bluuebunny/crossref_metadata_2025 huggingface dataset:
Practical Applications of Vibration Analysis Software for Diagnosis and Condition Monitoring of Turbomachinery
Authors: Remedios Norman , Feng Ningsheng , Hahn Eric J.
Published: March 2009

The benefits of modelling turbomachinery for diagnostic and condition monitoring purposes have not been fully appreciated by the power generation industry or the consultants who service the industry. This paper describes the capabilities and practical application of vibration analysis software for analysing rotor bearing systems of rigidly coupled rotors supported on several hydrodynamic bearings of various bearing profiles. The software has two distinct components — the measurement component and the modelling component. The combination of the two provides access to existing rotating machinery and machinery in the commissioning stage in order to identify the cause of vibration problems and the corrective action required. The modelling software evaluates the effects of bearing alignment changes and operating parameter changes on system stability and vibration response. The data collection analysis software that links with the modelling results provides valuable information about the measured shaft performance at the bearings. The combination of the two components provides an efficient and valuable tool that yields significant cost benefits. The application of the software to a 360Mw and 450Mw unit is evaluated.
Heat Transfer and Flow Characteristics Due to Interaction of Longitudinal Vortices by Vortex Generator Array
Authors: Sugisaki Daisuke , Motosuke Masahiro , Honami Shinji
Published: March 2009

This paper describes the turbulent heat transfer and the flow characteristics of the longitudinal vortices downstream of vortex generator array on the flat surface. Understanding on the heat transfer and flow characteristics is strongly required from the viewpoint of the heat transfer enhancement in an actual turbine blade design. The experiment was conducted in the test section of the wind tunnel which had a rectangular cross section and length of 2000mm. The reference velocity at the test section was 16 m/s and Reynolds number based on the momentum thickness was 1670. An array of the vortex generators with equal and/or unequal wing height was installed in the turbulent boundary layer. The experiments of the heat transfer on the flat surface were conducted by using the temperature sensitive liquid crystal. The surface of the test section was heated electrically by a thin stainless steel foil. The calibration of the hue of the liquid crystal and temperature was made by Neural Network method. Nusselt number corresponding to the turbulent heat transfer downstream of the array of the vortex generators is strongly affected by the longitudinal vortex motion. The local heat transfer depends on arrangement of the unequal wings of the vortex generator in co-rotating configuration. It is quite interesting that the longitudinal vortex located in the region of downwash motion of the adjacent vortex plays an important role in the merging process of the vortices. In conclusion, the array of the vortex generators is an effective device which can control the heat transfer and flow characteristics in the actual turbine blade cooling design.
Transition Flight Feasibility of a Fluidic Thrust Vectored Aerial Tail-Sitter: Numerical Approach
Authors: Saghafi Fariborz , Banazadeh Afshin
Published: March 2009

This paper describes a feasibility study of using numerical analysis technique, coupled with a non-linear simulation model of a conceptual fluidic-thrust-vectored unmanned aerial tail-sitter to obtain required thrust deflection angles for a transition manoeuvre in take-off. It also studies the aircraft behaviour in transition subjected to the changes in specified parameters like the thrust value and the engine distance from the centre of gravity. The focus of the research presented was to get the vehicle from zero speed on the ground, in vertical position, to a specified velocity at a specified attitude, in cruise position. It was also specified that, when the vehicle was considered to be flying, it should not reduce speed or be descending and that its angle of attack should remain within a reasonable bound, since extreme angle of attack region causes the simulation and analysis to fall in the uncertain zone. The aircraft pitch attitude was also specified to decrease steadily in every integration step regarding the aircraft velocity. The transition problem was mathematically constructed and coded into Matlab/Simulink for the purpose of analysis and simulation. The inputs to the simulation program were simply series of thrust deflection angles at a number of different instants of time. Simulation was performed for a constant vehicle configuration. It was found that transition was feasible for the thrust to weight ratio around 1.0947 and it took 15 seconds to accomplish, while no attempt was made for time optimization.
Experimental Investigation of a Stall Prediction System Using a Transonic Multistage Compressor
Authors: Nakakita Tomofumi , Kurosaki Masahiro , Kamiyoshihara Yukio
Published: March 2009

This paper describes the test results of a stall prediction system using a transonic multistage axial compressor. The test results show that there is a clear relationship between the stall margin and the stall-warning index measured at the first stage. The stall warning index is derived from auto correlation of casing wall pressure signals above the rotor tip. In the tests, the compressor installed with pressure transducers on the casing wall near the leading edges of the first three rotors was forced to stall while operating at a constant speed by closing the discharge valve. The test results where the stator vane settings of the first three stages were changed show that load distribution among stages does not have significant effects on the stall margin vs. stall-warning index relationship. Using some smoothing technique, undesired time variation of the stall-warning index can be reduced to the level necessary for practical active stall control with allowable response time delay.
Knowledge Based 2D Blade Design Using Multi-Objective Aerodynamic Optimization and a Neural Network
Authors: Huppertz Andre´ , Flassig Peter M. , Flassig Robert J. , Swoboda Marius
Published: March 2009

