bluuebunny/crossref_metadata_2025 huggingface dataset:
The Viability of Capacity Control of High Temperature Heat Pump Water Heaters Operating Non-Azeotropic Mixtures
Authors: Liebenberg Leon , Meyer Josua P.
Published: December 2014

A high temperature electrically-operated heat pump water heater is evaluated in terms of the viability of employing capacity control using non-azeotropic refrigerant mixtures (NARMs). The system coefficient of performance (COP) is improved by introducing capacity control, which offers continuous modulation by varying heat pump capacity to match the load. This is accomplished by using a non-azeotropic refrigerant mixture (NARM) and changing the composition (x) of the circulating mixture. The NARM R-22/ R-142b is selected due to the requirement for a high condensing temperature and a wide capacity range. The life-cycle cost effectiveness of this heat pump is compared with that of a conventional heat pump (operating a pure fluid). Computer simulations show that the capacity-controlled heat pump, operating between compositions of 100% R-22 and 70% R-22, shows a 29.6% improvement in energy conversion when compared with a conventional R-22 heat pump water heater. The payback periods of the capacity-controlled systems, are strongly dependent on electricity tariff, additional system cost, and period and duration of heat pump operation.
A Comparison of Tow Criteria Derived From Satellite- and Ship-Based Observations
Authors: Cooper Cortis K.
Published: December 2014

Three estimates of the 10-yr significant wave height (Hs) are developed for 16 tow scenarios from Perth, Singapore, and Korea to the northwest shelf of Australia. One of the estimates is based on Global Wave Statistics (Hogben, et al., 1986), a database of visual ship observations that has been used extensively by the oil industry. These results are compared to estimates derived from two recently released commercial satellite altimeter databases, SOS and CLIOSat. The mean of the 10-yr Hs for the 16 scenarios calculated from the ship data is 40% (2.6 m) larger then the satellite databases while the variance is 40% less. Evidence suggests the ship-based values are unrealistically high for a number of the scenarios. Results SOS are internally consistent and generally compare favorably with high-quality model hindcast studies in the region. The first-order statistics from CLIOSat compare well to SOS but there are substantial differences for some of the scenarios. Several of the CLIOSat-derived extremes are internally inconsistent and don’t compare well to hindcast results However, firm conclusions must await further work.
University Expertise and the Oil and Gas Industry: Development of Cost Effective Solutions to Applied Oil-Spill-Related Research Issues
Authors: Davis Donald W. , Guidry Roland J.
Published: December 2014

Immediately after the Exxon Valdez incident, the United States Oil Pollution Act of 1990 was passed. This Act clarified the lines of responsibility associated with future oil spills. In addition to this Federal legislation, Louisiana lawmakers in 1991 enacted the Oil Spill Prevention and Response Act. Financial awards associated with this Act support a wide-range of research activities. Since 1993, 24 projects have been funded. The scope and nature of this research includes:

• Oil Spill Awareness through Geoscience Education (OSAGE);

• Used Oil Recycling in Louisiana’s Coastal Communities;

• Evaluation and Characterization of Sorbents;

• Landsat TM and Synthetic Aperture Radar to Facilitate Coastline Delineation;

• Environmental Effects and Effectiveness of In-Situ Burning in Wetlands;

• Bioremediation Protocol for Small-Scale Oil Spills;

• Oil Spill Risk on Louisiana’s Largest Waterway;

• River Time-of-Travel Modeling;

• Composting Technology for Practical and Safe Remediation of Oil-Spill Residuals;

• Predictability of Oceanic and Atmospheric Conditions off the Mississippi Delta; and

• Phytoremediation for Oil Spill Cleanup and Habitat Restoration in Louisiana’s Marshes.

Each of these projects, and others, are the result of the marriage of industry and university researchers in the identification and solution of applied oil-spill-related problems. The alliance is a good one. Important environmental issues are addressed because the selection process ensures each research initiative has the potential of being implemented by the response community. The work and knowledge gained from these projects is a clear indication of how industry and the university community can function in a collaborative manner to solve important issues — a significant partnership that clearly shows how both can benefit and a model for others to follow.
A Better Way to Support Horizontal Pressure Vessels Subject to Thermal Loading
Authors: Tooth Alwyn S. , Cheung John S. T. , Ng Heong W. , Ong Lin S. , Nadarajah Chithranjan
Published: December 2014

When storing liquids at high temperature, in horizontal vessels, the current design methods aim to minimise the thermal stresses by introducing a sliding surface at the base of one of the twin saddle supports. However, regular site maintenance is required to ensure that adequate sliding is achieved This may be difficult and costly to carry out.

