bluuebunny/crossref_metadata_2025 huggingface dataset:
Vector Positioning for Cross Correlation PIV
Authors: Young C. N. , Gilbert R. , Johnson D. A. , Weckman E. J.
Published: March 2009

Continuing advances in digital imaging technology stimulate greater interest in applying particle image velocimetry (PIV) over increasingly larger fields of view. Unfortunately when larger fields of view are analyzed, velocity gradients in the image become more localized. In addition, non-uniformities in image illumination and particle number density become more prevalent. These factors, coupled with the requirement that large areas of interest (AOIs) must be employed to measure the full range of velocity, cause degradation of correlation results (i.e. broadening and/or splintering of the cross correlation peak) which leads to positional bias errors in the measured velocity field. More advanced super resolution strategies that employ an iterative AOI reduction process inherently reduce positional bias in PIV results but these strategies can break down in complex flows where velocity gradients are steep and particle dispersion does not remain uniformly random. To mitigate these problems a simple but effective technique is presented that enables individual velocity vectors to be placed within an AOI at locations toward which the cross correlation plane is biased. The method involves analysis of the correlation plane to extract the dominant features that are matched in two successive AOIs. To demonstrate the utility of the methodology results obtained from synthetic images are compared against results obtained using the conventional PIV approach.
A Numerical and Experimental Analysis of Flow in a Centrifugal Pump
Authors: Stickland M. T. , Scanlon T. J. , Ferna´ndez-Francos J. , Blanco-Marigorta E. , Parrondo J.
Published: March 2009

This paper describes the use of a rotating all mirror image derotator system in collaboration with Particle Image Velocimetry (PIV) to visualise and quantitatively examine the flow patterns between the blades of a centrifugal impeller. The authors have been able to obtain the relative velocities in a centrifugal impeller at rotational speeds between 300 and 600 revs per minute with water flow rates between 450 and 900 litres per hour. Velocity contours and vector maps of the relative flow field within a blade passage are presented for an impeller speed of 350 rpm and a flow rate of 510 l/h. The data are compared with the results of a computational fluid dynamics (CFD) model.
A Large-Eddy Simulation of Bubble-Liquid Jets
Authors: Yang M. , Zhou L. X. , Fan L. S.
Published: March 2009

A Large-Eddy Simulation (LES) with a two-way coupling is used to study bubble-liquid two-phase confined jets in a two-dimensional channel. The results show the large-eddy vortex structures of both liquid flow and bubble motion, the shear-generated and bubble-induced liquid turbulence. For comparison, the second-order moment (SOM) modeling was also carried out for the same case. Both LES and SOM results indicate much stronger bubble fluctuation than the liquid fluctuation, the enhancement of liquid turbulence by bubbles even for the higher velocity case. Both shear production and the production due to bubble-liquid interaction are important for the liquid turbulence generation in the case studied. The LES statistical results and the SOM simulation results are in qualitative agreement with each other.
Development of a Spatially-Filtered Method for Calculation of Multiphase Flow
Authors: Moses Brooks , Edwards Chris , Helenbrook Brian
Published: March 2009

Computer simulations of multiphase flows are currently limited to two distinct regimes: Fluid elements that are much larger than the computational grid cells can be modeled using fully-resolved calculations, and fluid elements that are much smaller than the grid cells can be modeled using point-particle approximations. However, many flows involve fluid elements for which neither of these limits is appropriate. For simulations of spray atomization, in particular, the grid size needs to be small enough to resolve the details of the injected fluid stream, yet resolving the smallest droplets produced would require an impossibly large number of grid points. To simulate spray atomization or other flows with a wide range of fluid element sizes, then, it is necessary to develop a computational framework that can bridge the fully-resolved and point-particle regimes. The development of such a framework is the topic of this paper. We begin by borrowing the mathematical framework of “large-eddy simulations” of turbulence—the equations for the flowfield are mathematically filtered, producing a set of equations which are smooth above a certain size and contain a set of terms which model the effects of the smaller scales. Because the filtering provides a mathematically valid smoothing of the fluid interfaces, it is also a natural way of simulating fully-resolved fluid elements on a fixed grid. The subfilter-scale terms can be shown to be zero in the fully-resolved limit, and so fully-resolved simulations provide an appropriate test of the basic filtered-multiphase method, independent of the complex subgrid modeling that would be necessary for unresolved elements. In anticpation of future calculations of droplets, we demonstrate the method with two-dimensional calculations of fluid cylinder oscillations, and compare the results to an analytical solution.
Thin Liquid Film Flow on a Rotating Annular Disk: Asymptotic Solution
Authors: Daripa Prabir , Dandapat B. S. , Ray P. C.
Published: March 2009