This paper presents a method to obtain optimized 2D blade sections using expert knowledge, a multi-criteria optimization approach and a neural network in an automated process. A special focus is put on neural networks, which are used to capture the complex correlations between aerodynamic and geometric parameters. The multi-criteria optimization is used to generate optimal training data for the neural network. The main objective of this investigation is to generate 2D blade sections from scratch including loss prediction using through flow quantities and a neural network approach without any CFD computations. First results are very promising in terms of computation time, model capacities and performance prediction of the neural network.
Development of Key Technologies for the Next Generation Gas Turbine
Authors: Ito Eisaku , Okada Ikuo , Tsukagoshi Keizo , Muyama Akimasa , Masada Junichiro
Published: March 2009

In order to prevent global warming, Kyoto Protocol has come into effect in February 2005. It is necessary for Japan to reduce 6% of amount of CO2 emission from 2008 to 2012. In such an environment, improvement of the thermal efficiency of the gas turbine for GTCC is highly required. Mitsubishi Heavy Industries, Ltd. participates in the national project developing 1700 degC gas turbine. In this national project, selected component technologies are investigated in detail. Key technologies for 1700degC gas turbine are determined and under development such as: (1) Combustor with exhaust gas recirculation system; (2) Turbine cooling technology; (3) Super heat resistant material; (4) Thermal barrier coating; (5) High efficiency high loading turbine; (6) High pressure high efficiency compressor. Current status of the technology developments is reviewed.
Counteracting Windpower Fluctuations Within a Separate Electric Power Grid
Authors: Domachowski Zygfryd
Published: March 2009

Since 1990, global wind energy capacity has been doubling every three years, along with a corresponding fall in the cost of wind turbines, measured per kWe of output. The price of electricity from windpower is now close to the price of electricity produced from conventional sources. However, such farms produce unreliable output due to the vagaries of the region’s wind profile and so can not meet demand. Without action there could be major problems with fluctuating power quality. The first thing to consider with wind generation is how to achieve the optimum power output from the turbine in relation to balancing supply and demand. Such renewable energy sources as wind needs local support from conventional sources. Technological solutions do exist to counteract such problems. One of them, which has been discussed is a separate electrical power system composed of windpower farm and of gas turbine power plant. Any fluctuations of windpower have to be damped due to an appropriate action of gas turbine power plant. For this purpose a specific power and frequency control system is required that would provide limiting the power and frequency fluctuations resulting from wind turbulence.
TMF Design Optimisation for Automotive Turbochargers Turbine Housings
Authors: Ahdad Farid , Groskreutz Mark , Wang HuiMing
Published: March 2009

Turbine housings for automotive turbochargers are complex castings that are subjected to transient thermal stress from exhaust gas temperature and flow variation under complex duty cycles. A fatigue model based on a cumulative damage approach (Chaboche model [1]) is used to predict crack initiation. As the stress varies with temperature, a modified Chaboche model based on a normalized stress is proposed. To determine the transient stress and temperature distributions due to the high rates of convection from the gas, and the complexity of the design, conjugate heat transfer CFD simulation is performed. The tongue of the turbine housing is a critical region in which cracks initiate within a short time. Heat transfer coefficients ( HTC ) and bulk temperature predictions from CFD, in general, can be validated by thermal measurement. But because of the geometry and the location of the tongue, it is impossible to measure the metal temperature. For this work 2 methods were presented: HTC calibrated by thermal measurement and HTC from CFD heat transfer Conjugate method, steady state analysis. Heat transfer Coefficients and bulk temperatures obtained with those 2 methods are different. The heat transfer from CFD analysis with 15 layers has an important HTC which is 3000 W/ m2 °C, it is equal to 1200 W/m2 °C for the calibrated method, but the bulk temperatures are not the same. A sensitivity study on predicted life shows that this difference results in no more than a 2 hr change for a total predicted life of 50 hrs. In the industrial approach this difference is quite acceptable. The design of a turbine housing is optimized based on this TMF methodology and shows very good results in testing, as presented here.
Update on Mitsubishi’s Large Frame 50 and 60Hz G-Series Gas Turbine Upgrades
Authors: Arimura H. , Iwasaki Y. , Shiozaki S. , Fukuizumi Y. , Koeneke C.
Published: March 2009

