bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Commissioning for the Piloted Syngas Burner
Authors: Foote John P. , Pillsbury Paul , Morton Frank C.
Published: November 2008

A gas turbine combuster has been designed to burn coal derived syngas with a lower heating value (LHV) of less than 3700 kJ/Nm3 (100 Btu/scf). The new Piloted Syngas Burner (PSB) is designed to operate with a continuous propane pilot during syngas firing to maintain flame stability. The amount of propane supplied to the pilot can be adjusted in response to a burner noise measurement or other indications of flame stability, with the ultimate goal of operating only on syngas. The burner has a very large combustion volume to promote burnout of less than 3700 kJ/Nm3 syngas and incorporates a high-efficiency liner cooling scheme, to allow utilization of high energy fuel for starting and backup. The PSB is being tested at the U.S. Department of Energy’s (DOE) Power Systems Development Facility (PSDF) in Wilsonville, AL, where it replaces the usual six combustor cans in a Rolls-Royce Allison 501-KM gas turbine. Syngas is supplied to the burner from a Transport Reactor coal gasifier. Initial operation of the PSB on propane startup fuel was successfully conducted during February 2003, and initial operation on syngas was successfully conducted during October 2003. The paper will discuss the results of the initial propane and syngas operation. The PSB is expected to be operated extensively in 2004.
Prognostic Enhancements to Diagnostic Systems (PEDS) Applied to Shipboard Power Generation Systems
Authors: Byington Carl S. , Roemer Michael J. , Watson Matthew J. , Galie Thomas R. , Savage Christopher
Published: November 2008

Numerous advancements have been made in gas turbine health monitoring technologies focused on detection, classification, and prediction of developing machinery faults and performance degradation. Existing monitoring systems such as ICAS (Integrated Condition Assessment System), which is the Navy’s program of record and is deployed on many US Navy ships, employ alarm thresholds and event detection using rule-based algorithms. Adding the capability to predict the future condition (prognostics) of a machine would add significant benefit to the Navy practice. The current paper describes a framework and development process that allows more “plug ‘n play” integration of new diagnostic and prognostic technologies using evolving Open System Architecture (OSA) standards. Although many modules were developed in the PEDS framework, specific gas turbine modules that focus on compressor and nozzle degradation algorithms are discussed. The modules use statistical prediction algorithms and were developed using seeded fault data generated by the Navy engineering station. The modules are fully automated, interact with the existing monitoring system, process real-time data, and utilize advanced forecasting techniques. Such an advanced prognostic capability can enable a higher level of condition-based maintenance for optimally managing total Life Cycle Costs (LCC) and readiness of assets.
Numerical Simulation of the Acoustic Pressure Field in an Annular Combustion Chamber With Helmholtz Resonators
Authors: Camporeale S. M. , Forte A. , Fortunato B. , Mastrovito M. , Ferrante A.
Published: November 2008

In modern gas turbines in which lean premixed flames are used to obtain low NOx emissions, large pressure oscillations may arise inside the combustor due to thermoacoustic combustion instability at frequencies corresponding to the natural acoustic frequency of the system. Such pressure fluctuations, that may cause structural damages, need to be damped in order to avoid a reduction of the operational range of the gas turbine. In this work Helmholtz resonators connected to the external envelope of the combustion chamber are examined as passive systems for damping the low frequency acoustic pressure in the case of an annular combustor. The acoustical behavior of the combustor has been first investigated by means of the Finite Element method, obtaining its acoustic eigenmodes and eigenfrequencies in order to tune the Helmholtz resonators on the frequency to be damped. In order to characterize the resonator, preliminary tests have been carried out on a simplified system composed of a Helmholtz resonator applied at the end of an impedance tube. Then the eigenmodes of the system obtained by connecting one or more resonators to the annular chamber and the damping effects obtained by varying the geometry, the number and the position of the resonators are analyzed. It appears that the peak of acoustic pressure characterizing the combustion chamber splits into two peaks of lower magnitude when the Helmholtz resonators are applied and the peak frequencies are correlated to the overall volume of resonant cavities, whilst lower effects are obtained by varying the position and the number of resonator units.
Simulation of PAHs in Trapped-Vortex Combustor
Authors: Katta Viswanath R. , Roquemore William M.
Published: November 2008

Residence time and thermo-chemical environment are important factors in determining soot-formation characteristics of jet engine combustors. For understanding the chemical and physical structure of the soot formed in these combustors knowledge on flow dynamics and formation of polycyclic aromatics-hydrocarbons (PAHs) is required. A time-dependent, detailed-chemistry computational-fluid-dynamic (CFD) model is developed for the simulation of the reacting flows in a trapped-vortex combustor. The axisymmetric trapped-vortex combustor of Hsu et al. was modeled by replacing injection holes with injection slots. Ethylene-air mixtures were used as fuel. Several calculations were made by varying the equivalence ratio and velocity of the main flow. Unsteady simulations revealed that the shearlayer vortices established outside the cavity flow enhance mixing of benzene in the wake region of the afterbody. However, in all the cases considered here, majority of the PAH species are produced in the cavity region. While fuel-rich condition resulted lower amounts of PAHs in the cavity region, soot is produced more in this region.
Detection and Localization of Fouling in a Gas Turbine Compressor From Aerothermodynamic Measurements
Authors: Millsaps Knox T. , Baker Jon , Patterson Jeffrey S.
Published: November 2008

