bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Probe-to-Specimen Distance Effect in Kidney Stone Treatment With Hydrodynamic Cavitation
Authors: Uzusen Dogan , Demir Ebru , Yavuz Perk Osman , Oral Ozlem , Ekici Sinan , Unel Mustafa , Gozuacik Devrim , Kosar Ali
Published: April 2015

The aim of this study is to focus on the effect of probe-to-specimen distance in kidney stone treatment with hydrodynamic bubbly cavitation. Cavitating bubbles were generated by running phosphate buffered saline (PBS) through stainless steel tubing of inner diameter of 1.56 mm at an inlet pressure of ∼10,000 kPa, which was connected to a 0.75 mm long probe with an inner diameter of 147 μm at the exit providing a sudden contraction and thus low local pressures. The bubbles were targeted on the surface of nine calcium oxalate kidney stones (submerged in a water pool at room temperature and atmospheric pressure) from three different distances, namely, 0.5 mm, 2.75 mm, and 7.75 mm. The experiments were repeated for three different time durations (5 min, 10 min, and 20 min). The experimental data show that amongst the three distances considered, the distance of 2.75 mm results in the highest erosion amount and highest erosion rate (up to 0.94 mg/min), which suggests that a closer distance does not necessarily lead to a higher erosion rate and that the probe-to-specimen distance is a factor of great importance, which needs to be optimized. In order to be able to explain the experimental results, a visualization study was also conducted with a high speed CMOS camera. A new correlation was developed to predict the erosion rates on kidney stones exposed to hydrodynamic cavitation as a function of material properties, time, and distance.
Filtration Characteristics of Fuel Neutral Particulates Using a Heterogeneous Multiscale Filtration Model
Authors: Gong Jian , Rutland Christopher J.
Published: April 2015

Filtration characteristics of fuel neutral soot particulate were studied using a recently developed heterogeneous multiscale filtration (HMF) model. In the HMF model, a probability density function (PDF) based pore size distribution and a porosity distribution across the filter wall are introduced to represent the heterogeneous multiscale porous structure. The HMF model was validated by an exhaust filtration analysis (EFA) system, which was designed for fundamental experimental filtration studies. Various sources of particulates from combustion engines were used in the filtration studies. Some particulates were sampled from a spark ignited direct injection (SIDI) engine fueled with gasoline and ethanol blends. Particulates from a compression ignition engine fueled with diesel for conventional and advanced combustion regimes were investigated as well. The microstructure of the porous wall was found to be more critical and necessary to simulate filtration of particulates from gasoline and advanced diesel combustion engines than those from conventional diesel combustion (CDC) engines. The interactions between the porous wall and trapped particulates were investigated. The dynamic filtration characteristics, including filtration efficiency, pressure drop and particulate distribution inside the wall are strongly dependent on total particulate volume rather than total particulate number concentration. The change of the filter structure as well as the shape of the particulate size distribution play important roles on particulate penetration.
Design, Modeling, Fabrication, Back-to-Back Test of a Magnetic Bearing System for High-Speed BLDCM Application
Authors: Han Bangcheng , Zheng Shiqiang
Published: April 2015

This paper describes in detail the design, construction, and testing of an active magnetic bearing (AMB) system for high-speed permanent magnet (PM) brushless DC motor (BLDCM) application. A back-to-back (BTB) test setup which consists of two BLDCMs connected by a high-speed flexible coupling is designed and built: the first one acts as the motor and the other one acts as the generator with resistive load. The dynamic model of the rigid rotor supported by AMBs, and its electromagnetic and feedback control design aspects are also provided. Mechanical design aspects are rotor assembly, radial AMB (RAMB), and thrust AMB (TAMB). Finally, full-loaded test results of the AMBs are given using the BTB experimental test setup that adopts two 100 kW electric machines supported by AMBs.
Efficient Steam System Incorporates Gas Turbine Principles
Authors: Jahnig C. E.
Published: April 2015

One approach to improving steam cycles is to apply certain gas turbine technology, namely, direct combustion to achieve a high working temperature. Direct combustion supplies heat and also working fluid, without the need for high temperature heat exchange. By burning hydrogen with pure oxygen the only product of combustion is steam; consequently, no inert gas is introduced into the system. In a similar manner direct combustion is used to maintain temperature during the first part of the expansion so as to approach an isothermal expansion rather than the adiabatic expansion typical of steam systems.

