bluuebunny/crossref_metadata_2025 huggingface dataset:
An Investigation of the Potential for Enhancing the Computational Turbomachinery Design Cycle Using Surrogate Models and High Performance Parallelisation
Authors: Kipouros Timoleon , Molinari Massimiliano , Dawes William N. , Parks Geoffrey T. , Savill Mark , Jenkins Karl W.
Published: March 2009

This paper describes the deployment of supplementary tools to the modern industrial aerodynamic design cycle in the context of multi-objective optimisation. The benefits arising through the use of these tools are demonstrated through a single-row stator compressor test case, minimising two of the flow characteristics most critical to the efficiency of the turbomachine: blockage and entropy generation rate. The automatic integrated design system used, MOBOS3D, is equipped with an application-specific optimiser and a RBF surrogate model, in order to decrease the computational cost of the design evaluation process. The metamodel is utilised inside the system and is constantly trained in real time from the current database of the simulated test cases. In addition, a new parallelisation strategy is implemented, which exploits the possibility of executing simulations on a cluster of clusters, reducing significantly the wall-clock time required for the design optimisation process of real-world applications.
Optical Non-Destructive Condition Monitoring of TBC’s
Authors: Heyes A. L. , Feist J. P. , Chen X. , Mutasim Z. , Nicholls J. R.
Published: March 2009

The paper describes recent developments of the thermal barrier sensor concept for non-destructive evaluation (NDE) of thermal barrier coatings and on-line condition monitoring in gas turbines. Increases in turbine inlet temperature in pursuit of higher efficiency will make it necessary improve or upgrade current thermal protection systems in gas turbines. As these become critical to safe operation it will also be necessary to devise techniques for online conditions monitoring and NDE. The authors have proposed thermal barrier sensor coatings (TBSC) as a possible means of achieving NDE for thermal barrier coatings. TBSC’s are made by doping the ceramic material (currently yttria stabilised zirconia) with a rare earth activator to provide the coating with luminescence when excited with UV light. The paper describes the physics of the thermo-luminescent response of such coatings and shows how this can be used to measure temperature. Calibration data is presented along with the results of comparative thermal cycle testing of TBSC’s, produced using a production standard APS system. The latter show the durability of TBSC’s to be similar to that of standard YSZ TBC’s and indicate that the addition of the rare-earth dopant is not detrimental to the coating. Also discussed is the manufacture of functionally structured coatings with discreet doped layers. The temperature at the bond coat interface is important with respect to the life of the coating since it influences the growth rate of the thermally grown oxide layer which in turn destabilises the coating system as it becomes thicker. Experimental data is presented indicating that duallayered TBSC’s can be used to detect luminescence from, and thereby the temperature within, sub surface layers covered by as much as 500μm of standard TBC material. A theoretical analysis of the data has allowed some preliminary calculations of the transmission properties of the overcoat to be made and these suggest that it might be possible to observe phosphorescence and measure temperature through an overcoat layer of up to approximately 1.56mm thickness.
Analytical Modeling of Turbine Cascade Leading Edge Heat Transfer Using Skin Friction and Pressure Measurements
Authors: Holley Brian M. , Langston Lee S.
Published: March 2009

The flow near the leading edge stagnation-line of a plane turbine cascade airfoil is analyzed using measurements, analytical modeling, and computational fluid dynamics (CFD) modeling. New measurements of skin friction and pressure indicate that the aerodynamics of the leading edge are well described by an exact analytical solution for stagnation-point or Hiemenz flow. The skin friction measurements indicate the extent over which the analytical model applies. Based on measurements from an earlier study, the highest heat transfer levels occur along the leading edge stagnation-line. The same parameters that characterize Hiemenz flow also characterize a stagnation-point potential flow, which is used to accurately predict the heat transfer levels along the stagnation-line. CFD analysis indicates that pressure predictions are better than skin friction predictions for characterizing the analytical modeling that is used for more accurate heat transfer evaluation. This provides an approach for predicting the peak heat transfer coefficient in a cascade based only upon surface static pressure calculations.
Using Fresh Air in Windbox Repowering of Existing Steam Power Plants
Authors: Nayyeri V. , Asna Ashary P.
Published: March 2009

Repowering is increasing efficiency and output power of an existing steam power plants by integration them with gas turbine. Several approaches are proposed for repowering regards to condition of existing power plants. One of those approaches which provides opportunity for existing boiler reusing is windbox repowering. In this method, one or several gas turbines are installed near the existing steam unit and the exhaust of gas turbines is used as preheated combustion air for boiler. The main difficulty in integration of gas turbine and boiler is decreasing flame temperature in supplementary combustion of boiler due to low oxygen content of gas turbine exhaust compared with fresh air and its effect on heat transfer process especially in radiative sections. When advanced gas turbines are used in windbox repowering, the fresh air should be used for increasing oxygen due to low oxygen percent. In this study, the effect of using fresh air in wind box repowering will be investigated and two main arrangements, preheating and not preheating of fresh air will be compared. This study shows the advantages of using preheated air for mixing with gas turbine exhaust when advanced gas turbines are used for windbox repowering.
A Simple Procedure to Reduce Secondary Flow Effect in Turbine Nozzle Guide Vanes
Authors: Nguyen Bao Q. , Squires Kyle D.
Published: March 2009