This paper presents a new method for condition assessment of axial flow compressors that provides a tool for specifying the magnitude and location of degradation due to fouling. A simple, meanline, stage-stacking analysis is developed, which includes the impact of blade roughness on the mass flow, work coefficient, and efficiency. The performance of a baseline, three-stage compressor with hydrodynamically smooth blades is calculated. Using the baseline geometry, the influence of roughness of the blade surfaces in the front, middle and rear stages are calculated. Empirical data for the increased total pressure losses and greater turning deviation that occurs due to rough blades are used. This analysis indicates that airfoil fouling in different stages, produce characteristic aerothermodynamic signatures, and hence the faults can be localized by the magnitudes of the various influence coefficients. This analysis also predicts that the most sensitive parameter for predicting fouling in the front stages is the percentage change in mass flow and the most sensitive parameter for predicting fouling in the rear stages is the adiabatic efficiency.
Micro Scale Slow-Pyrolysis Rotary Kiln for Syngas and Char Production From Biomass and Waste: Design and Construction of a Reactor Test Bench
Authors: Fantozzi Francesco , Desideri Umberto
Published: November 2008

Slow pyrolysis of waste and biomass may represent an interesting solution for renewable energy conversion in highly regenerative Gas Turbine (GT) or Internal Combustion Engines (ICE) based power cycles. The combined production of a medium LHV gas to fuel the GT or the ICE and of a high LHV byproduct (tar and/or char) that may contribute to maintain the pyrolysis process, makes pyrolysis highly competitive when compared to gasification. Nevertheless few simulations of such integrated plants are available in literature also because of the lack of general and robust modeling tools for the pyrolysis process. A pilot scale rotary kiln pyrolyzer was built at the University of Perugia to investigate the main benefits and drawbacks of the technology. The pyrolyzer will provide the experimental data that are necessary both to evaluate mass and energy balances, and to support the pyrolysis simulation activity that the authors are carrying out. Namely the test rig will provide, for each given quantity and composition of the biomass or waste in input, the gas, char and tar yields and compositions and the energy provided to maintain the process. This paper describes the main features and operational possibilities of the plant.
Comparison of Thermo-Hydraulic Characteristics for Two Types of Dimpled Surfaces
Authors: Borisov Igor , Khalatov Artem , Kobzar Sergei , Glezer B.
Published: November 2008

Heat transfer and pressure loss data have been obtained for internal flow in confined rectangular channel enhanced with two types of heat transfer augmenters: dimple concavities and combination of dimples on one side with concentrically arranged toroidal banks protruding into the channel on another side. Three different concavity array densities were studied for channel height bulk flow Reynolds numbers based on an equivalent inlet height of a rectangular passage* (foot note) and ranging from 770 to 26,500. Using the average heat transfer coefficient for the fully stabilized region, the overall heat transfer enhancements were compared to baseline smooth channel data. Friction coefficients were also compared to values for a smooth channel. As expected, the surface with banked dimples produces higher heat transfer at the cost of higher friction losses. Initial steps were made to optimize the density of the banked dimple geometry to achieve or exceed heat transfer performance of dimpled surface. Comparison was made for the same depth-to-dimple diameter ratio of 0.2. The results showed that heat transfer enhancements factor in the channel with one side augmented with dimples and another side augmented with banks at the density of 73% can reach 4.3 compared to the enhancement of 3.7 for a high density (67%) double-sided dimpled passage. The corresponding friction factor for studied dimple-bank configuration is reaching 27.0 compared to 2.3 for the dimpled channel. Obtained data indicates that a further improvement in thermo-hydraulic performance of dimpled surfaces is achievable.
Unsteady Aerodynamics of an Aero-Engine Double Swirler LPP Burner
Authors: Canepa Edward , Di Martino Pasquale , Formosa Piergiorgio , Ubaldi Marina , Zunino Pietro
Published: November 2008