The aim of the present work, therefore, is to dispense with the sliding support and to provide saddle designs which although fixed to the platform, or foundation, do not result in the storage/pressure vessel being over-stressed when thermal loading occurs. The paper provides general recommendations for the most appropriate saddle geometries, and details the way in which ‘Design by Analysis’ and ‘Fatigue Life Assessments’ may be carried out using the stresses which arise from these designs.
Stress Distribution in the Region Around Two Normally Intersecting Pipes due to In-Plane Bending Moments Using Finite Element Method
Authors: Harsokoesoemo Darmawan , Santoso Gatot
Published: December 2014

Numerically calculated stress in the region of two normally intersecting pipes due to in-plane bending moments using finite element program MECHANICA are presented in this paper. The computer results were processed and then presented in stress versus location (along several lines) diagrams. Other investigators’ results for similar problem are not easy to obtain due to differences in the problem, in modelling, in finite element program used and in methods of data presentation. Lock et al (1985) and Moffat et al (1984) works were the closest for comparison purposes.
Leakage Effects on the Rate of Change of Pressure at the Pipeline Exit
Authors: Chang Seungyong
Published: December 2014

This paper investigates leak effect on the outlet pressure at pipeline exit. A modified Weymouth equation (includes inclination effect) was used as a governing equation for this study. First, a brief summary of the modified Weymouth equation was reviewed. Next, predicted results by the equation were compared to those by field data for checking discrepancy. Then, to investigate leak effect, outlet pressure and ratio of outlet to inlet pressure were compared between no leak and leak conditions for horizontal, upward, and downward flows, respectively. Finally, effects of leak location as well as leak rate on the outlet pressure were also investigated for all pipeline inclinations.
On-Line Tool Monitoring of Tool Wear Chipping/Breakage and Temperature Using Ultrasonic Sensors
Authors: Patel N. D. , Nicholson P. S.
Published: December 2014

High frequency (50–120) MHz, ultrasonic, AIN-sensors have been successfully applied to the study of wear, chipping/breakage and temperature of triangular ceramic and carbide inserts. These sensors readily differentiate between signals from wear and chipping/breakage and, in flight-identify the damage location with simultaneous measurement of signal amplitude and transit time. The signals are unaffected by the machining process. The temperature of the chip/tool interface can be readily obtained during the cutting process by monitoring the transit time. Preliminary studies suggest these sensors also monitor the hardness of the workpiece and the chatter during the cutting. A specially-designed ultrasonic process-control system with 100 ps time resolution with data collection speed 1–10 kHz was necessary to observe the on-line data. The same system integrated with a focused transducer can be used to follow the workpiece dimension and surface finish, on-line. The ultrasonic, process control system that has been developed is robust and can be used for other NDE applications with a resolution of sub-micron thickness. It can also monitor residual stresses.
Establishment of an NDE Center at the Papua New Guinea University of Technology: Scope and Objectives
Authors: Bray Don E. , Gad G. S.
Published: December 2014

Papua New Guinea lies just north of Australia (Fig. 1). It is a developing island nation, with 462,839 km of land area, a population of 3.9 million people, and vast natural resources (Compton’s Interactive Encyclopedia, 1996). It is the largest island in the Oceania region of the world, which also includes Fiji, the Solomon Islands and Vanuatu. Most of these islands share similar resources, and prudent development of the resources requires utilization of nondestructive evaluation (NDE). NDE provides the means for flaw detection and size assessment, as well as evaluation of material degradation such as corrosion and hydrogen attack. These are factors which affect the service life of components and systems. Being aware of the state of degradation of these components and systems will enable cost effective maintenance, and reduce costly and dangerous failures. Recognizing the need for NDE expertise, the Papua New Guinea University of Technology at Lae has initiated a Center for Nondestructive Evaluation. Once operational, the center should serve the entire Oceania region, and provide resources, trained students and expertise that will enable the growth of the NDE industry within that area. It is widely accepted that NDE adds value to a product or process, not just cost. The amount of value is directly related to the engineering education of the personnel making NDE decisions. The growth of the NDE industry in these South Pacific Islands will add to the economy, as well as aid in the further creation of a population of engineers who are well educated in NDE.
Nondestructive Evaluation (NDE): Auralization of Ultrasonic Signals for the Detection of Corrosion
Authors: Holt Amos E. , Light Glenn M.
Published: December 2014

During nondestructive evaluation (NDE), an instrument is used to receive inspection signals and display them for visual interpretation. Southwest Research Institute (SwRI) has developed technology that allows NDE signals generated from conventional ultrasonic instrumentation to be completely converted into audible (aural) signals to enhance reliability of evaluation through the use of two senses (ears and eyes) to improve inspection reliability.

For example, detection of hidden corrosion on aircraft structures using conventional ultrasonic testing (UT) techniques is difficult because of thin walls and corrosion topography. These characteristics require use of high-frequency, high-spatial-resolution transducers to attempt to detect backwall signal amplitude. It is difficult to visually discriminate backwall signals of thin wing structure from the normal ringdown of the transducer.