This paper reports progress on Mitsubishi’s first commercial introductions of the M501G1 and M701G2 gas turbines for 60Hz and 50Hz, respectively. The first fire of the 50 Hz gas turbine took place late 2006 at Tokyo Electric Power Company’s (TEPCO’s) Kawasaki Thermal Power Station in Japan, and the 60 Hz unit in January 2007 at Portland General Electric’s Port Westward power plant at Portland, Oregon in the USA. The M501G1 and M701G2 gas turbines are upgrades to Mitsubishi G-series technology that was first introduced a decade ago utilizing steam from the bottoming cycle to cool the combustion liner, instead of compressor discharge air. In the abovementioned upgrades steam-cooling application is now extended to cool the turbine blade-rings thereby enabling better blade tip clearance control particularly during start-up transient conditions. It additionally benefits performance and reliability. Upgrades were also made to the row 1 and 2 vanes and row 1 blades utilizing advances in design technology since the original introduction of the G-series in 1997. Long-term reliability verification testing of the M501G1 gas turbine has been continuing at the Mitsubishi’s T-Point combined cycle power plant located at Takasago, Japan, since May 2003. This paper provides an update of that upgraded gas turbine with over three years of operating experience.
Low-Cycle Fatigue Behavior of HAYNES® 282® Alloy and Other Wrought Gamma-Prime Strengthened Alloys
Authors: Pike L. M.
Published: March 2009

Key properties for wrought gamma-prime strengthened alloys used in aero and land-based gas turbine engines include fabricability, creep strength, and resistance to thermal fatigue. Since a definitive test method for measuring thermal fatigue resistance has not yet been accepted in the industry, isothermal low cycle fatigue (LCF) data are often used as a substitute. In this study, the LCF behavior of several gamma-prime strengthened sheet alloys was investigated. The test program emphasized the LCF behavior of HAYNES® 282® alloy, a material designed for excellent creep strength and fabricability (especially weldability). Data was also taken on other gamma-prime strengthened alloys including 263 alloy, R-41 alloy, and Waspaloy alloy for which little to no data existed in literature for sheet material. Fully reversed, strain-controlled LCF testing was performed at temperatures ranging from 1200 to 1600°F (649 to 871°C) on 0.125” (3.2 mm) thick sheet. The results of the testing are presented along with some microstructural characterization. HAYNES and 282 are registered trademarks of Haynes International.
Gas Turbine Compressor System Design Using Dynamic Process Simulation
Authors: Samurin Norman A. , Talabisco George C.
Published: March 2009

Almost all petrochemical processes are modeled as steady state to establish the required sizes of pipe, vessels, compressors, pumps, and valves. A dynamic simulation study of the process compressor system design can now be done as part of the initial plant design activity. The system piping design and proper placement of the anti-surge valves (ASV) along with preliminary valve sizing can be evaluated. Additional control strategies may be evaluated for emergency shut down (ESD). This will confirm the system design to safely shutdown a compressor without surge. Many of the issues that may be uncovered during study execution can save time and expense before the initial commissioning of the process. For a plant start up, the driver capability, compressor loading, positions of valves, and control philosophy may be tested before the components are committed to hardware.
Over Rotor Casing Surface Streak Measurements in a High Speed Axial Compressor
Authors: Bennington Matthew A. , Cameron Joshua D. , Morris Scott C. , Gendrich Charles P.
Published: March 2009

Time averaged wall shear stress patterns were recorded during quasi-steady throttling to stall in a high speed compressor. The technique utilized a CCD camera to capture digital images of oil streaks on a transparent casing section located over the rotor. The most notable feature of the surface streaking was a bifurcation line of zero time average axial shear stress. The location of this feature was found to represent the location where the approach fluid and the reverse flow from the tip gap meet and separate from the casing surface. The location of this line with respect to the rotor leading edge was denoted as xzs. The values of xzs were found to be positive (downstream of the leading edge) at high flow coefficients, and moved upstream as the compressor mass flow was reduced. Compressor stall was observed to occur when xzs was negative, with magnitude of order 6% of the axial blade tip chord. In other words, the zero axial shear line crossed the leading edge plane at a flow coefficient slightly higher than the stall point. The present paper describes the location of xzs as a function of both the flow coefficient and the local blade tip clearance. Both of these independent variables were found to have a substantial impact on the endwall flow near the leading edge, with little variation downstream. A simplified model was used to better understand the flow mechanisms associated with changes in xzs. An interpretation of these results will be given in terms of experimental and computational efforts related to blade tip flows that are described in the recent literature.
A MATLAB Toolbox for the Intuitive Knowledge of Turbomachinery
Authors: Marineau Eric C. , Reggio Marcelo
Published: March 2009

This paper presents the characteristics and the usefulness of a MATLAB toolbox in teaching the effects of the design parameters on the performance and characteristics of axial and radial compressors, turbines and pumps. The teaching and learning of the working principles of turbomachines are challenging subjects as the understanding and application of various concepts from fluid dynamics, thermodynamics and dimensional analysis are required. It is believed that the current toolbox will help students acquire durable and intuitive knowledge as it provides an effective discovery environment. In this environment, the users progressively gain insight into the laws and rules of a system by manipulating the variables and visualizing the resulting consequences. For each type of components, distinct sets of input variables can be chosen, each one corresponding to a different design problem. Based on the mean radius analysis and using the input parameters provided by the user, the toolbox provides a preliminary design. The results are displayed in different type of graphics such as velocity triangles, efficiency contours and a sketch of the designed turbomachine. The toolbox Graphical User Interface (GUI) insures user-friendliness such that the user can strictly focus on the content.
Effect of Hole Spacing on Jet Array Impingement Heat Transfer
Authors: Goodro Matt , Park Jongmyung , Ligrani Phil , Fox Mike , Moon Hee-Koo
Published: March 2009