Lean premixing prevaporizing burners represent a promising solution for low-emission combustion in aeroengines. Since lean premixed combustion suffers from pressure and heat release fluctuations that can be triggered by unsteady large-scale flow structures, a deep knowledge of flow structures formation mechanisms in complex swirling flows is a necessary step in suppressing combustion instabilities. The present paper describes a detailed investigation of the unsteady aerodynamics of a large scale model of a double swirler aero-engine LPP burner at isothermal conditions. A 3-D laser Doppler velocimeter and an ensemble averaging technique have been employed to obtain a detailed time-resolved description of the periodically perturbed flow field at the mixing duct exit and associated Reynolds stress and vorticity distributions. Results show a swirling annular jet with an extended region of reverse flow near to the axis. The flow is dominated by a strong periodic perturbation which occurs in all the three components of velocity. Radial velocity fluctuations cause important periodic displacement of the jet and the inner separated region in the meridional plane. The flow, as expected, is highly turbulent. The periodic stress components have the same order of magnitude of the Reynolds stress components. As a consequence the flow mixing process is highly enhanced. While turbulence acts on a large spectrum of fluctuation frequencies, the large scale motion influences the whole flow field in an ordered way that can be dangerous for stability in reactive conditions.
Conjugate Heat Transfer Simulation of a Radially Cooled Gas Turbine Vane
Authors: Facchini Bruno , Magi Andrea , Scotti Del Greco Alberto
Published: November 2008

A 3D conjugate heat transfer simulation of a radially cooled gas turbine vane has been performed using STAR-CD™ code and the metal temperature distribution of the blade has been obtained. The study focused on the linear NASA-C3X cascade, for which experimental data are available; the blade is internally cooled by air through ten radially oriented circular cross section channels. According to the chosen approach, boundary conditions for the conjugate analysis were specified only at the inlet and outlet planes and on the openings of the internal cooling channels: neither temperature distribution nor heat flux profile were assigned along the walls. Static pressure, external temperature and heat transfer coefficient distributions along the vane were compared with experimental data. In addition, in order to asses the impact of transition on heat transfer profile, just the external flow (supposed fully turbulent in the conjugate approach) was separately simulated with TRAF code too and the behaviour of the transitional boundary layer has been analyzed and discussed. Loading distributions were found to be in good agreement with experiments for both conjugate and non conjugate approaches, but, since both pressure and suction side exhibit a typical transitional behavior, HTC profiles obtained without taking into account transition severely overestimate experimental data especially near the leading edge. Results confirm the significant role of transition in predicting heat transfer and, therefore, vane temperature field when a conjugate analysis is performed.
Measurements, Computation and Analysis of a Semi-Constrained, Axisymmetric Impinging Jet
Authors: Adolfson David A. , Simon Terrence W. , Ibrahim Mounir B.
Published: November 2008

Experiments, closed-form analysis and computation were conducted to investigate flow in a semi-constrained, axisymmetric impinging jet. The aspect ratios (i.e. plate separation divided by jet diameter, S/D) were 0.25 and 0.59. Reynolds numbers based on jet diameter were approximately 7,600 and 17,700. Data collection was via hot-wire anemometry and flow visualization. Data consisted of a series of mean velocity profiles across the wall-jet boundary layer in the attached-flow region, power spectral distributions at selected points within the boundary layer and flow visualization. Spectra were used to help identify transition to turbulence of the wall layer. Flow visualization was conducted by seeding the flow with neutrally-buoyant bubbles, illuminating the bubbles with a laser sheet and capturing pictures with a standard 35mm camera. An approximate closed-form analysis is presented. It gives theoretical values of shear stress of a stagnation flow which approximately models the target plate flow and yields a set of parameters for generalizing the experimental and CFD results. Numerical simulations of the flow based upon solution of the RANS equations and various turbulence closure models are presented. Results of analyses with three different closure models are discussed in this paper: a) all laminar (no turbulence), b) k-ω turbulence closure model and c) k-ε turbulence closure model. The results from the k-ω model are generally in better agreement with the experimental results than are the k-ε model results. The performance of the three models is discussed. A need for proper modeling of transition within the flow is shown. This study serves to support computation of flows which have impingement, acceleration, adverse pressure gradients, transition to turbulence and flow separation using the low-aspect-ratio, semi-constrained, steady impinging jet.
Validation of CESI Blade Life Management System by Case Hstories, On Line Measurements and In Situ NDT
Authors: Rinaldi Claudia , Bicego Valerio , Colombo Pier Paolo
Published: November 2008

A Life Management System was developed for hot components of large industrial gas turbines, in the form of a software tool for predicting component lives under typical operational transients (normal and also abnormal) and steady-state periods. The method utilises results of previous thermo-mechanical finite element and finite volume fluid mechanics analyses. The basic idea of this method is using data from structural and aero-thermal analyses (pressures and temperatures), blade life theory and material properties as an input to algorithms, and using operational and historical data to validate the predicted damage amounts. The software developed in this project, of general applicability to all GT models, has been implemented with reference to the geometries, materials and service conditions of a Fiat-Westinghouse model.
Flow Phenomenon in Steam Turbine Disk-Stator Cavities Channeled by Balance Holes
Authors: Moroz L. , Tarasov A.
Published: November 2008