Such a modified steam cycle is described in this paper and shows a projected fuel efficiency of 58% when the maximum temperature is 1093 C., or 50% for 815 C. maximum. Practical ways to supply hydrogen and oxygen are discussed.
Development of a Design Model for Airfoil Leading Edge Film Cooling
Authors: Wadia A. R. , Nealy D. A.
Published: April 2015

Leading edge showerhead cooling designs represent an important feature of certain classes of high temperature turbine airfoils. This paper outlines a methodology for predicting the surface temperatures of showerhead designs with spanwise injection through an array of discrete holes. The paper describes a series of experiments and analyses on scaled cylinder models with injection through holes inclined at 20, 30, 45, and 90 degrees for typical radial and circumferential spacing-to-diameter ratios of 10 and 4, respectively. The experiments were conducted in a wind tunnel on several stainless steel test specimens in which flow and heat transfer parameters were measured over the simulated airfoil leading edge surfaces. Based on the experiments, an engineering design model is proposed that treats the gas-to-surface heat transfer coefficient with film cooling in a manner suggested by a recent Purdue-NASA investigation and includes the important contribution of upstream (coolant inlet face) heat transfer. The experiments suggest that the averaged film cooling effectiveness in the showerhead region is primarily influenced by the inclination of the injection holes. The effectiveness parameter is not strongly affected by variations in coolant-to-gas stream pressure ratio, freestream Mach number, gas-to-coolant temperature ratio and gas stream Reynolds number. This is appropriately reflected in the design model in which the increase in coolant side heat transfer coefficient (with blowing ratio) is essentially offset by a simultaneous increase in the gas side film coefficient. The model is also employed to determine (inferentially) the average Stanton number reduction parameter for a series of pressure ratios varying from 1.004 to 1.3, Mach numbers ranging from 0.1 to 0.2, temperature ratios between 1.6 and 2.0, and Reynolds numbers ranging from 3.5 × 104 to 9.0 × 104. Design capabilities of the analytical model are explored for typical high temperature first stage turbine vanes and rotor blades operating at rotor inlet temperatures in excess of 1644°K.
Power Dense Gas Turbine APUs
Authors: Rodgers Colin
Published: April 2015

Future high performance aircraft will require more compact, lighter weight, and self-sufficient secondary power equipment capable of faster starting and delivering high specific powers over wider operating envelopes of inlet temperatures and altitudes.

Meeting these requirements may not be entirely compatible with improving thermal efficiency, particularly for the small air-breathing gas turbine since optimum cycle conditions differ for maximum specific power and specific fuel consumption. Further conflict lies in the necessity to provide faster start times with a limited capacity of stored on-board start energy, because compressor and turbine inertias must be minimized although compressor and turbine airflow-swallowing capacity must be maximized.

This paper discusses the numerous design disciplines which constrain power density for small gas turbine auxiliary power units. Several potentially profitable development avenues are suggested for continuing the improvement of aircraft system performance.
Industrial Silencers for Gas Turbine Power Plants
Authors: Weirich Paul T. , Capek Zdenek A.
Published: April 2015

In gas turbine power plants, the major sources of noise are turbine inlet and exhaust. The following aspects of gas turbine silencers are discussed:

A. Criteria for turbine inlet and exhaust silencers — Design requirements and materials to meet noise criteria and to increase life expectancy of silencers.

B. Description of exhaust silencer system — Consisting of expansion seal, transition, exhaust silencer and other equipment.

C. Field measurement of exhaust silencer system — Description of turbine unit, noise sources, location of measuring points, measured noise data, and discussion of results.
Corrosion of Materials in a Simulated CAES Exhaust Gas Environment
Authors: Lukas Holger
Published: April 2015

Cold end corrosion due to sulfuric acid is a phenomenum not uncommon in boilers and exhaust gas waste heat boilers. Normally, the operating conditions can be changed to reduce or eliminate the corrosion. In a Compressed Air Energy Storage (CAES) plant, this is not a practical solution. This paper presents the preliminary results of corrosion testing of various materials in a simulated CAES recuperator environment.
60% Efficient Gas Turbine System for Base Load Use
Authors: Jahnig C. E.
Published: April 2015

Efforts to improve the performance of combustion gas turbines has emphasized increasing the operating temperature. This paper shows that an alternative approach using higher pressure is very attractive, giving efficiencies of 55–60% together with much more power output at a given air flow. Maximum temperature is 1200 C. at a pressure of 300 atmospheres.

The new systems use supplemental combustion within the gas turbine to approach an isothermal expansion, in contrast to the adiabatic expansion normally used with gas turbines. Details for three specific systems are compared in the paper.
Improvements in Part-Load Efficiency by Reducing Pressure Ratio in Regenerative Gas-Turbine Engines
Authors: Korakianitis Theodosios P. , Wilson David Gordon
Published: April 2015

To obtain equal thermal efficiencies in gas-turbine engines, designers have the freedom (if space and mass constraints are not limiting) of exchanging compressor pressure ratio for heat-exchanger effectiveness. Because heat exchangers can have lower losses than compressors, a high-effectiveness heat-exchanger cycle can have a much higher thermal efficiency (theoretically 55–60%) than is possible with unregenerated cycles. What has not been known up to now is the effect of design-point pressure ratio on the part-load efficiency of gas-turbine engines. The work reported here shows that, for similar turbomachinery technology, design-point and part-load efficiencies improve as the design-point pressure ratio decreases and the heat-exchanger thermal ratio increases.
Application of Advanced Technology to In-Service Gas Turbines
Authors: Whittaker Robert Al
Published: April 2015

