bluuebunny/crossref_metadata_2025 huggingface dataset:
Intraoperative mechanical ventilation strategies for obese patients: a systematic review and network meta‐analysis
Authors: Wang C. , Zhao N. , Wang W. , Guo Libo , Guo Lei , Chi C. , Wang X. , Pi X. , Cui Y. , Li E.
Published: March 2015

Several intraoperative ventilation strategies are available for obese patients. However, the same ventilation interventions have exhibited different effects on PaO2/FIO2 concerning obese patients in different trials, and the issue remains controversial. Therefore, we conducted a network meta‐analysis to identify the optimal mechanical ventilation strategy. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, Embase, MEDLINE, CINAHL and Web of Science for studies published up to June 2014, and the PaO2/FIO2 in obese patients given different mechanical ventilation strategies was assessed. We assessed the studies for eligibility and extracted data and then pooled the data and used a Bayesian fixed‐effect model to combine direct comparisons with indirect evidence. Eligible studies evaluated different ventilation strategies for obese patients and reported the intraoperative PaO2/FIO2 ratio, atelectasis and pulmonary compliance. Thirteen randomized controlled trials were included for network meta‐analysis, including 476 patients who received 1 of 12 ventilation strategies. Volume‐controlled ventilation with higher PEEP plus single recruitment manoeuvres (VCV + higher PEEP + single RM) was associated with the highest PaO2/FiO2 ratio, improving intraoperative pulmonary compliance and reducing the incidence of intraoperative atelectasis.
Proteomic analysis provides new insights into the adaptive response of a dinoflagellate Prorocentrum donghaiense to changing ambient nitrogen
Authors: Zhang Ying‐Jiao , Zhang Shu‐Fei , He Zhi‐Ping , Lin Lin , Wang Da‐Zhi
Published: March 2015

Nitrogen (N) is the major nutrient limiting phytoplankton growth and productivity over large ocean areas. Dinoflagellates are important primary producers and major causative agents of harmful algal blooms in the ocean. However, very little is known about their adaptive response to changing ambient N. Here, we compared the protein profiles of a marine dinoflagellate Prorocentrum donghaiense grown in inorganic N‐replete, N‐deplete and N‐resupplied conditions using 2‐D fluorescence differential gel electrophoresis. The results showed that cell density, chlorophyll a and particulate organic N contents presented low levels in N‐deplete cells, while particulate organic carbon content and glutamine synthetase (GS) activity maintained high levels. Comparison of the protein profiles of N‐replete, N‐deplete and N‐resupplied cells indicated that proteins involved in photosynthesis, carbon fixation, protein and lipid synthesis were down‐regulated, while proteins participating in N reallocation and transport activity were up‐regulated in N‐deplete cells. High expressions of GS and 60 kDa chaperonin as well as high GS activity in N‐deplete cells indicated their central role in N stress adaptation. Overall, in contrast with other photosynthetic eukaryotic algae, P. donghaiense possessed a specific ability to regulate intracellular carbon and N metabolism in response to extreme ambient N deficiency.
Pharmacy as a centre for Protestant reform in Renaissance Venice
Authors: Kostylo Joanna
Published: March 2015

This article reveals the importance of the Renaissance pharmacy for the history of the Reformation. Focusing on the case of a Venetian apothecary and physician, Gian'Battista Gemma (1537–1608), the article highlights the role of Venetian pharmacies as sites of religious and scientific innovation, as well as healthcare provision and poor relief. It argues that a pharmacy was one of the most conspicuous and radical centres for unorthodox belief in Renaissance Venice. Drawing on recent studies of medical networks, spaces and identities, and questions related to cultural transfers, the article examines the way in which contemporary apothecaries and physicians integrated their religious pursuits into their professional activities. Like contemporary preachers, schoolmasters and master printers, Venetian men of medicine emerge as a particularly energetic group of cultural brokers who were able to give their reforming ideas broad influence through a variety of social, economic and professional means.
A Generalized Feed Forward Dynamic Adaptive Mesh Refinement and Derefinement Finite Element Framework for Metal Laser Sintering—Part I: Formulation and Algorithm Development
Authors: Patil Nachiket , Pal Deepankar , Khalid Rafi H. , Zeng Kai , Moreland Alleyce , Hicks Adam , Beeler David , Stucker Brent
Published: March 2015

A novel multiscale thermal analysis framework has been formulated to extract the physical interactions involved in localized spatiotemporal additive manufacturing processes such as the metal laser sintering. The method can be extrapolated to any other physical phenomenon involving localized spatiotemporal boundary conditions. The formulated framework, named feed forward dynamic adaptive mesh refinement and derefinement (FFD-AMRD), reduces the computational burden and temporal complexity needed to solve the many classes of problems. The current study is based on application of this framework to metals with temperature independent thermal properties processed using a moving laser heat source. The melt pool diameters computed in the present study were compared with melt pool dimensions measured using optical micrographs. The strategy developed in this study provides motivation for the extension of this simulation framework for future work on simulations of metals with temperature-dependent material properties during metal laser sintering.
Catalyst Durability Evaluation for Advanced Gas Turbine Engines
Authors: Snow G. C. , Pessagno S. L.
Published: March 2015