We consider the axisymmetric flow of a Newtonian fluid associated with the spreading of a thin liquid film on a rotating annular disk. The effects of surface tension and gravity terms are included. The asymptotic solution for the free surface of the thin film is found using an expansion for the film thickness in powers of a small parameter characterizing the thickness of the film and applying the method of matched asymptotic expansion. This solution can be used to calculate the thickness of the film, the velocity field, and the pressure at any point on the disk with good accuracy. Numerical results are presented for a specific initial distribution of the film thickness. Many features of the spin-coating thinning process are captured by our asymptotic solution. We also produce results which are in excellent agreement with the experimental findings of Daughton and Givens (6) and Hwang and Ma (9).
A Marker-VOF Algorithm for Incompressible Flows With Interfaces
Authors: Scardovelli Ruben , Aulisa Eugenio , Manservisi Sandro , Marra Valerio
Published: March 2009

In this paper, we present a three-dimensional (3D) reconstruction algorithm for Cartesian grids and a split advection algorithm which is based on a two-dimensional (2D) Eulerian-Lagrangian scheme that conserves mass exactly for incompressible flows. In the Volume-of-Fluid/Piecewise Linear Interface Calculation (VOF/PLIC) method a linear function in every grid cell cut by the interface approximates the free surface or the surface between two immiscible phases. The reconstruction is not continuous, and not accurate in regions with high surface curvature or when the interface develops thin filaments. Therefore, we have developed a new 2D mixed markers and VOF algorithm that follows the motion of a smooth interface with a good conservation of volume. Results are shown for flows with nonconstant vorticity.
Coupled Dynamics of a Solid Piercing a Fluid Free Surface
Authors: Ciobotaru Remus M. , Bidoae Razvan , Raad Peter E.
Published: March 2009

This paper reports on numerical investigations of the dynamics of a moving sphere interacting with free surface flow in a three-dimensional, rectangular, confined channel. Each simulation consists of two phases. During the first phase, the sphere is fixed and the fluid flow around it is allowed to reach a stationary state. In the second phase, the sphere is allowed to oscillate vertically. The Froude number is shown to influence the dynamics of the sphere. Also, the influence of three different initial positions on the dynamics of the sphere are presented and discussed. The first initial condition corresponds to a surface-piercing sphere while the second and the third conditions correspond to a submerged sphere at two different depths beneath the free surface. The drag coefficient computed for the two initial conditions involving a fully submerged sphere is compared with the experimental (published) values for a sphere in an unbounded domain. The motion of the fluid flow around the moving solid body is based on the solution of the complete Navier-Stokes equations. The free surface deformation is solved by the use of an Eulerian-Lagrangian Marker and Micro Cell (ELMMC) method.
Experimental Study and Computer Simulation of Heat Transfer for High Flux Cooling Applications With Microchannels in Micro-Electro-Mechanical Systems (MEMS)
Authors: Peng Shuzhi , Chandratilleke Tilak T.
Published: March 2009

This paper aims to apply experiment and computer simulation to investigate heat transfer characteristics of different fluids through microchannels with different geometries. An experimental apparatus with multi-functions, low uncertainties, high precision and temperature control was constructed. The experimental results are compared with the results of computer simulations and theoretical predictions from the conventional laminar flow theory. The flow rate, temperature and pressure drop were measured at steady states to analyse flow characteristics. It was concluded that the effect of allowance for machining of microchannels on heat transfer characteristics could be neglected under lower flow rate. The fluid mass flow rate, the inlet temperature of fluid, and the geometric parameters, particularly the hydraulic diameter and aspect ratio H/Wm in rectangular microchannels were found to have a significant influence on fluid flow and heat transfer characteristics.
Determining the Quality of Numerical Solutions of Flows Through Turbomachinery Components
Authors: Itter L. , Bo¨hle M.
Published: March 2009

Numerical methods are available in different forms. There are codes, which are developed by universities or offered by companies for commercial use. It is still a problem for the user to determine the quality of a numerical method. In many cases, a code is applied for the development of turbomachinery components and the detailed question arise how the quality of a numerical solution of a flow through a turbomachinery component can be determined. It is the subject of the present paper to describe a strategy for this task. There are two different approaches. For the first numerical results are compared to those, which are based on an analytical model and dimension analysis. In the present paper an analytical model is introduced, which can be applied for the estimation of the flow losses inside a radial impeller in dependence of the geometry and the swirl on the suction side. The results of the model are compared with the results of numerical solutions and the differences are discussed. The second approach contains the application of the Richardson extrapolation. By the application of this technique it is possible to find out the order of a numerical method and to perform considerations concerning the accuracy of the solution in dependence of the mesh resolution.
Comparison of Large Eddy Simulation and Experimental Results of the Flow Around a Forward-Backward Facing Step
Authors: Talotte Corinne , Addad Yacine , Laurence Dominique , Jacob Marc , Giardi He´le`ne , Crouzet Fabien
Published: March 2009