This paper discusses the technical issues and business considerations involved in the application of advanced technology to gas turbine replacement parts. Today’s gas turbine owners are facing increased demands on their older machines in the areas of increased fuel efficiency, increased power output, and reduced operating costs. These demands can only be met through the use of superior replacement parts, which is made possible through the application of state-of-the-art technology. This technology is being made available for most turbine, combustion, and controls replacement parts.
Gas Turbine Combustion of a Minimally Cleaned, Coal-Derived Low-BTU Gas
Authors: Blanton John C. , Smith Daniel P.
Published: April 2015

As part of the joint GE/DoE Water-Cooled Components Test Program,1 a series of tests were performed involving the combustion of a minimally cleaned low-Btu coal gas in a pressurized gas turbine simulator. The fuel gas was produced in a 1-ton/hr advanced fixed-bed gasifier using Illinois #6 coal, and filtered of particulate in a full-pressure, full-temperature cyclone separator. The resulting product had a gross heating value of approximately 5000 kJ/kg at a temperature of 540 °C and a pressure of 22 bar. Numerous contaminants also remained in the fuel gas, including approximately 100 ppmw particulate matter (coal dust of 3 μm average size), 2000–4000 ppmv ammonia, 2000–2500 ppmv H2S, and 0.5–1.0% vaporized tars, oils, phenols, and other condensible hydrocarbons.

The fuel gas was burned with air at 6–7 bar pressure and 400 °C temperature in a gas turbine combustion system at overall fuel-air ratios up to 0.25 (overall equivalence ratio 0.36). Gaseous emissions were sampled in the exhaust stream and measurements made for O2, CO2, CO, unburned hydrocarbons, NOx, and SOx. The CO and unburned hydrocarbon emissions were both below 20 ppmv at full firing conditions, indicating acceptable combustion efficiency. The NOx levels measured were up to 500 ppmv, and were due to the of conversion of fuel-bound nitrogen (ammonia principally). The SOx emissions directly followed the oxidation of fuel-bound sulfur (H2S principally). At part-load conditions, emissions of CO and unburned hydrocarbons were observed to increase, as expected. Stable operation was maintained down to a combustion system temperature rise of approximately 350 °C.
A Two-Dimensional Transonic Flow Model for Turbomachines Using an Implicit Lambda Scheme
Authors: Cruickshank J. O. , Brasz J.
Published: April 2015

A two-dimensional Euler solver allowing the calculation of transonic flow conditions and weak shocks for turbomachinery blade rows is presented. The algorithm is based on a second-order-accurate finite-difference version of the implicit lambda scheme applied to the Euler equations assuming isentropic flow conditions. Using a fairly simple grid point network with equal spacing in meridional and tangential directions, this algorithm has been used successfully to calculate stationary and rotating stages of axial, radial and mixed flow turbomachinery cascades. Predictions are shown for a Laval nozzle and a high-turning turbine nozzle and compared against theoretically and experimentally available data.
The Application of Variable Turbine Geometry Turbocharging to Precision Generator Sets
Authors: Alpert Alan M.
Published: April 2015

The precision generator set is a device required to be capable of step changes in electrical output from no-load to full-load almost instantaneously with essentially no change in frequency. As a result of the time required for a conventional turbocharger to respond to a load change, the precision generator set application has been the exclusive realm of relatively large naturally-aspirated engines, despite the potential weight and fuel consumption advantages of smaller, turbocharged units. The advent of variable turbine geometry for small, inexpensive turbochargers may provide the means by which turbocharged engines may enter into this specialized service. This paper describes the application of variable geometry turbocharging to the precision generator set from the feasibility study to the proof-of-concept as verified in the standard test series for such a generator set.
Investigation of Jet-Filming Airblast Atomizer
Authors: Qi-Shou Zhao , Yun-Fang Yu
Published: April 2015

The jet-filming airblast atomizer is another kind of airblast atomizer differing from a prefilming airblast atomizer. Its atomizing mechanism and performance were investigated experimentally and theoretically. The effects of design parameters on the mean droplet size SMD and the thickness of the liquid film were obtained. The inherent mechanism consisting of three atomizing processes was proved. From this, the performance curves of atomization and thickness of liquid film can be explained and the principles of design of this kind atomizer were derived. The results obtained show that the performance of the jet-filming airblast atomizer is better than that of the prefilming type, and it is simple in design. So it is advantageous to apply this kind of atomizer to an advanced aircraft engine.
Refurbishing Gas Turbine Blades: Technical and Economic Aspects
Authors: Deblon B. , Keienburg K. H.
Published: April 2015

Highly sophisticated technologies for the repair and refurbishing of gas turbine blades are available on the market today. It is difficult, however, for the users of gas turbines to decide at what time they should utilize these facilities and which repair procedures would best suit their situation. The aim of this paper is to assist this decision-making process. The most frequent and typical forms of wear and damage to gas turbine blades are first presented and the consequent effect on efficiency and power output is discussed. Suitable well proven repair methods are recommended for each of the described types of wear from the vantage point of a gas turbine designer and manufacturer.
Thermal Preconditioning of Coal/Water Mixtures for Gas Turbine Applications
Authors: Roffe Gerald , Miller Gabriel
Published: April 2015

Thermal preconditioning of coal/water mixtures (CWM) is a process proposed for use with stationary gas turbine engines. The CWM is heated before delivery to the combustor to vaporize the water and to pyrolyze and devolatilize the coal prior to injection. The process offers a number of potential advantages. Engines can be started without the use of an auxiliary fuel system, atomizing nozzles are eliminated, flame stability is increased, and char burnout is accelerated as a result of increased initial flame intensity.