Catalytic combustion has demonstrated the ability to provide low NOx emissions while maintaining high combustion efficiency. Recently, under joint NASA Lewis, EPA, and Acurex sponsorship, a catalytic reactor was tested for 1000 hours to demonstrate durability in combustion environments representative of advanced automotive gas turbine engines. At a 740K air preheat temperature and a propane fuel/air ratio of 0.028 by mass (ϕFA = 0.44), the adiabatic flame temperature was held at about 1700K. The graded cell monolithic reactor measured 5 cm in diameter by 10.2 cm in length and was operated at a reference velocity of 13.4 m/s at 1 atmosphere pressure. Measured NOx levels remained below 5 ppm while unburned hydrocarbon concentrations registered near zero and carbon monoxide levels were nominally below 20 ppm. The durability test included several parametric turndown studies and ended with a series of on/off cycling tests to further characterize reactor performance.
Redesigned 26-Inch Last-Stage for Improved Turbine Reliability and Efficiency
Authors: O’Connor M. F. , Robbins K. E. , Williams J. C.
Published: March 2015

Since its introduction in the mid-1950s, General Electric’s 26-in last stage bucket for large steam turbines has proven to be a popular and durable design. Since that time, however, major advances have been made in aerodynamic and structural design methods and manufacturing technology.

This paper describes an improved 26-in. last-stage bucket which has been developed for application to new large steam turbines and as replacement rows in operating units. The new bucket is a design having continuous coupling at the outermost periphery and near the midpoint of the vane, and benefits the user through substantial efficiency gains and improved reliability margins.
Properties of Ultra-Clean Coal-Water Slurry Fuels for Direct-Fired Gas Turbines
Authors: Smit F. J. , Anast K. R. , Bhasin A. K.
Published: March 2015

Under contract DE-AC21-83MC20700 from the Morgantown Energy Technology Center (METC), AMAX Extractive R&D prepared two 250-gallon lots of clean and ultra-clean coal-water slurry fuel for use in a U.S. Department of Energy program to develop coal-fueled direct-fired gas turbines for power generation. Both lots were prepared from Eastern Kentucky high volatile bituminous coal ground to pass 44 micrometers. The first lot, containing 1.95 percent ash, was prepared from coal cleaned by standard industry physical separations. Advanced chemical coal cleaning technology was used during preparation of the second lot which contained 0.40 percent ash. The grinding and cleaning operations and the rheology, composition and other properties of the two slurry fuels are described.
Gravel Bed Combustor for Solid Fuel Fired Gas Turbine
Authors: Ragland Kenneth W. , Aerts Danny J.
Published: March 2015

A fixed bed, downdraft combustor for solid fuels applicable to gas turbine cogeneration or combined cycles is described. The combustor has a refractory gravel bed, with fuel placed on top of the gravel and burning at the fuel-gravel interface. The gravel retains fuel particles in the combustion zone, preventing carryover of unburned char. Combustion temperature is held below the ash fusion temperature by using high excess air through the bed, thereby minimizing particulate ash agglomeration.

Previous work on fixed bed, downdraft combustors and coal fired gas turbines is reviewed. Recent results from test firing a 480 cm2 (0.5 ft2) gravel bed combustor at atmospheric pressure with 2 cm (0.75 in.) wood chips are presented. Heat release rates of 3500 MJ/hr m2 (300,000 Btu/hr ft2) and higher were obtained. Carbon carryover in the exhaust was negligible. Approximately 85 percent of the particulate ash emissions was less than 10 microns.
Benefits of Converting Utility Gas Turbines to Combined-Cycle Plants
Authors: Miliaras E. S. , Wilkinson P.
Published: March 2015

A large number of simple cycle gas turbines (about 8% of the total current electric generating capacity) had been installed by utilities by the late 1970s. Because of the low efficiency of these, older simple cycle gas turbines (about 25% at full load, much worse at part load) and the reduced demand for electricity, little use is now made of these machines by most utilities.

The paper considers the specific and broader benefits of converting these older gas turbines to combined-cycle plants. The benefits include dramatic efficiency improvement at all loads, improved operating reliability, low cost additions to utility generating capacity, and the potential availability of significant new capacity in many regions of the country in a short time.

The combined cycles can also be operated instead of oil-fired and coal-fired cycling steam plants — at significantly lower startup-up costs in fuel and operating personnel, and with considerable reduction in the wear and tear of the steam plants from cycling thermal stresses.