Computational fluid dynamic (CFD) analysis of the region the secondary flow path of high pressure steam turbine was conducted. Region included two adjacent to disc cavities and section of main flow path. The cavities were channeled by balance holes located in the disk. Two geometrical models were considered: single disk cavity and both cavities with balance holes. 2D axisymmetric and 3D analyses were conducted for the first model, however only 3D study was performed for the second one. Analysis of the single disk cavity has revealed appearance of vortexes in circumferential direction even in case when all boundary conditions and geometry features were close to the axi-symmetric case. The trend of the average pressure distributions along radius was found for 2D and 3D models. The transient analysis of the two cavity model revealed vortexes movement in circumferential direction with higher than disk rotation velocity. It induces periodic conditions at the inlet and outlet of balance hole and periodic steam mass flow rate through the holes. The flow pattern in the two cavities with balance holes is so complicated that common 1D net flow representation should be considered as significant simplification.
In-Situ Monitoring of Damage in SiC/SiC Composites Using Acousto-Ultrasonics
Authors: Gyekenyesi Andrew L. , Morscher Gregory N. , Cosgriff Laura M.
Published: November 2008

Acousto-ultrasonics (AU) is a nondestructive evaluation (NDE) technique that utilizes two ultrasonic transducers to interrogate the condition of a test specimen. The sending transducer introduces an ultrasonic pulse at a point on the surface of the specimen while a receiving transducer detects the signal after it has passed through the material. The aim of the method is to correlate certain empirical parameters of the detected waveform to characteristics of the material between the two transducers. The waveform parameter of interest is the attenuation due to internal damping for which information is being garnered from the frequency domain. Here, the three parameters utilized to indirectly quantify the attenuation are the ultrasonic decay rate, the mean square value of the power spectrum, and the centroid of the power spectrum. The sensitivity for each of these AU parameters was assessed with respect to the damage state of two types of SiC/SiC ceramic matrix composites (CMC). The two composite systems both had Hi-NicalonTM fibers with a carbon interface but had different matrix compositions that led to considerable differences in damage accumulation. Load/unload/reload tensile tests were performed and in-situ AU measurements were made over the entire stress range. After analyzing the AU parameters, the overall sensitivity of the AU technique to material change or damage was quantified and shown to correlate well with the observed damage mechanisms for both material systems. In addition, the AU response was shown to be dependent on the stress state of the composites. This stress dependent behavior was observed while unloading the specimens from the maximum stress, thereby, maintaining a constant damage state.
Austenitic Stainless Steels and Alloys With Improved High-Temperature Performance for Advanced Microturbine Recuperators
Authors: Maziasz Philip J. , Pint Bruce A. , Shingledecker John P. , More Karren L. , Evans Neal D. , Lara-Curzio Edgar
Published: November 2008

Compact recuperators/heat-exchangers increase the efficiency of both microturbines and smaller industrial gas turbines. Most recuperators today are made from 347 stainless steel and operate well below 700°C. Larger engine sizes, higher exhaust temperatures and alternate fuels all demand recuperator materials with greater performance (creep strength, corrosion resistance) and reliability than 347 steel, especially for temperatures of 700–750°C. The Department of Energy (DOE) sponsors programs at the Oak Ridge National Laboratory (ORNL) to produce and evaluate cost-effective high-temperature recuperator alloys. This paper summarizes the latest high-temperature creep and corrosion data for a commercial 347 steel with modified processing for better creep resistanc, and for advanced commercial alloys with significantly better creep and corrosion resistance, including alloys NF709, HR120. Similar data are also provided on small lab heats of several new ORNL modified stainless steels.
Thermodynamic and Pinch Analyses for Improving Efficiency and Structure of a CRCC Plant With Natural Gas Reforming and CO2 Absorption
Authors: Lazzaretto Andrea , Daniele Denis
Published: November 2008

The need for improving performance and efficiency of thermal systems while reducing costs and environmental impact generally implies complex structures with several components and re-circulating material and energy flows to be considered. Some of the links among these components are often imposed by technological or ambient constraints, other links are decided by the designer to pursue one of more desired objectives (typically efficiency maximization, reduction of costs and environmental impact). In particular, the objective of efficiency maximization requires to correctly exploit all thermal flows available, that is to match hot and cold streams in order to minimize losses for the overall system. To do that, a method was suggested by the first author that consists in maximizing the efficiency of a so called “basic plant configuration” in which hot and cold thermal flows are considered independently of the structure of the heat exchanger network that will realize the heat transfer, whereas the other components have a fixed position in the structure lay-out. The method is applied here to a Chemically Recuperated Combined Cycle (CRCC) power plant with natural gas reforming and CO2 absorption. Optimum matching of hot and cold streams is obtained using thermodynamic and Pinch Technology evaluations at each step of an overall design improvement procedure of the total plant. Results show how the information obtained by combining Pinch Analysis and thermodynamic evaluations can be useful to obtain guidelines for improving the design configuration and parameters of complex energy systems.
Unsteady Simulation and Investigation of Tip Leakage Flow Based on Dissipation Function
Authors: Hassanvand Mohsen , Tao Wang Song , Tai Feng Guo , Qi Wang Zhong
Published: November 2008