This project was an initial examination of technical questions affecting the feasibility and utility of the process. Heat transfer rates were measured for high solids loadings CWM in tubular heaters, the influence of the boiling process was studied, devolatilization rates were measured for the conditions of interest in gas turbine applications, the potential for organic sulfur volatilization was assessed and the effect of the process on heat rate for a combined cycle power plant was examined. The results of this initial examination showed the process to be both technically and economically feasible. CWM was vaporized and devolatilized in a small heat exchanger and a clearly defined steam/char/volatile suspension was produced. Temperatures of 750K to 870K and residence times of less than 1 second were found to be adequate to complete the process.
Experimental Investigation on Spatial Development of Streamwise Vortices in a Turbine Inlet Guide Vane Cascade
Authors: Sonoda Toyotaka
Published: April 2015

In order to obtain a better understanding of secondary flow in a turbine cascade, spatial development of a leading-edge horseshoe vortex has been investigated experimentally in a large-scale, low-speed, high-accelerated, plane turbine inlet guide vane cascade. Flow has been visualized by issuing kerosene vapor into the inlet boundary layer and the vane suction surface boundary layer, respectively.

Based on many cross-sectional photographs normal to the flow and supplemental measurements of the wall static pressure on the vane and the endwall, the evolution of a leading-edge horseshoe vortex into streamwise vortices and the generation of a new type streamwise vortex pair on the suction surface near the endwall are discussed.
Sampling and Analysis of Alkali in High-Temperature, High-Pressure Gasification Streams
Authors: McCurry Cynthia K. , Romanosky Robert R.
Published: April 2015

This paper describes the experiences leading to successful sampling of hot, contaminated, coal-derived gas streams for alkali constituents using advanced spectrometers. This activity was integrated with a multi-phase, combustion test program which addressed the use of minimally treated, coal-derived fuel gas in gas turbines. Alkali contaminants in coal-derived fuels are a source of concern, as they may induce corrosion of and deposition on turbine components. Real-time measurement of alkali concentrations in gasifier output fuel gas streams is important in evaluating these effects on turbine performance. An automated, dual-channel, flame atomic emission spectrometer was used to obtain on-line measurements of total sodium and potassium mass loadings (vapors and particles) in two process streams at the General Electric fixed-bed coal gasifier and turbine combustor simulator facility in Schenectady, New York. Alkali measurements were taken on (1) slipstreams of high temperature, high pressure, minimally clean, low-Btu fuel gas containing entrained particles from the gasifier and (2) a slipstream of the exhaust gas from the combustor/turbine simulator. Alkali detection limits for the analyzer were found to be on the order of one part per billion. Providing a representative sample to the alkali analyzer at the limited flows required by the instrument was a major challenge of this activity. Several approaches and sampling hardware configurations were utilized with varying degrees of success during this testing campaign. The resulting information formed the basis for a second generation sampling system which has recently been successfully utilized to measure alkali concentrations in slipstreams from the described fixed-bed coal gasifier and turbine combustor simulator.
Component Development for the KTT MKI Automotive Gas Turbine
Authors: Holmqvist Göran , Malmrup Lars
Published: April 2015

The KTT system is a gas turbine propulsion system designed especially for the automotive application. It’s main features are the three turbines on three different shafts and the close integration of the turbine and transmission into one unit.

The first experimental engine, the MkI, based on this system is being developed by United Turbine, a subsidiary to AB Volvo, in Sweden. This paper describes some results of the development of the main components for this engine; the compressor, the turbines and the heat exchanger system. Details on test equipment are given.

The results presented are not final and development continues. These results also provide a base for future engine designs.
Closed Cycle With Fluidized Bed Coal Firing Applications in Refineries
Authors: Bellofatto Oreste , Galli Augusto , Casmirri Carlo , Marziali Glauco
Published: April 2015

This paper considers the utilization of FB coal firing in advanced refineries and compares the main features of this application with those of refineries feeded by conventional steam power station.
Particulate Flow in the Rotor and Stator Elements of Turbomachines
Authors: Abdel Azim A. F. , Rouleau W. T.
Published: April 2015

In order to examine both primary and secondary erosion of turbomachines, two examples were studied: the impeller of a centrifugal compressor and the stationary straight infinite cascade. The first example was examined when particulates of large diameters bombarded its internal surface, thus providing a primary erosion pattern. An inviscid flow is assumed since the trajectories of large diameter particles are slightly influenced by viscous effects. Tracing these trajectories for silica and alumina particles defined four areas on the internal surfaces of the impeller which experienced the highest rate of material removal due to the successvie impacts. The viscous model of a centrifugal compressor is also under investigation by the authors.

