bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
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.
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.
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.
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%).
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.
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.
Real Time Thermodynamic Transient Model for Three Spool Turboprop Engine
Authors: Crainic C. , Harvey R. , Thompson A. 
Published: December 2014

Previous real time engine models used for control development and test have utilized either linear techniques or simplified aero-thermodynamics. With the increased speed now available from dedicated PC based computer systems it was felt that it should be possible to develop a full aerodynamic and thermodynamic model of the engine that would have the capability to run in a real time bench environment and approach the accuracy of our best unlimited time models.
The paper describes such a model that has successfully been produced for a three spool turboprop engine, and shows that it matches, in a real time environment, the transient performance of a model run with unlimited execution time. This model has the additional capability of starting from zero speed and running back down to zero speed on shut down, all in real time environment.
The model was based on an existing model of a three spool turboprop engine which already included full transient heat transfer and volume dynamics effects. Modifications to this that were necessary to satisfy the requirement to model the starting regime and to decrease the convergence time resulted in a more efficient model methodology. The component map representation was changed as was the iteration logic, by removing internal iterations and by making the solver matrix more strongly diagonal.
For the real time environment the code had to provide a solution within a maximum of 10 ms. The final real-time model only differed from the modified full transient model in the use of the solver logic. The number of overall iterative passes were limited to two, and balances that were shown not to significantly modify the accuracy of the solution were removed. The net result of the work is the elimination of two simplified models.
Thermo-Economics of a Small 50 KW Turbogenerator
Authors: Rodgers C. 
Published: December 2014

Recent projections foster the belief that small high temperature heat exchanged gas turbines incorporating ceramic rotors, and ceramic exhaust beat exchangers, may eventually have thermodynamic efficiencies competitive with Diesel cycle engines. Small high speed Brayton cycle gas turbine turbogenerators on the near term verge of production will indeed have improved thermal efficiencies, but ceramic material technology has not yet matured to the engine production stage. Although thermal efficiency is a dominant driver, manufacturing costs and long term engine durability are still a major concern to the engine manufacturer. As a consequence the thermodynamic performances of small gas turbines are still, in this last decade of the 20th century, primarily constrained by the temperature limits of the metallic stator/rotor and metallic heat exchanger.
This paper reviews optimum thermo-economic design considerations for a small 50 KW output turbogenerator, covering the effect of cycle performance parameters on, engine configuration, rotational speeds engine weight, manufacturing and direct operating costs. The effect of design pressure ratio on part load thermal efficiency is also addressed for applications with extended operating time at low output powers.
Environmental Influence on the Thermoeconomic Optimization of a Combined Plant With NOx Abatement
Authors: Agazzani A. , Massardo A. F. , Frangopoulos C. A. 
Published: December 2014

Methods to analyze, improve and optimize thermal energy systems have to take into account not only energy (exergy) consumption and economic resources but also pollution and degradation of the environment. The term “environomics” implies a method which takes thermodynamic, economic and environmental aspects systematically into consideration for the analysis and optimization of energy systems. For optimization of energy systems, the environmental aspects are quantified and introduced into the objective function.
In this particular work, the environomic approach is followed for the analysis and optimal design of a combined-cycle plant. In addition to the basic configuration, two alternatives for NOx abatement are studied: Selective Catalytic Reduction (SCR) and steam injection. The optimization problem is solved for each configuration and the results are compared with each other. The effect of the unit pollution penalties and of the limits imposed by regulations is studied. Some general conclusions are drawn.
Multiple Evaporation Steam Bottoming Cycle
Authors: Jericha H. , Fesharaki M. , Seyr A. 
Published: December 2014

Improvements to the steam bottoming cycles hold the promise of raising the combined cycle thermal efficiency to values near and above 60%. Up to now, steam bottoming cycles with three pressure levels of steam evaporation have been realised. A further advantage seems possible by the use of double fluids, such as mixtures of steam and ammonia.
In the cycle proposed here, the authors limit Themselves to the use of steam and water only, in order to avoid all the difficulties, that may arise from such mixtures. The solution given here, relies on multiple evaporation levels, more than three up to five and even more. They should be to be achieved with the help of newly developed steam turbochargers, which allow the unification of the steam flow from three different neighbouring pressure levels, into one steam flow to be transmitted via the live steam line to the main turbine. This large number of evaporation levels, together with the required economisers for feed water heating and the ensuing superheaters arranged in the proper way, gives a steam water heat acceptance curve, which can be closely matched to the exhaust gas cooling line, so that the heat transfer from the gas turbine exhaust to the steam bottoming cycle can be effected with a minimum of temperature differences.
It should be pointed out that the steam pressures are selected in the undercritical region, and that a total combined cycle efficiency very near to 60% can be achieved. Using most modern gas turbine models together with this novel bottoming cycle will even allow to exceed the value of 60%. Examples given have been calculated for standard gas turbine models.
Development of a Programmable Logic Controller Based Fuel Control System for the G.E. LM-1600 Gas Turbine
Authors: King Dan A. , Patrick Jim 
Published: December 2014