When additional, new peaking capacity is needed, these older, converted gas turbines can be replaced with new, more efficient machines.
On-Line Temperature Profile Display System
Authors: Venkataraju K. , Satheeratnam A. G. , Ramanathan R.
Published: March 2015

Combustor development depends on two important factors, namely combustor efficiency and exit temperature profile. A microprocessor based system has been designed to have on-line display of exit temperature profiles during the development testing of a gas turbine engine. The system acquires temperature data from thirty thermocouples around the circumference and at various radial positions of the engine. The signals from the thermocouples are fed to a microprocessor through an analog input subsystem. The microprocessor computes the temperatures, averages the values and plots the radial profile on a colour graphic terminal. On the colour graphic terminal, ideal temperature profiles for various engine speeds are drawn. On the ideal temperature profile, actual temperature profiles are superimposed for various speeds during the testing of a gas turbine engine. In addition, circumferential profile is also plotted in off-line.
Development of a Low-NOx LBG Combustor for Coal Gasification Combined Cycle Power Generation Systems
Authors: Sato M. , Abe T. , Ninomiya T. , Nakata T. , Yoshine T. , Hasegawa H.
Published: March 2015

From the view point of future coal utilization technology for the thermal power generation systems, the coal gasification combined cycle system has drawn special interest recently. In the coal gasification combined cycle power generation system, it is necessary to develop a high temperature gas turbine combustor using a low-BTU gas (LBG) which has high thermal efficiency and low emissions.

In Japan a development program of the coal gasification combined cycle power generation system has started in 1985 by the national government and Japanese electric companies. In this program, 1300°C class gas turbines will be developed. If the fuel gas cleaning system is a hot type, the coal gaseous fuel to be supplied to gas turbines will contain ammonia. Ammonia will be converted to nitric oxides in the combustion process in gas turbines. Therefore, low fuel-NOx combustion technology will be one of the most important research subjects.

This paper describes low fuel-NOx combustion technology for 1300°C class gas turbine combustors using coal gaseous low-BTU fuel as well as combustion characteristics and carbon monoxide emission characteristics.

Combustion tests were conducted using a full-scale combustor used for the 150 MW gas turbine at the atmospheric pressure. Furthermore, high pressure combustion tests were conducted using a half-scale combustor used for the 1 50 MW gas turbine.
ATTAP/AGT101 Ceramics Technology Update
Authors: Boyd G. L. , Kreiner D. M.
Published: March 2015

The feasibility of applying ceramics to the gas turbine was demonstrated during the AGT101 Program, when over 250 hours were accumulated on ceramic components in engine tests at temperatures up to 1204C (2200F). The follow-on program, designated the Advanced Turbine Technology Applications Project (ATTAP), began in late August 1987 to further develop ceramic technology. This program addresses ceramic component fabrication technology, design methods development and the supporting data base, and verification of ceramic component durability in an operating engine environment. These technologies must be demonstrated so that a commercialization development decision can be made at the end of ATTAP.
A New Method for Optimizing Friction Damping in Randomly Excited Systems
Authors: Cameron T. M. , Griffin J. H.
Published: March 2015

A method is developed that can be used to calculate the stationary response of randomly excited nonlinear systems. The method iterates to obtain the fast Fourier transform of the system response, returning to the time domain at each iteration to take advantage of the ease in evaluating nonlinearities there. The updated estimates of the nonlinear terms are transformed back into the frequency domain in order to continue iterating on the frequency spectrum of the staionary response.

This approach is used to calculate the response of a one degree of freedom system with friction damping that is subjected to random excitation. The one degree of freedom system provides a single mode approximation of systems (e.g. turbine blades) with friction damping. This study investigates various strategies that can be used to optimize the friction load so as to minimize the response of the system.
The Performance Prediction and Demonstration of a Centrifugal Compressor for the Multiple Purpose Small Power Unit (MPSPU)
Authors: Yoshinaka Tsukasa , Thompson R. G. , Létourneau Jean
Published: March 2015

This paper describes an analytical procedure for the prediction of the design point performance of a small centrifugal compressor. Results of a subsequent performance demonstration are presented. The geometry of the compressor was derived from an existing stage used in the PW200 engine, but rematched to 6:1 pressure ratio.

Test data obtained from subsequent performance demonstration showed that the predicted performance had been achieved, but at 103% of design speed. A possible cause of this discrepancy is proposed.
A Coupled Iterative Method for Calculation of Film-Cooled Wall Temperature of Gas-Turbine Combustion Chambers
Authors: Zhirui Dong , Changqing Zhu
Published: March 2015

This paper provides a numerical method for calculation of the film-cooled wall temperature profile of the combustion chambers. It is named Convection-Conduction-Radiation Coupled Iterative Method (CCRCIM). CCRCIM will solve problem with complex boundary conditions including longitudinal conduction between two or more individually cooled louvers. As an example to apply CCRCIM, the wall temperature profile and the heat flow profile of WP-7B flame tube with hole-drilled film-cooled construction has been calculated. The calculated temperature profile agrees well with that shown by thermal paint.
Development of a Coal-Fueled Gas Turbine Slagging Combustor
Authors: Cowell L. H. , LeCren R. T.
Published: March 2015

A slagging combustor for a coal-fueled gas turbine engine is being developed. The work to date has been accomplished using a bench-scale combustor with one-tenth the heat input required for the full-scale gas turbine unit. The combustor features a fuel-rich slagging primary zone with hot refractory walls. Both single and multiple primary air/fuel injectors have been tested. Aerodynamic jet impaction on a target at one end of the primary zone removes much of the slag. The jet impaction is the result of the single air/fuel injector flow for multiple injectors, the intersection of the multiple jets forms a central jet. There is an additional particulate rejection impact separator between the primary and secondary zones to remove the slag that escapes the primary zone. Secondary air is introduced via multiple jets that rapidly mix with the incoming gas from the particulate removal device, resulting in a minimal formation of thermal NOx and the completion of the combustion process.

