power Generation
Authors: Kaikko Juha , Backman Jari L. H. , Koskelainen Lasse , Larjola Jaakko
Published: March 2009

Externally-fired microturbines (EFMT) yield promising performance in small-scale utilization of biofuels. As in larger gas turbines, the part-load performance of the EFMT is very sensitive to the selected power control method, and in general subject to severe degradation at part load. The control parameters typically include the maximum combustion gas temperature or turbine inlet temperature and the speed of the shaft. At the design point, power generation efficiency can be increased by allowing a fraction of air to bypass the burner and the combustion gas – air heat exchanger. At the same time the heat exchanger size is increased. Therefore, the by-pass flow affects the optimal sizing of the EFMT as well. In this paper, the effect of by-pass flow on the part-load performance of a single-shaft EFMT in combined heat and power generation is analyzed. In the application, the microturbine is operated by the heat demand. The control methods incorporate the use of the maximum combustion gas temperature, the speed of the shaft, and the amount of by-pass air. The focus of the study is to determine the economically optimal control scheme for the engine. The economy model uses the profit flow from the EFMT as a criterion. The results show that the inclusion of the by-pass variation in the control methods can improve the economy of temperature-controlled EFMT at part load but has no benefits when using speed control.
Long-Term Oxidation Behavior of Selected High Temperature Alloys
Authors: Srivastava S. Krishna , Newburn Michael J. , Cotner John P. , Richeson Mark A.
Published: March 2009

Long-term oxidation behavior of alloys cannot be estimated reliably by extrapolation of short-term results; therefore long-term testing is imperative. Such data often are not available. Oxidation testing for a period of 360 days has been conducted for several high temperature alloys extensively used in the gas turbine industry. The alloys tested comprised of HASTELLOY® X alloy, HAYNES® 230®, HR-120®, and 214™ alloys, the first three being chromia forming and the last one being an alumina forming alloy. The specimens were exposed to flowing air at 1800°F(982°C), 2000°F(1093°C), 2100°F(1149°C) and 2200°F(1204°C). The tests were interrupted and the specimens were weighed every 30 days. At the completion of each test, the samples were examined metallographically to determine the internal attack. The magnitude of oxidation attack was studied in terms of the weight change and total metal affected. The paper will report the results of the long-term oxidation testing and the analysis of the corrosion attack with the optical and scanning electron micrographs. HASTELLOY, HAYNES, 230 and HR-120 are registered trademarks and 214 is a trademark of Haynes International, Inc.
High-Speed Permanent-Magnet Motors for the Oil and Gas Industry
Authors: Weeber K. , Stephens C. , Vandam J. , Gravame A. , Yagielski J. , Messervey D.
Published: March 2009

Recent years have seen an increase in high-speed electric compression for Oil & Gas applications where high-speed electric motors drive compressors directly without intermediate gears. To date induction machines have been the predominant workhorse of the industry. The permanent-magnet machine technology provides an alternative that promises a highly reliable and robust system design, especially in applications where motor and compressor are fully integrated and share the same process gas environment. This paper provides an update on the recent progress in developing the permanent magnet technology for Oil & Gas applications in which the process gas may contain corrosive elements.
Trends in Film Cooling Effectiveness Caused by Increasing Angle of Diffusion Through a Row of Conical Holes
Authors: Zuniga H. A. , Krishnan Vaidyanathan , Ling J. P. C. W. , Kapat J. S.
Published: March 2009