The stationary infinite cascade of a typical turboexpander was subjected to fine particulate impacts. These fine particles were greatly influenced by both the viscous effects and secondary flow. Thus three-dimensional viscous flow was defined experimentally using a laser-Doppler anemometer (LDA). The pressure surface, especially the turning section, suffered from the highest erosion damage. These results compared favorably with the experimental results of the Ruston and Hornsby turbine operating with Greta Coal. The erosion rates of the first stage Ruston Turbine after 124.8 hours of operation showed similar results.
A Quasi-Three Dimensional Calculation System for the Flow Within Transonic Compressor Blade Rows
Authors: Calvert W. J. , Ginder R. B.
Published: April 2015

A calculation system has been set up to predict both the internal flow field and the overall performance of a transonic compressor blade row. The system iterates between an inviscid-viscous time-marching blade-to-blade (S1) treatment and a streamline curvature throughflow calculation for the pitchwise-averaged flow in the meridional plane (S2). A blade geometry package and a data transfer/display program are used to link the S1 and S2 methods to give a semi-automatic convergence procedure. The only empirically-based correlation or correction required is an extra loss imposed near the blade hub and tip to allow for end effects. The system has been applied to a high bypass ratio transonic fan rotor near design point. The converged solution was in good agreement with the measured performance.
Comparison of Partial vs Full Admission for Small Turbines at Low Specific Speeds
Authors: Macchi Ennio , Lozza Giovanni
Published: April 2015

Several methods are available for the optimization of basic design parameters and the preliminary efficiency prediction of axial flow turbine stages. However, their application is often questionable for stages having low specific speed and/or small volume flow rates. In particular, the question may arise whether a better performance is achieved by a partial admission, impulse stage or by a full admission reaction stage having lower blade height.

The paper firstly reviews the available loss correlation methods applicable to partial admission turbines, then a comparison is performed between the efficiency achievable by partial and full admission stages designed for the same operating conditions. The turbine design procedure for both options is fully automatized by an efficiency optimization method similar to the one described in previous authors’ papers.

The results of calculations are presented in the paper as a function of similarity parameters (specific speed, size parameter, expansion ratio). It is found that the results obtained with different correlations are relatively similar for “conventional” turbine stages (low expansion ratio, moderate size parameters), while important differences take place for very small sizes and/or in presence of important compressibility effects.

The presented results can be useful: 1) to decide whether selecting full or partial admission solutions; 2) to optimize the degree of admission and the other basic design parameters, and 3) to predict with reasonable accuracy the stage efficiency.
Prediction of Small Rotating Stall in Axial Compressors Using Actuator Disc Theory
Authors: Mathioudakis K.
Published: April 2015

A theoretical study of the development of rotating stall in axial compressors is presented. A small perturbation analysis is used for this purpose. The compressor is considered as a series of vaneless spaces and blade rows. The axisymmetric mean flow is of the free vortex type and blade rows are represented as actuator discs. The perturbations are three dimensional and steady with respect to a rotating reference frame. For high hub-tip ratio annuli the transfer relations for the perturbations are expressed in a matrix form. This formulation allows the prediction of the occurrence and development of rotating stall in single or multiple blade row configurations. The results of the prediction compare favourably with experimental data.
Development of Small Rotating Stall in a Single Stage Axial Compressor
Authors: Mathioudakis K. , Breugelmans F. A. E.
Published: April 2015

In this paper we present the results of a detailed experimental study of the development of small rotating stall, as it appears in a one stage axial compressor. Stationary hot-wire probes are used to measure the variation of amplitude and propagation speed of the disturbances caused by small stall. Measurements near the rotor blade surface with rotating probes provide additional information on the nature of the phenomenon. The development of the cell pattern for different operating conditions is studied. The different character from what is known as “big stall” is demonstrated.
Experimental Study of the Spray Characteristics of a Research Airblast Atomizer
Authors: Acosta Waldo A.
Published: April 2015

An experimental study of airblast atomization was conducted using an especially designed atomizer in which the liquid first impinges on a splash plate, then is directed radially outward and is atomized by the air passing through two concentric, vaned swirlers that swirl the air in opposite directions. The effect of flow conditions, air mass velocity (mass flow rate per unit area, ρAUA) and liquid to air ratio on the mean drop size was studied. Seven different ethanol solutions were used to simulate changes in fuel physical properties. The range of atomizing air velocities was from 30 to 80 m/s. The mean drop diameter was measured at ambient temperature (295 K) and atmospheric pressure.
A Comparison Between Full and Simplified Navier-Stokes Equation Solutions for Rotating Blade Cascade Flow on S1 Stream Surface of Revolution
Authors: Naixing Chen , Fengxian Zhang
Published: April 2015

A method for solving the Navier-Stokes equations of the rotating blade cascade flow on S1 stream surface of revolution is developed in the present paper.

In this paper a complete set of full and simplified Navier-Stokes equations is given which includes stream-function equation, energy equation and entropy equation, equation of state for a perfect gas, formula for estimating density and formulas for calculating viscous forces, work done by viscous force, dissipation function and heat-transfer term.