Variables that have been evaluated include coal-water mixture properties such as top and mean particle size, viscosity, loading and ash fusion temperature, and primary zone parameters such as volume, cross-sectional area, loading, and equivalence ratio.

Combustor performance was compared with single or multiple fuel injectors, relating the combustor performance to the spray characteristics of the two injector configurations. Modifications of the single injector were evaluated with the goal of attaining at least the same atomization performance as the smaller injectors used in the multiple injector configuration.

Flow visualization, computer modelling, and cold-flow velocity traverses have been employed to aid the development program. The results of the subscale development are being used to design and develop the full-size combustor for integration with the engine.
The CW251B12 Gas Turbine Engine
Authors: Diakunchak Ihor S.
Published: March 2015

The latest variant of the W251 family of engines, the CW251B12, rated at 48 MW, is described in this paper. The improved performance, compared to the CW251B10 model, is achieved by the redesign of the compressor for increased mass flow and efficiency and by hot end modifications, which allow a modest increase in firing temperature. Some of the details of the compressor redesign and turbine modifications are outlined. The uprated engine performance information is provided, as well as plans for the full load factory Prototype tests for engine performance and mechanical integrity verification.
Threshold Performance Optimization of a Rotor-Bearing System Subjected to Leakage Excitation
Authors: Wang J. H. , Shih F. M.
Published: March 2015

The fluid leakage in shroud of the blades and the labyrinth seal of turbomachinery may induce instability and limit the output rating. In this work, the optimization technique has been used to find the diameters of shaft elements and the bearing supports so that the optimized rotor-bearing system can sustain larger fluid leakage force. The results show that the threshold performance of rotor-bearing systems can be significantly improved by slight modification of the shaft diameters. The results also indicate that, the threshold performance can be improved more significantly by the combination of optimum bearing supports and optimum shaft diameters.
Probabilistic Structural Analysis for Advanced Space Propulsion Systems
Authors: Cruse T. A. , Unruh J. F. , Wu Y.-T. , Harren S. V.
Published: March 2015

The paper reports on recent extensions to ongoing research into probabilistic structural analysis modeling of advanced space propulsion system hardware. The advances concern probabilistic dynamic loading, and probabilistic nonlinear material behavior.

In both cases, the reported work represents a significant advance in the state-of-the-art for these topics. Random, or probabilistic loading is normally concerned with the loading described in power spectral density (PSD) terms. The current work describes a method for incorporating random PSD’s along with random material properties, damping, and structural geometry.

The probabilistic material response is concerned with the prediction of nonlinear stress-strain behavior for physical processes that can be linked to the original microstructure of the material. Such variables as grain size and orientation, grain boundary strength, etc. are treated as random, initial variables in generating stochastic stress-strain curves. The methodology is demonstrated for a creep simulation.
The General Electric LM5000 Marine Gas Turbine
Authors: Stancliff Robert C.
Published: March 2015

The General Electric LM5000 Marine Gas Turbine (see figure 1) intended for application to commercial and naval ships requiring high power (50,000 BHP nominal), high thermal efficiency (38 percent), and compact, marinized and relatively light weight prime movers is described. Ship candidates include Fast Support Ships, Aircraft Carriers [in a Combined Nuclear and Gas Turbine (CONAG) propulsion system], Battleships and large surface effect ships.

The LM5000 marine gas turbine is a marinized version of the LM5000 industrial gas turbine which was derived in 1977 from the CF6-50 aircraft engine. The CF6-6 model of this family of aircraft engines was the parent of the over 648 GE LM2500 marine gas turbine now used on the ships of 18 navies, 32 ship programs and 247 ships of the world. Over 2100 of the CF6-50 mode] engines are used on over 600 of the McDonald Douglas DC-10, the Airbus A300 and the Boeing 747 aircraft.

Since reliability and durability are dependent upon engine family experience, the hardware commonality with the CF6-50 aircraft engine is described as well as the associated experience, performance, installation and maintainability features.
Mechanisms of Degradation and Failure in a Plasma Deposited Thermal Barrier Coating
Authors: Demasi-Marcin Jeanine T. , Sheffler Keith D. , Bose Sudhangshu
Published: March 2015

Failure of a two layer plasma deposited thermal barrier coating is caused by cyclic thermal exposure and occurs by spallation of the outer ceramic layer. Spallation life is quantitatively predictable, based on the severity of cyclic thermal exposure. This paper describes and attempts to explain unusual constitutive behavior observed in the insulative ceramic coating layer, and presents details of the ceramic cracking damage accumulation process which is responsible for spallation failure. Comments also are offered to rationalize the previously documented influence of interfacial oxidation on ceramic damage accumulation and spallation life.
Dynamic Modeling of a Combined-Cycle Plant
Authors: Ahluwalia K. S. , Domenichini R.
Published: March 2015