Using aural UT, a trained inspector can listen to sounds generated by aural UT equipment and detect the presence of hidden corrosion with higher reliability than using conventional UT.
Fiber Optic Sensors for Damage Detection in Composite Materials
Authors: Asundi Anand
Published: December 2014

An absence of proper design rules has limited the application of composite materials to specific areas. However, within these application areas there is still a need to regular monitor the component resulting in significant downtime and loss of revenue. To overcome this it is proposed to have an on-line monitoring system capable of global checking of the component. Fiber optic polarimetric sensors are chosen in this study to globally characterize the health of a component. Polarimetric sensors have better sensitivity than intensity sensors and at the same time are more rugged than interferometric sensors. In this study, the effect of debonds and fiber breakages are investigated in composite bend specimens.
The Recent Development Status and Future Role of Fuel Cells
Authors: Anahara Rioji
Published: December 2014

One of the most important tasks through the 21st century is to ensure a stable supply of energy and maintain a balanced clean global environment. The principal advantage of fuel cell power plants lies in their favorable environmental impact. Fuel cell development is of utmost important in the light of the recent worldwide clean air movement.
Modeling the Transient Formation of Flammable Atmospheres Within Cylinderical Vessels Containaing Some Fuel
Authors: Bunama R. , Karim G. A.
Published: December 2014

A two dimensional axisymmetric computational model based on a finite difference scheme has been developed to model the transient formation of flammable atmospheres upon the diffusion of fuel vapour following the exposure of liquid fuel surfaces to air within cylindrical vessels at constant pressure and initial temperature. The Transient equations of Momentum, Energy, Species Continuity and Transport properties are solved.

Two typical common fuels, n-pentane and methanol where modeled. The effects of convection and temperature gradients produced by the extraction of the latent heat of vaporization from the liquid fuel surface were taken into account and the thermodynamic and transport properties were taken to be variable. The results of the 3-D axisymmetric model were compared with the corresponding values obtained using a 1-D model and checked favorably with some experimental results obtained with n-pentane and air.
The Effect of Co-Flowing Stream Velocities on the Flow Characteristics of Jets Issuing From Elliptic Nozzles
Authors: Papanikolaou N. , Wierzba I.
Published: December 2014

The flow structure of cold and ignited jets issuing into a co-flowing air stream was experimentally studied using a laser Doppler velocimeter. Methane was employed as the jet fluid discharging from circular and elliptic nozzles with aspect ratios varying from 1.29 to 1.60. The diameter of the circular nozzle was 4.6 mm and the elliptic nozzles had approximately the same exit area as that of the circular nozzle. These non-circular nozzles were employed in order to increase the stability of attached jet diffusion flames.

The time-averaged velocity and r.m.s. value of the velocity fluctuation in the streamwise and transverse directions were measured over the range of co-flowing stream velocities corresponding to different modes of flame blowout that are identified as either lifted or attached flames. On the basis of these measurements, attempts were made to explain the existence of an apparent optimum aspect ratio for the blowout of attached flames observed at higher values of co-flowing stream velocities. The insensitivity of the blowout limits of lifted flames to nozzle geometry observed in our previous work at low co-flowing stream velocities was also explained.
Ignition and Combustion of Isolated Coal Water Slurry Droplet
Authors: Bhadra Tanmoy , Annamalai Kalyan
Published: December 2014

A digital image processing technique is used to investigate the ignition and combustion characteristics of an isolated coal water slurry droplet in low Re flow. Coal water slurry droplet study is useful for dilute coal suspensions based on the premise that ignitability of a spray of coal water slurry must depend on the ignition characteristic of an isolated coal water slurry droplet. A flat flame burner is used for optical accessibility and also for simulating vitiated gases as existing in boiler burners. A quartz wire of 0.175 mm dia is chosen for low thermal conductivity to hold the droplet above the flat flame burner. The following sequence of events are observed: (i) Ignition occurs at the leading edge of the droplet, (ii) For coal water slurry droplet of the order less than 1 mm ejection of volatiles as jets in the direction of convective flow followed by coalescence, (iii) For a droplet with diameter of the order greater than 1 mm it was observed that the volatile combustion occurs away from the droplet in the wake of the combustible gases made upstream, (iv) Combustion of coal water slurry droplet is intermittent. Ignition time and volatile combustion times were obtained for a typical coal water slurry droplet. Calculations were carried out to determine the number of particles, interparticle spacing and density of coal water slurry droplet.
The Application of Computerised Maintenance Management System to Equipment Failure History
Authors: Samaha Mohammed E.
Published: December 2014

This paper discusses how equipment failure history stored in a computerised maintenance management system has been effectively used through the application of Weibull analysis to give an indication of the component failure mechanism (e.g., infant mortality, random failure, premature wear-out). Weibull analysis was also used to predict plant and equipment reliability by calculating the number of failures expected to occur in the future using Mean Time Between Failures (MTBF). Examples are given for component, equipment, and system failure studies for crude oil pump stations shipper pumps, steam turbines, and natural gas liquidation compression trains.
Remediation of Contaminated Sediments
Authors: Radhakrishnan Ramalingam , Ariza Carlos H.
Published: December 2014

The impact of Polynuclear Aromatic Hydrocarbons (PAHs) on sediments, together with the ultimate transport and migration of constituent chemicals in their dissolved or sorbed states, has led to environmentalists to develop several techniques for cleaning contaminated sediments. Dredging operations for opening new channels or just for maintenance of the existing channels will resuspend the sediments increasing the release of PAHs into the aquatic environment.

The impact of Polynuclear Aromatic Hydrocarbons (PAHs) on sediments, together with the ultimate transport and migration of constituent chemicals in their dissolved or sorbed states, has led to environmentalists to develop several techniques for cleaning contaminated sediments.