Data which illustrate the effects of hole spacing on the heat transfer from an array of jets impinging on a flat plate are presented. Considered are Reynolds numbers ranging from 8200, to 30500, and Mach numbers from 0.1 to 0.2. The spacing of the holes used to produce the impinging jets is either 8D or 12D in both the streamwise and spanwise directions. Local and spatially-averaged Nusselt numbers show strong dependence on the impingement jet Reynolds number for both situations. Experimental results show that local Nusselt numbers show some dependence on the Mach number for the smaller jet hole spacing, with negligible dependence for the larger jet hole spacing. This is partially a result of the accumulating cross-flows produced by the jets, as well as the interactions of the vortex structures which initially form around the jets, and then impact and interact as they advect away from stagnation points along the impingement target surface. Spatially-averaged Nusselt numbers generally decrease as x/D increases when hole spacing is 8D, whereas Nusselt numbers are generally about constant as x/D increases when hole spacing is 12D. This is partially due to cross-flow effects, as well as behavior of each jet in the array, which is similar to that of a single, isolated jet for the larger hole spacing. Spatially-averaged Nusselt numbers for 8D jet hole spacing are also often higher than values for the 12D jet hole spacing when compared at the same x/D location.
An Integrated Combined Heat and Power Distributed Energy Resource Solution for Modular Applications
Authors: Smugeresky Craig S.
Published: March 2009

Heat recovery for Combined Heat and Power (CHP) applications has been developed and fully integrated into a Capstone® Micro Turbine™ Distributed Energy Resource (DER) power generation system. The Capstone C6XiCHP Series Micro Turbine products have the ability to generate up to 65 kW of electrical power and 120 kW of thermal heat recovery in a fully integrated single package. Users are able to scale up to 2.0 MW of electrical power generation combined with up to 3.6 MW of heat energy when the C6XiCHP in applied in multiple unit (MultiPac™) arrays. Because multiple units are used and operated as a single generator system, users can operate each individual C6XiCHP at full load efficiency and turn off unused C6XiCHP units to follow site demand without incurring efficiency penalties associated with part-load operation.
Thermoeconomic Optimization of an Ice Thermal Storage System
Authors: Sanaye Sepehr , Mostakhdemi Masoud , Toski Hossein Babaie
Published: March 2009

The gas turbine power output and efficiency decrease with increasing ambient temperature. Compressor inlet air cooling is one way to compensate these losses. In this paper thermoeconomic optimization of an ice (latent) thermal storage systems (TES) has been studied as a gas turbine inlet cooling system. The objective function included the capital and operational costs of the gas turbine and compression refrigeration system as well as corresponding cost due to system exergy destruction. The system design parameters were obtained using numerical search optimization technique.
Airfoil Heat Transfer Characteristics in Syngas and Hydrogen Turbines
Authors: Mazzotta Danny W. , Chyu Minking K. , Alvin Mary Anne
Published: March 2009

Hydrogen or coal-derivative syngas turbines promise increased efficiency with exceptionally low NOx emissions compared to the natural gas based turbines. To reach this goal, turbine inlet temperature (TIT) will need to be elevated to a level exceeding 1700°C [1, 2]. The thermal load induced by such a temperature increase alone will lead to immense challenges in maintaining material integrity of turbine components. In addition, as working fluid in the gas path will primarily be steam, possibly mixed with carbon oxides, the aero-thermal characteristic in a hydrogen turbine is expected to be far different from that of air/nitrogen enriched gas stream in a gas turbine. For instance, steam has distinctly higher density and specific heat in comparison to a mixture of air and combustion gases as they are expanded in a conventional gas turbine. Even if the temperature limits remain about the same, the expansion in a hydrogen turbine will have to proceed with a greater enthalpy drop and therefore requires a larger number of stages. This also implies that the flow areas may need to be expanded and blade span to be enlarged. Meanwhile, a greater number of stages and hot surfaces need to be protected. This also suggests that current cooling technology available for modern day gas turbines has to be significantly improved. The ultimate goal of the present study is to systematically investigate critical issues concerning cooling technology as it is applicable to oxy-fuel and hydrogen turbine systems, and the main scope is to develop viable means to estimate the thermal load on the turbine “gas side”, that is eventually to be removed from the “coolant side”, and to comparatively quantify the implication of external heat load and potential thermal barrier coating (TBC) degradation on the component durability and lifing. The analysis is based on two well-tested commercial codes, FLUENT and ANSYS.
Comparison of Heat Transfer From Staggered Pin Fin Arrays With Circular, Cubic and Diamond Shaped Elements
Authors: Chyu M. K. , Yen C. H. , Siw S.
Published: March 2009