Greater use is being made of dynamic simulation of energy systems as a design tool for selecting control strategies and establishing operating procedures. This paper discusses the dynamic modeling of a gas-fired combined-cycle power plant with a gas turbine, a steam turbine, and an alternator — all rotating on a common shaft. A waste-heat boiler produces steam at two pressures using heat from the gas turbine flue gas. The transient behavior of the system predicted by the model for various upset situations appears physically reasonable and satisfactory for the operating constraints.
Three-Dimensional Solutions for Inviscid Incompressible Flow in Turbomachines
Authors: Abdallah S. , Smith C. F.
Published: March 2015

A primitive variable formulation is used for the solution of the incompressible Euler’s equation. In particular, the pressure Poisson equation approach using a non-staggered grid is considered. In this approach, the velocity field is calculated from the unsteady momentum equation by marching in time. The continuity equation is replaced by a Poisson-type equation for the pressure with Neumann boundary conditions. A consistent finite-difference method, which insures the satisfaction of a compatibility condition necessary for convergence, is used in the solution of the pressure equation on a non-staggered grid. Numerical solutions of the momentum equations are obtained using the second order upwind differencing scheme, while the pressure Poisson equation is solved using the line successive over-relaxation method. Three turbomachinery rotors are tested to validate the numerical procedure. The three rotor blades have been designed to have similar loading distributions but different amounts of dihedral. Numerical solutions are obtained and compared with experimental data in terms of the velocity components and exit swirl angles. The computed results are in good agreement with the experimental data.
Thermal Barrier Characteristics of Partially Stabilized Zirconia Coatings on INCOLOY Alloy 909 (A Controlled Expansion Alloy)
Authors: Smith Gaylord D.
Published: March 2015

INCOLOY alloy 909 is a low expansion alloy used in critical seal and shaft applications within the gas turbine engine. However, because of its poor oxidation resistance at elevated temperatures, the maximum service temperature is limited. Since its coefficient of expansion is similar to that of partially stabilized zirconia for temperatures to 1200°F (649°C), it has been proposed to use this metal-ceramic combination for dimensionally critical, air cooled jet engine components. This coating system should extend temperature limitations by reducing metal temperatures and providing oxidation resistance. The performance advantage offered by a thermal barrier coating has been investigated at temperatures up to 2000°F (1093°C) and the results are presented in this paper. Metal temperatures and heat flow rates of coated and bare specimens are compared for two air cooling flow rates.
A Method for Calculating Axial Turbomachine End Wall Turbulent Boundary Layers
Authors: Shun Kang , Fengjun Liu , Zhongqi Wang
Published: March 2015

Based on two families of relative stream-surface theory, the differential and integral equations of the endwall boundary layer in the S2 stream surface (hub to tip stream surface) have been established in the orthogonal curvilinear coordinate system in the present paper. By directly associating the blade force defects with the warping of S2 stream surface near the endwall, we have proposed a new method for predicting the endwall boundary layer. This method can be used to conduct the interactions of the end wall boundary layer with the S2 stream surface potentisl flow, in order to get the iterative solution of the end wall boundary layer flow with the potential flow in S2 stream surface. The predicted results have shown that the present method is acceptable.
An Experimental Investigation of Heat Transfer Coefficients in a Spanwise Rotating Channel With Two Opposite Rib-Roughened Walls
Authors: Taslim M. E. , Rahman A. , Spring S. D.
Published: March 2015

Liquid crystals are used in this experimental investigation to measure the heat transfer coefficient in a spanwise rotating channel with two opposite rib-roughened walls. The ribs (also called turbulence promoters or turbulators) are configured in a staggered arrangement with an angle of attack to the mainstream flow, α, of 90° for all cases. Results are presented for three values of turbulator blockage ratio, e/Dh (0.1333, 0.25, 0.333) and for a range of Reynolds numbers from 15,000 to 50,000 while the test section is rotated at different speeds to give Rotational Reynolds numbers between 450 and 1800. The Rossby number range is 10 to 100 (Rotation number of 0.1 to 0.01). The effect of turbulator blockage ratios on heat transfer enhancement is also investigated. Comparisons are made between the results of geometrically identical stationary and rotating passages of otherwise similar operating conditions. The results indicate that a significant enhancement in heat transfer is achieved in both the stationary and rotating cases, when the surfaces are roughened with turbulators. For the rotating case, a maximum increase over that of the stationary case of about 45% in the heat transfer coefficient is seen for a blockage ratio of 0.133 on the trailing surface in the direction of rotation and the minimum is a decrease of about 6% for a blockage ratio of 0.333 on the leading surface, for the range of rotation numbers tested. The technique of using liquid crystals to determine heat transfer coefficients in this investigation proved to be an effective and accurate method especially for nonstationary test sections.
Simulation of Three-Dimensional Viscous Flow Within a Multistage Turbine
Authors: Adamczyk John J. , Celestina Mark L. , Beach Tim A. , Barnett Mark
Published: March 2015