Previous studies have concluded that increasing the diffusion angle in conical film cooling holes leads to an improvement in film cooling effectiveness. Discharge coefficient and film cooling effectiveness measurements are conducted to characterize these effects. Three test-plates, each with one row of eight pure conical-shaped cooling holes of diffusion angles of 2, 4, and 6 degrees, with respect to the hole-centerline, are used in this study. In addition, the effects of an added entry-length (cylindrical starting section) are also investigated in the form of a 2-degree conical hole with a 4-diameter cylindrical entry-length. Area ratios for these holes range from 1.7 to 2.83. Coolant is injected at 35 degrees to the horizontal, into the main flow. The interactions between the coolant jets downstream of the injection point are also investigated. Temperature sensitive paint, TSP, is the technique used to acquire the temperature distribution downstream of the cooling holes, and thus, ascertain the laterally-averaged film cooling effectiveness. Data are obtained for blowing ratios ranging from 0.5 to 1.5. Results and trends are compared with those published on a study on conical holes by the authors, as well as published data for shaped holes, which indicate that the higher conical angles do increase laterally-averaged effectiveness. Moreover, the added entry-length, while providing a metering diameter, does improve the effectiveness in the near-hole region particularly at the higher blowing ratios.
Development and Testing of the Backup Bearing System for an AMB Energy Storage Flywheel
Authors: Hawkins Lawrence , McMullen Patrick , Vuong Vinh
Published: March 2009

A 140 kW energy storage flywheel has been developed to provide 15 seconds of ride-through power for industrial UPS applications. The flywheel, which operates in a vacuum, is supported by Active Magnetic Bearings (AMB) to minimize bearing losses, and has a high power motor/generator coupled to an efficient power conversion module. The backup bearing system was tested extensively due to the potential for very long spin down times in the event of a failure in or loss of power to the magnetic bearing system. Key issues encountered during testing are discussed and solutions identified. High fidelity orbit and time-history data from a full speed drop and spin down are presented and discussed in detail. The final backup bearing system is capable of three 2.75 hour spin downs from 36,000 rpm.
Performance Enhancements to the Industrial Avon Gas Turbine
Authors: Blackburn Jerry , Frendt Gary , Gagne´ Martine , Genest Jean-Daniel , Kohler Toby , Nolan Brian
Published: March 2009

This paper summarises the design, development and validation work of a package of modifications made to the well-established Avon aero derivative gas turbine. Modern turbine aerofoil design technologies were applied to the Avon hot end section, resulting in significant performance enhancements of the engine in terms of heat rate and power. A summary of the key design changes is made and the experimental validation data is reviewed. The implications of the design changes to the engine operational characteristics and component lifing implications where applicable are also reviewed. Key performance data is also presented in the paper.
Advanced Gas Turbine Combustion System Development for High Hydrogen Fuels
Authors: Wu Jianfan , Brown Phillip , Diakunchak Ihor , Gulati Anil , Lenze Martin , Koestlin Berthold
Published: March 2009

Integrated Gasification Combined Cycle (IGCC) technology makes possible the utilization of low cost coal and opportunity fuels, such as petroleum coke, residual oil and biomass, for clean efficient and cost effective electricity generation. Siemens is a leading supplier of products and services for IGCC plants and it is adapting its most advanced gas turbines for successful integration into IGCC plants. To expedite this, Siemens is pursuing combustion system development for application in IGCC plants operating on syngas/hydrogen fuels. Detailed combustion system testing has been carried out during 2005 and 2006 on syngas/hydrogen fuels derived from different feed stocks and gasification processes. The test programs addressed both the F- and G-Class firing temperatures and operating conditions. Fuel transfer capability to and from natural gas, which is the startup and backup fuel, and syngas was explored over the operating range. Optimization studies were carried out with different diluent (H2O and N2) addition rates to determine the effect on emissions and operability. The focus of this development was to ensure that only combustion system modifications would be required for successful enriched hydrogen syngas fuel operation. This paper summarizes the results from the Siemens combustion system development programs to demonstrate that low emissions and wide engine operating range can be achieved on hydrogen fuel operation in advanced 50 Hz and 60 Hz gas turbines in IGCC applications with carbon dioxide capture.
Data Visualization, Data Reduction and Classifier Fusion for Intelligent Fault Detection and Diagnosis in Gas Turbine Engines
Authors: Donat William , Choi Kihoon , An Woosun , Singh Satnam , Pattipati Krishna
Published: March 2009