This study investigates the effects of pin shape of staggered arrays on heat transfer enhancement. Three different pins: circular, cubic, and diamond, are studied. The arrays consists of twelve rows of five columns with geometry configuration of ST/D = 2.5 and SL/D = 2.5, H/D = 1. Tests were conducted at Reynolds number between 12,000 and 19,000. The heat transfer measurement uses a liquid crystal imaging technique combined with a one-dimensional, transient conduction model and a lumped heat-capacitance model. The results reveal that the heat transfer from the cubic pin arrays and diamond pin arrays is higher than that from the circular pin arrays at the same Reynolds number. However, the circular pin arrays provide the lowest pressure loss among the three arrays. Considering the trade-offs between heat transfer and pumping power, the circular pin arrays may still be the better choice as a heat exchanger.
Determination of CFD Turbulence Scales for Lobed Mixer Jet Noise Prediction
Authors: Meslioui Sid-Ali , Cunningham Mark , Germain Patrick
Published: March 2009

Many turbofan engine exhaust designs feature internal forced mixers to rapidly mix the hot core flow with the cold bypass flow before the nozzle exit, primarily to enhance mixing and thus improve Specific Fuel Consumption (SFC). Although the design is intended for performance improvement, it may also considerably reduce low frequency noise because of the lower relative mixed jet velocity compared to a confluent nozzle. In reality, the presence of the mixer adds complexity to the jet flow fields and additional high frequency source noise commonly labeled “mixer excess noise”. There is no industry standard on predicting such jet noise contribution. As a remedy to this, a new method was recently developed by the Institute of Sound and Vibration Research (ISVR), UK, and Purdue University, USA, under the AeroAcoustics Research Consortium (AARC) contract to predict jet noise of lobed mixers. The method essentially relies on SAE ARP876D or ESDU98019 far field noise spectra predicted for single stream jets, with appropriate filtering to decompose the spectrum into an enhanced jet spectrum and a fully mixed jet spectrum. The process is similar to the four source model earlier developed for the coplanar separate flow jets. In addition to mixer flow parameters, the prediction method requires the knowledge of two parameters related to mixer excess noise: a turbulence factor Fm, defined as the ratio of the turbulence in a forced mixer to the ‘normal’ turbulence in a single-stream mixed jet at equal distances downstream of the nozzle; and LenJ that represents the axial length of the effective jet over which Fm exceeds unity. Extensive analysis of NASA scale model lobed mixers noise data showed that the method is promising. RANS CFD was also performed to numerically determine equivalent turbulence scales based on the turbulent kinetic energy in forced mixer jets relative to confluent mixer jets. The present paper extends this work, refining the prediction method and providing validation of the new method with full-scale engine noise data. In addition, the potential of CFD to enhance noise prediction for lobed mixer jets by providing the turbulence scales needed for the empirical model is further investigated. A new definition of the equivalent CFD turbulence parameters is proposed that agrees well with those derived from empirical jet noise model. Comparison of the CFD results with NASA PIV data for a confluent mixer configuration showed that the CFD methodology is not yet fully mature and additional work is required. However, the resolution of the mixer turbulence scales predicted by CFD analysis is sufficient to identify noise trends between two mixer designs. As a result, CFD is seen as a tool with the potential to identify mixer designs that result in lower jet noise.
The Air Injection Power Augmentation Technology Provides Additional Significant Operational Benefits
Authors: Akita Eiji , Gomi Shin , Cloyd Scott , Nakhamkin Michael , Chiruvolu Madhukar
Published: March 2009

The Air Injection (AI) Power Augmentation technology (HAI for humid Air injection and DAI for dry air injection) has primary benefits of increasing power of combustion turbine/combined cycle (CT/CC) power plants by 15–30% at a fraction of the new plant cost with coincidental significant heat rate reductions (10–15%) and NOx emissions reductions (for diffusion type combustors up to 60%) (See References 1, 2, 3): Figure 1A is a simplified heat and mass balance for the PG7241 (FA) combustion turbine with HAI. The auxiliary compressor supplies the additional airflow that is mixed with the steam produced by the HRSG and injected upstream of combustors. Figure 1B presents the heat and mass balance for the PG7142 CT based combined cycle power plant with HAI. It is similar to that presented on Figure 1A except that the humid air is created by mixing of steam, extracted from the steam turbine, with the supplementary airflow from the auxiliary compressor. The maximum acceptable injection rates are evaluated with proper margins by a number of factors established by OEMs: the compressor surge limitations, maximum torque, the generator capacities, maximum moisture levels upstream of combustors, etc.
Overview of the U.S. Department of Energy’s Office of Fossil Energy Advanced Turbine Program for Coal Based Power Systems With Carbon Capture
Authors: Dennis Richard A. , Harp Rundle
Published: March 2009