Further improvements of flow in tip clearance demand a better understanding of its complex structure and this would not be possible if we are not able to provide an interpretative or a more realistic presentation of its main effects, i.e., viscous dissipation and mixing. To do so and to gain further insights into the details and distribution of viscous dissipation, a commercial N-S solver has been employed for simulation and investigation of the unsteady flow field inside the tip clearance of a turbine rotor in first stage. The main objective of this paper is to introduce the direct implementation of dissipation function for viscous dissipation assessment in tip leakage flow. This idea seems to be the simplest and at the same time, the most straightforward approach to simulate and calculate the viscous dissipation caused by viscous effects. It is shown that the dissipation function can be employed as a strong and convenient tool in direct identification and assessment of regions of high viscous dissipation. It has been found that in tip leakage flow, regions of high viscous effects are located near casing rather than blade tip. Near casing, leakage flow creates a source point in pressure side and a sink point in suction side on rotor blade tip projection on the casing. It is shown that the time-averaged viscous dissipation in tip leakage flow is dissimilar for rotor blades. This result, which is caused by flow unsteadiness, is a helpful hint that can be taken by blade designers to design non-uniform rotor blades, that is, to design blades with different geometries and aerodynamic loads, both circumferentially and radially, to minimize the viscous dissipation. The casing passage vortex, the end wall boundary layers, and the wakes from the upstream stator significantly enhance the unsteadiness of the flow to the tip region of rotor blades. Results indicate that there exists a strong interaction between leakage flow and annulus-wall boundary layer.
Installation and Planned Testing of the 625 kW Molten Carbonate Ship Service Fuel Cell
Authors: Nickens Anthony , Hoffman Donald , Cervi Mark , House Edward
Published: November 2008

The U.S. Navy Ship Service Fuel Cell (SSFC) program is approaching the testing phase of the 625 KW molten carbonate ship service fuel cell generator. Testing is scheduled to occur in fiscal year 2005. The objective of the SSFC program is to develop diesel fueled shipboard fuel cell power systems with optimized performance characteristics (cost, weight, volume, and efficiency) which, when considered in the total ship environment, provide superior performance at a competitive cost compared to traditional shipboard generators. Emphasis has been placed on adapting commercially developed fuel cell technology to meet Navy/Marine requirements including operation in a salt-laden air, reforming and purification of naval logistics fuel, ship motion, shock and vibration. Fuel Cell Energy Inc., under an ONR contract. is adapting its commercial direct carbonate fuel cell technology for use with naval logistics fuels to provide power suitable for ship application. This paper provides a description of the fuel cell system and details of the installation and planned operation of the unit at the Philadelphia test site.
Flutter of Mistuned Bladed Disks and Blisks With Aerodynamic and FMM Structural Coupling
Authors: Kielb Robert E. , Feiner Drew M. , Griffin Jerry H. , Miyakozawa Tomokazu
Published: November 2008

This paper presents the initial results from a research effort on blisk and bladed disk mistuning including both structural and aerodynamic coupling. The structural coupling model is based on the Fundamental Mistuning Model (FMM, developed by Feiner & Griffin). This effort extends the FMM technique to accept the aerodynamic coupling coefficients from computational fluid dynamic (CFD) codes. The extended model is applied to a representative engine case. The model and initial studies to identify flutter sensitivities to random and near alternate mistuning are presented. Comparisons are given of tuned and mistuned flutter for only aerodynamic coupling, and with both aerodynamic and structural coupling. For the case studied herein the beneficial effect of mistuning on flutter predicted by aerodynamic coupling models is shown to be greatly inhibited by the inclusion of the structural coupling effects.
A Parametric Analysis for Optimal Selection of a Gas Turbine Cogeneration System
Authors: Sarabchi K. , Ansari A.
Published: November 2008

Cogeneration is a simultaneous production of heat and electricity in a single plant using the same primary energy. Usage of a cogeneration system leads to fuel energy saving as well as air pollution reduction. A gas turbine cogeneration plant (GTCP) has found many applications in industries and institutions. Although fuel cost is usually reduced in a cogeneration system but the selection of a system for a given site optimally involves detailed thermodynamic and economical investigations. In this paper the performance of a GTCP was investigated and an approach was developed to determine the optimum size of the plant to meet the electricity and heat demands of a given site. A computer code, based on this approach, was developed and it can also be used to examine the effect of key parameters like pressure ratio, turbine inlet temperature, utilization period, and fuel cost on the economics of GTCP.
Comparative Investigation of Various Humidified Gas Turbine Cycles
Authors: Yari M. , Sarabchi K.
Published: November 2008