SNCF (Socie´te´ Nationale des Chemins de Fer franc¸ais), PSA (Peugeot Citroe¨n), EDF (Electricite´ de France) and ECL (Ecole Centrale de Lyon) are involved in a common project whose issue is the potential evaluation of numerical simulation in aeroacoustics for transport applications. One of the methods chosen in the project consists in the calculation of the aeroacoustic source term through a Large Eddy Simulation (LES) and its implementation into a code based on the Linearized Euler’s Equations for the acoustic propagation (LEE). This paper presents a comparison of LES and experimental results of the aerodynamic field around a forward-backward facing step and the principle of the chain-up of LES results and LEE calculations.
Experimental and Computational Studies of Chaotic Stirring in Complex 3D Flows
Authors: Sotiropoulos Fotis , Lackey Tahirih C. , Jones S. Casey
Published: March 2009

Recent progress in experimental and computational studies of complex chaotically advected 3D flows is reviewed for the confined swirling flow in a cylindrical container with a rotating bottom and the open flow in a helical static mixer. The concept of Lagrangian averaging along particle paths, whose theoretical foundation stems from ergodic theory, is proposed as a powerful tool for constructing Poincare´ maps in numerical studies of confined flows. The same concept has also been employed to develop the first non-intrusive experimental technique for constructing Poincare´ maps in complex 3D flows. The potential of these ergodic concepts is demonstrated in computational and experimental studies for the confined swirling flow. Numerical computations for the helical mixer flow show that increasing the Reynolds number from Re = 100 to 500 leads to the appearance of unmixed islands in the flow. The mechanism that leads to the formation of such islands is shown to be linked to the growth of coherent helical vortices in the flow.
Turbulent Flow in a Stirred Tank With Permeable Impeller Blades
Authors: Kritzinger H. P. , Deelder B. C. , Kleijn C. R. , Derksen J. J. , Van den Akker H. E. A.
Published: March 2009

This paper presents results from the experimental investigation of single-phase flow in a prototype stirred tank reactor, which uses monolith catalyst blocks as impeller. These monolith catalyst supports have been used for a dual role: (i) as stirrer blades for agitation and (ii) to bring reactants in contact with the catalyst in a way that eliminates the need for product filtration. The reactors are under investigation as replacement for the standard slurry stirred tank reactors used in the catalytic processes in chemical industry. The flow field in the reactor with this novel impeller, was determined using LDA. Mean and fluctuating velocity data were measured for different monolith blocks and impeller speeds. Results show the normalized flow in the bulk of the tank to be independent of impeller speed and monolith type. Flow velocities through the monolith channels, which are crucial to bring the reactants in contact with the catalyst impregnated in the monolith walls, were measured with LDA. These velocities were found to be of the order of 30–70% of the impeller tip velocity, dependent on the impeller speed and monolith type.
Mechanism of Breakage of Drops in Oil/Water Dispersion in Kenics Mixer
Authors: Aylianawati  , Eddleston T. , Pacek A. W.
Published: March 2009

The mechanism of breakage in the turbulent flow in Kenics mixer has been investigated theoretically and experimentally. Drops trajectories (as a function of drop size and Re number) in the mixer were calculated using particle/drops tracking model and areas in the mixer where drops were exposed to the highest energy dissipation rate were identified. The calculated trajectories were experimentally verified in a glass Kenics mixer and the drop deformation/breakage was analyzed using high-speed video camera. The results indicate that even in turbulent flow, the mechanism of drop breakage depends on the Re number and position in the mixer.
Kinetic Modeling and Monte-Carlo Simulations of Droplet Coalescence in a Turbulent Gas Flow
Authors: Villedieu Philippe , Simonin Olivier
Published: March 2009

Two-phase gas-droplet flows are involved in a lot of industrial applications, especially in the combustion field (Diesel engine, turbomachinery, rocket engine,…). Among all the characteristics of the spray, the droplet size distribution generally has a major influence on the global performances of the system and must be accurately taken into account in a numerical simulation code. This is a difficult task because the carrier gas flow is very often turbulent. Hence, droplets located in the vicinity of the same point may have different velocities and coalesce, leading at the end to a strong modification of the initial droplet size distribution. The first part of our contribution will be devoted to the presentation of a new kinetic model for droplet coalescence in turbulent gas flows. This model is an extension, to the case of sprays, of the ideas introduced by Simonin, Deutsch and Lavie´ville in [1]. The key ingredient is the use of the “joint density function”, fgp (t, x, r, v, u), representing the density of droplets at time t, located at point x, with radius r and velocity v and “viewing” an instantaneous turbulent gas velocity u. The great advantage of using fgp (t, x, r, v, u) instead of the usual density function fp (t, x, r, v) is the possibility to close the collision operator, in the governing kinetic equation, with less restrictive assumptions on the velocity correlations of two colliding droplets. The link between this model and the usual one (relying on the so-called “chaos assumption”) will be discussed. In the second part of our contribution, we shall present a new Monte-Carlo algorithm derived from our kinetic model. Numerical simulation results, for some academic test cases (homogeneous isotropic turbulence), will be shown and compared to the results obtained with a classical algorithm for droplet collision, based on the chaos assumption (see for example [2] or [3]). The figure 1 below shows a comparison between the temporal evolution of the mass mean radius computed by a classical collision model (neglecting the influence of gas and droplet velocity correlation) and by the “joint-pdf” based model. In the first case, the growth rate of the droplet, due to coalescence phenomena, is overestimated. Moreover, figure 2 shows that the droplet kinetic energy, induced by the turbulent gas motion, decays rapidly with the chaos assumption based model, as already noticed by Lavie´ville et al [1] in the case of solid particle collisions.
Numerical Investigation of Influence of Surging Motion on Viscous Flows Around a Wigley Hull Running in Incident Waves
Authors: Hinatsu Munehiko , Hino Takanori
Published: March 2009

