bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Scalar Dissipation Rate Model to Siemens DLE Combustors
Authors: Sadasivuni Suresh Kumar , Bulat Ghenadie , Sanderson Victoria , Swaminathan Nedunchezhian 
Published: July 2013

The standard design process for the Siemens Industrial Turbomachinery, Lincoln, Dry Low Emissions combustion systems has adopted the Eddy Dissipation Model with Finite Rate Chemistry for reacting computational fluid dynamics simulations. The major drawbacks of this model have been the over-prediction of temperature and lack of species data limiting the applicability of the model.
A novel combustion model referred to as the Scalar Dissipation Rate Model has been developed recently based on a flamelet type assumption. Previous attempts to adopt the flamelet philosophy with alternative closure models have failed, with the prediction of unphysical phenomenon. The Scalar Dissipation Rate Model (SDRM) was developed from a physical understanding of scalar dissipation rate, signifying the rate of mixing of hot and cold fluids at scales relevant to sustain combustion, in flames and was validated using direct numerical simulations data and experimental measurements.
This paper reports on the first industrial application of the SDRM to SITL DLE combustion system. Previous applications have considered ideally premixed laboratory scale flames. The industrial application differs significantly in the complexity of the geometry, unmixedness and operating pressures. The model was implemented into ANSYS-CFX using their inbuilt command language. Simulations were run transiently using Scale Adaptive Simulation turbulence model, which switches between Large Eddy Simulation and Unsteady Reynolds Averaged Navier Stokes using a blending function.
The model was validated in a research SITL DLE combustion system prior to being applied to the actual industrial geometry at real operating conditions. This system consists of the SGT-100 burner with a glass square-sectioned combustor allowing for detailed diagnostics. This paper shows the successful validation of the SDRM against time averaged temperature and velocity within measurement errors.
The successful validation allowed application of the SDRM to the SGT-100 twin shaft at the relevant full load conditions. Limited validation data was available due to the complexity of measurement in the real geometry. Comparison of surface temperatures and combustor exit temperature profiles showed an improvement compared to EDM/FRC model. Furthermore, no unphysical phenomena were predicted.
This paper presents the successful application of the SDRM to the industrial combustion system. The model shows a marked improvement in the prediction of temperature over the EDM/FRC model previously used. This is of significant importance in the future applications of combustion CFD for understanding of hardware mechanical integrity, combustion emissions and dynamics of the flame.
Combustion Dynamics Validation of an Annular Reheat Combustor
Authors: Singla Ghislain , Noiray Nicolas , Schuermans Bruno 
Published: July 2013

This paper deals with a detailed thermoacoustic assessment of an annular reheat combustor. Extensive tests have been conducted in the GT26 Test Power Plant in Switzerland. To this end, the combustion chamber has been instrumented with advanced pulsation sensors, an optical probe, strain gauges and accelerometers. A large number of dynamic pressure sensors recorded the acoustic pressure wave propagations in the axial and circumferential directions over a very large frequency range.
A modal analysis technique has been developed to extract the acoustic mode shapes from the experimental data. This technique allows for decomposition in standing and traveling waves, hence revealing the nature of the acoustic field. The extracted mode shapes showed a very good agreement with results from 3-d finite element calculations.
Combustion stability has been quantified by a methodology that extracts pulsation growth rates from experimental data. This novel method relies on advanced statistic processing of the instantaneous pulsation amplitudes. It has the advantage that it is insensitive to probe location, which is of particular advantage for high frequencies (higher than 1 kHz).
Extended Fuel Flexibility Testing of Siemens Industrial Gas Turbines: A Novel Approach
Authors: Andersson Mats , Larsson Anders , Lindholm Annika , Larfeldt Jenny 
Published: July 2013

Opportunity gaseous fuels are of great interest for small and medium sized gas turbines. The variety of gaseous fuels that Siemens Industrial Turbomachinery AB (SIT) is requested to make judgments on is continuously expanding. From such requests follows an increasing need for testing new fuels.
The SIT novel approach for fuel flexibility testing, EBIT, has been to combine the single burner rig testing with a full scale engine test to give a cost effective and flexible solution. The combination of the two approaches is accomplished by using a separate feed of testing fuel to one or more burners in a standard gas turbine installation where the other burners use standard fuel from standard fuel system for engine operation. The separate feed of testing fuel can be operated as a slave to engine governor heat demand, but can also be controlled independently.
This paper describes how EBIT has been implemented and tested. Combustion monitoring techniques and measurements to check behavior and predictions for full scale engine tests are presented. Results from testing with a blended natural gas with more than 50% of heat input from pentane, C5H12, in a SGT-700 engine shows that the EBIT concept is possible and powerful.
The SIT 3rd generation DLE burner proves to be very fuel flexible and tolerant to high levels of pentane in the fuel. Less than 20% increase in NOx emissions can be expected when using pentane rich fuels. The burner is used in the SGT-800 47MW engine and the SGT-700 31MW engine.
Novel Burner Concept for Premixed Surface-Stabilized Combustion
Authors: Kornilov V. N. , Shakariyants S. , de Goey L. P. H. 
Published: July 2013