Various advanced gas turbine cycles have been proposed to compete with combined cycles. One of the promising cycles is humid air turbine cycle. The latest configuration proposed for this cycle is known as part flow evaporative gas turbine cycle (PEvGT) in which humidification is combined with steam injection. Having advantages of both steam injected and humid air cycles, it is regarded as a very desirable plant for future. The objectives of this paper are: Development of a comprehensive model for analysis of PEvGT cycle in order to predict its performance parameters depending on different design conditions. It should be noted that the model validated with available data in literature. Comparing the performance of PEvGT cycle with full flow evaporative gas turbine cycle (FEvGT) and stand alone steam injected gas turbine cycle (STIG). Based on a computer code developed for this research, a parametric analysis was carried out for the above-mentioned cycles for a wide range of pressure ratio and turbine inlet temperature variations. The obtained results show that the specific net work of PEvGT cycle, for given conditions, is higher than for both FEvGT and STIG cycles. On the other hand, the efficiency of PEvGT is higher than STIG but is slightly lower than FEvGT cycle.
Sensor Needs for Control and Health Management of Intelligent Aircraft Engines
Authors: Simon Donald L. , Garg Sanjay , Hunter Gary W. , Guo Ten-Huei , Semega Kenneth J.
Published: November 2008

NASA and the U.S. Department of Defense are conducting programs which support the future vision of “intelligent” aircraft engines for enhancing the affordability, performance, operability, safety, and reliability of aircraft propulsion systems. Intelligent engines will have advanced control and health management capabilities enabling these engines to be self-diagnostic, self-prognostic, and adaptive to optimize performance based upon the current condition of the engine or the current mission of the vehicle. Sensors are a critical technology necessary to enable the intelligent engine vision as they are relied upon to accurately collect the data required for engine control and health management. This paper reviews the anticipated sensor requirements to support the future vision of intelligent engines from a control and health management perspective. Propulsion control and health management technologies are discussed in the broad areas of active component controls, propulsion health management and distributed controls. In each of these three areas individual technologies will be described, input parameters necessary for control feedback or health management will be discussed, and sensor performance specifications for measuring these parameters will be summarized.
A Test Bed for Small Aero Gas Turbines for Education and for University: Industry Collaboration
Authors: Jackson A. J. B. , Laskaridis P. , Pilidis P.
Published: November 2008

Engine testing is a necessary but nonetheless expensive and time consuming process. Most of the facilities used to test an engine at sea level static conditions are enclosed test beds. In these facilities the existence of secondary mass flow within the test chamber and around the engine gives rise to various drag components that affect the thrust measurements. For this reason, the net thrust measured in an indoor test bed is lower than the true gross thrust delivered by the engine and measured during outdoor tests. Thrust correction factors, therefore, need to be calculated and applied. For the past five years Cranfield University has been involved in a research study evaluating the performance of gas turbines in test beds, and this work continues. Recently, Cranfield purchased a small gas turbine and invested in the design and construction of a small test bed facility that provides experimental data for the support of the analytical computational fluid dynamics (CFD) analysis. The purpose of this micro-turbojet and test bed facility is to mimic large scale facilities and provide appropriate experimental data for calculating thrust correction factors. The data are also used together with three dimensional CFD models to provide a better understanding of the aerodynamic and engine performance issues involved. Tests have been completed successfully and the facility is capable of detecting the small thrust differences between indoor and outdoor test. Thrust correction factors have been derived through a back to back process. This is an excellent result showing that the equipment is performing as designed. In addition to providing useful results and conclusions in support of ongoing research the facility is also used for postgraduate projects focusing on the performance of small engines in test beds. Analytical design tolls such as commercial CFD and in house engine performance programs are used to predict engine performance and parameters. The results are then validated against the test data. This paper describes the present state of technical progress, which is under development. Its other purpose is to describe the educational value of the analytical and experimental techniques, the objective of which is to mimic the overall engine development process.
Analysis of Enclosure Fires Using the Isis-3D™ CFD Engineering Analysis Code
Authors: Suo-Anttila Ahti , Wagner K. C. , Greiner Miles
Published: November 2008

The Isis-3D™ computational fluid dynamics (CFD) code is currently under development for the Defense Threat Reduction Agency (DTRA) as a tool for risk assessment and engineering level analysis. It is designed to provide reasonably accurate estimates of the total heat transfer to objects from large fires under a variety of circumstances, predict the medium characteristics such as temperature and species concentration distributions, and use fairly short computer turnaround times. Isis-3D™ models liquid fuel evaporation, transport of fuel vapor, oxygen and other relevant species, reaction and heat release, and soot and other gaseous species formation, destruction, and transport. It models diffuse radiation within the fire and view factor radiation from the fire edge to nearby objects and the surroundings. One-dimensional transient sub-grid modules are also embedded into Isis-3D™. Either or both “ends” of each module are coupled to the flowing medium region, or objects within the three-dimensional medium. These modules allow the code to calculate the one-dimensional response of simple solid objects to the fire environment without affecting the computational fluid dynamics time step. The sub-grid modules can include thermal conduction, convection, momentum, mass, and species exchange. For example, they can be used to simulate the decomposition of organic materials (e.g. burning wood), the evaporation of liquid fuels, and the injection of gases, such as fire suppressants. Fast-running radiation heat transfer and chemical reaction models embedded in the code are designed to enable it to give engineering-level accurate results for large-fire heat transfer even when relatively coarse computational grids are employed. Low to medium level resolution Isis-3D™ simulations (less than 60,000 nodes) are relatively fast running and hence well suited for risk assessments, parametric scenario variations, and engineering level analyses. This paper includes comparisons of Isis-3D™ predictions to two enclosure fire experiments, the classical Steckler room fire experiments and the Sandia National Laboratories (SNL) Igloo enclosure fires. The Steckler fire experiments were steady state fires with a fixed heat input. The SNL Igloo tests were larger scale, unsteady fuel pan fires. Comparisons of the predicted temperature distributions within the enclosures for several tests are shown. A typical application of Isis-3D™ is also illustrated wherein the CO2 fire suppressant distribution within the cable room of a nuclear power plant is predicted as a function of time.
Steam Generator Analysis Tools and Modeling of Degradation Mechanisms
Authors: Yetisir M. , Pietralik J. , Tapping R. L.
Published: November 2008