The U.S. Department of Energy’s Office of Fossil Energy Turbine Program is implementing a new research program to develop turbines for integrated gasification combined cycle (IGCC) systems that capturer CO2. On September 8, 2005 the U.S. DOE Office of Fossil Energy announced a $130 million investment of government money in turbine related technology to promote the development of IGCC power systems that can capture CO2 and minimize the emissions of criteria pollutants. These funds will be matched at various levels by the industry partners. In part through this investment the FE Advanced Turbine Program is designed to attain three primary goals: 1) By 2010 develop advanced coal based power systems capable of 45–50% efficiency at < $1000 / kW, 2) By 2012, develop technologies for capture and sequestration of carbon dioxide that result in less than 10 percent increase in the cost of electricity and 3) By 2015 demonstrate coal based energy plants that offer zero emissions (including CO2) w/ multi product production. The program has an additional primary objective to provide turbine based technology for the FutureGen Project. To attain these goals the program is organized into four areas: H2 fueled turbines for IGCC and FutureGen applications, Oxy-fuel turbines for IGCC and FutureGen applications; MW-scale H2 fueled turbines and CO2 compression technology. The paper will report on the program goals, status of these new projects and early progress towards these goals and objectives.
Fatigue Crack Growth Behavior Evaluation of Grainex Mar-M 247 for NASA’s High Temperature, High Speed Turbine Seal Test Rig
Authors: Delgado Irebert R. , Steinetz Bruce M. , Rimnac Clare M. , Lewandowski John J.
Published: March 2009

The fatigue crack growth behavior of Grainex Mar-M 247 is evaluated for NASA’s Turbine Seal Test Facility. The facility is used to test air-to-air seals for use primarily in advanced jet engine applications. Because of extreme seal test conditions of temperature, pressure, and surface speeds, surface cracks may develop over time in the disk bolt holes. An inspection interval is developed to preclude catastrophic disk failure by using experimental fatigue crack growth data. By combining current fatigue crack growth results with previous fatigue strain-life experimental work an inspection interval is determined for the test disk. The fatigue crack growth life of the NASA disk bolt holes is found to be 367 cycles at a crack depth of 0.501 mm using a factor of 2 on life at maximum operating conditions. Combining this result with previous fatigue strain-life experimental work gives a total fatigue life of 1032 cycles at a crack depth of 0.501 mm. Eddy-current inspections are suggested starting at 665 cycles since eddy current thresholds are currently at 0.381 mm. Inspection intervals are recommended every 50 cycles at maximum operating conditions.
Performance Characteristics of Thermal Barrier Coatings: A Case Study
Authors: Shahoo Purush , Sobieski Peter A.
Published: March 2009

Degradation of hot section components in the turbine section of gas turbines used in the power generation industry can cause significant problems including financial penalties associated with down time and a decrease in operating efficiency. High temperature oxidation and hot corrosion can cause severe material loss. The use of thermal barrier coatings to mitigate such factors is becoming increasingly common and has been used for many years in land-based gas turbines. However, the experience of equipment users has had limited publicity. The purpose of this paper is to share some of the experiences of a large integrated power company and an independent service provider of turbomachinery refurbishment. A variety of thermal barrier coatings from a few selected vendors were run in a rainbow test over a two year period. Inspections of the stationary nozzle segments were carried out after the first and second year. The findings regarding the performance of the coatings are discussed within. Differences between the coatings application processes, the coating raw material, the vendors and location of part in the nozzle are discussed.
Development of an 8MW-Class High-Efficiency Gas Turbine, M7A-03
Authors: Tanimura Kazuhiko , Murakami Naoki , Matsuoka Akinori , Ishida Katsuhiko , Kato Hiroshi , Sakai Takeshi , Taniguchi Tomoki , Taki Hiroshi
Published: March 2009

The M7A-03 gas turbine, an 8 MW class, single shaft gas turbine, is the latest model of the Kawasaki M7A series. Because of the high thermal efficiency and the high exhaust gas temperature, it is particularly suitable for distributed power generation, cogeneration and combined-cycle applications. About the development of M7A-03 gas turbine, Kawasaki has taken the experience of the existing M7A-01 and M7A-02 series into consideration, as a baseline. Furthermore, the latest technology of aerodynamics and cooling design, already applied to the 18 MW class Kawasaki L20A, released in 2000, has been applied to the M7A-03. Kawasaki has adopted the design concept for achieving reliability within the shortest possible development period by selecting the same fundamental engine specifications of the existing M7A-02 – mass air flow rate, pressure ratio, TIT, etc. However, the M7A-03 has been attaining a thermal efficiency of greater than 2.5 points higher and an output increment of over 660 kW than the M7A-02, by the improvement in aerodynamic performance of the compressor, turbine and exhaust diffuser, improved turbine cooling, and newer seal technology. In addition, the NOx emission of the combustor is low and the M7A-03 has a long service life. These functions make long-term continuous operation possible under various environmental restraints. Lower life cycle costs are achieved by the engine high performance, and the high-reliability resulting from simple structure. The prototype M7A-03 gas-turbine development test started in the spring of 2006 and it has been confirmed that performance, mechanical characteristics, and emissions have achieved the initial design goals.
A Simulation Model of a Four-Stroke Spark Ignition Engine Fueled With Landfill Gases
Authors: Narayanan Guruprasath , Bade Shrestha S. O.
Published: March 2009