In this paper, we investigate four key issues associated with data-driven approaches for fault classification using the Pratt and Whitney commercial dual-spool turbofan engine data as a test case. The four issues considered here include: (1) Can we characterize, a priori, the difficulty of fault classification via self-organizing maps? (2) Do data reduction techniques improve fault classification performance and enable the implementation of data-driven classification techniques in memory-constrained digital electronic control units (DECUs)?, (3) When does adaptive boosting, an incremental fusion method that successively combines moderately inaccurate classifiers into accurate ones, help improve classification performance?, and (4) How to synthesize classifier fusion architectures to improve the overall diagnostic accuracy? The classifiers studied in this paper are the support vector machine (SVM), probabilistic neural network (PNN), k-nearest neighbor (KNN), principal component analysis (PCA), Gaussian mixture models (GMM), and a physics-based single fault isolator (SFI). As these algorithms operate on large volumes of data and are generally computationally expensive, we reduce the dataset using the multi-way partial least squares (MPLS) method. This has the added benefits of improved diagnostic accuracy and smaller memory requirements. The performance of the moderately inaccurate classifiers is improved using adaptive boosting (AdaBoost). These results are compared to the results of the classifiers alone, as well as different fusion architectures. We show that fusion reduces the variability in diagnostic accuracy, and is most useful when combining moderately inaccurate classifiers.
A Comparison of Two Methods for Predicting Emissions From Aircraft Gas Turbine Combustors
Authors: Allaire Douglas L. , Waitz Ian A. , Willcox Karen E.
Published: March 2009

This paper discusses the development and comparison of two emissions modeling methods for predicting NOx and CO emissions from aircraft gas turbine combustors. We compare an empirical and a physics-based approach. The objective is to assess the strengths and weaknesses of the methods for predicting the emissions of current and potential future gas turbine engines for the purpose of assessing design tradeoffs and interdependencies in a policy-making setting. The empirical method is based on a P3-T3 approach using polynomial fits to certification data. The physics-based method is developed using high-level combustor design parameters and ideal reactors. The predictive capability of each method is assessed by comparing model estimates of NOx and CO emissions to certification data from three different industry combustors.
Real-Time, Self-Learning Optimization of Diesel Engine Calibration
Authors: Malikopoulos Andreas A. , Assanis Dennis N. , Papalambros Panos Y.
Published: March 2009

Compression ignition engine technologies have been advanced in the last decade to provide superior fuel economy and high performance. These technologies offer increased opportunities for optimizing engine calibration. Current engine calibration relies on deriving static tabular relationships between a set of steady-state operating points and the corresponding optimal values of the controllable variables. The values of these tabular relationships are interpolated to provide values of the controllable variables for each operating point while the engine is running. These values are controlled by the electronic control unit to achieve desirable engine behavior, for example in fuel economy, pollutant emissions, and engine acceleration performance. These strategies, however, are less effective during transient operation. Use of learning algorithms is an alternative approach that treats the engine as an “autonomous” system, namely, one capable of learning its optimal calibration for both steady-state and transient operating points in real time. In this approach, while the engine is running the vehicle, it progressively perceives the driver’s driving style and eventually learns to operate in a manner that optimizes specified performance indices. Major challenges to this approach are problem dimensionality and learning time. This paper examines real-time, self-learning calibration of a diesel engine with respect to two controllable variables, i.e., injection timing and VGT vane position, to minimize fuel consumption. Some promising simulation-based results are included.
Design and Bench-Top Testing of Multiplexed Fiber Delivered Laser Ignition System for Natural Gas Engines
Authors: Joshi Sachin , Reynolds Adam , Willson Bryan , Yalin Azer P.
Published: March 2009