Cleanup of petroleum contaminated sediments using reactors is presented in this paper. Applicability of biological treatment alone or in combination with other technologies is discussed in detail.
An Investigation of Possible Contributing Variables in Compound Wear Process
Authors: Pumwa John , Griffin Richard B.
Published: December 2014

This paper reports the results of a series of compound wear experiments conducted using heat treated 1042 steel sliding against A2 tool steel under normal atmospheric environmental conditions for severe wear. Compound wear takes place where there is sliding and impact motion occurring simultaneously. The influential variables that are considered in the statistically designed experiment are: normal impact load, frequency, and the rotational sliding speed with lubrication as an extra class variable. Experiments were conducted using a multi-purpose wear testing facility. The frictional force was determined from strain gauges. LabView™ software was used to monitor and store the continuous load and strain signals for further analysis. Using these data an empirical relationship modeling wear has been determined.
Tribo-Chemistry of Particles Collected During In Situ Gasification of Texas Lignite
Authors: Masudi Houshang , Griffin Richard B.
Published: December 2014

Particles collected during in situ gasification of Texas lignite experiments were analyzed for chemical elements. Results obtained by energy dispersive x-ray analysis revealed that the dominating elements in both particles and lignite are Si, S, Al, Fe, and Ca. The concentration of these elements depends on the selected region and varies within the particle size range. Semi-quantitative analysis revealed the same results. This paper presents the scanning electron microscopy (SEM) micrograph and energy dispersive x-ray analysis (EDXA) for particles and Rockdale lignite.
Algorithms for Large Eigenvalue Problems in Vibration and Buckling Analyses
Authors: Leung A. Y. T.
Published: December 2014

The eigenvalue problem plays a central role in the dynamic and buckling analyses of engineering structures. In practice, one is interested in only a few dozens of the eigenmodes of a system of thousands of degrees of freedom within a particular eigenvalue range. For linear symmetric eigenproblems, [K]{x} = λ[M]{x}, the eigensolutions are well behaved. The recommendations are subspace iteration or the Lanczos method working with [A] = [K-λ0 M]−1 where λ0 is the middle of the eigenvalue range of interest. Subspace iteration gets both eigenvalues and eigenvectors. Lanczos gives the approximate eigenvalues which can easily be improved by inverse iteration to obtain the eigenvectors as by-products. For real nonsymmetric or complex symmetric linear eigenprohlems and polynomial eigenproblems, the eigensolutions may be defective. All classical methods, including subspace iteration fail. We recommend to use the Lanczos method to obtain the approximate eigenvalues of interest and to improve them by a new variance of inverse iteration, one vector at a time, and to get the independent generalised vectors as hy-products. We develop solution method for the special case that the approximate eigenvalue is indeed exact rendering a set of singular linear equations which can not be solved by existing algorithms.
Electromagnetic Vibration Control of Secondary Structures
Authors: Leung A. Y. T. , Sy B. T.
Published: December 2014

A new active controller for vibration reduction of secondary structures is studied. The secondary structure is exemplified by a steel Euler beam. The output electromagnetic force from an electric current whirling machine is used as controller force. The excitation is given by a shake table to represent earthquake ground motion. The effectiveness of the controller is examined by varying the phase angle and electromagnetic force amplitude of the electric current whirling machine. We quantify the effectiveness as equivalent added modal damping of the Euler beam.
Hybrid Modelling; Mixed Rigid and Flexible Systems
Authors: Esat Ibrahim , Banisoleiman K.
Published: December 2014

The paper presents the Euler Newton formulation of oscillatory behaviour of a multi-body system interconnected by discrete stiffness elements. The dynamical system is treated as geometrically and materially linear, where assembly of the global stiffness matrix may be achieved. The formulation is extended to incorporate flexible shafting systems. It is assumed that flexible shafts are connected to rigid bodies of finite size and the connection is assumed to be built-in or pin jointed. Flexible shafting system is formulated using beam finite element formulation.
Vibration of Square Plates Containing Eccentric Holes
Authors: Sabir A. B. , Davies G. T.
Published: December 2014

The natural frequencies of square plates containing circular holes is investigated using the finite element method. The holes are eccentrically located, and the effect of this eccentricity on the natural frequency is examined when the plates are subjected to a variety of inplane loads.

The natural frequencies are calculated by using the 12 degree of freedom non conforming rectangular and the 9 degree of freedom non conforming triangular bending elements. To determine the inplane stress distribution, strain based inplane elements are used. The displacement fields for these elements are based on assumed strain functions which satisfy the exact requirement of rigid body motion.

In the present paper, the lowest natural frequencies and the corresponding modes of vibration are determined for simply supported or clamped plates containing circular holes. Initially the plate is unloaded at the middle surface, and the effect of the degree of eccentricity on the natural frequency is examined. Result are also given for plates subjected to uniform uniaxial and biaxial compression.