A simulation model for establishment of performance parameters of a spark ignition engine fueled with landfill gas-methane and landfill gas-hydrogen mixtures is described. A two zone model was employed to estimate combustion duration, ignition lag, associated mass burning rates and performance parameters for various operating conditions in an internal combustion engine. The modeling consists of two main modules: a) a fuel-air and residual gas properties calculation, and b) equilibrium combustion product properties calculation with 13 species of equilibrium combustion products. The fuel-air and residual gas module calculates gas properties required in compression stroke and in an unburned zone of a combustion chamber. The equilibrium combustion products module calculates gas properties for the burned zone during combustion and expansion phases. In addition to engine parameters, combustion duration estimation methods were presented to accommodate the presence of high quantities of diluents such as carbon dioxide and nitrogen in methane to represent landfill gases, generally encountered in practice. Similarly, an effect of addition of hydrogen in landfill gas on performance of a spark ignition engine was also incorporated in the model. The pressure traces and other engine output parameters were modeled and compared with the experimental observations obtained in a variable compression single cylinder four-stroke spark ignition Co-operative fuel research (CFR) engine for different fuels that include methane, landfill gas and landfill gas–hydrogen mixtures and found satisfactory agreement. Matlab was used as the programming software in the model.
3D-CFD Simulation of Diesel and Dual Fuel Engine Combustion
Authors: Liu Chengke , Karim G. A.
Published: March 2009

A 3D-CFD model with a reduced detailed chemical kinetics of the combustion of diesel and methane fuels is developed while considering turbulence during combustion to simulate the mixture flow, formation and combustion processes within diesel and diesel/methane dual fuel engines having swirl chambers. The combustion characteristics of the pilot injection into a small pre-chamber are also investigated and compared with those within a swirl chamber. Modeling results were validated by a group of corresponding experimental data. The spatial and temporal distributions of the mixture temperature, pressure and velocity under conditions with and without liquid fuel injection and combustion are compared in the swirl and main combustion chambers. The effects of engine speed, injection timing, and the addition of carbon dioxide on the combustion process of dual fuel engines are investigated. It is found that in the absence of any fuel injection and combustion, the swirl center is initially formed at the bottom left of the swirl chamber, and then moved up with continued compression in the top-right direction toward the highest point. The swirling motion within the swirl and main combustion chambers promotes the evaporation of the liquid pilot and the combustion processes of diesel and dual fuel engines. It was observed that an earlier autoignition can be obtained through injecting the pilot fuel into the small prechamber compared to the corresponding swirl chamber operation. It is to be shown that reduced engine emissions and improved thermal efficiency can be achieved by two-stage HCCI combustion.
Spray Characterization From Common Rail Injection System for Use in Locomotive Engines
Authors: El-Hannouny Essam , Longman Douglas , McConnell Steven , Xie Xingbin , Lai Ming-Chai , Poola Ramesh , Goetzke Michael
Published: March 2009

New U.S. Environmental Protection Agency regulations are forcing locomotive manufacturers and railroads to reduce pollutant emissions from locomotive operation. Locomotive engines will be required to meet the applicable standards at the time of original manufacture. A variety of emissions-reduction technologies can be used, such as alternative fuels, additives in lubricant oil, and aftertreatment technologies (e.g., selective catalytic reduction and particulate traps). Emissions reduction can also be accomplished inside the cylinder, using advanced diesel fuel injectors that have a significant impact on the quality of spray and charge preparation before engine combustion and subsequent events. High-speed optical measurements have been collected at elevated ambient pressures for sprays from a modular common rail injection system at Argonne National Laboratory in order to investigate spray structure and dynamics. High-speed laser imaging was used to explore the effects of various parameters on the spray structure. The experimental parameters included were ambient gas density, injection pressure, number of spray holes, injection strategy, and internal orifice size. Spray symmetry and structure were found to depend significantly on the nozzle geometry or manufacturing variances and the operating conditions.
MAHLE Advanced EGR Systems for Commercial Diesel Engines to Meet Future Emission Demands
Authors: Warth Marco , Lerch Boris , Loch Adam , Elsaesser Alfred
Published: March 2009

Given the ever more stringent emission regulations modern diesel engines undergo these days, the need for advanced EGR systems becomes crucial in all major applications, in particular on- & off-road commercial diesel engines. One of the key aspects of these so-called advanced EGR systems thereby is to reliably provide the engine with the appropriate, high amounts of EGR over the entire range of operating conditions. Whereas common systems are either optimized for low-torque/low-speed operating conditions, or a narrow range around one specific engine speed, the advanced systems aim to both cover the entire operating range and significantly increase the current level of EGR. The advanced EGR systems developed at MAHLE make use of two types of fast acting devices in a modular approach. Depending on the engine size/layout and the amount of EGR needed, the devices are either placed directly in the EGR line or the intake manifold. Using the latest technical advances in mechatronics, the oscillating valves can be opened or closed within less than 3ms, which makes it not only possible to accurately control the amount of EGR fed back into the engine, it also allows to boost the amount of EGR using the exhaust pressure oscillations. In addition to these oscillating valves, rotational flaps have been developed to significantly reduce the complexity of the systems, while still offering similar benefits in terms of EGR rates and variability. Shown hereafter are the results from thorough investigations conducted on both European and US heavy-duty diesel engines. Focusing on some of the most common engine characteristics, such as EGR rates, emissions of nitrogen oxide and fuel consumption, significant benefits can be seen using the newly developed technologies. Compared to conventional measures, such as increased exhaust backpressure and/or constant charge-air throttling, the advanced systems prove to be both more efficient and flexible in terms of EGR rates, as well as beneficial regarding some of the most important engine characteristics.
Emission and Combustion Characteristics of Biodiesel (Jatropha Curcas) Blends in a Medium Duty IDI Transportation Engine
Authors: Gangwar Harish Kumar , Agarwal Avinash Kumar
Published: March 2009