A comparison between the full and the simplified Navier-Stokes equations is made. The viscous terms of both full and simplified Navier-Stokes equation solutions are also compared in the present paper. The comparison shows that the simplified Navier-Stokes equations are applicable.
Investigation of the Sampling Representativeness With Different Probes in a Gas Turbine Combustor
Authors: Shou-Sheng Wu , Hua-Fang Wang , Li Li
Published: April 2015

Three types of 12-orifice mixing cruciform sampling probes, i.e. the sampling orifices with or without stub pipes and arranged in spiral form or on three radii, and one single orifice traversing probe were used to investigate the sampling representativeness in the measurement of gas turbine emissions. The results obtained in the experiment show that the distribution of carbon monoxide, CO, and smoke number, S.N., may have certain relations with the distribution of fuel and air in the combustor, and the three types of probes mentioned, the angular position of the cruciform probe and the manner of extracting sample off the mixing probe can make a deviation of less than 1 S.N. for smoke and about 5% for carbon monoxide.
Design and Development Test of a Heavy-Duty Industrial Gas Turbine Combustion System for Low-Btu Coal Gas Fuel
Authors: Beebe K. W. , Blanton J. C.
Published: April 2015

A heavy-duty industrial gas turbine combustion system has been designed and developed for low-Btu coal gas fuel with heating value in the 100 to 150 Btu/scf range (4.22 to 6.33 MJ/ncm). The new design uses a unique high-swirl fuel injector to provide rapid fuel/air mixing and a stable flame front. A full-scale, full-pressure laboratory development test program has been conducted with simulated clean low-Btu coal gas fuel, and the combustion system has operated successfully with minimally cleaned raw coal gas from a fixed bed gasifier in a process evaluation test facility at the General Electric Research and Development Center. Laboratory test results are presented for important combustor operating parameters including exhaust emissions, combustion efficiency, exhaust temperature profile, dynamic pressure, and metal temperature distribution.
Onshore Test Method for a 3 Unit 60 MW Gas Turbine-Generator Power Module
Authors: Herdlevaer Johannes , Black Gordon Hugh
Published: April 2015

There has been an increasing demand for onshore testing of equipment destined for offshore operation.

The justification for this requirement can be summarized as follows:

1. High cost of offshore commissioning where even minor faults detected, constitutes potentially serious problems.

2. Consequenses of delay of platform start-up are enormous.

3. Skilled experienced personel and diagnostic equipment is available onshore, and rectification of new units will benefit from the existence of previous experience.

4. Spare and renewal parts availability.

This paper describes the method for string testing of a 3 unit 60 mw utility gasturbine-generator power module built for the gullfaks A platform in the Norwegian sector of the north sea.

It describes the test facility and test equipment set up and also the test program which was followed.

At the time of writing the paper the test program was barely initiated, and for that reason the test results will be presented in the form of an addendum to this paper during the meeting.
Assessment of Single- and Two-Zone Modeling of Centrifugal Compressors, Studies in Component Performance: Part 3
Authors: Japikse D.
Published: April 2015

Single- and two-zone modeling, as used to describe the performance of centrifugal compressors, is evaluated against basic laboratory data. The historical industrial usage of single-zone modeling is reviewed and documented while indicating inherent errors as well as areas of applicability. Enhanced accuracy of two-zone modeling (also called jet-wake modeling in limited instances) is demonstrated and advantages for advanced design optimization studies are documented. An original and rigorous derivation of the two-zone (jet-wake) modeling equations is given which resolves discrepancies in earlier derivations. This paper is part of a seven-paper series presenting the foundation, history and application of two-zone modeling.
Weight Reduction in a Marine Gas Turbine Inlet
Authors: Reinauer G. A. , Peszynski M.
Published: April 2015

Major design changes to the Propulsion Gas Turbine Air Inlet on the US Navy’s CG47 Class Guided Missile Cruisers have resulted in significant superstructure weight savings. The majority of weight reduction resulted from use of finite element analysis (FEA) computer modeling techniques applied to structural optimization. FEA models of the forward and aft deckhouses provided the necessary capability to analyze each structure’s response to loads simulating a nuclear air blast, shock, and vibration. Integration of the moisture separator housings into each deckhouse structure allowed improved structural stability and additional weight reductions. FEA modeling and a redesign of the major inlet system 32% lighter than inlets installed onearly ships of this class. The first of the lightweight deckhouses has been installed on the CG52 Cruiser.
Experimental Determination of Centrifugal Impeller Discharge Flow and Slip Factor
Authors: McGuire J. T. , Gostelow J. P.
Published: April 2015

The use of a miniature pressure transducer to measure the flow field at the discharge of an industrial centrifugal pump impeller is described. Periodic signals were elucidated using a phase lock averaging program. A new technique was used in which, with one easily calibrated transducer, total and static pressures and flow angle were measured. Axial traversing enabled the discharge flow to be surveyed and the slip factor to be deduced directly. The measured slip factor was in good agreement with design correlations.
General Curved Surface Fitting and Calculation of Flow Along Arbitrarily Twisted Stream Surface
Authors: Wenquan Wu , Haoyu Yu
Published: April 2015

