bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization Assessment of Hybrid MCFC-Gas Turbine Cycles
Authors: Basurto Maria-Teresa , Pilidis Pericles , Hales Richard 
Published: July 2014

The intention of this paper is to offer a general description of the Molten Carbonate Fuel Cell (MCFC), its performance parameters, and the work done on the integration of MCFCs and gas turbines into an hybrid cycle to achieve high efficiencies. The paper describes results obtained for several hybrid configurations, some of them using pressurised MCFCs, others using atmospheric pressure MCFCs. Each configuration is analysed for different values of the cycle parameters, as part of the optimization process done to find an optimum solution. Finally, some conclusions are presented.
An important part of the work corresponds to the development of the code MC-GreenCell that simulates the performance of MCFC. This code, developed by the authors, estimates power, voltage, electrical current densities, heat losses, temperatures, gases flow rates and compositions, resulting from the steam reformer and from the MCFC stack. The code was utilized together with a commercial code on the assessment of the design point performance of the hybrid system. In the future the code will be used to evaluate the off-design performance of the cycle. The code has been validated using MCFC field data available from current projects.
The study focuses on hybrid cycles of 1÷25 megawatt size that may be used in commercial or industrial cogeneration, distributed power generation for hospitals, public buildings, etc.
Modelling of Alkali Contaminant Flows in Evaporative Gas Turbines
Authors: Bartlett Michael A. , Westermark Mats O. 
Published: July 2014

A new advanced gas turbine cycle, called the Evaporative Gas Turbine (EvGT), also known as a Humid Air Turbine (HAT), has recently been demonstrated in Sweden, with a pilot plant built and operational. As the EvGT cycle involves complex interactions between air and water streams, air quality aspects need to be carefully examined. This article examines different strategies to prevent contamination and turbine corrosion and presents a theoretical model simulating the flow of alkali salts in the EvGT cycle for different ambient salt concentrations, cycle configurations and equipment performance.
Similar to the existing pilot plant, the EvGT cycle studied in this article requires no external water source to meet its water demands. Instead, water is condensed from the flue gas and recycled to the humidification tower. Recirculating the condensate implies that the best strategy to ensure a high air quality and hinder impurity build up and transfer within the cycle is to filter the incoming air. Furthermore, air intake filters could simplify or eliminate the need for condensate treatment. The humidification tower is an important area for the transfer of contaminants to and from the water and air streams. Minimising droplet entrainment and bleeding off a fraction of the humidifying water are key strategies to protect the turbine, while the capture of airborne particles in the humidifying water film improves the air quality.
The model constructed predicts that a small blow down from the water circuit (typically 0.1-3.5% of the feed water flow) is sufficient to ensure that the alkali concentration does not exceed those in an equivalent dry gas turbine. This blow down can then be treated and partly recycled to the water circuit or discarded.
System Description and Test Planning for a Combined Heat and Power (CHP) Plant Composed by a Micro Gas Turbine and an Absorption Chiller / Heater
Authors: Banetta Stefano , Paganucci Fabrizio , Giglioli Romano 
Published: July 2014

The paper deals with the set-up and preliminary test-planning of an innovative mini cogeneration plant, in which exhaust gases coming from a 45 kWe rated turbogenerator directly feed an absorption chiller / heater with a 170 kWth chilling and a 160 kWth heating capability. Electric power is partly used on site to satisfy the plant auxiliary systems power demands and partly vectorised to the main building of the Engineering Faculty (15 km from the plant site) through the main electric grid. Thermal power is exploited locally for any season air conditioning of laboratory rooms.
The paper describes the plant layout and the technical solutions adopted for installation and diagnostic purposes.
This plant has been conceived even as a test-bed for Remote Monitoring (RM) and Plant Condition Monitoring (PCM) techniques development and testing. To this purpose dedicated diagnostics have been set up and mathematical models of all the main components are being developed to perform the identification of their operational parameters (e.g. efficiencies) on the basis of the acquired parameters. These are aimed at obtaining both a correct management of the plant and an early diagnosis of malfunctions to achieve the ability of following an on-condition maintenance philosophy to reduce maintenance costs and outage periods.
Numerical Study of Hot Gas Ingestion Into an Engine Type High-Pressure Turbine Rotor-Stator Cavity
Authors: Förster Ingo , Martens Eckhard , Friedl Winfried-Hagen , Peitsch Dieter 
Published: July 2014