Secondary flow contributes about one-third of the total loss in turbine nozzle. Although secondary flow characteristics are well understood, it is still a challenge to mitigate the secondary flow effect. Several methods have been proposed to reduce secondary flow loss in turbine blade rows. They include: blade 3D stacking, blade 3D design, and end wall contouring, either axisymmetric and non-axisymmetric. The latter approach produces fully 3D end wall geometry, in contrast to the conventional axisymmetric shape. Several authors have applied elaborated procedure to adjust the end wall geometry of turbine blade rows. In this paper, we present a simple method to modify the hub wall of a turbine nozzle guide vane row with a single function. This function requires 2 geometry parameters which are established by CFD. The numerical results for a high work turbine nozzle guide vane show that a reduction in secondary kinetic energy is possible.
Automated Tool-Orientation Determinations for 4-Axis Non-Gouge, Non-Interference Milling of Axial-Flow Compressors Airfoils
Authors: Chen Zezhong C. , Liu Gang
Published: March 2009

As important components of gas turbine engines, axial-flow compressors have been improved with a more complex and accurate airfoil design to meet high aerodynamic requirements; specifically, the pressure and suction surfaces of the airfoils (or blades) are now represented with free-form surfaces in CAD software systems. Since quality of the blades affects efficiency of the engines and safety of the aircrafts, some types of compressors are produced with the blades and the hub as a single piece on 4-axis CNC milling machines. However, it is still quite challenging to automatically determine cutter sizes and orientations without gouging and interference during the 4-axis milling, because the geometric shape of the blades is complex and the blades overlap with each other. As a result, the established method of determining tool size and orientation in industry is by trial and error in a repetitive process of selecting cutters and planning tool-paths with CAM systems. To address this problem, a novel approach is proposed to automatically determine cutter sizes and orientations for 4-axis milling of the axial-flow compressors blades without gouging and interference. The main contribution of this work is that (1) a mathematical model for optimizing cutter sizes in 4-axis milling is established; and (2) by applying a global optimization method — the particle swarm optimization method — to this model, the maximum allowable size of a cutter and its corresponding orientation can be found at each cutter-contact (CC) point on the surface being machined. Therefore, all the maximum allowable sizes of cutters for all the CC points and the corresponding cutter orientations can be computed. A group of standard cutters are then selected; each of which can sweep particular CC points without damaging the compressor. Since it is efficient and reliable, this newly proposed approach can be directly implemented in commercial CAD/CAM software systems to benefit the manufacturing industry.
The Lubricant Flow Structure and Pressure Generation in a Journal Bearing With Diamond-Knurled Stator Surface
Authors: Li Hongmin , Braun Minel J.
Published: March 2009

Journal bearings are popularly used in turbo machinery. The load carrying capacity and the dynamic behavior, stiffness and damping, of a journal bearing are determined by lubricant and bearing parameters: clearance, and shaft diameter and rotation speed, and surface morphology of the rotor and stator surfaces. It has been found that journal bearings with roughened stator surfaces have better performance. This paper presents a numerical investigation on the flow of lubricant in the knurls, in the fluid film between the rotor and the land of the stator, and the pressure generated on the rotor surface in a knurled journal bearing. Three computational models are developed and compared. The full Navier-Stokes equations are solved with a finite volume algorithm to simulate the fluid flow and the pressure generation. The total forces on the rotor surfaces are correlated to the bearing eccentricity and compared to the forces on the smooth bearing shaft of the same clearance. The effects of knurls on the bearing performance will be analyzed and guidance on further investigations on knurled journal bearing is presented.
Aircraft Engine Fault Detection Using Dynamic/Adaptive Threshold Approach
Authors: Yedavalli Rama K. , Li Wenfei
Published: March 2009

Fault detection plays a critical role in aircraft engines and the performance of their control systems. A real challenge in fault detection applications is the design of a scheme which can distinguish between model uncertainties and occurrence of faults. Therefore, a technique to accommodate uncertainties in the model, help in reducing false alarms and missed detections is essential for the enhancement of engine operations. In this paper, a dynamic/adaptive threshold algorithm is developed for aircraft engine fault detection based on both ‘unstructured’ time-varying perturbations in the model parameters as well as external disturbances. The residuals are errors between estimated and measured variables of the outputs. With this design approach, the residual crossing the dynamic/adaptive threshold indicates the occurrence of fault. By this method of ‘dynamic/adaptive threshold’, model uncertainties do not trigger a false alarm as in normal case with a constant threshold. Simulation results based on an engine Component Level Model (CLM) are shown to demonstrate the effectiveness of the proposed method.
Repair of Advanced Gas Turbine Blades
Authors: Anton Reiner , Heinecke Brigitte , Ott Michael , Wilkenhoener Rolf
Published: March 2009