The degradation of steam generators (SGs) has a significant effect on nuclear heat transport system effectiveness and the lifetime and overall efficiency of a nuclear power plant. Hence, quantification of the effects of degradation mechanisms is an integral part of a SG degradation management strategy. Numerical analysis tools such as THIRST, a 3-dimensional (3D) thermalhydraulics code for recirculating SGs; SLUDGE, a 3D sludge prediction code; CHECWORKS a flow-accelerated corrosion prediction code for nuclear piping, PIPO-FE, a SG tube vibration code; and VIBIC and H3DMAP, 3D non-linear finite-element codes to predict SG tube fretting wear can be used to assess the impacts of various maintenance activities on SG thermal performance. These tools are also found to be invaluable at the design stage to influence the design by determining margins or by helping the designers minimize or avoid known degradation mechanisms. In this paper, the aforementioned numerical tools and their application to degradation mechanisms in CANDU® recirculating SGs are described. In addition, the following degradation mechanisms are identified and their effect on SG thermal efficiency and lifetime are quantified: primary-side fouling, secondary-side fouling, fretting wear, and flow-accelerated corrosion (FAC). Primary-side tube inner diameter fouling has been a major contributor to SG thermal degradation. Using the results of thermalhydraulic analysis and field data, fouling margins are calculated. Individual effects of primary- and secondary-side fouling are separated through analyses, which allow station operators to decide what type of maintenance activity to perform and when to perform the maintenance activity. Prediction of the fretting-wear rate of tubes allows designers to decide on the number and locations of support plates and U-bend supports. The prediction of FAC rates for SG internals allows designers to select proper materials, and allows operators to adjust the SG maintenance strategy. CANDU nuclear power plants are pressurized heavy-water reactors that differ in design from pressurized water reactors (PWRs). As a result of this difference, degradation mechanisms in PWRs might be somewhat different; for example, unlike CANDU systems, PWRs do not experience significant primary-side fouling. However, the methodologies presented in this paper are applicable to both CANDU and PWR SGs.
Preparatory Activities of the Fugen Decommissioning
Authors: Iguchi Yukihiro , Tajiri Tsuyoshi , Kiyota Shikou
Published: November 2008

Advanced Thermal Reactor “Fugen” is a 165MWe, heavy water moderated, light-water cooled, pressure-tube type reactor. In February 1998, the Atomic Energy Commission of Japan decided to end the mission of ATR development and introduced a new policy that development and research of decommissioning of Fugen should be promoted in order to carry out the decommissioning smoothly after the shutdown. The Fugen NPS has shut down permanently in March 2003, and based on the report titled Activities of Fugen NPS after permanent shutdown, “Fugen” has been preparing for the project, including necessary development of technologies. The development of decommissioning for “Fugen” is divided into two areas. One area is developement of unique technology for dismantling special components such as the reactor core and the heavy water system. Another area is improvement and enhancement of existing technologies. Especially the former area requires effort and comprises development of the reactor dismantlement, tritium decontamination of heavy water system and engineering support systems. The concrete activities are as follows: The density and amount of radioactive nuclides in all equipment or concrete including the reactor core need to be evaluated for the decommissioning. To prepare for decommissioning, analysis, measurement and evaluation of the neutron flux density have been executed during reactor operation. Special dismantling process is necessary for the heavy water system and the reactor that are unique to Fugen. Some studies and tests are going on for the safe dismantling based on existing technologies and their combination. It is important to execute the decommissioning economically and rationally. Therefore, systems engineering approach is necessary in order to optimize the work load, exposure dose, waste mass and cost by selecting appropriate dismantling process at the planning stage of the decommissioning. For this reason, in order to make a decommissioning plan efficiently, we have been developing an Engineering Support System for decommissioning by adopting new information technologies such as three-dimensional- (3D-) CAD system and virtual reality (VR) system. Moreover, the technical results of technology development and decommissioning activity should be organized and opened to the public so that they can contribute to other decommissioning projects. For this purpose, information exchange and co-operation with domestic and international organizations are underway.
Characterisation of Full-Scale Inactive Cement-Based Intermediate Level Nuclear Wasteforms After One Decade of Storage
Authors: Caldwell Robert J. , Bowmer Newton J. , Butcher Edward J. , Godfrey I. Hugh
Published: November 2008