The rims of high pressure turbines in aeroengines are sealed with air via the internal air system. This sealing is required to avoid occurrence of hot gas ingestion into the rotor-stator cavities. Due to a rapid decrease of turbine disc life at higher temperatures, such ingestion would present a hazard to the integrity of the discs and subsequently to the safety of the aircraft. One of the driving factors for ingestion is the circumferential pressure variation downstream of vanes and blades due to the aerodynamic wakes. Small ingestion cavities close to the annulus are commonly used to damp down this pressure variation. Substantial ingestion into these cavities is permitted. The actual sealing of the rotor-stator cavity itself is accomplished with a secondary seal.
A numerical simulation of the flow in an engine type rotor-stator cavity was carried out using a commercial CFD code. The cases studied comprise relevant features as rotor-stator and ingestion cavities, leakage across rotor blade shanks and circumferential pressure variation downstream of an NGV. The simulation was carried out at relevant engine temperatures and pressures.
The paper will firstly present the effects of a variation of the rim sealing mass flow on the flow field, ingestion and temperature increase in the cavity. These results were solely gained by computational means. For validation of a new air system design, engine tests on the BR715 jet engine have been performed. The data measured in these tests not only serve for certification purposes, but also may be used as input for CFD calculations. Thus, the experimental data was the baseline for comparison with the results from the present study.
Analysis of the Influence of Cooling Steam Conditions on the Cooling Efficiency of a Steam-Cooled Vane Using the Conjugate Calculation Technique
Authors: Krüger Uwe , Kusterer Karsten , Lang Gernot , Rösch Hauke , Bohn Dieter , Martens Eckhard 
Published: July 2014

Closed circuit steam cooling of blades and vanes in modern gas turbines is an promising alternative instead of film-cooling using compressor air. The temperature drop across the first-stage nozzle, which is convectively steam-cooled, is reduced significantly in comparison to an intensive film-cooled vane using compressor air. Thus, the firing temperature (temperature in front of the first-stage blade row) can be increased while the combustion temperature can remain as low as necessary for low-Nox purpose.
In this paper, a steam-cooled test configuration consisting of a 3-vane cascade is numerically analysed. A computer code using a Conjugate Calculation Technique is applied. The CHTflow code has been developed at the Institute of Steam and Gas Turbines in Aachen. Due to the direct coupling of fluid flow and solid body, heat transfer boundary conditions at the external and internal surfaces become unnecessary. Validation of the code for a similar convection-cooled configuration is also given here.
The presented investigations focus on the thermal load analysis and the cooling efficiency analysis of the test configuration. It consists of a planar cascade with a convection-cooled central vane where cooling fluid can be supplied to 22 radial passages. One main aspect of the paper is to show the influence of cooling steam conditions (low-, medium & high-pressure steam supply) on the local and global cooling efficiencies. The results show that, for reaching a defined cooling efficiency level, medium steam pressure supply might be advantageous in comparison to a high-pressure level in supply. Although a lower pressure level demands an increase in steam mass flow, the overall effect on the thermal efficiency of the whole process is acceptable if one keeps in mind the advantages of handling steam at lower pressure levels. For further comparison, convective air-cooling with reasonable cooling conditions and comparable flow and heat transfer characteristics is analysed. For the given geometry of the configuration, sufficient cooling of the trailing edge becomes problematic for steam- and air-cooling application.
Experimental Investigation of Transition to Turbulence as Affected by Passing Wakes
Authors: Kaszeta Richard W. , Simon Terrence W. , Ashpis David E. 
Published: July 2014

This paper presents experimental results from a study of the effects of periodically passing wakes upon laminar-to-turbulent transition and separation in a low-pressure turbine passage. The test section geometry is designed to simulate unsteady wakes in turbine engines for studying their effects on boundary layers and separated flow regions over the suction surface by using a single suction surface and a single pressure surface to simulate a single turbine blade passage. Single-wire, thermal anemometry techniques are used to measure time-resolved and phase-averaged, wall-normal profiles of velocity, turbulence intensity and intermittency at multiple streamwise locations over the turbine airfoil suction surface. These data are compared to steady-state wake-free data collected in the same geometry to identify the effects of wakes upon laminar-to-turbulent transition. Results are presented for flows with a Reynolds number based on suction surface length and stage exit velocity of 50,000 and an approach flow turbulence intensity of 2.5%. While both existing design and experimental data are primarily concerned with higher Reynolds number flows (Re > 100,000), recent advances in gas turbine engines, and the accompanying increase in laminar and transitional flow effects, have made low-Re research increasingly important.
From the presented data, the effects of passing wakes on transition and separation in the boundary layer, due to both increased turbulence levels and varying streamwise pressure gradients are presented. The results show how the wakes affect transition. The wakes affect the flow by virtue of their difference in turbulence levels and scales from those of the free-stream and by virtue of their ensemble-averaged velocity deficits, relative to the free-stream velocity, and the concomitant changes in angle of attack and temporal pressure gradients. The relationships between the velocity oscillations in the freestream and the unsteady velocity profile shapes in the near-wall flow are described. In this discussion is support for the theory that bypass transition is a response of the near-wall viscous layer to pressure fluctuations imposed upon it from the free-stream flow. Recent transition models are based on that premise. The data also show a significant lag between when the wake is present over the surface and when transition begins.
On the Impact of Blade Count Reduction on Aerodynamic Performance and Loss Generation in a Three-Stage LP Turbine
Authors: Gier Jochen , Ardey Sabine 
Published: July 2014