The availability and reliability of gas turbine units are critical for success to gas turbine users. Advanced hot gas path components that are used in state-of-the-art gas turbines have to ensure high efficiency, but require advanced technologies for assessment during maintenance inspections in order to decide whether they should be reused or replaced. Furthermore, advanced repair and refurbishment technologies are vital due to the complex nature of such components (e.g., Directionally Solidified (DS) / Single Crystal (SC) materials, thin wall components, new cooling techniques). Advanced repair technologies are essential to allow cost effective refurbishing while maintaining high reliability, to ensure minimum life cycle cost. This paper will discuss some aspects of Siemens development and implementation of advanced technologies for repair and refurbishment. In particular, the following technologies used by Siemens will be addressed: • Weld restoration; • Braze restoration processes; • Coating; • Re-opening of cooling holes.
Impact of Rotational Speed on the Discharge Characteristic of Stepped Labyrinth Seals
Authors: Paolillo Roger , Moore Sean , Cloud David , Glahn J. Axel
Published: March 2009

Current and future gas turbine engines are subject to increasing performance requirements and improved fuel efficiencies. The resultant engine cycles increase core flow temperatures requiring additional cooling flow while requiring a reduction in parasitic leakage by more than 25% to meet the performance goals. The achievement of the reduced leakage requires that seal design concepts be tested and improvements validated in engine like conditions before they are introduced into the actual engine. A previous paper [1] described a set of rotating seal designs that have been tested in various combinations of rotating and static design features for low leakage potential. This paper is a continuation of the previous effort and focuses in particular on the effect of rotational speeds on the discharge characteristic of various stepped labyrinth seal designs. Leakage reductions will be characterized in terms of CD/DD,0 (i.e. ratio of leakage rate with rotation over leakage rate without rotation) as a function of circumferential to axial through flow velocity, U/Cax. For large velocity ratios of U/Cax > 5, leakage reductions of more than 20% were observed. Experimental data are compared with literature [2].
Approach to Monitor and Assess the Quality of Sensor Data in Support of Calibration and Condition Based Maintenance for Turbine Powered Navy Vessels
Authors: Palmer Carl A. , Mackos Nicholos A. , Roemer Michael J.
Published: March 2009

This paper describes a flexible, widely applicable sensor health monitoring system, as developed in partnership with Northrop Grumman Ship Systems (NGSS) under a small business innovative research contract for the US Navy. Traditional signal processing techniques were employed in conjunction with data driven models and fault identification and classification techniques to provide a robust analysis of sensor health. Key aspects of the system include: • Analysis of both high and low bandwidth data; • Modules that assess a sensor’s performance on an individual basis. These are designed to detect noise, incipient faults, spiking and signal dropout; • Modules that assess a sensor’s performance from an overall system perspective, enabling early identification of sensor drift and calibration issues; • Algorithms for high bandwidth signals designed to detect clipping, abnormal signal mean and range, and signal shape anomalies that enable identification of certain mechanical and electrical failures; • Mode detection algorithms that enable dynamic weighting of calculated health parameters in order to mitigate false alarms and missed detects; • Fusion algorithms that combine and interpret the output from the aforementioned modules, to provide estimates of overall sensor health and failure mode. The system’s capabilities were exercised on 1) laboratory datasets generated in-house with implanted faults, 2) data from tests conducted on the power distribution system driven by a Rolls-Royce MT30 gas turbine slated to power the Navy’s DDG1000 destroyer, and 3) from a low pressure air compressor (LPAC) found on legacy Navy weapons systems. The ability to detect and classify various electrical faults, issues related to calibration, and certain mechanical failures was validated. The system is suitable for offline mining of historical data, embedded on-line monitoring, and for application in distributed computing networks.
Effects of Steady Tip Clearance Asymmetry and Rotor Whirl on Stall Inception in an Axial Compressor
Authors: Cameron Joshua D. , Bennington Matthew A. , Ross Mark H. , Morris Scott C. , Corke Thomas C.
Published: March 2009