For plates loaded by inplane uniformly distributed shear, tension and compression regions are produced. Hence for these plates, the natural frequencies are determined when the circular holes are located either in the tension or compression zones.
Transient Response of a Right-Angled Bent Cantilever Subjected to Out-of Plane Tip Loading
Authors: Wang B. , Xiao Z. M. , Lu G.
Published: December 2014

This paper provides an analysis of the transient behaviour of a right-angled bent cantilever beam subjected to a suddenly applied force at its tip perpendicular to its plane. A double-hinge mechanism is required to complete the possible deformation under a rectangular force pulse (constant force applied for a finite duration) with a four-phase response mode. The kinematics of the various response phases are described and the partitioning of the input energy at the plastic hinges during the motion is evaluated.
Experiments and FEA on Horizontal Pressure Vessels Under Thermal Expansion
Authors: Ng H. W. , Cheung J. S. T. , Ong L. S. , Tooth A. S.
Published: December 2014

This paper reports on the numerical and experimental research on saddle mounted horizontal pressure vessels subjected to heating by its hot liquid contents. The overall purpose of the research is to obtain design formulae relating design variables of horizontal pressure vessels mounted on fixed non-sliding saddle supports. Two experimental techniques were utilised to obtain stresses and strains for the situation of the saddle supports being rigidly fixed to ground. The first technique involves room temperature testing whereby one saddle base is displaced by the expected thermal expansion displacement (i.e. isothermal push-pull). The other technique utilised direct thermal heating by introducing hot liquid into the vessel, a more complicated yet more realistic test. These two techniques are not equivalent because in the hot test, the vessel will expand both axially and radially, whereas the radial expansion will be absent in the isothermal push-pull test. Experimental tests were conducted for the above two loadings techniques on two model vessels with different saddle designs. The resulting strains measured at the maximum stress locations showed that they can be reliably predicted when push-pull tests are carried out. Additionally, FE analyses were conducted for the two techniques for comparison. The experimental results are discussed with the FE predicted values, with particular reference to their agreement with push-pull tests and the hot liquid tests.
An Experimental Study on Hydrogen Powered Electric Vehicle
Authors: Kishida Koji , Tanaka Mitsuo , Kanai Ken , Kato Yoshiaki , Ito Akihiro
Published: December 2014

Based upon research experience on fuel cell technology at the Fukui University of Technology, an effort has been made to develop a hydrogen powered electric vehicle as a means of applying fuel cells, A polymer electrolyte fuel cell stack was chosen as the device of energy conversion from hydrogen to electricity. First, a detailed study on the performance of the fuel cell stack was carried out to assure compatibility with the vehicle energizing system. It was found that it should function well as the prime power source for electric vehicles. Selection of the traction motor was one of the optimization studies. As a result of tests with various motors, two brushless d-c motors were adopted. A small electric vehicle, weighing 300kg and loaded with a H2-tank of 10 litres (15MPa), achieved 20 km/h and the duration was 2 hours.
IGCC: The Italian Answer to the Heavy Oil Surplus
Authors: Piazza G. , Bressan L. , Fadabini L.
Published: December 2014

The design, construction and operation of an IGCC cogeneration plant requires commercial planning, regulatory processing and financial coordination as well as technical engineering. This paper is an overview of the ISAB Energy Project a heavy oil fueled IGCC cogeneration plant that produces electric power and process steam. Crucial activities before and after design include formation of the equity partnership, early feasibilities studies, basic design and permitting, structuring of cogeneration contracts, and financing the project. Particular attention is given to the parties involved in project financing and how they manage the various aspects of financial risk that characterize this type of plant.
Analysis of Windmilling Characteristics for a Twin-Spool Turbofan Engine
Authors: Choi Min-Su , Kang In-Shik , Lim Jin-Shik , Hong Yong-Shik
Published: December 2014

The windmilling characteristics of twin-spool, high bypass ratio turbofan engine have been analyzed. This analysis is an extension of the previously reported analysis for a single-spool turbojet engine. As before, the aerodynamic performances of engine components are determined by incorporating the available cascade loss correlations. For a given flight condition, the steady-state windmilling conditions are determined by iteratively balancing the mass flow rate and angular momentum through the two spools. Compared to the turbojet analysis, the new analysis requires determination of bypass ratio and work split between the two spools. Some of the calculation results have been compared against the limited data available for a CF-6 engine, and the two show good agreement. The present method is thus shown to be capable in predicting turbofan engine’s windmilling characteristics during its design stage.
The Influence of Rotation on the Internal Flow of a Cooled Turbine Blade With Serpentine-Shaped Cooling Channels
Authors: Otsuki Y. , Sugimoto T. , Tanaka R. , Bonn D. E. , Becker V. J. , Gler J. , Kusterer K. A.
Published: December 2014

Numerical 3-D investigations have been carried out in order to analyze the cooling gas flow pattern inside a turbine blade configuration. The blade is not an actual industrial configuration but is representative for contemporary configurations. The cooling gas enters the serpentine cooling channels through the blade foot. The cooling gas mass flow is divided into two serpentine flows. One covers the front part of the blade and is ejected at the tip, the other serves the rear region and is ejected through a slot in the trailing edge. Internal turbulence promoters are neglected. Boundary conditions typical for front stage blade cooling gas states were chosen.