This paper presents the effect of surging motion on viscous flows around a Wigley ship running in incident waves through CFD simulation. The computational method used is based on the Navier-Stokes equations in unstructured grid system with pseudo-compressibility assumption. Since a ship changes its attitude when it runs in incident waves, we have to modify the code to be able to treat the ship motion by use of a moving grid technique. In order to simulate surging motion, the ship is connected with a spring to keep its mean position. We show the influence of surging motion on wake and ship resistance using springs of different strengths. Numerical results and discussions are shown.
POD Analysis of In-Cylinder Flows
Authors: Fogleman Mark , Rempfer Dietmar , Lumley John L. , Haworth Daniel
Published: March 2009

Both time-dependent and time-invariant Proper Orthogonal Decompositions are performed on LES and PIV data as an initial step in a study of tumble breakdown in in-cylinder flows. Evidence of tumble instability during compression is found in the time-dependent POD of both data sets. Time-invariant POD modes are presented which will be used later in low-dimensional models of these systems.
Development of the Large-Scale Structures in the Intermediate Region of the Three-Dimensional Wall Jet
Authors: Sun Hongguang , Ewing Dan
Published: March 2009

The development of the large-scale structures in the intermediate region of the three-dimensional wall jet was examined using measurements of the mean streamwise vorticity and the two-point, two-time correlations of the streamwise fluctuating velocity in the vertical and lateral directions. It was found that a dominant large-scale double horse-shoe structure persisted to 40 diameters downstream of the jet exit. It was also found that the structure continued to evolve throughout the intermediate field. In particular, the inner horse-shoe vortex was induced toward the wall, while the position of the outer horseshoe vortex relative to the half-width moved toward the centerline. The inclination of this structure relative to the wall also increased as the flow evolved downstream. These changes in the structure combined to cause the lateral spread rate of the jet to aprroximately double in the intermediate field.
The Measurements of Mean Flow Angles Between an Automotive Fan and Stator
Authors: Kopp Gregory A. , Martinuzzi Robert J.
Published: March 2009

Measurements of the mean velocity vector were conducted to determine the exit angle from an automotive engine cooling fan module. The measurements were made at 15 locations along a radius between the hub and the band. The radius investigated was located in a plane roughly half-way between the blade trailing edge and stator leading edge. A two-component laser Doppler velocimeter and a four-wire hot-wire probe were used to measure the flow fields. It was found that the results obtained from hot-wire anemometry will have significant bias errors when used to measure the velocity vectors between the fan and the stator unless phase-averaged data are obtained with the probe re-oriented by phase. The differences between the techniques occur because the distribution of instantaneous swirl angles is bi-modal. Further, the mean flow angle is close to a local minimum in the probability density function of the swirl angle. This will act to increase errors in measurement devices whose accuracy depends on flow direction (the quantity being measured) such as five-hole probes which are used in industry.
Reconstruction of Solid-Air Two Phase Flow CT Image Using Sampled Pattern Matching Method
Authors: Takei Masahiro , Li Hui , Ochi Mitsuaki , Saito Yoshifuru , Horii Kiyoshi
Published: March 2009

A new reconstruction method, which is called sampled pattern mating method (SPM), has been applied to an ill-posed inverse problem of a capacitance-computed tomography for solid air two-phase flow. As a result, the accuracy of the reconstructed image is improved as compared with a conventional Newton-Rampson iterative method. Moreover, the particles volume ratio in solid air two-phase flow calculated by SPM method is more accurate than the conventional method.
Multiphase Digital Particle Image Velocimetry in a Dispersed, Bubbly, Axisymmetric Jet
Authors: Chaine G. , Nikitopoulos D. E.
Published: March 2009

A particle image velocimetry (PIV) technique developed for application to two-phase flows is presented and validated. The technique is capable of simultaneously measuring carrier and bubble phase velocities on a plane. The validation experiments have been conducted in a vertical upwards, two-phase (water-air) bubbly jet flow at a Reynolds numbers of 5,673 and 11,345 and low bubble concentration matching the experiments of Stanley and Nikitopoulos (1998). Comparisons with measurements obtained by Stanley and Nikitopoulos (1998) using Phase Doppler Analysis (PDA) experiments indicate that the agreement between the two techniques is very satisfactory (deviations of the order of 5%) for both single-phase and two-phase jet carrier-flow velocities. In addition, bubble phase velocity measurements obtained from backlit visualizations of the bubbly jet flow using the bubble-tracking method of Fiedler et al. (2001) are successfully compared to those obtained from PIV. The PIV study confirms that bubbles experience a substantial deceleration in the unmixed core of the jet near field and illustrates carrier-phase mean-flow modification consistent with past point-wise measurements.
Experimental and Numerical Study of Convective Heat Transfer in an Array of Slot Jets
Authors: Buchlin Jean-Marie , Gouriet Jean-Baptiste , Planquart Philipe , van Beeck Jeroen , Renard Michel
Published: March 2009