Effects of rotor centerline offset and whirl on the pre-stall and stall inception behavior of a high-speed tip-critical axial compressor were investigated. The observations were made using a circumferential array of unsteady pressure transducers. The maximum amount of rotor offset and whirl used in this investigation was 26% and 13% of the design axisymmetric tip clearance respectively. Measurements were conducted using transient throttle movements which quickly decreased the mass flow in the compressor until the onset of rotating stall. A second set of measurements used quasi-transient throttling starting from a mass flow about 0.5% larger than the stalling mass flow. These data were analyzed with the traveling wave energy method, visual inspection of the filtered pressure traces, and a two-point spatial correlation technique. For the uniform tip clearance case rotating stall occurred while the slope of the pressure rise characteristic was negative. As expected, the flow breakdown exhibited “spike” inception with no observable rotating disturbances in the pre-stall time period. The introduction of small levels of steady and unsteady tip clearance asymmetry did not significantly alter the time average performance of the stage; circumferential variations in pressure rise and flow coefficient were minimal and the stalling flow coefficient remained unchanged. However, significant short length-scale rotating disturbances were observed in both of these cases prior to stall inception. As in the symmetric tip clearance case, short length-scale disturbances initiated rotating stall in the non-uniform tip clearance experiments. The location of the generation of the incipient stall cells with respect to the non-uniform tip clearance was strongly effected by the rotor offset/whirl.
Effect of Syngas Composition and CO2-Diluted Oxygen on Performance of a Premixed Swirl-Stabilized Combustor
Authors: Shaddix Christopher R. , Williams Timothy C. , Schefer Robert W.
Published: March 2009

Future energy systems based on solid fuel gasification for co-production of power and fuels may require gas turbine operation on unusual gas fuel mixtures. In addition, global climate change concerns may dictate the production of a CO2 product stream for end-use or sequestration, with potential impacts on the oxidizer used in the gas turbine. In this study the operation at atmospheric pressure of a small, optically accessible swirl-stabilized premixed combustor is investigated when burning fuels ranging from pure methane to shifted or filtered syngas mixtures. Both air and CO2-diluted oxygen are used as oxidizers. CO and NOx emissions for these flames have been determined over the full operation range from lean blowout to slightly rich conditions. In practice, CO2-diluted oxygen systems will likely be operated close to stoichiometric conditions to minimize oxygen consumption. The presence of hydrogen in the syngas fuel mixtures results in compact, high temperature flames, resulting in increased flame stability and higher NOx emissions. The lean blowout limit decreases with increasing H2 content in the syngas. Similarly, CO emissions for lean stoichiometries decrease with increasing H2 content. CO emissions near the stoichiometric combustion point do not become significant until φ > 0.95, at which point CO emissions rise more rapidly for combustion in O2-CO2 mixtures than for combustion in air.
Efficient and Robust Rub Control With an Active Auxiliary Bearing
Authors: Ginzinger Lucas , Ulbrich Heinz
Published: March 2009

In this contribution, a new approach to control a rubbing rotor by applying an active auxiliary bearing is presented. The auxiliary bearing is attached to the foundation via two unidirectional actuators. The control force is applied indirectly using the auxiliary bearing, only in case of rotor rubbing. During a normal operation state, the feedback control does not interfere with the rotor system at all. A robust control system has been developed which significantly reduces the intensity of rubbing by stabilizing the rotor system and assuring an optimal rubbing state in case of a too large rotor amplitude. The two-phase control strategy guarantees a smooth transition from free rotor motion to the state of synchronous full annular rub. A test rig has been developed to experimentally verify the control system. Various experiments show the success of the control strategy. In case of rubbing, the contact forces are reduced up to 80 per cent, which results in significantly lower loads. At the same time, the rotor deflection is decreased too. For industrial applications, the activation of the control system can be operated fully automatically. The high efficiency of the control algorithm allows an implementation on microcontrollers. The developed control of the auxiliary bearing reduces the load and the noise of the system during rotor rubbing significantly.
The Experimental Study of Matching Between Centrifugal Compressor Impellers and Vaneless Diffusers for Turbochargers
Authors: Tamaki Hideaki , Yamaguchi Satoshi
Published: March 2009

The operating range of centrifugal compressors for turbochargers using vaneless diffuser is considered from measurements of the separate pressure rise of the impeller and the diffuser. In some cases, the peak pressure rise of the stage corresponds to the peak pressure rise of the impeller (which is considered to correspond to inducer stall). From these measurements a new correlation for the onset of inducer stall is proposed. In other cases the stability of the vaneless diffuser (defined as positive slope of the pressure rise versus flow characteristic) determines the stability of the stage. A 1D analysis of the pressure rise versus flow rate in a vaneless diffuser captures the main physical effects due to friction and provides a guide to the effect of design changes for increasing the range. Subsequent tests confirm that reduction of diffuser height is the most effective measure for reducing the surge flow rate.
Development of a Combined Cycle Gas Turbine/Steam Plant for Training Marine and Power Engineers
Authors: Sarnacki W. Peter , Kimball Richard , Fleck Barbara
Published: March 2009