This paper consists of two parts. (1) General curved surface fitting and grid refining. A method of fitting a set of given discrete points on several stream lines to give a smooth and arbitraily twisted stream surface was developed. Based upon the small deformation theory for thin plate, the Kirchhoff’s Equation was solved and twofold transformations were incorporated. The first step is the transformation from physical surface into computational surface and the second is affine transformation. The accuracy of the result is about 0.004% and the CPU time needed is reasonable for engineering application. Then the refined computational grid and the calculation for the geometrical quantities of the grid are carried out on the fitted surface. (2) Calculation of the flow along the fitted stream surface. Employing non-orthogonal curvilinear coordinate system, the fitted stream surface is selected as a coordinate surface, so that there are only two velocity components even when the stream surface is arbitrarily twisted, and it is very convenient to define the stream function. The general equation for the quasi-linear stream function governing the flow along the fitted stream surface was employed. This was solved with the method of direct decomposition of matrix. The numerical examples are also included in this paper. The present method can be used for S1 and S2 stream surfaces and other engineering calculations.
Growth, structure, and high temperature stability of zirconium diboride thin films
Authors: Stewart David M. , Frankel David J. , Lad Robert J.
Published: April 2015

Morphologically stable, electrically conductive thin films are required for emerging harsh environment sensors that can operate at temperatures above 1000 °C. Zirconium diboride (ZrB2) is an ultrahigh temperature ceramic with a melting temperature greater than 3200 °C and in bulk form has an electrical conductivity of ∼107 S/m. Thin films of varying Zr:B ratio have been deposited on sapphire substrates by electron beam coevaporation from elemental sources. An appropriate ratio of the elemental fluxes was determined to produce nearly stoichiometric ZrB2 thin films. Films deposited at ambient substrate temperatures are amorphous as measured by x-ray diffraction, while films grown at 600 °C show textured ZrB2 nanocrystallites in an amorphous matrix, regardless of composition. When annealed in ultrahigh vacuum at 800 and 1000 °C for 1 h, nanocrystalline films show further grain growth with a 〈101¯0〉 ZrB2 preferred orientation normal to the substrate, while the low nucleation rate in the amorphous films inhibits the formation of any substantial grains. Film conductivity ranges between 0.13 and 6.3 × 105 S/m, increasing with zirconium content and crystallite grain size. Besides grain growth, no micron-scale structural or morphological changes were observed with annealing, suggesting that ZrB2 films can act as stable electrodes in high temperature environments.
Shielding technique for deposition of Au electrical contacts on graphene by sputtering
Authors: Li Bing , Pan Genhua , Jamil Nawfal Y. , Al Taan Laith , Awan Shakil , Avent Neil
Published: April 2015

Here, the authors report on a novel shielding technique for the fabrication of electrical contacts on exfoliated graphene by sputtering and lift-off process. The technique solves this problem by removing unwanted gold film in patterning contacts and reduces the high contact resistivity typically found in sputtered devices ranging from 260 to 940 kΩ μm induced by sputtered Au on graphene. By using a shielding tube integrated into our sputtering machine and optimizing the sputtering parameters, contact resistivity as low as 1.04 kΩ μm has been achieved. Consequently, the total device resistivity is significantly reduced, and the yield rate of the devices fabrication has also increased from 17% to 90%.
Phase-control of a rising sun magnetron using a modulated, addressable, current source
Authors: Fernandez-Gutierrez Sulmer , Browning Jim , Lin Ming-Chieh , Smithe David N. , Watrous Jack
Published: April 2015

It has been proposed that the use of gated field emitters with a faceted cathode in place of the conventional thermionic cathode could be used to control the current injection in a magnetron, both temporally and spatially. In this work, this concept is studied using the particle-in-cell code VORPAL. The magnetron studied is a ten-cavity, rising sun magnetron, which can be modeled easily using a 2D simulation. The magnetron has a ten-sided faceted cathode. The electrons are injected from three emitter elements on each of the ten facets. Each emitter is turned ON and OFF in sequence at the oscillating frequency with five emitter elements ON at once to obtain the five electron spokes of the π-mode. The simulation results show that the modulated, addressable cathode reduces startup time from 100 to 35 ns, increases the power density, controls the RF phase, and allows active phase control during oscillation.
Dosimetric characterization of a microDiamond detector in clinical scanned carbon ion beams
Authors: Marinelli Marco , Prestopino G. , Verona C. , Verona‐Rinati G. , Ciocca M. , Mirandola A. , Mairani A. , Raffaele L. , Magro G.
Published: April 2015

Purpose:

To investigate for the first time the dosimetric properties of a new commercial synthetic diamond detector (PTW microDiamond) in high‐energy scanned clinical carbon ion beams generated by a synchrotron at the CNAO facility.