The paper describes a study of convective heat transfer in a multiple-jet systems composed of straight and inclined slot nozzles. The application concerned is the fast cooling of moving strip. The experimental approach involves the application of infrared thermography associated with the steady-state heated foil technique. Three-dimensional numerical simulations performed with the code FLUENT compare agreeably with the IR data. The study aims to determine the effect on the average heat transfer coefficient of the slot Reynolds number up to the value of 100000, the nozzle spacing normalised by the slot hydraulic diameter in the range 6 ≤ W/S ≤ 18, the normalised nozzle emergence length, E/S, from 5 to 17 and the normalised nozzle to strip standoff distance Z/S from 3 to 10. The geometrical arrangements tested include perpendicular (90°) and tilted (60°) nozzles. A thermal entrainment phenomenon is found for cooling system of small width. A corrective factor is derived to account for this effect. The experimental findings are compared with existing correlation; deviations, which are observed at high values of the Reynolds number may reach 25%. The numerical simulation emphasises the benefit to use H2/N2 gas mixture to enhance significantly the cooling rate.
Performance Monitoring Systems for Power Plants: General Features and Application Models
Authors: Gambini M. , Vellini M.
Published: March 2009

The general features and benefits of a performance monitoring system (PMS) and its capabilities on plant auditing and management are illustrated. The criteria for the validation and reconciliation of the measured data are tackled and the energetic diagnosis of components, by means the comparison between current performance and expected one, is shown. A “on line–real time” monitoring system evaluates the current performance of the power plant immediately and realistically, as well as it informs the operator of problems as soon as they occur and provides diagnostic information so that the operator can remedy the problem. After generals about PMS, two application models are shown: the first one deals with the reconciliation of measured data and it has been numerically developed with reference to a heat recovery steam generator; the second one deals with the energetic diagnosis of plant components and it has been developed with reference to a steam condenser.
Implementation of SCR Systems for Three Boilers at the TVA Paradise Fossil Site
Authors: Schreyer Donald , Manaker Arnold , Pritchard Scot
Published: March 2009

In 1998, TVA undertook the implementation of Selective Catalytic Reduction systems at the Paradise Generating Station. The station has three fossil-fired cyclone boilers totaling 2515 Mw of power generation which have been online since the early 1960s for Paradise Units 1 and 2, and since 1970 for Unit 3. Design efforts started late 1998 with Paradise Unit 2, a 704 Mw cyclone-fired unit that went into operation for the May 2000 ozone season. This was followed by Paradise Unit 1, an identical 704 Mw unit that went into operation for the May 2001 ozone season. Paradise Unit 3, an 1107 Mw unit, is currently in manufacture and erection for placement into service for the 2003 ozone season. The Paradise Units 1 & 2 SCR modules are among the largest single modules in service for treating the entire flue gas path. The system design considered the operation of the boiler without overfire air NOx control, where the emission of NOx would be 688.5 g/GJ (1.6 lb/MMBtu) and with overfire air NOx emission of 370 g/GJ (0.86 lb/MMBtu). Paradise Units 1 & 2 are fitted with scrubbers and burn a high sulfur fuel. Paradise 3, not currently fitted with a scrubber, fires a blend of PRB and Utah bituminous coal. The SCR is configured with two modules. The SCR project guarantees are 90% NOx reduction, 2-ppm ammonia slip and a catalyst life of 20,000 hours. Each of the cyclone units retained their tubular air heaters. Each unit required the erection of either temporary or new ductwork from the air heater to the downstream equipment to allow the demolition of equipment that had been part of the gas path but is no longer in service. The old equipment had to be removed to permit the building of the SCRs. Each SCR unit is equipped with a full flow bypass and man-safe dampers. These man-safe dampers permitted the construction and maintenance of the SCR while the boiler was in operation. Paradise Unit 2’s SCR was fitted with steam soot blowers. Sonic horns were tested on a section of Unit 2 and based on the results, Paradise Unit 1 was fitted only with sonic horns for catalyst cleaning. The anhydrous ammonia unloading and storage facility is more than a mile from the ammonia vaporizers that are located at grade adjacent to their respective SCR unit. The monthly ammonia consumption under full power conditions for Paradise Units 1 & 2 and 90% NOx reduction is 1,703.3 m3 (450,000 gallons) per month with the overfire air system in service. This paper addresses the issues and decisions related to integration of the SCR systems and the experiences of manufacturing and erecting each of the SCR units.
Development of Surface-Stabilized Fuel Injectors With Sub-Three PPM NOx Emissions
Authors: Weakley Christopher K. , Greenberg Steven J. , Kendall Robert M. , McDougald Neil K. , Arellano Leonel O.
Published: March 2009