This work outlines a procedure for simulating the flow field within multistage turbomachinery which includes the effects of unsteadiness, compressibility, and viscosity. The associated modeling equations are the average passage equation system which governs the time-averaged flow field within a typical passage of a blade row embedded within a multistage configuration. The results from a simulation of a low aspect ratio stage and one-half turbine will be presented and compared with experimental measurements. It will be shown that the secondary flow field generated by the rotor causes the aerodynamic performance of the downstream vane to be significantly different from that of an isolated blade row.
Laser Transit Anemometry Investigation of a High Speed Centrifugal Compressor
Authors: Japikse David , Karon David M.
Published: March 2015

A detailed experimental investigation of a small centrifugal compressor stage has been completed using laser transit anemometry. Measurements at the inlet and discharge of an impeller have been made while recording data relative to a blade passage. Classical primary and secondary flow regimes within the rotor have been shown plus several compact “cell-like” regions. Various components of velocity and turbulence intensity are presented. This study has demonstrated the capability of using the laser transit anemometer for investigating the kinematics of small, high speed turbomachinery components.
LDV Measurements and the Flow Analysis in the Vaneless Region of a Radial Inflow Turbine
Authors: Lakshminarasimha A. N. , Tabakoff W. , Metwally A.
Published: March 2015

Detailed experimental measuremets was carried out in the vaneless (vortex) region of a radial inflow turbine using a three component LDV. A viscous and incompressible axisymmetric computational code was developed to analyze the flow. The experimental and theoretical results were compared to obtain the degree of non-uniformity of the flow in the circumferential direction.
Gas Turbine and Turbomachinery Education at Carleton University
Authors: Sjolander S. A. , Saravanamuttoo H. I. H.
Published: March 2015

Although a relatively small industrial nation, Canada has a very well developed gas turbine industry with both an original design and manufacturing capability and a large industrial user base. Research and teaching at Carleton University has focused on the needs of the Canadian industry over many years. Particular strengths have been established in the areas of experimental aerodynamics for turbomachinery and the use of mathematical modelling for engine performance investigations. Strong links are maintained with both manufacturers and users, and the well-trained engineers produced by the program readily find employment in the industry.
Mathematical Formulation of Blade Surfaces in Turbomachinery: Part I — Theoretical Surface Formulations
Authors: Rautenberg M. , Engeda A. , Wittekindt W.
Published: March 2015

This paper justifies recent trends in the mathematical definition of blade surfaces of impellers and rotors. The authors introduce a simple and efficient surface definition method, which is highly suited for numerical manufacture. Examples of a centrifugal compressor impeller, a mixed flow pump impeller and a gas turbine blade manufactured using the method are also presented.

In this first part the theoretical approach and the mathematical derivations of the authors STRAIGHT-LINE-SURFACE structure method is introduced.
Mathematical Formulation of Blade Surfaces in Turbomachinery: Part II — Practical Examples of Determined Surfaces
Authors: Rautenberg M. , Engeda A. , Wittekindt W.
Published: March 2015

In an attempt to develop a general method for the surface definitions of turbomachinery blades, the powerful tool straight-line-surface structures method has been introduced and practically tested. At a glance the method may seem too complex to qualify for general use. But the accuracies achived, the flexibilities in the method and the exact compatibility for feeding datas directly to a milling machine certifies it as a worthy method.
The Influence of Diffuser Vane Leading Edge Geometry on the Performance of a Centrifugal Compressor
Authors: Clements W. W. , Artt D. W.
Published: March 2015

A series of experiments was carried out on two turbocharger compressors to determine the influence of pressure face angle, semi-vaneless space suction surface profile and diffuser leading edge radius ratio on stage performance. It was found that whilst compressor performance was virtually unaffected by changes in pressure face angle, performance was sensitive to changes in the semi-vaneless space suction surface profile. Straight wedge diffusers produced higher stage efficiencies than any diffuser with a concave suction surface profile between the leading edge and throat. Optimum stage performance was achieved with diffuser leading edge radius ratios between 1.06 and 1.10.
Steam Injecting a Mature Gas Turbine in a Modern Cogeneration Plant
Authors: Kaempffer L. , Williams K.
Published: March 2015

Factors such as low capital cost, good match of power and heat requirements, and proven reliability, can sometimes lead an end user into purchasing mature gas turbines for use in a modern cogeneration plant.

Invariably, older gas turbines were not specifically designed for low NOx emissions and steam injection.

This paper presents what the author(s) believe to be the simplest method of modifying an existing fuel system design to provide the best NOx reduction possible using steam injection, without significantly increasing carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions. Results of emissions tests are presented, along with a discussion on the projected limits for NOx control attainable using this new system.

Also presented, is an idea for improving cogeneration efficiency and capability, by placing the turbine cooling air cooler in the steam generation circuit.
A Comparison Between Engine Test Results and Design Predictions of Turbine Blade Cooling Performance
Authors: Hannis J. M. , Smith M. K. D.
Published: March 2015

Significant differences exist between the behaviour of cooled turbine blades under engine conditions and their behaviour as predicted in design calculations.