Past research has demonstrated the feasibility of using optical sparks for engine ignition, and has shown potential benefits associated with reduced cyclic variability and increased rate of cylinder pressure rise, thus extending the lean operating limit of natural gas engines. This contribution details the design and bench-top testing of a fiber-optic delivery system for ignition of natural gas engines. The system is designed for use on a Caterpillar G3516C engine and is comprised of a single Nd:YAG laser as the energy source, a multiplexer for switching the beam between cylinders, fiber optics to deliver the laser pulses to individual cylinders, and optical plugs to couple the beam into the cylinders. The optical fibers are a critical component of the system and discussion of use of both solid core silica fibers and cyclic olefin polymer-coated silver hollow fibers is included. The multiplexer design is presented and optical testing of the multiplexed fiber delivery on the bench-top is reported. Design considerations for engine integration are introduced.
Experimental Study on the Effects of Injector Nozzle and Piston Bowl Geometry on Combustion and Performance in Medium-Speed Diesel Engines
Authors: Kim Byong-Seok , Kim Ki-Doo , Yoon Wook-Hyeon , Ryu Seung-Hyup
Published: March 2009

In recent years, many regulations of exhaust gas emissions have been enhanced in not only automotive engines but also marine and power generation engines. So we have done the various studies to reduce NOx in a medium speed diesel engine, HYUNDAI HiMSEN, for satisfying the next IMO(International Maritime Organization) regulation (Tier2, 20∼30% reduction for current limit). The selected parameters for in this study are fuel injector nozzle and piston bowl geometry. These have significant effect on engine performance and combustion. In this study, engine performance experiments have been carried out to investigate the effects of fuel injector nozzle geometry including the nozzle hole diameter, hole number, hole length, and injection angle on the fuel oil consumption and NOx emission of HYUNDAI HiMSEN engine. Also experiments have been carried out to evaluate engine performance and combustion with changing piston bowl geometry including the diameter and depth of piston bowl. The measured parameters of engine performance include cylinder pressure, fuel pump pressure, injection pressure, and heat release rate and NOx, etc. We could find out the optimum point of the nozzle geometry and the piston bowl shape regarding to the trade-off curve on fuel oil consumption versus NOx emission to minimize fuel oil consumption and to satisfy NOx regulation of HYUNDAI HiMSEN engines.
Assessing the Impact of Pressure Pulses in Exhaust Manifold During Blowdown Process on In-Cylinder Distribution Using T-RECS
Authors: Sengupta Jeet , Abbaspour Mohammad , Chapman Kirby S.
Published: March 2009

In an internal combustion engine, both the two-stroke and the four-stroke variety, the ejection of exhaust gases from the cylinder is termed as blowdown. In a two stroke engine, during blowdown the in-cylinder gases which are at a pressure higher than the exhaust manifold pressure rush out of the exhaust port into the manifold, resulting in a high pressure wave propagating through the manifold. In a multi-cylinder engine where the exhaust ports of each cylinder are connected to the manifold, the high pressure pulses in the manifold will impact the in-cylinder performance of the cylinders downstream of the first cylinder. This impact was investigated using the Turbocharger Reciprocating Engine Computer Simulation (T-RECS), a zero-dimensional cycle simulation tool developed at the National Gas Machinery Laboratory (NGML). The manifold pressure distributions were generated using the NGML developed Virtual Pipeline Simulation Tool (VPST), which is a one-dimensional pipe flow simulation software package. The analysis assumed that at any given instant the exhaust port of only one cylinder is open while the exhaust ports of all other cylinders remain closed. The results showed that the in-cylinder pressure distributions could become significantly altered under the influence of the exhaust manifold pressure pulses. The knowledge gained would help in utilizing the pressure pulses more effectively in tuning the exhaust manifold.
Numerical Study of the Effect of Fuel Spray Velocity and Targeting on Fuel Evaporation Rate in a Port Fuel Injection Engine by Using Kiva3-V2 Simulation Code
Authors: Nassiri-Toosi A. , Lotfi Nozari A. , Etghani M.
Published: March 2009