The integration of micro turbine engines into the engineering programs offered at Maine Maritime Academy (MMA) has created a dynamic, hands-on approach to learning the theoretical and operational characteristics of a turbojet engine. Maine Maritime Academy is a fully accredited college of Engineering, Science and International Business located on the coast of Maine and has over 850 undergraduate students. The majority of the students are enrolled in one of five majors offered at the college in the Engineering Department. MMA already utilizes gas turbines and steam plants as part of the core engineering training with fully operational turbines and steam plant laboratories. As background, this paper will overview the unique hands-on nature of the engineering programs offered at the institution with a focus of implementation of a micro gas turbine trainer into all engineering majors taught at the college. The training demonstrates the effectiveness of a working gas turbine to translate theory into practical applications and real world conditions found in the operation of a combustion turbine. This paper presents the efforts of developing a combined cycle power plant for training engineers in the operation and performance of such a plant. Combined cycle power plants are common in the power industry due to their high thermal efficiencies. As gas turbines/electric power plants become implemented into marine applications, it is expected that combined cycle plants will follow. Maine Maritime Academy has a focus on training engineers for the marine and stationary power industry. The trainer described in this paper is intended to prepare engineers in the design and operation of this type of plant, as well as serve as a research platform for operational and technical study in plant performance. This work describes efforts to combine these laboratory resources into an operating combined cycle plant. Specifically, we present efforts to integrate a commercially available, 65 kW gas turbine generator system with our existing steam plant. The paper reviews the design and analysis of the system to produce a 78 kW power plant that approaches 35% thermal efficiency. The functional operation of the plant as a trainer is presented as the plant is designed to operate with the same basic functionality and control as a larger commercial plant.
Experimental Investigation and Evaluation of a Low NOx Natural Gas-Fired Mesh Duct Burner
Authors: Ramadan Omar B. , Gauthier J. E. Donald , Hughes Patrick M. , Brandon Robert
Published: March 2009

To increase the thermal output of a micro-turbine powered CHP system, a low NOx natural gas-fired, mesh duct burner was designed built and tested. The gas-fired burner was installed in the exhaust duct of a recuperated micro-turbine of a micro-cogeneration unit. The full-scale experimental burner was integrated with an Ingersol-Rand 70 kW micro-turbine system for the evaluation. Three wire-mesh burners with different pressure drops were used. Each burner has a conical shape made from FeCrAL alloy mat (NIT100S by ACOTECH) and their design based on a heat release per unit area of 2500 kW/m2 and a total heat release of 240 kW at 100% excess air. The local momentum of the gaseous mixture introduced through the wire-mesh was adjusted so that the flame stabilized outside the burner mesh (surface combustion). Performance of the duct burner was tested and the effect of excess air and firing rate on the stable burning zones, and emissions (NOx, CO) were measured. The range of thermal inputs at which surface combustion was maintained for the duct burner was defined by direct observation of the burner surface and monitoring of the temperature in the combustion zone. Stable combustion with low emission of pollutants was achieved at atmospheric pressure for a firing rate range of 175 to 310 kW. The total system (micro-turbine and duct burner) was shown to produce less than 5 ppm NOx for the conditions tested.
Landfill Gas: A Fuel for IC Engine Applications
Authors: Narayanan G. , Bade Shrestha S. O.
Published: March 2009

Landfill gases and biogases are low Btu gases which were, until recently, underutilized. However interest on the utilization of these gases for energy production has been increasing due to environment concerns and global warming caused by burning fossil fuels, energy security concerns and renewable nature of these gases. The main portion of landfill gas or biogas is comprised of methane and carbon dioxide with some other gases in small proportions. Release of methane directly to the atmosphere causes about 21 times global warming effects than carbon dioxide. Thus landfill gas is flared often, where the energy recovery is not economically viable in practice. Using landfill gas to generate energy encourages more efficient collection reducing emissions into the atmosphere and generates revenues for the operators. However the use of landfill gases for electricity generation is not perceived as an attractive option because of some disadvantages. Thus it becomes necessary to address disadvantages involved by studying the landfill gases in a technological perspective and motivate the utilization of the landfill gas for the future energy needs. This paper discussed landfill gas as a fuel for a spark ignition engine to produce power in an effective way and effects of additions of a small quantity of hydrogen in the fuel mixtures. The effect of the composition changes in landfill gases on the performance of the engine is also presented.
Mitigation of Sulfur Effects on a Lean NOx Trap Catalyst by Sorbate Reapplication
Authors: Parks James E.
Published: March 2009

Lean NOx trap catalysis has demonstrated the ability to reduce NOx emissions from lean natural gas reciprocating engines by >90%. The technology operates in a cyclic fashion where NOx is trapped on the catalyst during lean operation and released and reduced to N2 under rich exhaust conditions; the rich cleansing operation of the cycle is referred to as “regeneration” since the catalyst is reactivated for more NOx trapping. Natural gas combusted over partial oxidation catalysts in the exhaust can be used to obtain the rich exhaust conditions necessary for catalyst regeneration. Thus, the lean NOx trap technology is well suited for lean natural gas engine applications. One potential limitation of the lean NOx trap technology is sulfur poisoning. Sulfur compounds directly bond to the NOx trapping sites of the catalyst and render them ineffective; over time, the sulfur poisoning leads to degradation in overall NOx reduction performance. In order to mitigate the effects of sulfur poisoning, a process has been developed to restore catalyst activity after sulfur poisoning has occurred. The process is an aqueous-based wash process that removes the poisoned sorbate component of the catalyst. A new sorbate component is reapplied after removal of the poisoned sorbate. The process is low cost and does not involve reapplication of precious metal components of the catalyst. Experiments were conducted to investigate the feasibility of the washing process on a lean 8.3-liter natural gas engine on a dynamometer platform. The catalyst was rapidly sulfur poisoned with bottled SO2 gas; then, the catalyst sorbate was washed and reapplied and performance was reevaluated. Results show that the sorbate reapplication process is effective at restoring lost performance due to sulfur poisoning. Specific details relative to the implementation of the process for large stationary natural gas engines will be discussed.
Energy Efficiency Improvement of Diesel Aftertreatment With Flow Reversal and Central Fuelling
Authors: Zheng Ming , Banerjee Siddhartha , Xu Xiaohong , Asad Usman , Han Xiaoye , Wang Meiping , Reader Graham T.
Published: March 2009

