bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Use of Helmholtz Resonators for Damping Acoustic Pulsations in Industrial Gas Turbines
Authors: Bellucci Valter , Paschereit Christian Oliver , Flohr Peter , Magni Fulvio 
Published: July 2014

In modern gas turbines operating with premix combustion flames, the suppression of pressure pulsations is an important task related to the quality of the combustion process and to the structural integrity of engines. High pressure pulsations may occur when the resonance frequencies of the system are excited by heat release fluctuations independent of the acoustic field (“loudspeaker” behavior of the flame). Heat release fluctuations are also generated by acoustic fluctuations in the premixed stream. The feedback mechanism inherent in such processes (“amplifier” behavior of the flame) may lead to combustion instabilities, the amplitude of pulsations being limited only by nonlinearities.
In this work, the application of Helmholtz resonators for damping low-frequency pulsations in gas turbine combustion chambers is discussed. We present a nonlinear model for predicting the acoustic response of resonators including the effect of purging air. Atmospheric experiments are used to validate the model, which is employed to design a resonator arrangement for damping low-frequency pulsations in an ALSTOM GT11N2 gas turbine. The predicted damper impedances are used as the boundary condition in the three-dimensional analysis of the combustion chamber. The suggested arrangement leads to a significant extension of the low-pulsation operating regime of the engine.
Liquid Fuel Spray Characterization for the Design of the Dual-Fuel PGT10B Combustor
Authors: Tap F. A. , Modi R. , Van Buijtenen J. P. 
Published: July 2014

The Dry Low NOx (DLN) silo combustor of the Nuovo Pignone PGT10B gas turbine is being redesigned to meet Dual-Fuel capability. A prototype with specially designed fuel injectors, placed on airfoil-shaped elements, was tested at cold conditions (using water instead of Diesel fuel) to map the spray mass distribution at the premixer exit. The resulting profile showed high concentrations of liquid near the premixer centerline and on the premixer wall.
Parallel to this test, a small-scale experimental and numerical study was made of a single atomizer of the fuel system, placed in cross flow position. This small-scale study was launched in order to gain insight in the behavior of the spray, as well as to assess the relative importance of spray modeling parameters. The PDPA experiments and 2D CFD simulations of these experiments showed fair agreement on the average drop size distribution and drop size-velocity correlation. The flow visualization also revealed liquid film formation on the surface of the airfoil, behind the injector, due to the low atomization pressure differential at cold conditions.
Using this modeling experience, the spray patternation test with the prototype combustor has been modeled using an existing 3D CFD model of the premixer. The model also showed high liquid concentration on the wall, but not near the centerline. From the results of the small-scale study it is concluded that the measured high concentration near the premixer centerline is not a result of the flow field. It is assumed that in the complete assembly the liquid film from the injector vanes accumulates on the center body, resulting in a high liquid concentration downstream on the premixer centerline.
Overall, the application of CFD analyses on the tests performed proved to be a very useful tool to evaluate the test results. The modeling experience identified the important factors in modeling the fuel spray in a gas turbine environment, but further evolution of computer resources is required before large-scale test results will be reproducible with CFD models.
A Combined Eulerian and Lagrangian Method for Prediction of Evaporating Sprays
Authors: Burger M. , Klose G. , Rottenkolber G. , Schmehl R. , Giebert D. , Schäfer O. , Koch R. , Wittig S. 
Published: July 2014