This paper presents a comparison between engine test data, static cascade rig data, and design predictions. Wherever possible, the reasons for the differences are identified and cross referenced to recently reported research work. In some cases hard supportive evidence for phenomena observed on research rigs has been obtained from engine tests.

The data is presented for two subsonic aerofoil designs with several different cooling configurations.
Gas Turbine Exhaust Expansion Joints, Diverter and Damper Designs for the New Generation of Higher Temperature, High Efficiency Gas Turbines
Authors: Bachmann Lothar , Koch W. Fred
Published: March 2015

The purpose of this paper is to update the industry on the evolutionary steps that have been taken to address higher requirements imposed on the new generation combined cycle gas turbine exhaust ducting expansion joints, diverter and damper systems. Since the more challenging applications are in the larger systems, we shall concentrate on sizes from nine (9) square meters up to forty (40) square meters in ducting cross sections. (Reference: General Electric Frame 5 through Frame 9 sizes.)

Severe problems encountered in gas turbine applications for the subject equipment are mostly traceable to stress buckling caused by differential expansion of components, improper insulation, unsuitable or incompatible mechanical design of features, components or materials, or poor workmanship.

Conventional power plant expansion joints or dampers are designed for entirely different operating conditions and should not be applied in gas turbine applications. The sharp transients during gas turbine start-up as well as the very high temperature and high mass-flow operation conditions require specific designs for gas turbine application.
Installation of Refurbished (Used) Gas Turbines for Utility Application Utilizing State-of-the-Art Improvements
Authors: Backus Oscar
Published: March 2015

Four Pratt and Whitney FT4C-1 Twin Pacs manufactured in 1971 and purchased new by an electric utility (Portland General Electric) were sold in 1986 to the City of Austin Electric Utility to provide 200,000 KW for Austin’s system peaking requirements. The equipment was refurbished and reinstalled for the City of Austin and was declared commercial in September, 1988 for a total installed price of $155/KW. The equipment was provided by Energy Services Inc. (ESI) with complete refurbishment and incorporation of state-of-the-art improvements. The base bid for the equipment included complete installation, check-out, start-up and training and was evaluated against competing new equipment bids for similar services. This paper, written by the user, discusses the utility decision to solicit bids for both major types of gas turbine equipment (heavy duty and aircraft-derivative), method of evaluation, key construction points, state-of-the-art improvements, and emissions test results.
Gas Turbine Research at the University of British Columbia
Authors: Evans R. L.
Published: March 2015

This paper describes two gas turbine related research projects in the department of Mechanical Engineering at the University of British Columbia. Of the two projects described, one involves fundamental turbomachinery research while the second is a more applied project concerned with gas turbine based cogeneration systems in process industries. In the fundamental research area, both an experimental and computational study of unsteady boundary layer development on turbomachinery blading is described. The applied research program involves an engineering and economic assessment of a gas turbine based cogeneration system for sawmills. The system is designed to use wood-waste generated during the saw-milling process as a source of heat for an indirectly fired gas turbine. Studies to date indicate that such a system could result in many sawmills becoming completely energy self-sufficient.
Influence of the Radial Component of Total Pressure Gradient on Tip Clearance Secondary Flow in Axial Compressors
Authors: Moyle Ian N.
Published: March 2015

The interaction of tip leakage and the rotor passage secondary flow is examined. An analytical expression is developed which relates radial components of the total pressure gradient near the wall to the passage geometry, tip speed, skew, throughflow and wall skin friction coefficient. This expression provides a correlation with the differences observed in the passage secondary velocity patterns associated with tip clearance gaps in experimental compressors. The analysis is qualitatively supported by comparison with secondary flow velocity measurements from a small sample of published test data.
Stability Analysis of Dual Rotor System by Extended Transfer Matrix Method
Authors: Gupta K. D. , Gupta K. , Athre K.
Published: March 2015

This paper presents a general formulation for the stability problem of a linear model of dual rotor system with intershaft bearing(s) employing an ‘extended’ transfer matrix method [9] using complex variables. The stability criterion employed is essentially an extension of leonhard’s stability criterion. An alternative concept of ‘margin of stability’ has been suggested. In contrast to other methods, the present formulation maintains the integrity of dual rotor system in totality, by considering exact junction conditions at intershaft bearing. And it is felt that it would prove to be an potential method for analyzing the stability of complex rotor systems.
The Evolution of Marine Gas Turbine Controls
Authors: Sylvestre R. A. , Dupuis R. J.
Published: March 2015

The background and evolution of gas turbine fuel controls is examined in this paper from a Naval perspective.

The initial application of aero-derivative gas turbines to Navy ships utilized the engine’s existing aircraft fuel controls which were coupled to the ship’s hydro-pneumatic machinery control system. These engines were adapted to naval requirements by including engine specific functions.