Mixture formation process in internal combustion engines is known as a very effective process on transient response, output power, emissions and engine performance. A homogenous mixture of fuel and air will increase engine performance. To achieve a homogenous mixture, we should increase the fuel evaporation rate. As a result, the fuel mass in liquid phase and fuel film will decrease and their disadvantageous effects will be minimized. With a given mass of fuel if the value of fuel mass in vapor phase is increased, the quality of mixture and hence the engine performance will improve due to better combustion. In this paper, the effects of injection parameters such as fuel spray velocity and targeting angle on fuel evaporation rate in a port fuel injection engine using Kiva-3V simulation code are studied. The results have shown that with a given mass of fuel, increasing the spray velocity will increase the evaporation rate and hence the mass of fuel in vapor phase will be increased. Furthermore, changing the spray targeting angle so that the fuel spray hits the hot areas of the intake valve, such as valve stem and rear surface of the intake valve, will increase the evaporation rate. Also results have shown that fuel spray velocity is more effective than fuel spray targeting angle on evaporation rate.
The Effects of Compression Ratio and Expansion Ratio on Engine Performance Including the Second Law of Thermodynamics: Results From a Cycle Simulation
Authors: Caton Jerald A.
Published: March 2009

This investigation quantified the effects of compression ratio and expansion ratio on performance, efficiency, and second law parameters for an automotive, spark-ignition engine. The well known increase in engine performance for increasing compression ratio and expansion ratio is demonstrated. These increases for brake engine performance are modest for compression ratios greater than about 10 for the conditions studied. The results demonstrated that the increasing friction and heat losses for the higher compression ratios are of the same order as the thermodynamic gains. Also, the results included the destruction of availability during combustion. For a part load condition, the availability destroyed decreased from about 23% for a compression ratio of 4 to about 21% for a compression ratio of 10. In addition, this study examined cases with greater expansion ratios than compression ratios. The overall cycle for these cases is often called an “Atkinson” cycle. For most cases, the thermal efficiency first increased as expansion ratio increased, attained a maximum efficiency, and then decreased. The decrease in efficiency after the maximum value was due to increased heat losses, increased friction, and ineffective exhaust processes (due to the reduced cylinder pressure at the time of exhaust valve opening). For part load cases, the higher expansion ratio provided only modest gains due to increased pumping losses associated with the constant load requirement. For the wide open throttle cases, however, the higher expansion ratios provided significant gains. For example, for a compression ratio of 10, expansion ratios of 10 and 30 provided brake thermal efficiencies of about 34% and 43%, respectively. Although the net thermodynamic gains are significant, large expansion ratios such as 30 may not be practical in most applications.
Characterization of Particulate Matter Emissions From a 4-Stroke, Lean-Burn, Natural Gas Engine
Authors: Quillen Kris , Bennett Maren , Volckens John , Stanglmaier Rudolf H.
Published: March 2009

Regulatory agencies are becoming increasingly concerned with particulate emissions as the health and environmental effects are becoming better understood. While much research has been performed on diesel engines, little is known about particulate matter (PM) emissions from natural gas internal combustion engines. In this project, tests were conducted on a Waukesha VGF F18 natural gas engine running at full load. PM10 combustion emissions were collected on Teflon and quartz filters and a scanning mobility particle sizer (SMPS) was used to determine the particle size distribution. Tests were performed at 4, 5, 6, and 7% exhaust oxygen (O2) levels. Overall, it was found that a large number of small particles were emitted from this engine. The total mass based PM emissions were found to be 0.0148 gm/bkW-hr, which is slightly greater than the tier-4 nonroad diesel particulate emissions standard. Particle distributions revealed that the geometric mean diameter (GMD) of the natural gas particles was approximately 30 nm and did not change with air to fuel ratio. Particulate concentrations were found to decrease at leaner engine operating conditions. Results showed a strong correlation between the NOx and particle concentrations, while an inverse correlation between CO and particle concentrations was revealed.
Study of Diesel Jet Variability Using Single-Shot X-Ray Radiography
Authors: Kastengren A. L. , Powell C. F. , Wang Y.-J. , Wang J.
Published: March 2009