Polydisperse sprays in complex three dimensional flow systems are important in many technical applications. Numerical descriptions of sprays are used to achieve a fast and accurate prediction of complex two-phase flows.
The Eulerian and Lagrangian methods are two essentially different approaches for the modeling of disperse two-phase flows. Both methods have been implemented into the same CFD - package which is based on a 3D body-fitted Finite Volume method. Considering sprays represented by a small number of droplet starting conditions, the Eulerian method is clearly superior in terms of computational efficiency. However, with respect to complex polydisperse sprays, the Lagrangian technique gives a higher accuracy. In addition, Lagrangian modeling of secondary effects such as spray-wall interaction enhances the physical description of the two-phase flow. Therefore, in the present approach the Eulerian and the Lagrangian methods have been combined in a hybrid method. The Eulerian method is used to determine a preliminary solution of the two-phase flow field. Subsequently, the Lagrangian method is employed to improve the accuracy of the first solution using detailed sets of initial conditions. Consequently, this combined approach improves the overall convergence behavior of the simulation.
In the final section, the advantages of each method are discussed when predicting an evaporating spray in an intake manifold of an IC-engine.
CFD Simulation of Humid Air Premixed Flame Combustion Chamber for Evaporative Gas Turbine Cycles
Authors: Bianco M. , Camporeale S. M. , Fortunato B. 
Published: July 2014

Evaporative cycles, such as Recuperated Water lnjected (RWI) cycle, Humid Air Turbine (HAT) cycle, Cascaded Humidified Advanced Turbine (CHAT) offer the attractive possibility to increase plant efficiency without the use of a steam turbine, necessary for gas-steam combined cycles, appearing, therefore, as an interesting solution for industrial power applications such as electric utilities and independent power producers.
It is expected that water addition may contribute to reduce NOx emissions in premixed flame combustors. In order to analyse this solution, a lean-bum combustor, fed with an homogeneous mixture formed by methane and humid air, has been analysed through CFD simulations, in order to predict velocity field, temperatures and emissions. The study has been carried out under the hypothesis of a two-dimensional, axisymmetric combustion chamber assuming, as set of operation conditions, atmospheric pressure, inlet temperature of 650 K, fuel-air equivalence ratio of the methane-air mixture ranging from 0.5 to 0.7 and water-air mass ratio varying from 0% to 5%. In the simulation, the presence of turbulence in the flow has been taken into account using a RNG k-ε model, whilst the chemical behaviour of the system has been described by means of a five-step global reduced mechanism including the oxidation mechanism and the NOx formation mechanism.
The analysis of the results shows that the moisture in the premixed flow reduces both NOx and CO emissions at constant equivalence ratio; moreover the lean blow-out limit is shifted toward higher equivalence ratio. The main effect of the water seems to be the increase of the specific heat the mixture which causes a reduction in flame temperature, slowing the chemical reactions responsible of NOx formation.
The reasonable agreement has been found between the simulation results concerning NOx emissions and recent experimental results carried out on premixed flamed with humid air. A discussion is also provided about the adopted turbulence models and their influence on the emission results.
Application of an Advanced CFD-Based Analysis System to the PW6000 Combustor to Optimize Exit Temperature Distribution: Part II — Comparison of Predictions to Full Annular Rig Test Data
Authors: Snyder Timothy S. , Stewart Jesse F. , Stoner Matthew D. , McKinney Randal G. 
Published: July 2014

Pratt & Whitney is developing a 107 kN (24,000 pound) thrust PW6000 engine for the 100-seat aircraft market. The combustor for this engine has been designed by combining the TALON emissions concept demonstrated on the PW4000 engine family with an advanced CFD-based analysis system to optimize the combustor exit temperature distribution. The design objective is to provide a low cost highly reliable engine, which produces low emissions.
This paper is the second of two parts, which describe an advanced CFD-based analysis system used to optimize the combustor exit temperature distribution for turbine life. The analysis system applied the identical Allstar solver, which is described and validated in part I, to the PW6000 combustor. All calculations in this paper were completely predictive in nature. The effect of dilution hole pattern changes on the exit temperature profile was determined by solving the flowfield from the prediffuser inlet to the combustor exit. Results from the study were used to understand the physical processes taking place inside the prediffuser and combustor that impact the exit temperature profile and from this understanding a hole pattern configuration was identified. Full annular rig measurements of the pressure drop and airflow distribution throughout the model along with exit temperature profile measurements agreed very well with CFD predictions. A second target exit temperature profile was defined based upon engine testing and the analysis tool demonstrated the ability to define a second dilution hole pattern that met the target profile to optimize turbine life. An annular rig test again confirmed the CFD predictions.
Parametric studies were also performed on the prediffuser inlet pressure profile to predict how the turbine inlet temperature profile would change. These studies were used to desensitize the combustor temperature profile to prediffuser inlet profile changes that may occur over the life of the engine. The predictive capability of this CFD-based analysis tool has significantly reduced experimental development costs and has optimized the combustor exit temperature profile to meet PW6000 design objectives.
Modelling of NOx Formation of a Premixed DLE Gas Turbine Combustor
Authors: Eggels R. L. G. M. 
Published: July 2014