Vegetable oils, due to their agricultural origin, are able to reduce net carbon-di-oxide emissions to the atmosphere along with import substitution of petroleum products. However, several operational and durability problems in using straight vegetable oils as CI engine fuels are reported in the literature, which are because of their higher viscosity and low volatility compared to mineral diesel. In the present research, experiment were designed to study the effect of lowering Jatropha oil’s viscosity by transesterification and thereby eliminating adverse effects on combustion characteristics of the engine. In the present experimental research, Jatropha methyl ester is produced by transesterification of jatropha oil using methanol in presence of basic catalyst (Sodium hydroxide). Experimental investigations have been carried out to examine the combustion characteristics of in an indirect injection (IDI) transportation diesel engine running with diesel, biodiesel and its blends with diesel. Engine tests were performed at different engine loads ranging from no load to rated (100%) load at fixed engine speed (2000 rpm). A careful analysis of cylinder pressure rise, instantaneous heat release and cumulative heat release was carried out. All test fuels exhibited similar combustion stages as diesel however biodiesel and its blends showed earlier start of combustion and lower heat release during premixed combustion phase at all engine load. Maximum cylinder pressure reduces as the fraction of biodiesel increases in the blend and at higher engine loads, the crank angle position of peak cylinder pressure for biodiesel blends shifted away from top dead center. The maximum rate of pressure rise was found to be higher for diesel at higher engine loads however total combustion duration was higher for biodiesel blends.
Influence of the Air-Path Operating Parameters on the Low Temperature Combustion in a Single-Cylinder Diesel Engine
Authors: Beatrice Carlo , Avolio Giovanni , Del Giacomo Nicola , Guido Chiara
Published: March 2009

The present paper describes the effects of some air-path operating parameters on the performance of a modern common-rail diesel engine when it runs under Low Temperature Combustion (LTC) conditions. Aim of the experimental work was to explore the potential of the control of each parameter on the improvement of LTC application to the modern LD diesel engines for passenger cars, in order to meet future NOx emissions limits avoiding penalties in fuel consumption and drivability. In particular, the effects on LTC performance of the following operating parameters were analysed: intake air temperature, exhaust EGR cooler temperature, intake pipe pressure, exhaust pipe pressure and swirl ratio. Tests are carried out with a single-cylinder research diesel engine derived from FIAT 1.9 JTD 16V Multi-Jet in the EURO4 version. Results analysis have shown a significant influence of some examined parameters on the improvement of EGR tolerability, that has led to sensitive NOx reduction, within fixed limits in fuel consumption and smoke. On the contrary, engine behaviour is insensitive to the variation of the other air-path parameters.
Investigation of Mixture Preparation Effects on Gasoline HCCI Combustion Aided by Measurements of Wall Heat Flux
Authors: Chang Junseok , Filipi Zoran S. , Kuo Tang-Wei , Assanis Dennis N. , Najt Paul M. , Rask Rodney B.
Published: March 2009

The gasoline HCCI engine holds a promise of achieving very high part-load efficiency combined with extremely low NOx and soot emissions. However, the load range of HCCI operation is limited by the misfire limit at the low end, and knock limit at the high end. Therefore, the future practical implementation will likely be a dual-mode engine, operating in the HCCI mode at part load and switching to SI at higher loads. Expanding the limits will be critical for maximizing the fuel economy benefits in the vehicle. The mixture stratification, both thermal and compositional, can have very tangible impact on HCCI combustion; and gaining a deeper insight into these effects is critical for expanding the HCCI range of operation. This paper presents results of the comprehensive experimental investigation of the mixture preparation effects on a single-cylinder gasoline engine with exhaust re-induction. The effects include type of mixture preparation (external mixing vs. direct injection), charge motion, and injection timing. A combination of pressure-based combustion diagnostics, emissions analysis, and heat flux measurements on the combustion chamber wall quantifies the effects on combustion and provides insight into reasons for observed engine behavior. As an example, the instantaneous temperature and heat flux measurements show the fuel impingement locations and allow assessing the fuel film dynamics and their effect on mixture stratification. The effects of direct injection and partial closing of the swirl control valve were relatively small compared to extending the injection timing late into the intake process or completely closing the swirl control valve and allowing charge storage in the port.