The variability of diesel jet structure, both as a function of time and between individual injection events, has important implications on the breakup and mixing of the jet. It is accepted that diesel jets become unstable due to interactions with the ambient gas, leading to breakup of the jet. This concept is the principle behind the Kelvin-Helmholtz and Rayleigh-Taylor models of diesel atomization. Very little information regarding diesel jet variability is available, however, in the near-nozzle region of the diesel jet, where primary breakup of the jet occurs. This is due to the presence of many small droplets, which strongly scatter visible light and render the spray opaque. X-ray radiography has been successfully used in recent years to probe the structure of diesel sprays with high spatial and temporal resolution. All of these previous measurements, however, were ensemble-averaged, measuring only persistent features of the spray. In the current study, measurements are performed at individual measurement points of single diesel injection events. These measurements are taken at several points near the injector exit for a non-hydroground nozzle with a single axial hole at two injection pressures (500 and 1000 bar). The variability of the start of injection, end of injection, and the time history of the spray density during the injection event are examined, as well as how these quantities change for different transverse positions across the jet.
Low Cost Engine Management System (EMS) for the Cost Sensitive Two-Wheeler Application: Idle Speed and A/F Ratio Control Using PID and Fuzzy Logic Control Algorithms
Authors: Manivannan P. V. , Ramesh A.
Published: March 2009

In this work an Engine Management System (EMS) using a low cost 8-bit microcontroller specifically for the cost sensitive small two-wheeler application was designed and developed. Only the Throttle Position Sensor (TPS) and the cam position sensor (also used for speed measurement) were used. A small capacity 125CC four stroke two-wheeler was converted into a Port Fuel Injected (PFI) engine and was coupled to a fully instrumented Eddy Current Dynamometer. Air-fuel ratio was controlled using the open loop, lookup-table [speed (N) and throttle (α)] based technique. Spark Time was controlled using a proportional / fuzzy logic based close loop control algorithm for the idle speed control to reduce fuel consumption and emissions. Test results show a significant improvement in engine performance over the original carbureted engine, in terms of fuel consumption, emissions and idle speed fluctuations. The Proportional controller resulted in significantly lower speed fluctuations and HC / CO emissions than the fuzzy logic controller. Though the fuzzy logic controller resulted in low cycle by cycle variations than the original carbureted engine, it leads to significantly higher HC levels. The performance fuzzy logic can be improved by modifying the membership function shapes with more engine test data.
Experimental Investigation of the Effect of Biodiesel Utilization on Lubricating Oil Degradation and Wear of a Transportation CIDI Engine
Authors: Sinha Shailendra , Agarwal Avinash Kumar
Published: March 2009

Increased environmental awareness and depletion of fossil petroleum resources are driving industry to develop alternative fuels that are environmentally more acceptable. Biodiesel is an alternative fuel derived from vegetable oils by modifying its molecular structure. In the present experimental research work, methyl ester of rice-bran oil (ROME) is derived through transesterification of rice-bran oil using methanol in presence of sodium hydroxide (NaOH) catalyst. On the basis of previous research for performance, emission and combustion characteristics, a 20% blend of ROME (B20) was selected as optimum biodiesel blend. In the present research, the experimental investigation was aimed to investigate the effect of biodiesel on wear of in-cylinder components. Endurance tests were conducted on a medium duty direct injection transportation diesel engine with 20% blend of the ROME with mineral diesel. Tests were conducted under predetermined loading cycles in two phases: engine operating on mineral diesel and engine fuelled with 20% biodiesel blend. After completion of the tests, engines were dismantled for observing the physical condition of the various parts, e.g. piston rings, bearings, cylinder liner, cylinder head etc. Physical measurements of various vital parts were also carried out to assess the wear of the parts of engine. The physical wear of various parts except big end bearings were found to be lower in case of 20% biodiesel fuelled engine. Wear metals in the lubricating oil samples drawn from the engines at regular intervals were investigated. Relatively lower wear concentration of all wear metals except lead were found in the lubricating oil of B20 fuelled engine. Two quantify the wear of cylinder liners, surface parameters at different locations in the liner (TDC, BDC and mid-stroke) were measured and investigated. A qualitative analysis was also carried out by taking surface profiles and conducting scanning electron microscopy at same locations.
Experimental Investigation on the Performance and Emission Characteristics of Direct Injection Medium Duty Transport Diesel Engine Using Rice-Bran Oil Biodiesel
Authors: Sinha Shailendra , Agarwal Avinash Kumar
Published: March 2009