To comply with the stringent emission regulations industrial gas turbines operate under lean premixed conditions. To be able to predict emissions in an early design phase, advanced premixed combustion models are required. The rate of NOx formation is sensitive to temperature and some radical concentrations, therefore the flame predictions have to be accurate and detailed. It is well known that there are several routes (thermal, prompt, N2O mechanism) by which NOx can be formed. As lean premixed gas turbines operate at relative low flame temperatures, the contribution of the prompt NO and N2O mechanisms has to be accounted for.
The modelling of NOx formation is done in a post-processor, as the influence of nitrogen species on the main combustion characteristics is negligible. This post-processor is based on flame calculations using a Flame Generated Manifold method. This is a reduced reaction mechanism, so that only a limited number of variables have to be solved during the CFD computations.
A post-processor method has been developed to compute NO formation. Differential equations are solved for NO and N2O, other species including nitrogen are solved using a steady-state equation.
The flame and post-processor models are applied to 2-D and 3-D models of an industrial series staged gas turbine. Parameter studies for the fuel split between the two stages and inlet fuel/air ratio variations have been carried out and the data has been compared with generic engine data.
Advanced Burner Development for the Vx4.3A Gas Turbines
Authors: Streb Holger , Prade Bernd , Hahner Thomas , Hoffmann Stefan 
Published: July 2014

The Vx4.3A gas turbine family has already been well received by the market. Nevertheless the market drives technology towards both increased turbine inlet temperatures and reduced emissions.
The HR3 burner was originally developed for the V4.2 and Vx4.3 fleet featuring silo combustors in order to mitigate the risk of flashback and to improve the NOx- emissions (Prade, Streb, 1996). Due to its favourable performance characteristics in the Vx4.3 family the advanced HR3 burner was adapted to the Vx4.3A series with annular combustor.
The paper reports upon the design, testing and field evaluation steps which were necessary to implement the burner for the 50 and 60 cycle gas turbines.
With CFD calculations the flow field and the mixing of natural gas and combustion air have been optimised. A number of tests in the Siemens test facilities confirmed these predictions. The atmospheric 3 burner segment combustion test rig allows to test flame interaction, stability and exhaust gas emission simultaneously.
In the Siemens Berlin Test Facility which provides a platform for full scale gas turbine testing 24 HR3-burners were implemented into a V84.3A gas turbine with a base load power output of 184 MW at ISO conditions for prototype testing before introducing this new burner generation into the bigger 50 cycle family V94.3A.
Implementation of 24 scaled HR3 burners were installed in the V94.3A of Cottam Development Centre (Great Britain) and demonstrated an excellent performance. The gas turbine reached an ISO base load output of 265 MW with NOx emissions well below 25 ppmvd.
Due to the very promising test results in Berlin and Cottam, this burner modification, which can be retrofitted to all VX4.3A gas turbines, was implemented nearly fleet wide.
From Concept to Commercial Operation: The Tri-Fuel Injector Used for LPG and Naphtha Applications
Authors: Newman A. W. , Nixon P. S. , Wilms R. I. , Taylor D. M. , Cornwell M. D. 
Published: July 2014