Reducing the number of blades in low pressure turbines is a desirable option for decreasing total operation costs. From an aerodynamical point of view this directly leads to an increased blade load. However, increasing the blade load above a certain level results in viscous effects like separation bubbles and finally full separation. This becomes especially significant for aero engine turbines, which operate at high altitudes and thus low Reynolds numbers. The underlying local flow phenomena and the effect on the aerodynamic performance of such configurations are addressed in this paper.
This investigation is based on a three-stage low pressure turbine typical for aero engines. Different setups are employed with different number of guide vanes in certain stages. Furthermore, the Reynolds number is varied within a wide range. These configurations are investigated numerically using a modern steady-state transitional Navier-Stokes solver and experimental results from the same turbine. Based on this information, a detailed analysis of the viscous flow phenomena is performed with focus on the influence of separation bubbles on the loss production after the transition. These results are discussed with respect to blade count reduction.
Secondary Air Systems in Aeroengines Employing Vortex Reducers
Authors: Negulescu Dimitrie , Pfitzner Michael 
Published: July 2014

A secondary air system in modern aero engines is required to cool the compressor and turbine discs and make sure that no hot gas ingestion occurs into the cavities between the turbine discs, which could cause an inadvertent reduction of disc life.
A high integrity solution for guiding the air from the compressor to the turbine is through an inner bleed from the compressor platform and through the space between the disc bores and the shaft connecting the fan with the low pressure turbine.
Since strongly swirling air is taken from the compressor platforms to a much lower radius, a means of deswirling the air has to be used to avoid excessive pressure losses along the flow path.
The paper describes a system utilizing tubeless vortex reducers to accomplish this deswirl, which are compared to a more conventional air system utilizing tubes. The working principles of both types of vortex reducer and guidelines for the design of a secondary air system using vortex reducers are explained with supporting evidence from rig tests and CFD calculations. Opportunities for the aerodynamic optimisation of the tubeless vortex reducer are elaborated and the experience gained using the system during the development of the BR700 engine is described.
Status of AMG (Advanced Material Gas-Generator) Research and Development Program
Authors: Kuriyama T. , Miyagawa H. , Uyama M. , Yamamoto S. , Yokoi S. , Hiromatsu M. 
Published: July 2014

Research and Development program of Advanced Material Gas-Generator (AMG) was initiated in 1993 as a ten year program with a joint investment from the Japan Key Technology Center and fourteen participating Japanese companies.
The program objective is to establish basic key technologies for next generation gas-generator using advanced materials, which should have the features of significantly low fuel consumption with reduced weight and size, and should be environmentally acceptable, toward the realization of future industrial, marine and aircraft gas turbines.
In the initial phase of AMG program the conceptual study of advanced gas-generator was carried out in order to clarify technical issues and define requirements for each component. Based on the results of conceptual study, Polymer Matrix Composites (PMC), Metal Matrix Composites (MMC), Ceramic Matrix Composites (CMC) and Titanium Aluminide (TiAl) were considered as the candidate materials for the advanced material gas-generator. Then AMG is intensively proceeding R&D for next generation gas-generator using these advanced materials, and is now getting technical fruits.
This paper introduces the outline of AMG project and conceptual study, then describes some topics of each R&D themes.
Field and Application Experience of the Titan 130 Industrial Gas Turbine
Authors: Rocha George , Kurz Rainer 
Published: July 2014

The two-shaft Titan 130 industrial gas turbine was introduced into commercial service in 1998 and has gained field experience in mechanical-drive and compressor-set applications. A single-shaft configuration is also available for electrical power generation applications. The 14-MW class two-shaft engine is nominally rated at 19,500 hp with a simple-cycle efficiency of more than 35% at ISO operating conditions. It is available with two combustor options: a dry, low-pollutant emissions combustion system featuring Solar’s proven SoLoNOx technology or a diffusion-flame type combustor adapted from Solar’s proven Mars gas turbine.
The Titan 130 gas turbine design is an aerodynamic scale of the existing Taurus 70 product. The unit features a modified Mars air compressor and turbine section components directly scaled from the Taurus 70, resulting in a low-risk product design well-suited for industrial service applications. A major element of the development strategy included an extended field evaluation trial in actual operating conditions to demonstrate overall product durability. The first Titan 130 mechanical-drive package was placed into service at a natural gas pipeline compressor station and successfully completed a planned 8000-hour field evaluation program. Extensive inspection and operating data have been evaluated and the unit continues to operate in normal commercial service.
A mechanical-drive package requires the successful marriage between the driver and the driven equipment. Most applications require a combination of high efficiency and high performance flexibility. Emphasis was placed on providing excellent gas compressor coverage for this product. The successful application of such a compression system is discussed and supported by site test data.
This paper provides details of the Titan 130 field evaluation program, design enhancements and typical compressor set application performance characteristics.
Power Turbine Remaining Life Assessment
Authors: deBeer Bruce , Chilcott Paul , Seib Dave 
Published: July 2014