ALZETA Corporation has developed surface-stabilized fuel injectors for use with lean premixed combustors which provide extended turndown and ultra-low NOx emission performance. These injectors use a patented technique to form interacting radiant and blue-flame zones immediately above a selectively-perforated porous metal surface. This allows stable operation at low reaction temperatures. This technology is a successful extension of ALZETA’s line of proven Pyromat™ SB metal fiber burners. A proof-of-concept injector in a full-pressure test rig at NETL in Morgantown, West Virginia achieved sub-3 ppm NOx emissions with concurrent single-digit CO emissions, both corrected to 15% O2. Operating conditions ranged between inlet pressures of 182.4 kPa (1.8 atm) and 1236.2 kPa (12.2 atm), inlet temperatures between 86° C (186° F) and 455° C (850° F) and calculated adiabatic flame temperatures between 1466° C (2670° F) and 1593° C (2900° F). Testing with prototype fuel injectors in test rigs at Solar Turbines last year yielded similar results. In May of 2001, a Solar Saturn 1 MW gas-turbine engine was operated to 95% load with a surface-stabilized injector. Programs are moving forward to adapt these injectors to the Solar Turbines Taurus 60 and Titan 130 engines. Engine tests are scheduled to begin in 2003.
Thermodynamic Performance of Complex Gas Turbine Cycles
Authors: Sanjay  , Singh Onkar , Prasad B. N.
Published: March 2009

This paper deals with the thermodynamic performance of complex gas turbine cycles involving inter-cooling, re-heating and regeneration. The performance has been evaluated based on the mathematical modeling of various elements of gas turbine for the real situation. The fuel selected happens to be natural gas and the internal convection / film / transpiration air cooling of turbine bladings have been assumed. The analysis has been applied to the current state-of-the-art gas turbine technology and cycle parameters in four classes: Large industrial, Medium industrial, Aero-derivative and Small industrial. The results conform with the performance of actual gas turbine engines. It has been observed that the plant efficiency is higher at lower inter-cooling (surface), reheating and regeneration yields much higher efficiency and specific power as compared to simple cycle. There exists an optimum overall compression ratio and turbine inlet temperature in all types of complex configuration. The advanced turbine blade materials and coating withstand high blade temperature, yields higher efficiency as compared to lower blade temperature materials.
Technical Demonstration of Distributed Power Generation From Solid Wastes
Authors: Yoshikawa Kunio
Published: March 2009

An innovative small-scale gasification system for solid wastes is proposed which is known as STAR-MEET system. In this system, a fixed-bed pyrolyzer combined with a high temperature reformer using high temperature steam/air mixture is employed. From the experimental results using rubber chips as a fuel, it has been demonstrated that injection of high temperature steam/air mixture into the pyrolysis gas effectively decomposes tar and soot components in the pyrolysis gas into CO and H2, and almost dust and tar free clean reformed gas can be generated. The STAR-MEET system requires high temperature steam/air generator, and a 900C class metallic type compact heat exchanger has been successfully developed. This gasification system generates low BTU gas from solid wastes. Thus power generation experiments using a dual fueled (light oil gas and low BTU gas) small diesel engine were done using a simulated low BTU gas produced from natural gas diluted with nitrogen. Compared with light oil only driven, dual fueled engine shows similar thermal efficiency while significantly low NOx emission. Finally, power generation experiments using a complete STAR-MEET plant has been successfully done. These results demonstrates small-scale gasification and power generation system using solid wastes is quite feasible.
Probabilistic Analysis of Turbine Disc SCC Incubation and Propagation
Authors: Lam Tony C. T. , Dewey Robert
Published: March 2009

Stress corrosion cracking (SCC) is a common problem found on aging low-pressure turbine (LP) rotors that operate in a wet/dry stream environment. While much has been published on the growth rate of SCC in turbine rotor-disk materials, incubation time is rarely addressed. Since no effective way has been demonstrated to prevent disk rim SCC from occurring other than to replace the damaged rim with a weld repair of higher chromium content, a better understanding of incubation time could provide operators with a means to treat SCC before cracks are large enough to start to grow. This paper discusses the critical mechanisms involved in the SCC incubation, process and describes a probabilistic approach to make meaningful assessments of incubation time. Data published for General Electric turbine rotors is used to test the model.
Hydrogen Gasifier From Acid Water and Its Energy Systems
Authors: Kato Seizo , Shimizu Tatsuya
Published: March 2009