The tri-fuel injector is an extension of the standard dual fuel multi passage injector to cover additional fuels such as Liquid Petroleum Gas (LPG) and Naphtha at medium pumping pressure (less than 40 Bara). There is an additional passage designed for metering the LPG or Naphtha in liquid phase. The fuel system uses a non-contacting rotary pump with modern inverter technology for the pumping of these fuels.
Both tri-fuel injector and fuel system are now in commercial operation on two Tornado engines using LPG, natural gas and diesel fuels. The LPG system is operating just below 30 Bara pumping pressure, and has accumulated about 1029 operating hours on the lead engine. LPG load shedding capability has been proven on one engine. Commercial operation of the Typhoon engine on Naphtha at medium pumping pressures (< 40 Bara), with an improved tri-fuel injector, will commence in the near future.
Thermodynamic Analysis of Hydrogen Combustion Turbine Cycles
Authors: Desideri Umberto , Ercolani Piergiacomo , Yan Jinyue 
Published: July 2014

The “International Clean Energy System Technology Utilizing Hydrogen (World Energy Network)”: WE-NET is a research program directed at the development of the technologies needed build a hydrogen-based energy conversion system. It proposes to set up a world energy network to convert renewable energy, such as hydropower and solar energy, into a secondary and transportable form to supply the demand centers, and to make possible the utilization of existing power generation, transportation, town gas, etc.
Within the framework of this program Mitsubishi Heavy Industries, Hitachi and Westinghouse Power Corporation are working to develop an hydrogen-fueled combustion turbine system designed to meet the goals set by the WE-NET Program. The hydrogen–fueled power generation cycle will be able to satisfy the requirements of an efficiency based on the lower heating value higher than 70% and of reliability, availability and maintainability equivalent to current base-loaded natural gas-fired combined cycle. The use of hydrogen will eliminate emissions of CO2 and SOx and significantly reduce those of NOx.
This paper presents a thermodynamic analysis of some concepts of hydrogen fuelled cycles which have been studied in the WE-NET program and makes a comparison of their performance.
De Minimis Approach for Meeting Anti-Degradation to Address Water Quality Issues With Respect to NPDES Discharges From New GTCC Plants
Authors: White Erik D. , Semer Robin A. , Scharre David C. , Childress Neil B. 
Published: July 2014

States are required to develop and adopt anti-degradation policies and implementation procedures pursuant to federal regulations [1] to protect existing in stream water quality and water uses. States are requiring National Pollutant Discharge Elimination System (NPDES) dischargers from new sources, which could result in lowering of existing water quality, to perform an anti-degradation demonstration as part of the NPDES permit application process. These evaluations are appropriate where a proposed discharge may have a significant adverse impact on water quality. However, they are an unnecessary burden on both the permit applicant and the reviewing agency where the proposed discharge is minor relative to existing water quality. Therefore, de minimis evaluations provide a technical approach that States can use to avoid the need for, or limit the scope of, anti-degradation demonstrations where the impact at the proposed discharge is minor.
This paper provides a de minimis evaluation approach for addressing anti-degradation as part of an NPDES permit application process. The approach, which ascertains what conditions would or would not constitute a “de minimis lowering of water quality,” was recently used in support of a new combined-cycle power plant in one of the central states.
Design, Development and Testing of a Gas Turbine Steam Injection and Water Recovery System
Authors: Lupandin Vladimir V. , Romanov Victor I. , Krivutsa Villy A. , Lupandin Viktor V. 
Published: July 2014