The evolution of naval gas turbine controllers first to analog electronic, and more recently to distributed digital controls, has increased the system complexity and added a number of levels of machinery protection. The design of a specific electronic control module is used to illustrate the current state of the technology.

The paper concludes with a discussion of the further need to address the issues of fuel handling, metering and control in Navy ships with particular emphasis on integration in the marine environment.
Physical Aspects of Deposition From Coal Water Fuels Under Gas Turbine Conditions
Authors: Wenglarz Richard A. , Fox Ralph G.
Published: March 2015

Deposition, erosion, and corrosion (DEC) experiments were conducted using three coal-water fuels (CWF) in a staged subscale turbine combustor operated at conditions of a recuperated turbine. This rich-quench-lean (RQL) combustor appears promising for reducing NOx levels to acceptable levels for future turbines operating with CWF. Specimens were exposed in two test sections to the combustion products from the RQL combustor. The gas and most surface temperatures in the first and second test sections represented temperatures in the first stators and rotors, respectively, of a recuperated turbine. The test results indicate deposition is affected substantially by gas temperature, surface temperature, and unburned carbon due to incomplete combustion.

The high rates of deposition observed at first stator conditions showed the need for additional tests to identify CWF coals with lower deposition tendencies and to explore deposition control measures such as hot gas cleanup.
A Secondary Flow Calculation Method for One Stage Axial Transonic Flow Compressors, Including Shock-Secondary Flow Interaction
Authors: Kaldellis J. , Douvikas D. , Falchetti F. , Papailiou K. D.
Published: March 2015

A secondary flow calculation method is presented, which makes use of the meridional vorticity transport equation. Circumferentially mean flow quantities are calculated using an inverse procedure.

The method makes use of the mean kinetic energy integral equation and calculates simultaneously hub and tip secondary flow development. Emphasis is placed upon the use of a coherent two-zone model and particular care is taken in order to describe adequately the flow inside an unbounded (external), semi-bounded (annulus) and fully-bounded (bladed) space. Along with the velocity field, the losses, the defect forces and the corresponding additional work realized inside the viscous wall shear layer are calculated for stationary and rotating flow.

An approximate model for the interaction of the viscous shear layers and the external flow is used, which takes into account the meridional and the peripheral blockage. When shock waves are present in the external flow, an approximate interaction model is used, additionally, which calculates the static pressure field resulting from the interaction of the shock wave and the corresponding wall shear layer.

The method has been applied to two one stage transonic flow compressors and the results of the comparison between theory and experiment are presented and discussed.
Numerical Simulation of the Two Dimensional Viscous Compressible Flow in Blade Cascades Using a Solution Adaptive Unstructured Mesh
Authors: Sidén Gunnar L. D. , Dawes William N. , Albråten Per J.
Published: March 2015

An explicit finite element procedure has been coupled with an automatic mesh generation procedure for mesh adaptive steady state simulations of two-dimensional viscous compressible flows in cascades. Turbulence is modelled by a two-layer algebraic eddy viscosity model. Results show good behavior in comparison with measurements and results of a conventional H-mesh viscous flow solver. Computed loss approaches measured loss as the mesh is refined.

Currently, the unstructured solver suffers in efficiency terms because the automatic mesh generator tends to produce inefficient equilateral triangles in the regions of shock waves and boundary layers where stretched elements would be more appropriate. This means that, at least for the Navier-Stokes equations, the unstructured approach is not yet competitive with conventional structured techniques. Nevertheless, this will change once the key advantages of geometric flexibility and user independent solutions force rapid development.
A Small Air Turbine Power Plant Fired With Coal in an Atmospheric Fluid Bed
Authors: Foster-Pegg R. W.
Published: March 2015

An efficient, indirectly heated, steam-injected air turbine power or cogeneration plant, fired with coal in an atmospheric fluid bed, is described. The plant, described in the paper, will meet all environmental standards and will generate about 35 MW.

The plant offers a high power to steam ratio without requiring a condensing steam turbine and can operate efficiently without any export steam. Eliminating a condensing steam turbine, cooling tower, etc., reduces the capital cost and produces a low $/kw installation. If necessary, most of the water injected into the air turbine can be recovered from the exhaust air and reused.

All the equipment for the plant is commercially available.
Solution of Combustor Noise in a Coal Gasification Cogeneration Application of 100 MW-Class Combustion Turbines
Authors: Scalzo A. J. , Sharkey W. T. , Emmerling W. C.
Published: March 2015

The field conversion of two W501D5 combustion turbines to burn medium BTU fuel gas supplied by a DOW Chemical coal gasification process at Plaquemine, Louisiana resulted in excessive 105 Hz airborne sound and a corresponding unacceptable non-synchronous engine vibration when burning natural gas. A joint Westinghouse and DOW Chemical corrective action program is described including field tests.

Test results indicated that the combustion noise phenomenon was related to the strength of the primary air scoop recirculation pattern and its compatibility with the fuel and steam momentum vectors. A design was selected that eliminated the non-synchronous combustion noise generated vibration and reduced the 100 Hz third-octave noise from 115 db to 97 db, an intensity reduction of 64 to 1.