This paper presents the results of a laboratory-based programme to characterise full-scale, 500L cement-based wasteforms stored for over a decade. The wasteforms were prepared from inactive intermediate level waste (ILW) simulants, representing a range of ferric-based flocs produced during spent fuel reprocessing, using a blended ordinary Portland cement (OPC) / pulverised fuel ash (PFA) grout. The characterisation includes petrographic analysis, determination of moisture/density relationships, acid neutralisation capacity (ANC), and extraction analysis as a function of depth. The results of the study, conducted on full depth cores, indicate that the chosen matrix was well suited to the ferric floc waste that it was designed to contain. Carbonation and desiccation of the high water/solids wasteforms was limited to the near surface and the beneficial morphological and chemical characteristics of the matrix showed very little spatial variability.
Simulation of Multiphase Heat Transfer in Pebble Bed Modular Reactor
Authors: Troshko Andrey A. , Walavalkar Ajey Y.
Published: November 2008

Computational Fluid Dynamics in conjunction with an Eulerian multiphase model of heat transfer in a Pebble Bed Modular Reactor (PBMR) was validated against experimental data obtained in a test rig. The cooling gas and packed fuel pebbles constituted two phases. The velocity of pebble phase was fixed to zero and a drag law accounting for a packed bed condition was used. The density of the gas phase varied with temperature. Volume averaged effective thermal conductivities accounting for radiation and packed spheres geometry were used for both phases. Model predictions compared favorably with the experiment for two gases — helium and nitrogen and two power levels. It was found that accounting for increased affective porosity close to walls results in more realistic velocity field prediction.
Developed a Spacer Grid for the Future PWR Fuel Assembly by Considering the Thermal/Hydraulic and Mechanical/Structural Performance
Authors: Yoon Kyung-Ho , In Wang-Kee , Kang Heung-Seok , Song Kee-Nam
Published: November 2008

The spacer grid is one of the structural components for the fuel assembly. In order to increase or extend the fuel life cycle, a spacer grid which has a much higher performance from the thermal/hydraulic and mechanical/structural point of view will be needed. From the thermal/hydraulic viewpoint, the CHF margin is very important in order to extend its life. Particularly, the mixing flow or cross flow between the subchannels have to be reinforced for this purpose. From the mechanical/structural viewpoint, the critical strength and the fuel rod support behaviour of a spacer grid are the same as the TH performance improvement for the next generation fuel. A computational fluid dynamics (CFD) analysis was performed to investigate the coolant mixing in a nuclear fuel bundle that is promoted by the mixing vane on the grid spacer. Single and multiple subchannels of one grid span of the fuel bundle were modeled to simulate a 5by5 rod array experiment with the mixing vane. The three-dimensional CFD models were generated by a structured multi-block method. The standard k-ε turbulence model was used in the current CFD simulation since it is practically useful and converges well for the complex turbulent flow in a nuclear fuel bundle. The CFD predictions of the axial and lateral mean flow velocities showed a somewhat larger difference from the experimental results near the spacer but represented the overall characteristics of the coolant mixing well in a nuclear fuel bundle with the mixing vane. Comparison of the single and multiple subchannel predictions shows a good agreement for the flow characteristics in the central subchannel of the rod array. The simulation of the multiple subchannels shows a slightly off-centered swirl in the peripheral subchannels due to the external wall of the rod array. It also shows no significant swirl and crossflow in the wall subchannels and the corner subchannels. In addition to this, the impact and the stress analysis of a spacer grid are accomplished by the FE method. The FE model was created using I-DEAS [4], and the ABAQUS/explicit version 6.3 commercial code was used for the solver. The FE analysis procedure was established, the FE analyses results were verified by the experimental method. The developed spacer grid will be evaluated from the thermal/hydraulic and mechanical/structural design criteria.
A Case Study for INPRO Methodology Based on Indian Advanced Heavy Water Reactor
Authors: Anantharaman K. , Saha D. , Sinha R. K.
Published: November 2008

Under Phase 1A of the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO) a methodology (INPRO methodology) has been developed which can be used to evaluate a given energy system or a component of such a system on a national and/or global basis. The INPRO study can be used for assessing the potential of the innovative reactor in terms of economics, sustainability and environment, safety, waste management, proliferation resistance and cross cutting issues. India, a participant in INPRO program, is engaged in a case study applying INPRO methodology based on Advanced Heavy Water Reactor (AHWR). AHWR is a 300 MWe, boiling light water cooled, heavy water moderated and vertical pressure tube type reactor. Thorium utilization is very essential for Indian nuclear power program considering the indigenous resource availability. The AHWR is designed to produce most of its power from thorium, aided by a small input of plutonium-based fuel. The features of AHWR are described in the paper. The case study covers the fuel cycle, to be followed in the near future, for AHWR. The paper deals with initial observations of the case study with regard to fuel cycle issues.