Empirical and theoretical studies are made between the inlet and central heating schemes in a flow reversal embedment of diesel aftertreatment converters in order to investigate the influences of gas flow, heat transfer, chemical reaction, oxygen concentration, and substrate properties. The periodic flow reversal converter is found effective to treat engine exhausts that are difficult to cope with conventional unidirectional flow converters. However, the previous work indicates that the exhaust temperature from modern diesel engines is commonly insufficient to sustain a high conversion or regeneration rate and thus supplemental heating techniques are commonly applied. A technique of fuelling at the central region of a flow-reversal embedment is found more energy-efficient to raise the temperature of the catalytic flow-bed and therefore to drastically reduce the supplemental heating to the substrate. An effective fuel delivery technique has been tested to improve the fuel dispersion of the central fuel delivery strategy at various engine-out exhaust temperatures, compositions, and flow rates.
Design and Development of Double Helix Fuel Injection Pump for Four Stroke V-16 Rail Traction Diesel Engine
Authors: Kathpal A. K. , Gautam Anirudh , Agarwal Avinash Kumar , Baskaran R.
Published: March 2009

The diesel fuel-injection system of ALCO DLW 251 engine consists of single cylinder injection pumps, delivery pipes, and fuel injector nozzles. Fuel injection into the combustion chamber through multi-hole nozzles delivers designed power and fuel efficiency. The two most important variables in a fuel injection system of a diesel engine are the injection pressure and injection timing. Proper timing of the injection process is essential for satisfactory diesel engine operation and performance. Injection timing needs to be optimised for an engine based on requirements of power, fuel economy, mechanical and thermal loading limitations, smoke and emissions etc. Since each of these requirements varies with the operating conditions, sometimes contrary to the requirements of the other parameters, the map of optimised injection timing can be very complex. The ALCO DLW 251 engine’s fuel injection pump is jerk type to permit accurate metering and timing of the fuel injected. The pump has a ported barrel and constant-stroke plunger incorporating a bottom helix for fuel delivery control with constant injection timing. From the point of view of good power and fuel economy, combustion should take place so that the peak firing pressure occurs at about 10–15° after TDC and is usually a few degrees after combustion starts. For this to happen, fuel should be injected at an appropriate time, depending on Injection delay and Ignition delay. Both these factors are dependent on the speed and load. Changing the operating point of the engine may change either one or both types of delay, altering the moment of start of combustion. Various researchers have shown that both the Injection and the Ignition delay are reduced as the engine speed is decreased resulting in advancement of injection timing at lower speeds (and loads). This condition will be corrected by varying the static injection timing, which can be achieved by providing a modified helix on the plunger to delay the start of fuel injection, for the lower speeds and loads. A new double helix (upper and lower helix) fuel injection pump for the ALCO DLW 251 16 V engine has been designed. The new fuel injection pump has been tested on the engine test cell at Research Designs & Standards Organisation and has shown an improvement of 1.2% in locomotive duty cycle fuel consumption. This paper describes the design & development of double helix fuel injection pump and discusses the engine tests completed to verify the projected improvements in fuel efficiency.
An Analysis of Ring Temperature, Oil Film Temperature and Oil Film Thickness on a Piston Ring of an IC Engine in Consideration of Ring Movement: Effect of Ring Sliding Face Profile
Authors: Ishijima Takashi , Shimada Akiko , Kodaira Shinichiro , Sakamoto Hiroshi , Harigaya Yasuo , Suzuki Michiyoshi , Takiguchi Masaaki
Published: March 2009

For the clarification of the lubrication and thermal problems between ring and liner of internal combustion engines, an unsteady thermohydrodynamic lubrication model considering the ring temperature and the ring movement in the piston ring groove was developed. Then using the method of thermohydrodynamic lubrication, the effect of the profile of top ring sliding face on the oil film thickness and friction losses was analyzed. The ring is width of 3mm and thickness of 4.5mm. Profiles in sliding face of the ring used are two types. Ring 1 has a flat in the middle and a roundness in the corner, and Ring 2 has a barrel face. The ring temperature on the sliding surface shows the characteristic temperature distribution, and the temperature difference between ring lower face and middle of ring has about 19 °C. The oil film thickness changed in a cycle increases with increase of barrel height. The friction mean effective pressure FMEP decreases with the increase of barrel height both Ring 1 and Ring 2. FMEP of Ring 2 is more effective than that of Ring 1.
A Novel Way of Manipulating and Optimizing CAM Profiles for Internal Combustion Engines
Authors: Makkapati Satheesh , Ku Kim , Poe Steve
Published: March 2009