The fossil fuel depletion and the CO2 warming due to the combustion are becoming serious environmental issues. Therefore, alternative energy systems minimumizing fossil fuels dependence are now required to be developted. Hydrogen is a best candidate for alternative energy sources friendly to the environment, but the essential point is how we produce hydrogen, independently of fossil fuel with a minimum energy input. This work aims first at proposing an alternative hydrogen gasifier from acid water by immersing ionicity metals, and second at applying the gasifier to a hydrogen ultra micro gas turbine electric generator charger system to construct hydrogen self supply energy system. First, D2SO4 as acid aqueous solutions and (Zn+Cu) and Zn plates as ionicity metals electrodes are selected here for H2 gasifier. The hydrogen production rate is experimentally characterized by changing the pH and temperature of the solution and the metal surface area. The gasifier has a good performance of hydrogen production of about 18 l/min at 60°C per unit electrode area under the pH = ∼1.0. This flow rate increases almost linearly to the acid temperature. In addition, the zinc resolved into the acid water, ZnSO4 in the case of D2SO4 for example, is able to be easily recrystalized on the electrode by reasonable electricity input of ∼2.5V. Second, the produced hydrogen is applied to ultra micro turbo electric generator / charger as hydrogen self supply system. This smart system is well applicable to hydrogen electric car, because of an ideal power source having small size, lightweight, low vibration, early start, no NOX and CO2 emissions, very low fuel consumption, long trip, etc. In the experiment a car turbo charger is converted into a compressorturbine system, and a high revolution electricity generator is connected to the turbo system. A combustor is designed for very low hydrogen consumption by ultra lean burning which causes almost no NOX emission due to low temperature < 1000°C. The turbo system is tested, resulting in a high efficiency, in spite of its small size, enough to generate electricity for charging a battery of electric car. By using these two elements, we aim to construct HSSES (Hydrogen Self Supply Energy System) which is found to be attractive especially for small electric cars and home cogenerations.
Repowering Considerations for Converting Existing Power Plants to Combined Cycle Power Plants
Authors: Singh Anup , Kopecky Don
Published: March 2009

Most of the recent combined cycle plants have been designed and constructed as Greenfield Plants. These new plants have been designed mostly as Merchant Plants, owned and operated by Independent Power Producers. There is about 260,000 MW of conventional coal-fired and gas-fired capacity in the USA that is more than 30 years old. About 30,000 MW of conventional gas-fired capacity exists in the area of The Electric Reliability Council of Texas (ERCOT) with relatively poor heat rates in comparison to modern combined cycle plants. These plants are good candidates for HRSG repowering. In addition, there are several coal-fired units in the 200 MW range with steam turbines in relatively good shape or in a condition that can be refurbished and used in repowering. The installed cost of repowered (also called Brownfield) capacity is about 20%–40% less than for comparable Greenfield capacity. There are also other advantages to repowering. Since the site is already existing, it is easier to get the various environmental and construction permits. The efficiency of the repowered units will be significantly higher than the existing units in their current status thus increasing the overall performance of the entire system. The paper will discuss various considerations required for repowering, including steam turbine refurbishment, demolition/relocation of existing equipment, recent cost studies, and various considerations for equipment such as HRSGs.
Heat Transfer Characteristics of Turbulent Flames in Three-Dimensional Furnaces
Authors: Khalil Essam E.
Published: March 2009

The recent advances in numerical methods and the vast development of computers have directed the designers to better development and modifications to air-flow pattern and heat transfer in combustion chambers. Extensive efforts are exerted to adequately predict the air velocity and turbulence intensity distributions in the combustor zones, and to reduce the air pollution and noise abatement to ultimately produce quite and energy efficient combustor systems. The present work utilizes mathematical modeling techniques to primarily predict what happens in three-dimensional combustion chambers simulating boiler furnaces, and areo engines in terms of flow regimes and interactions. The present work also demonstrates the effect of chamber design and operational parameters on performance, wall shear stresses, and vorticity under various operating parameters. The governing equations of mass, momentum and energy are commonly expressed in a preset form with source terms to represent pressure radients, turbulence and viscous action. The physical and chemical characteristics of the air and fuel are obtained from tabulated data in the literature. The flow regimes and heat transfer plays an important role in the efficiency and utilization of energy. The behavior was found to be strongly dependent on turbulent shear, mixing, blockage, wall conditions and location of fuel and air inlets. Eddies can be strong enough to have higher velocities typically near reactants supply openings. Excessive transverse flow velocities cause extra macromixing; the air flow regimes are complex and of three-dimensional nature; with the advance of computational techniques it is possible to accurately simulate three-dimensional flows. The results reported in this work were obtained with the aid of the three-dimensional program 3DCOMB; applied to axisymmetrical and three-dimensional complex geometry with and without swirl. The present numerical grid comprises, typically, 144000-grid node covering the combustion chamber volume in the X, R or Y and Z coordinates directions. The numerical residual in the governing equations typically less than 0.001%. A modified grid generation formula was proposed and incorporated in the present work. Examples of large industrial furnaces are shown and were in good agreement with available measurements in the open literature. One may conclude that flow patterns, turbulence and heat transfer in combustors are strongly affected by the inlet swirl, inlet momentum ratios, combustor geometry; both micro and macro mixing levels are influential. Greater tangential velocities and turbulence characteristics are demonstrated in situations with higher swirl intensities. The present modeling capabilities can adequately predict the local flow pattern and turbulence kinetic energy levels in complex combustors.
GENCOs’ Arbitrage by STRATIGIST in the Deregulated Power Markets
Authors: Yamin H. Y. , Othman Hisham
Published: March 2009