Methods:

The detector response was evaluated in a water phantom with actively scanned carbon ion beams ranging from 115 to 380 MeV/u (30–250 mm Bragg peak depth in water). Homogeneous square fields of 3 × 3 and 6 × 6 cm2 were used. Short‐ and medium‐term (2 months) detector response stability, dependence on beam energy as well as ion type (carbon ions and protons), linearity with dose, and directional and dose‐rate dependence were investigated. The depth dose curve of a 280 MeV/u carbon ion beam, scanned over a 3 × 3 cm2 area, was measured with the microDiamond detector and compared to that measured using a PTW Advanced Markus ionization chamber, and also simulated using fluka Monte Carlo code. The detector response in two spread‐out‐Bragg‐peaks (SOBPs), respectively, centered at 9 and 21 cm depths in water and calculated using the treatment planning system (TPS) used at CNAO, was measured.

Results:

A negligible drift of detector sensitivity within the experimental session was seen, indicating that no detector preirradiation was needed. Short‐term response reproducibility around 1% (1 standard deviation) was found. Only 2% maximum variation of microDiamond sensitivity was observed among all the evaluated proton and carbon ion beam energies. The detector response showed a good linear behavior. Detector sensitivity was found to be dose‐rate independent, with a variation below 1.3% in the evaluated dose‐rate range. A very good agreement between measured and simulated Bragg curves with both microDiamond and Advanced Markus chamber was found, showing a negligible LET dependence of the tested detector. A depth dose curve was also measured by positioning the microDiamond with its main axis oriented orthogonally to the beam direction. A strong distortion in Bragg peak measurement was observed, confirming manufacturer recommendation on avoiding such configuration. Very good results were obtained for SOBP measurements, with a difference below 1% between measured and TPS‐calculated doses. The stability of detector sensitivity in the observation period was within the experimental uncertainty.

Conclusions:

Dosimetric characterization of a PTW microDiamond detector in high‐energy scanned carbon ion beams was performed. The results of the present study showed that this detector is suitable for dosimetry of clinical carbon ion beams, with a negligible LET and dose‐rate dependence.
Path specific Doppler compensation in time-reversal communications
Authors: Jesus Sérgio M. , Siddiqui Salman I. , Silva António
Published: April 2015

Passive time reversal (pTR) is a low complexity receiver scheme that uses multichannel probing for time signal refocusing, thus reducing time spreading and improving inter-symbol interference. Recognizing that signals traveling through different paths are subject to arrival-angle-related Doppler displacements, this letter proposes a further improvement to pTR that applies correcting frequency shifts optimized for beams formed along each specific path arrival angle. The proposed channel equalizer is tested with real data, and the results show that the proposed approach outperforms both pTR and the modified pTR channel combiners providing an MSE gain of 4.9 and 4.2 dB, respectively.
Individual, Social, and Neighborhood Associations With Sitting Time Among Veterans
Authors: Millstein Rachel A. , Hoerster Katherine D. , Rosenberg Dori E. , Nelson Karin M. , Reiber Gayle , Saelens Brian E.
Published: April 2015

Background:

Sedentary behavior is an increasingly recognized health risk factor, independent of physical activity. Although several correlates of sedentary behavior are known, little research has identified them among U.S. veterans, a population that faces disproportionate chronic disease burden.

Methods:

A survey was mailed to 1997 randomly selected veterans at a large urban Veterans Affairs medical center in 2012 and remailed in 2013 to nonresponders, resulting in a 40% response rate. We examined individual-, social-, and neighborhood-level factors in association with self-reported sitting time. Factors correlated with sitting time at P < .05 were included in a multiple linear regression model.

Results:

In the multivariate model, higher depression (B = 7.8), body mass index (B = 5.1), functional impairment (B = 4.2), and self-rated health (B = 68.5) were significantly associated with higher sitting time, and leisure time physical activity (B = –0.10) and being employed (B = –71.3) were significantly associated with lower sitting time.

Conclusions:

Individual-level, but not social- and neighborhood-level, variables were associated with sitting time in this population. This study identified individual-level targets for reducing sitting time and improving overall health among veterans.
Measurement Considerations of Peak Stepping Cadence Measures Using National Health and Nutrition Examination Survey 2005–2006
Authors: Kang Minsoo , Kim Youngdeok , Rowe David A.
Published: April 2015

Background:

This study examined the optimal measurement conditions to obtain reliable peak cadence measures using the accelerometer-determined step data from the National Health and Nutrition Examination Survey 2005–2006.

Methods:

A total of 1282 adults (> 17 years) who provided valid accelerometer data for 7 consecutive days were included. The peak 1- and 30-minute cadences were extracted. The sources of variance in peak stepping cadences were estimated using Generalizability theory analysis. A simulation analysis was conducted to examine the effect of the inclusion of weekend days. The optimal number of monitoring days to achieve 80% reliability for peak stepping cadences were estimated.

Results:

Intraindividual variability was the largest variance component of peak cadences for young and middle-aged adults aged < 60 years (50.55%–59.24%) compared with older adults aged ≥ 60 years (31.62%–41.72%). In general, the minimum of 7 and 5 days of monitoring were required for peak 1- and 30-minute cadences among young and middle-aged adults, respectively, whereas 3 days of monitoring was sufficient for older adults to achieve the desired reliability (0.80). The inclusion of weekend days in the monitoring frame may not be practically important.

Conclusions:

The findings could be applied in future research as the reference measurement conditions for peak cadences.