The design life of an industrial power turbine has traditionally been 100,000 hours or 5,000 starts, based on a specific set of assumed operating conditions. Actual operating conditions vary from site to site, and are often less severe than the initial assumptions used by the manufacturer. This is why Dresser-Rand has developed a Remaining Life Assessment program. The objective of this program is to assist operators in extending the life of expensive components, determining inspection intervals, developing component replacement schedules, and establishing a spare parts stocking program.
A comprehensive remaining life assessment must take into account unit operating history, a thorough non destructive examination of the components being considered for reuse, thermal and structural analyses using current analytical techniques, and material evaluations. There is some amount of variability in the input and output for each of these steps. Defects smaller than a given size are not always detected, material test results have a statistical distribution, and each operating cycle is unique. Traditionally the expected life has been based on a predetermined set of assumptions, such as stress analyses using typical dimensions, minus three sigma fatigue and creep properties, etc. The Dresser-Rand approach accounts for these inherent variations and establishes the statistical probability of successfully extending power turbine life without failure or unplanned maintenance as a function of time.
Optimum Design of Squeeze Film Dampers Supporting Multiple-Mode Rotors
Authors: El-Shafei A. , Yakoub R. Y. 
Published: July 2014

In this paper a study of the optimum design of squeeze film dampers for multi-mode rotors is presented. The optimum design program obtains the best possible damper parameters for a given rotor to satisfy the minimization requirements for the objective function. The objectives are to: minimize the amplitude response of the rotor at the critical speed, minimize the force transmitted to the support at the operating speed or maximize the power dissipated by the damper. A combination of these objectives can also be used, with weighting factors to weigh the importance of each of these objectives. These are the possible objectives for the design of squeeze film dampers for aircraft engine applications.
The basis of the optimum design program is an extremely fast algorithm which is able to quickly calculate the unbalance response of a rotor, for circular centered orbits of the journal in the damper. A commercial routine is used for the optimization, and is based on a complex direct search technique. The variation of the optimum clearance, length, and retainer spring stiffness are plotted against various rotor parameters. Recommendations for the design of squeeze film dampers are made. Application to an aircraft engine, illustrate the power of the developed algorithm.
A Test Case for the Numerical Investigation of Wake Passing Effects on a Highly Loaded LP Turbine Cascade Blade
Authors: Stadtmüller Peter , Fottner Leonhard 
Published: July 2014

The paper presents a compilation of experimental data on the effects of wake-induced transition on a highly loaded LP turbine cascade intended to be used for further numerical work. Although the underlying physics is not yet completely understood, the benefits of wake passing are already known and employed in the design process of modern gas turbines. For further optimizations, the next step seems to be now to enable numerical simulations detailed enough to capture the major effects while being as uncomplicated as possible at the same time to be cost-effective. The experimental results constituted in this systematic investigation are available for download and should serve as a basic data set for future calculations with different turbulence and transition models, thereby shedding some light on the complexity and modeling required for a suitable numerical treatment of the wake-induced transition process.
The data introduced in this test case was acquired using a turbine cascade called T106D-EIZ with increased blade pitch compared to design point conditions in order to achieve a higher loading. A large separation bubble forms on the suction side and allows to study boundary layer development in great detail. The upstream blade row was simulated by a moving bar type wake generator. The measurements comprise hot wire data of the bar wake characteristics in the cascade inlet plane (velocity deficit and turbulence level), boundary layer surveys with surface-mounted hot films sensors and a hot wire probe at various locations and measurements of the total pressure loss coefficient. Unsteady pressure transducers are embedded into the suction side of a cascade blade and in a wake rake to resolve the local pressure distributions over time. They yield quantitative values easily comparable to the output of numerical simulations.
The objective of this paper is to enable and to invite interested researchers to validate their code on the data set. From the extensive test program, a very limited number of operating points have been selected to focus the work. The standardized data files include a “reference” case with an exit Reynolds number of 200.000 and an exit Mach number of 0.4 as well as two points with higher Mach or lower Reynolds number for constant wake passing frequencies and background turbulence levels.