This paper presents different kinds of arbitrage opportunities in deregulated power markets such as arbitrage between energy and ancillary service, arbitrage of bilateral contracts, and arbitrage between gas and power. STRATEGIST is a C++ software package that incorporates a probabilistic approach for the evaluation of composite reliability of generation, load forecast and fuel prices using different probability distributions. STRATEGIST analyses the risk and arbitrage opportunities in a deregulated power market. This package is to be used by GENCOs to maximize their profit as well as to hedge the GENCOs to against crucial loss of profit. A typical scenario for applying this package is a GENCO which tries to supply its native load and trade bilateral transactions and would be interested in determining the risk associated with different alternatives. STRATEGIST is designed based on a comprehensive analysis of various risks in a portfolio.
A Model for Sizing High Consequence Areas Associated With Natural Gas Pipelines
Authors: Stephens Mark J. , Leewis Keith , Moore Daron K.
Published: March 2009

The failure of a high-pressure natural gas pipeline can lead to various outcomes, some of which can pose a significant threat to people and property in the immediate vicinity of the failure location. The dominant hazard is thermal radiation from a sustained jet or trench fire. An estimate of the ground area affected by a credible worst-case failure event can be obtained from a model that characterizes the heat intensity associated with rupture failure of the pipe where the escaping gas is assumed to feed a sustained trench fire that ignites very soon after line failure. An equation has been developed that relates the diameter and operating pressure of a pipeline to the size of the area likely to experience high consequences in the event of an ignited rupture failure. The model upon which the hazard area equation is based consists of three parts: 1) a fire model that relates the rate of gas release to the heat intensity of the fire as a function of distance from the fire source; 2) an effective release rate model that provides a representative steady-state approximation to the actual transient release rate; and 3) a heat intensity threshold that establishes the sustained heat intensity level above which the effects on people and property are consistent with the adopted definition of a so-called High Consequence Area. The validity of the proposed model is established by a comparison between the predicted extent of the damage area and the actual extent of damage for significant gas pipeline failure incidents reported in the public domain.
Geometric Dent Characterization
Authors: Dinovitzer A. , Lazor R. , Carroll L. B. , Zhou J. , McCarver F. , Ironside S. , Raghu D. , Keith K.
Published: March 2009

The Canadian pipeline design standard (CSA Z662) requires the repair of smooth dents with depths exceeding 6% of the pipeline’s outside diameter. This limit on dent depth is reduced in the presence of additional localized effects such as pipe wall gouges, corrosion, planar flaws or weld seams. It has been noted, however, that pipelines have operated satisfactorily with dents in excess of 10% while others with 3% dents have failed. Based upon observation of this type the question arises, “Is there more to characterizing a dent than its depth?” An ongoing group sponsored project at BMT Fleet Technology Limited (FTL) is exploring the issue of dent characterization using a dent assessment model developed at FTL. The objective of this project is to develop a rapid dent life expectancy characterization technique based upon dent geometry, line pressure history and line pipe material properties. This paper will outline the general characterization approach being considered and demonstrate some of the observed and expected relationships between service life and dent geometry. The relative importance of each dent characteristic (geometric measures, line pipe material and line pressure history) will be discussed to demonstrate the potential of the rapid characterization approach being developed.
Microstructure/Property Examination of Weld HAZ in Grade 100 Microalloyed Steel
Authors: Poorhaydari K. , Patchett B. M. , Ivey D. G.
Published: March 2009

The weld thermal cycle in microalloyed pipeline and structural steels results in significant changes in microstructure and, consequently, mechanical properties of the weld heat-affected zone (HAZ). To have better control of the properties of the HAZ, knowledge of these changes and correlation with mechanical property variations is required. The first step in achieving this is to construct a methodology to examine different regions of the HAZ thoroughly, so that important characteristics such as grain size, microstructure, precipitate type and distribution, and mechanical properties are determined. The next step would be using this methodology to examine different regions of the HAZ under different welding conditions (the most important of which is heat input) and therefore to understand the effects of the welding process. In this paper, a methodology for studying HAZ microstructure/property relationships is demonstrated for a Grade 100 microalloyed steel welded autogenously (no filler metal). Microhardness measurements are used to assess the mechanical property variation across the HAZ. Optical microscopy (OM) and transmission electron microscopy (TEM) are used for grain structure examination and precipitate analysis. The relationship between microstructure and mechanical properties, with emphasis on precipitate reactions, is presented for different regions of the HAZ.
Coatings and Backfill System Optimisation
Authors: Thompson Ian , Espiner Richard , Barnett Julian
Published: March 2009

Early consideration of geotechnical conditions in coating selection and backfill design could prove technically, economically and environmentally beneficial. In addition, bedding, padding and backfilling requirements are not specified on a project specific basis and the current methodology for design, engineering and construction does not allow optimisation of the coating and backfill system. This paper is intended to review the financial and technical issues that need to be considered when selecting external coating systems for the corrosion protection of high-pressure transmission pipelines.