Generating an optimum cam profile for an internal combustion engine application is usually a very involved process. This is because of the challenge faced by the engine engineers to perform several trade-offs between fuel economy, performance, durability and emissions. Typically, the trade offs are worked out using several computer codes and with the involvement of a cross-functional team of engineers. Hence, there is a need to develop a tool that can encapsulate the various computer codes and can manipulate the cam profile with ease. With the existence of such an automated tool, optimization of the cam profile can be achieved with a specified trade-off between the several metrics identified above. This paper describes the development of such a tool, and discusses the ingredients that make it flexible and computationally efficient. Results from the use of this tool are documented in this paper as well.
Characterization and Mitigation of Spark Plug Electrode Erosion in Natural Gas and Automotive Engine Applications
Authors: Lin H. T. , Brady M. P. , Kass M. D. , Theiss T. J. , Domingo N. , Levina I. , Lykowski J.
Published: March 2009

Microstructural characterization was conducted for laboratory gasoline and natural gas reciprocating engine tested spark plug electrodes made from a range of model, developmental, and commercially available electrode alloys. These alloys were selected to explore the effects of differing electrode alloy thermal, chemical, and mechanical characteristics on erosion resistance, and were tested with and without sparking surface alloy insert pads (platinum group and novel Cr-based alloys). Extensive internal oxidation and cracking were observed in both gasoline and natural gas engine tests, indicative of an inherent degree of susceptibility of currently-used electrode materials when heated to elevated temperatures, no matter what the ignition conditions. Highly-alloyed heat-resistant alloys with excellent oxidation resistance in many high-temperature environments suffered from increased rates of erosion, as the gains in oxidation resistance appear to have been offset by hotter running temperatures resulting from decreased electrode alloy thermal conductivity. Promising early results were obtained with a novel Cr-6MgO-0.5Ti-0.3La2O3 insert pad electrode alloy, investigated as an alternative to Pt- or Ir- base alloys, which showed little erosion and good resistance to cracking and oxidation.
Characteristics of Particulate Emissions of Compression Ignition Engine Fueled With Biodiesel Derived From Soybean
Authors: Kim Myung Yoon , Yoon Seung Hyun , Hwang Jin Woo , Lee Chang Sik
Published: March 2009

An experimental investigation was performed on the effect of engine speed and EGR (exhaust gas recirculation) on the particle size distribution and exhaust gas emissions in a compression ignition engine fueled with biodiesel derived from soybean. The results obtained by biodiesel fuel were compared to those obtained by petroleum diesel fuel with sulfur contents of 16.3 ppm. The scanning mobility particle sizer (SMPS) was used for size distribution analysis and it measured mobility equivalent particle diameter in the range of 10.4 to 392.4 nm. In addition to the size distribution of the particles, exhaust emissions such as oxides of nitrogen (NOx), hydrocarbon (HC), and carbon monoxide (CO) emissions and combustion characteristics under different engine operating parameters were investigated. The engine operating parameters in terms of engine speed, EGR, injection pressure, and intake pressure were varied to investigate the individual impact of the operating parameters. As the engine speed was increased for the both fuels, the larger size particles which dominantly contributes particle mass was increased, however total numbers of particle were reduced. Comparing to petroleum diesel fuel, the combustion of biodiesel fuel in the engine reduced particle concentration of relatively larger size where most of the particle mass is found. Moreover, dramatically lower hydrocarbon and carbon monoxide emissions were found at the biodiesel fueled engine. However, the NOx emission of biodiesel fueled diesel engine shows slightly higher concentration compared to diesel fuel at the same injection timing.
Application of Auto-Associative Neural Networks to Transient Fault Detection in an IC Engine
Authors: McDowell Neil , McCullough Geoff , Wang Xun , Kruger Uwe , Irwin George W.
Published: March 2009