The computations have been performed with the modern CHTFlow computer code, which solves the fully compressible 3-dimensional Navier-Stokes equations. First the influence of the diffusive transport mechanisms is investigated and shown to be quite important. Through comparison of computation in a fixed and rotating frame of reference, the significant influence of rotation is demonstrated.
Application of Active Combustion Instability Control to a Heavy Duty Gas Turbine
Authors: Seume J. R. , Vortmeyer N. , Krause W. , Hermann J. , Hantschk C.-C. , Zangl P. , Gleis S. , Vortmeyer D. , Orthmann A.
Published: December 2014

During the prototype shop tests, the Model V84.3A ring combustor gas turbine unexpectedly exhibited a noticeable “humming” caused by self-excited flame vibrations in the combustion chamber for certain operating conditions. The amplitudes of the pressure fluctuations in the combustor were unusually high when compared to the previous experience with silo combustor machines. As part of the optimization program, the humming was investigated and analyzed.

To date, combustion instabilities in real, complex combustors cannot be predicted analytically during the design phase. Therefore, and as a preventive measure against future surprises by “humming”, a feedback system was developed which counteracts combustion instabilities by modulation of the fuel flow rate with rapid valves (Active Instability Control, AIC). The AIC achieved a reduction of combustion-induced pressure amplitudes by 86%.

The combustion instability in the Model V84.3A gas turbine was eliminated by changes of the combustor design. Therefore, the AIC is not required for the operation of customer gas-turbines.
Gas Turbine Operating Experience in a Power / Seawater Desalination Cogeneration Mode
Authors: Khawaji Akili D. , Khan Tariq , Wie Jong-Mihn
Published: December 2014

The Royal Commission power, desalination and seawater cooling (PD&SC) plant located in Madinat Yanbu Al-Sinaiyah, Saudi Arabia, includes eight MS-7001 E frame 7 gas turbine generators (GTGs). The GTGs are used in cogenerating electricity and process steam primarily required for desalinating seawater by a multi-stage flash (MSF) evaporation process. This paper describes the operating experience of the GTGs in a simple cycle and a cogeneration mode coupled to heat recovery steam generation. The significant problems, countermeasures and the GTG and heat recovery steam generator (HRSG) reliability, availability and performance are also discussed in the paper.
The Te Awamutu Cogeneration Project From Stranded Asset to Base Load
Authors: Morrissey Eamonn
Published: December 2014

This paper reviews the development of the Electricity Corporation of New Zealand’s first gas turbine based cogeneration project, discusses the design work performed, the project implementation and provides lessons learnt for future projects.

The Project employs a TP&M FT4 TwinPac Gas Turbine Generator Set which has been relocated to Anchor Product’s dairy factory at Te Awamutu where it provides hot exhaust gas for a Heat Recovery Boiler which generates steam for use in the dairy factory processes and a steam turbine.

The gas generators were converted from liquid fuel to natural gas and the free turbines were overhauled. All auxiliaries were relocated and upgraded as required by the new operating regime or changes in legislation, and a new microprocessor based Control and Instrumentation system purchased. Plant design is such that the Heat Recovery Boiler can accept hot gas from only one gas turbine at a time while the second is available for peaking duty as required.
Simulation of a Steam Injected Gas Turbine Plant Control System
Authors: Zang Shusheng , Pan Jaqiang
Published: December 2014

The design of a modern Linear Quadratic Regulator (LQR) is described for a test steam injected gas turbine (STIG) unit. The LQR controller is obtained by using the fuel flow rate and the injected steam flow rate as the output parameters. To meet the goal of the shaft speed control, a classical Proportional Differential (PD) controller is compared to the LQR controller design. The control performance of the dynamic response of the STIG plant in the case of rejection of load is evaluated. The results of the computer simulation show a remarkable improvement on the dynamic performance of the STIG unit.
Industrial Users Choose Fuel Flexible GT11N2 for Burning Blast Furnace Gas in Combined Cycle Power Plants
Authors: Gnädig G. , Reyser K. , Fischer W. , Schmidli J.
Published: December 2014

Stricter environmental regulations and the need for high-efficiency energy generation have led an increasing number of industrial users to investigate alternatives to burning waste gases from the industrial plants in conventional thermal power plants. Combined cycle power plants using gas turbines capable of burning low-caloric fuels such as blast furnace gas can meet these requirements with thermal efficiencies of more than 45%.
Internal Combustion Steam Cycle (G.I.S.T. Cycle): Thermodynamical Feasibility and Plant Lay-Out Proposals
Authors: Caputo C. , Gambini M. , Guizzi G. L.
Published: December 2014

In this paper a new kind of steam cycle provided with internal combustion is proposed. The internal combustion of natural gas and compressed air inside the steam flow has been conceived to carry out a steam heating (SH a/o RH) until TIT (Turbine Inlet Temperature) much higher than those of the conventional steam power plants. By this internal combustion it seems possible to overcome the present limits to TIT in steam plants which are, as known, especially related to the technological problems of the superheater tube materials in the conventional external combustion steam boilers.