Over the past several years, there has been increased interest in alternative diesel fuels to control emissions and provide energy security. Biodiesel is a fuel that can be made from renewable biological sources such as vegetable oils and animal fats, has been recognized as an environment friendly alternative to mineral diesel. In present investigation, rice bran oil (non-edible) was transesterified to methyl ester and reaction conditions for transesterifcation process for rice bran oil were optimized. Various properties like viscosity, density, flash point, calorific value of the biodiesel thus prepared are characterized as per ASTM norms (ASTM D6751) and found comparable to diesel. Steady state engine dynamometer test at full throttle conditions have been carried out to evaluate the performance and emission characteristics of a medium duty transportation DI diesel engine. Engine was fuelled with various blends of rice-bran oil biodiesel (ROME) and mineral diesel ranging from 5% biodiesel to 100% biodiesel (5, 10, 20, 30, 50, and 100%). Performance and emission data were compared to the baseline data obtained using mineral diesel. Same engine without any hardware modification has been adopted for tests on all fuel blends. The results of this experimental investigation showed that biodiesel and biodiesel blends exhibited almost similar torque and power characteristics. Biodiesel blends up to 20% produced slightly higher torque and improved performance. Improvement in fuel conversion efficiency was found for lower concentration blends i.e. up to 20%. Lowest efficiency was found for 100% biodiesel blend. All the biodiesel blends emitted lower total hydrocarbon, carbon monoxide emissions and smoke opacity but slightly higher NOx emissions during the full throttle tests. Emission tests with all the fuel blends have also been carried out using European 13 MODE test (ECE R49) procedure. Drastic reduction in THC and CO and slight increase in NOx was observed.
Cycle-by-Cycle Exhaust Temperature Monitoring for Detection of Misfiring and Combustion Instability in Reciprocating Engines
Authors: Gardiner David P. , Allan William D. , LaViolette Marc , Bardon Michael F.
Published: March 2009

This paper describes a means of achieving cycle-by-cycle combustion monitoring of reciprocating engines without the use of cylinder pressure sensors. This approach is intended primarily for engines that are not equipped with indicator passages (that would facilitate the installation of cylinder pressure sensors) but are (or can be) equipped with fittings for individual cylinder exhaust thermocouples. The monitoring system uses rugged exhaust temperature probes and advanced signal processing and analysis to detect cycle-by-cycle variations in exhaust temperatures and correlates these with conventional combustion analysis parameters. The system is particularly useful for detecting the deteriorations in combustion stability that precede misfiring as well as individual misfire events if they occur. Engine test results are presented showing the correlation between the exhaust temperature signal and parameters based upon cylinder pressure measurements. The ability to detect low level combustion instability and isolated, individual misfires has been demonstrated on a 95 liter V12 industrial natural gas engine. It as also been shown that successful acquisition of high fidelity exhaust temperature signals for the combustion analysis can be achieved in the presence of the high levels of electromagnetic interference typical of a power generation facility.
The Potential for Exhaust Heat Recovery by Thermochemical Recuperation for Hydrogen Enriched Internal Combustion
Authors: Vernon David R. , Jordan Eddie A. , Woolley Jonathon M. , Erickson Paul A.
Published: March 2009