The paper describes experience gained in design and development of gas turbine units for electrical generator or mechanical drive application featuring steam injection into the gas turbine combustion chamber combined with a water recovery system from the gas turbine exhausted gases (units are known as “Aquarius”). Prototype test rigs, and test results on prototype and commercial units are discussed. These units have power output of 16 MW (“Aquarius-16”) and 25 MW (“Aquarius-25”) with efficiency of 45% and 43%, ISO respectively.
Special test rigs were designed and built to prove concept of water recovery from gas turbine exhausted gases and to study contact condenser operation over a wide range of ambient temperatures.
The first prototype test rig, comprising of SPE “Mashproekt” GT 100K gas turbine engine, 100 kW electrical generator, waste-heat recovery boiler and contact type condenser started operation in 1986.
To the Author’s knowledge there is one more plant in operation with water recovery from February 1993 located inside the “CARROZZERIA BERTONE” plant near Turin, Italy (Ennlo Macchi, Aurelio Poggio “A COGENERATION PLANT BASED ON A STEAM INJECTION GAS TURBINE WITH RECOVERY OF THE WATER INJECTED: DESIGN CRITERIA AND INITIAL OPERATING EXPERIENCE”, ASME paper 94-GT-17).
The second prototype unit, “Aquarius-25”, comprising of SPE “Mashproekt” steam injected GT 15000S gas turbine engine, waste heat recovery boiler, contact water condenser and a generator (power output of 25 MW and efficiency of 43%) is currently in operation. This unit has accumulated more than 12,000 fired hours in development tests since January 1995.
“Aquarius-16” - commercial mechanical drive unit with 16 MW power output and efficiency of 45% was built and factory tested in 1998 (more than 1600 fired hours). It was built around the SPE “Mashproekt” GT 10000S steam injected gas turbine engine. This unit is scheduled to start commercial operation at UKRGASPROM “Stavishenskaya” gas compression station (Ukraine) in 2001.
Droplet Entrainment From a Shear-Driven Liquid Wall Film in Inclined Ducts: Experimental Study and Correlation Comparison
Authors: Ebner J. , Gerendás M. , Schäfer O. , Wittig S. 
Published: July 2014

The primary objective of the present study is to clarify the droplet disintegration mechanism and the film properties of liquid oil films driven by shear stress, which is induced by a co-current gas flow. This work focuses on the flow behavior within the starting length of the complex two-phase flow and the effect of inclination on the entrainment rate. Many investigations have been performed in the past to determine the droplet entrainment in the gas core for fully-developed flow conditions with respect to their relevance in pipes of power plants and various chemical engineering systems (Hewitt and Taylor, van Rossum, Ishii and Grolmes [1, 2, 3]). In more recent work the effect of inclination has been studied in detail (Lee and Mjani, Azzopardi, Azzopardi et al. [4, 5, 6]). Nevertheless, a lack of knowledge can be realized for droplet entrainment within the starting length of this complex flow type.
Thus, fundamental experiments have been carried out to provide a data base for droplet entrainment of liquid disintegrated from an oil film within its starting length at several inclination angles of the flow. The experimental results have been compared with correlations from literature. Additionally, the wall film thickness has been measured to allow a fully-coupled modelling of entrainment and liquid film properties depending on global flow parameters. Based on film Reynolds number, Weber number, a dimensionless film flow length and a modified Froude number, taking into account the angle of inclination, correlations have been developed, where those from literature are not applicable.
An Experimental Study of Liquid Film Thickness in Annular Air/Oil Flow in a Vertical Pipe Using a Laser Focus Displacement Meter
Authors: Busam S. , Ebner J. , Wittig S. 
Published: July 2014

The development of modern aero-engines is leading to increased pressure and temperature levels which makes increasing demands on the engines’ safety and reliability. In particular the vent-system of the bearing chambers located in the hot section of the engine represents a critical component in the design process due to the complex two-phase flow phenomena. The air/oil mixture that is discharged out of the bearing chambers has a strong influence on the overall pressure losses and it shows locally enhanced heat transfer where oil coking or oil fires with the risk of flashback into the bearing chamber can occur.
In order to gain a deeper insight into the interacting flow of air and oil, a glass pipe test section with a inner tube diameter of 10 mm was integrated into the vent-line of the high speed bearing chamber test rig operated at the Institut für Thermische Strömungsmaschinen, University of Karlsruhe, Germany. Therewith, an experimental study of the oil film along the wall in vertical annular upflow was performed by use of a laser focus displacement meter. This instrument which was introduced by Takamasa et al. [1] allows accurate measurements of film thickness to be made in real time with a sensitivity of 2 microns and a datarate of 1.5 kilohertz.
Comprehensive measurements were conducted at two locations of the pipe 320 mm apart in flow direction. A wide range of oil and air flow rates was examined to study their impact on the local film thickness. Both fluids were heated up to the same temperature of 70°C and 100 °C, respectively, to vary the oil viscosity by a factor of 2.