The proposed cycle has been named with the acronym GIST (Gas Injection STeam) since the hot gases resulting from a combustion close to stechiometric conditions are injected inside the steam flow.

This paper provides a first critical approach to these new kinds of thermodynamical cycles. At the first the thermodynamical and technological problems related to the combustion inside steam are explained and discussed. Then, different plant lay-out solutions are proposed with a critical discussion on their overall performance. At the last two GIST solution have been defined that seem very interesting: the first is an hybrid plant scheme (i.e. provided with multi-fuel supply) which involves performances higher than conventional steam power plants (net electric efficiency of about 47%); the second is a plant scheme with full natural gas supply (i.e. without multi-fuel steam boiler) wich involves very relevant performances (net electric efficiency of about 57%).
Prevention of Low-Frequency Vibration of High-Capacity Steam Turbine Units by Squeeze-Film Damper
Authors: Kanki H. , Kaneko Y. , Kurosawa M. , Yamamoto T.
Published: December 2014

The cause of the low-frequency vibration (subsynchronous vibration) of a high pressure turbine was investigated by the analytical study and vibration exciting test for the actual machine in operation. From the results, it is found that the low-frequency vibration is caused by the decrease of the rotor system damping at high-loading operating conditions. As a countermeasure, a squeeze-film damper is designed in order to increase the damping of the rotor system. After the verification test of the squeeze-film damper’s capability in the workshop, it was installed on the actual turbine. Vibration exciting tests for the high pressure turbine under the actual operating conditions were carried out. These field tests confirmed that the damping of the rotor system was increased as expected in the design and consequently the low-frequency vibrations disappeared completely under all operating conditions.
Comparison of Two-Equation Turbulence Models for Prediction of Heat Transfer on Film-Cooled Turbine Blades
Authors: Garg Vijay K. , Ameri Ali A.
Published: December 2014

A three-dimensional Navier-Stokes code has been used to compute the heat transfer coefficient on two film-cooled turbine blades, namely the VKI rotor with six rows of cooling holes including three rows on the shower head, and the C3X vane with nine rows of holes including five rows on the shower head. Predictions of heat transfer coefficient at the blade surface using three two-equation turbulence models, specifically, Coakley’s q-ω model, Chien’s k-ε model and Wilcox’s k-ω model with Menter’s modifications, have been compared with the experimental data of Camci and Arts (1990) for the VKI rotor, and of Hylton et al. (1988) for the C3X vane along with predictions using the Baldwin-Lomax (B-L) model taken from Garg and Gaugler (1995). It is found that for the cases considered here the two-equation models predict the blade heat transfer somewhat better than the B-L model except immediately downstream of the film-cooling holes on the suction surface of the VKI rotor, and over most of the suction surface of the C3X vane. However, all two-equation models require 40% more computer core than the B-L model for solution, and while the q-ω and k-ε models need 40% more computer time than the B-L model, the k-ω model requires at least 65% more time due to slower rate of convergence. It is found that the heat transfer coefficient exhibits a strong spanwise as well as streamwise variation for both blades and all turbulence models.
Development of Hub Corner Stall and its Influence on the Performance of Axial Compressor Blade Rows
Authors: Hah Chunill , Loellbach James
Published: December 2014

A detailed investigation has been performed to study hub corner stall phenomena in compressor blade rows. Three-dimensional flows in a subsonic annular compressor stator and in a transonic compressor rotor have been analyzed numerically by solving the Reynolds-averaged Navier-Stokes equations. The numerical results and the existing experimental data are interrogated to understand the mechanism of compressor hub corner stall. Both the measurements and the numerical solutions indicate that a strong twister-like vortex is formed near the rear part of the blade suction surface. Low momentum fluid inside the hub boundary layer is transported toward the suction side of the blade by this vortex. On the blade suction surface near the hub, this vortex forces fluid to move against the main flow direction and a limiting stream surface is formed near the hub. The formation of this vortex is the main mechanism of hub corner stall. When the aerodynamic loading is increased, the vortex initiates further upstream, which results in a larger corner stall region. For the transonic compressor rotor studied in this paper, the numerical solution and the measured data indicate that a mild hub corner stall exists at 100 percent rotor speed. The hub corner stall, however, disappears at the reduced blade loading which occurs at 60 percent rotor design speed. The present study demonstrates that hub corner stall is caused by a three-dimensional vortex system and that it does not seem to be correlated with a simple diffusion factor for the blade row.
Solid Fuel Gasification for Gas Turbines
Authors: Green Alex E. S. , Peres Sergio , Mullin James P. , Anderson Robert W.
Published: December 2014

Gas turbines (GT) have emerged as the most efficient means of transforming heat into mechanical work and with efficient generators are serving as major components of new electricity generation systems. The CCTL research and development efforts are directed towards developing a low cost solid fuel (SF) cogasifier fed by low cost local feedstocks to be coupled with smaller GT systems. The benefits of such systems can be enhanced if valuable by-products are produced or additional community purposes are served. We consider cogasification of biomass with other domestic fuels as a long term strategy for effective utilization of biomass. Our theoretical and experimental work indicate that blending oxygenated fuels such as biomass, MSW, RDF and dried sewage sludge with carbonaceous fuels such as coals, coke and chars in a small cogeneration system will have technological, economic and environmental advantages.
Preliminary Gas Turbine Combustor Design Using a Genetic Algorithm
Authors: Despierre Arnaud , Stuttaford Peter J. , Rubini Philip A.
Published: December 2014

A genetic algorithm, coupled with a versatile preliminary design tool, is employed to demonstrate the concept of an autonomous design procedure for gas turbine combustors with user specified performance criteria.