Nova Gas Transmission Ltd. (NGTL) has been developing integrated turbine fuel control systems since the late 1980s. This is part of a long term vision to completely integrate the control systems at its compressor stations. These systems are integrated into the “off the shelf” Programmable Logic Controller (PLC) used for unit sequencing and shutdowns.
As part of this effort NGTL began development of a fuel control system for the General Electric LM-1600 gas turbines in 1993. These systems, now successfully in service, proved to be the most challenging to develop. NGTL uses gas turbine packages, eleven of which are LM-1600s, to drive the compressors used in its gas pipeline system. This paper includes some brief background reasons why NGTL has chosen to develop fuel control systems and describes in detail the development of the fuel control system for the LM-1600. Discussion of the control challenges of the LM-1600 includes fuel throttle valve and actuator selection and options, control system hardware and software development (consistent with the General Electric Installation Design Manual (IDM) requirements) and, engine model development. The model application, office testing, site performance testing and the static and dynamic test results are also discussed. The paper also describes NGTL’s future plan for installation of LM-1600 fuel control systems on its fleet.
Ceramic Stationary Gas Turbine Development Program: Fourth Annual Summary
Authors: van Roode Mark , Brentnall William D. , Smith Kenneth O. , Edwards Bryan D. , McClain John , Price Jeffrey R. 
Published: December 2014

A team led by Solar Turbines Incorporated is conducting a three phase program under the sponsorship of the United States Department of Energy, Office of Industrial Technologies, to improve the performance of stationary gas turbines in cogeneration through the selective replacement of metallic hot section components with ceramic parts. Preliminary and concept design were completed in Phase I. Detailed design, component fabrication, and rig and engine testing are all being conducted in Phase II. Field engine testing will be performed in Phase III. This review summarizes progress on Phases II and III for the program for 1996.
In 1996 the primary activities involved testing of uncooled first stage silicon nitride blades and SiC/SiC CFCC liners in a Centaur 50S engine modified to accept the ceramic components. Cumulative engine test experience by the end of November, 1996 has reached 52 hrs. The longest operating time on a single engine build at full load is 16 hours. Ceramic parts were also proof tested in rigs prior to engine testing. Preparations are currently underway for a 4,000 hour field test at the enhanced oil recovery site of ARCO Western Energy in Bakersfield, California.
Modeling of Industrial Pumping System Dynamics
Authors: Al-Nahwl Ammar A. , Graf Martin B. 
Published: December 2014

A method for modeling the dynamics of industrial pumping systems is presented. The approach extends existing models for aero-engine like applications to capture dynamic features of interest in industrial, ground-based, applications. Those include the driver-driven (e.g., turbine-pump or compressor) interaction, the driver speed regulation subsystem, and their impact on stability. The method utilizes a lumped parameter modeling approach that involves developing and analyzing a set of nonlinear ordinary differential equations which describe the system dynamics.
A model of a baseline industrial pumping system comprised of a turbine driving a process compressor is formulated first. Components in the compressor flow path include an inlet duct, a plenum, and a discharge valve. The resulting model captures the system’s instability onset point, the post-stall behavior, and the sensitivity to system parameters. Two non-dimensional groups are found to play a dominant role in characterizing the overall dynamics: the ratio of fluid compliance to fluid inertia on the compressor side (B-parameter), and the ratio of the mechanical inertia of the rotating assembly to the fluid inertia. Low values of the B-parameter have a strong stabilizing effect and are associated with high frequency surge oscillations. In contrast, low values of the mechanical to fluid inertia ratio have a stabilizing effect only in a limited region of the compressor operating range, and have little effect on surge frequency. For the baseline system considered in this study, stabilizing effects of these two ratios were observed at values less than 0.4 and 0.2 respectively.
The baseline system model is then expanded to include a turbine speed controller. This allows examination of large transient events such as station shutdown and the phenomena of turbine hunting. It is found that the parameters of the turbine speed controller can affect the stability during such transients, but have little impact on the post-stall behavior.