In internal combustion engines a large portion of the chemical energy held in the original fuel is exhausted as waste heat. This exhaust heat represents a significant potential source of energy to be harnessed. The thermochemical recuperation process uses an endothermic reformation reaction to upgrade fuel into a hydrogen rich gas, thereby converting a portion of the exhaust heat into chemical energy. Enriching the primary fuel mixture with this hydrogen rich gas enables combustion with very lean or dilute mixtures resulting in low temperature combustion. The low temperature combustion regime can achieve higher efficiency and lower emissions than standard combustion regimes. Hydrogen enrichment via thermochemical recuperation does not require hydrogen refueling station infrastructure nor significant on-board hydrogen storage and could be used with existing engines. This technology shows promise in increasing the efficiency and reducing the emissions in internal combustion engines while also laying the groundwork for hydrogen production technologies and eventually for fuel cell systems. The promise of future application of this technology motivates further investigations. Thermochemical recuperation to produce the hydrogen required is carried out through a series of processes starting with fuel and water vaporization, superheating of the vapor and finally reformation of the mixture in a catalytic reactor. Based on the fuel being reformed and the catalyst being used, each of these processes takes place at a different temperature. The difference between the temperatures of these processes and the temperature of the exhaust stream drives heat transfer and determines the amount of thermal energy potentially recovered. This work will use computer models to explore various strategies for recovering thermal energy using a thermochemical recuperation process. The parameters used in this modeling effort come from reformation experiments and engine experiments underway in the Hydrogen Production and Utilization Laboratory at the University of California, Davis as well as engine and reformer models.
An Experimental Investigation of HCCI Combustion Stability Using N-Heptane
Authors: Li Hailin , Neill W. Stuart , Chippior Wally , Taylor Joshua D.
Published: March 2009

In this paper, cyclic variations in the combustion process of a single-cylinder HCCI engine operated with n-heptane were measured over a range of intake air temperatures and pressures, compression ratios, air/fuel ratios, and exhaust gas recirculation (EGR) rates. The operating conditions produced a wide range of combustion timings from overly advanced combustion where knocking occurred to retarded combustion where incomplete combustion was detected. Cycle-to-cycle variations were shown to depend strongly on the crank angle phasing of 50% heat release and fuel flow rate. Combustion instability increased significantly with retarded combustion phasing especially when the fuel flow rate was low. Retarded combustion phasing can be tolerated when the fuel flow rate is high. It was also concluded that the cyclic variations in imep are primarily due to the variations in the total heat released from cycle-to-cycle. The completeness of the combustion process in one cycle affects the in-cylinder conditions and resultant heat release in the next engine cycle.
High Temperature Lubricant for Advanced High Output Diesel Engine
Authors: Saad Philipe , Kamo Lloyd , Mekari Milad , Saad Dorsaf
Published: March 2009

Adiabatics INC. developed a high temperature lubricant (HTL) to work under the rigid regime of advanced high output diesel engine operating parameters. The advanced diesel engine requirements are 410 °C (770 F) top ring reversal (TRR) temperature, 175 °C (350 F) sump temperature and friction coefficient of μ = 0.085 – 0.10. The thermal oxidation of lubricant, tribology lubrication breakdown, and formation of deposit which occur under engine rigid working condition, are studied and analyzed. This paper includes tests data of the developed high temperature lubricant used in the tribology complex test bench, on low heat rejection (LHR) single cylinder diesel engine, lubricant screening tests, and also the lubricant was tested in a full scale 6 cylinder production Cummins ISB-305 diesel engine. The ISB-305 diesel engine has been modified; the engine has been tested per future combat system specifications, the engine demonstrated high performance of 510 hp output.