The chosen preliminary design program utilises a network based approach which provides considerable geometric flexibility allowing for a wide variety of combustor types to be represented. The physical combustor is represented by a number of independent, though interconnected, semi-empirical sub-flows or elements. A full conjugate heat transfer model allows for convection, conduction and radiative heat transfer to be modelled and a constrained equilibrium calculation simulates the combustion process. The genetic algorithm, whose main advantage lies in its robustness, uses the network solver in order to progress towards the optimum design parameters defined by the user. The capabilities of the genetic program are demonstrated for some simple design requirements, for example zone fuel/air ratio, pressure drop and wall temperatures.
Reduction of Unsteady Blade Loading by Beneficial Use of Vortical and Potential Disturbances in an Axial Compressor With Rotor Clocking
Authors: Hsu S. T. , Wo Andrew M.
Published: December 2014

This paper demonstrates reduction of stator unsteady loading due to forced response in a large-scale, low-speed, rotor/stator/rotor axial compressor rig by clocking the downstream rotor. Data from the rotor/stator configuration showed that the stator response due to the upstream vortical disturbance reaches a maximum when the wake impinges against the suction surface immediately downstream of the leading edge. Results from the stator/rotor configuration revealed that the stator response due to the downstream potential disturbance reaches a minimum with a slight time delay after the rotor sweeps pass the stator trailing edge. For the rotor/stator/rotor configuration, with Gap1= 10% chord and Gap2= 30% chord, results showed a 60% reduction in the stator force amplitude by clocking the downstream rotor so that the time occurrence of the maximum force due to the upstream vortical disturbance coincides with that of the minimum force due to the downstream potential disturbance. This is the first time, the authors believe, that beneficial use of flow unsteadiness is definitively demonstrated to reduce the blade unsteady loading.
Experience With Active Control of Exhaust Noise From a Large Frame Combustion Turbine
Authors: Beeson Lisa A. , Schott George A.
Published: December 2014

Low frequency noise generated by combustion turbine exhaust is one of the most difficult environmental impacts to control. When a combustion turbine power plant is located near residential areas or other sensitive receptors, it is imperative to minimize the low frequency noise being emitted. In the past, available technology was limited to passive and reactive silencers and massive enclosures or barrier walls. These techniques are expensive and can have significant impacts on megawatt output and heat rate. Active noise control technology offers an alternative for applications near sensitive receptors.

An active noise control system was installed on the exhaust stack of a combustion turbine with an objective to cancel exhaust noise at frequencies below 35 Hertz (Hz).

Unlike passive and reactive low frequency silencing, the active noise control system does not impact combustion turbine performance. The technology can be applied to new apparatus and can be retrofit to existing facilities with minimal changes to the design.
Grain Boundary Cracking and Microstructural Changes Induced by the Grinding of IN738LC Turbine Blades
Authors: Fitzgerald Thomas J. , Carr Thomas J.
Published: December 2014

In this study, the microstructure of IN738LC turbine blades ground by two different vendors was examined. Turbine blades from a grinding vendor reporting the occasional appearance of “linear indications” were evaluated. The indications were found to be grain boundary cracks, some over 1 mm in depth, running perpendicular to the grinding direction. The cracked blades showed signs of surface melting which can be regarded as a prerequisite for grain boundary cracking in the grinding of IN738LC. Blades ground by a different vendor, not reporting grinding problems, were also examined and no surface melting was seen. No fundamental difference was seen in the as-cast microstructure between the blades from the two vendors. All the observations in this study thus indicate that the grinding cracks in the blades from the first vendor resulted from improper or uncontrolled grinding conditions.
Allison 501-K17 SSGTGS Technical Directive Experience
Authors: Patterson Jeffrey S. , Hoffman Donald J. , Ochs Linda M.
Published: December 2014

The Allison 501-K17 Ship Service Gas Turbine Generator Set (SSGTGS) is used is provide ship board electrical power on several U.S. Navy Class ships, including the DD-963 Spruance Destroyer, the DDG-993 Kidd Guided Missile Destroyer and CG-47 Ticonderoga Guided Missile Cruiser Classes. The first of these units were placed in service during the mid 1970s. The Naval Sea Systems Command (NAVSEA) in conjunction with the Naval Surface Warfare Center, Carderock Division, Ship Systems Engineering Station (NSWCCD-SSES) have undertaken a major upgrade effort to improve the reliability, operation, serviceability and maintainability of the unit. This paper examines the process of this program and details the specific improvements made to the unit as a result of this effort. In addition, this paper outlines the experience gained as a result of installing these upgrades in the Fleet.