The tailpipe emissions from automotive engines have been subject to steadily reducing legislative limits. This reduction has been achieved through the addition of sub-systems to the basic four-stroke engine which thereby increases its complexity. To ensure the entire system functions correctly, each system and / or sub-systems needs to be continuously monitored for the presence of any faults or malfunctions. This is a requirement detailed within the On-Board Diagnostic (OBD) legislation. To date, a physical model approach has been adopted by the automotive industry for the monitoring requirement of OBD legislation. However, this approach has restrictions from the available knowledge base and computational load required. A neural network technique incorporating Multivariant Statistical Process Control (MSPC) has been proposed as an alternative method of building interrelationships between the measured variables and monitoring the correct operation of the engine. Building upon earlier work for steady state fault detection, this paper details the use of non-linear models based on an Auto-associate Neural Network (ANN) for fault detection under transient engine operation. The theory and use of the technique is shown in this paper with the application to the detection of air leaks within the inlet manifold system of a modern gasoline engine whilst operated on a pseudo-drive cycle.
An Experimental Investigation of Biodiesel Injection Characteristics Using a Light-Duty Diesel Injector
Authors: Miers Scott A. , Kastengren Alan L. , El-Hannouny Essam M. , Longman Douglas E.
Published: March 2009

The objective of this research was to experimentally evaluate the effects of two biodiesel fuels with different viscosities on fuel injection characteristics using a light-duty, common-rail, diesel injection system. A pure biodiesel (B100) and a 50/50 blend of pure biodiesel and refined, bleached, and deodorized vegetable oil (B50V50) were compared with a laboratory diesel fuel equivalent (D100). The fuel viscosity ranged from 2.6 cSt (D100) to 10.9 cSt (B50V50). Three injection pressures and two injector nozzle geometries and surface finishes were also investigated. Measurements of the injected fuel quantity showed that as fuel viscosity increased, the injected volume decreased and the variability in the injected volume tended to increase. This effect was more significant in an injector nozzle with converging, highly hydro-ground holes than one with straight, lightly hydroground holes. The rate-of-injection (ROI) data were quite similar for D100 and B100 when using the straight, lightly hydro-ground nozzle. There is a marked reduction in peak injection rate for the B100, compared to D100, when the highly hydro-ground nozzle was utilized. With both nozzles, the B50V50 blend produced narrower ROI curves with peak injection rates equal to or exceeding those of D100 fuel. For all three fuels, the start-of-injection delay increased as fuel viscosity increased. The end-of-injection time was very similar for D100 and B100 but was advanced for the B50V50 blend.
Thermal Spraying of Cylinder Bores With the PTWA Internal Coating System
Authors: Bobzin K. , Ernst F. , Zwick J. , Schlaefer T. , Cook D. , Kowalsky K. , Bird K. , Gerke D. H. , Sharp R. E. , Raab K. R. , Lindon S.
Published: March 2009

A major goal for the automotive industry over the next years is the reduction in CO2 emissions. This can be accomplished by reducing fuel consumption for new production vehicles and by increased remanufacturing of old worn engines. Both of these objectives can be addressed with the use of PTWA (Plasma Transferred Wire Arc) thermal spray of cylinder bores. Key factors in this development relating to new production engines focus on the reduction in overall vehicle weight and also the improvement of engine efficiency by reducing the internal friction losses. Substantial weight savings can be achieved with the use of aluminum engines. However, most aluminum engines require cast iron liners to be used as the wear surface. Additional weight savings and potential friction reduction can be achieved by replacing these heavy cast iron liners with a low friction, wear resistant PTWA coatings on the cylinder bores. In addition to being applied to new engines for automotive production, this same process can also be used to repair worn cylinder bores in both aluminum and cast iron engine blocks. This technology makes it possible to salvage engine blocks that would otherwise be scrapped. In addition, PTWA thermal spray can be used to reduce costs for engines that are already remanufactured using expensive over-sized pistons. With reduced costs and salvaging previously scrapped components, the use of the thermal spray technology can increase the amount of remanufacturing for critical engine components. The reduced CO2 emissions results from remanufactured components requiring 50% to 80% less energy to produce than the new production manufactured equivalents [1].
A Multi-Axis Imaging Study of Spark-Assisted Homogeneous Charge Compression Ignition Phenomena in a Single-Cylinder Research Engine
Authors: Zigler Bradley T. , Walton Stephen M. , Karwat Darshan M. , Assanis Dimitris , Wooldridge Margaret S. , Wooldridge Steven T.
Published: March 2009

High-speed imaging combined with the optical access provided by a single-cylinder research engine offer the ability to directly study ignition and combustion phenomena. Such data provide valuable insight into the physical and chemical mechanisms important in advanced engine combustion strategies. In this study, crank-angle resolved chemiluminescence imaging data both orthogonal to and along the piston axis were used to investigate homogeneous charge compression ignition (HCCI) operation of a single-cylinder four-valve optical engine fueled using indolene. This preliminary study focused on identifying how multi-axis imaging can contribute to understanding the effects of spark-assist on HCCI performance. Operating conditions of advanced spark ignition timing for extending the lean limits of bulk charge compression ignition were used. The experiments were performed at a fixed equivalence ratio of φ = 0.56, with fixed intake conditions (wide open throttle with air preheat). The multi-axis imaging provides a clear indication of the propagation of a reaction front from the spark kernel. The combination of orthogonal and axial views may provide valuable information spatially resolving volumetric heat release, thereby providing an indication of the fractional energy release due to the spark assist compared to the energy released by auto-ignition.