Surface-stabilized combustion is credited with high burning rates, extended lean flammability limits, wide modulation range and other advantages. This makes it an attractive technology for compact low-emission combustors.
The experimental gas turbine surface burners reported to this date are produced from compressed and sintered Fe-Cr-Al fiber mats. The authors have developed a new concept of surface burner fabricated by braiding ceramic cords around a ceramic frame. This simple method produces a basket-type surface suitable for stabilizing lean premixed flames over a broad range of operating conditions. The use of ceramics extends possibilities for operation at very high inlet temperatures with reduced risks of material sintering and oxidation.
This paper presents test results with an experimental burner on a pressurized combustion rig with optical access. The experiments were performed under the following conditions: inlet temperatures of 22–740 C, pressures of 1–3 bar, thermal power between 4 kWTh and 32 kWTh and equivalence ratios of 0.28–0.95. Measurements of flue gas composition and pressure drop are also reported in the paper. The operating window for low-NOx and low-CO combustion is analyzed.
With the demonstrated performance, the burner could cover the operating envelope of a 3 kWe recuperated micro turbine [1]–[2] with no pilot and no staging. This would also limit NOx to <40 ppm @ 0% O2 within the micro turbine load range of 100% to 50%.
Hydrogen Combustion Within a Gas Turbine Reheat Combustor
Authors: Poyyapakkam Madhavan , Wood John , Mayers Steven , Ciani Andrea , Guethe Felix , Syed Khawar 
Published: July 2013

This paper describes a novel lean premixed reheat burner technology suitable for Hydrogen-rich fuels. The inlet temperature for such a combustor is very high and reaction of the fuel/oxidant mixture is initiated through auto-ignition, the delay time for which reduces significantly for Hydrogen-rich fuels in comparison to natural gases. Therefore the residence time available for premixing within the burner is reduced. The new reheat burner concept has been optimized to allow rapid fuel/oxidant mixing, to have a high flashback margin and to limit the pressure drop penalty.
The performance of the burner is described, initially in terms of its fluid dynamic properties and then its combustion characteristics. The latter are based upon full-scale high-pressure tests, where results are shown for two variants of the concept, one with a pressure drop comparable to today’s natural gas burners, and the other with a two-fold increase in pressure drop. Both burners indicated that Low NOx emissions, comparable to today’s natural gas burners, were feasible at reheat engine conditions (ca. 20 Bars and ca. 1000C inlet temperature). The higher pressure drop variant allowed a wider operating window. However the achievement of the lower pressure drop burner shows that the targeted Hydrogen-rich fuel (70/30 H2/N2 by volume) can be used within a reheat combustor without any penalty on gas turbine performance.
Laminar Flame Speed and Ignition Delay Time Data for the Kinetic Modeling of Hydrogen and Syngas Fuel Blends
Authors: Krejci M. C. , Mathieu O. , Vissotski A. J. , Ravi S. , Sikes T. G. , Petersen E. L. , Keromnes A. , Metcalfe W. , Curran H. J. 
Published: July 2013

Laminar flame speeds and ignition delay times have been measured for hydrogen and various compositions of H2/CO (syngas) at elevated pressures and elevated temperatures. Two constant-volume cylindrical vessels were used to visualize the spherical growth of the flame through the use of a schlieren optical setup to measure the laminar flame speed of the mixture. Hydrogen experiments were performed at initial pressures up to 10 atm and initial temperatures up to 443 K. A syngas composition of 50/50 by volume was chosen to demonstrate the effect of carbon monoxide on H2−O2 chemical kinetics at standard temperature and pressures up to 10 atm. All atmospheric mixtures were diluted with standard air, while all elevated-pressure experiments were diluted with a He:O2 of 7:1 to minimize instabilities. The laminar flame speed measurements of hydrogen and syngas are compared to available literature data over a wide range of equivalence ratios where good agreement can be seen with several data sets. Additionally, an improved chemical kinetics model is shown for all conditions within the current study. The model and the data presented herein agree well, which demonstrates the continual, improved accuracy of the chemical kinetic model.
A high-pressure shock tube was used to measure ignition delay times for several baseline compositions of syngas at three pressures across a wide range of temperatures. The compositions of syngas (H2/CO) by volume presented in this study included 80/20, 50/50, 40/60, 20/80, and 10/90, all of which are compared to previously published ignition delay times from a hydrogen-oxygen mixture to demonstrate the effect of carbon monoxide addition. Generally, an increase in carbon monoxide increases the ignition delay time, but there does seem to be a pressure dependency. At low temperatures and pressures higher than about 12 atm, the ignition delay times appear to be indistinguishable with an increase in carbon monoxide. However, at high temperatures the relative composition of H2 and CO has a strong influence on ignition delay times. Model agreement is good across the range of the study, particularly at the elevated pressures. Also, an increase in carbon monoxide causes the activation energy of the mixture to decrease.
Experimental Study on Combustion Characteristics of Conventional and Alternative Liquid Fuels
Authors: Vukadinovic Vlade , Habisreuther Peter , Zarzalis Nikolaos 
Published: July 2013

Gas turbine combustor design relies strongly on the turbulent flame velocity over the whole turbine operation range. Due to the fact that turbulent flame velocity depends strongly on the laminar one, its characterisation at different thermodynamic conditions is necessary for further optimisation of gas turbines. The Markstein number, which quantifies the response of the flame to the stretch, also has to be considered. Additionally, the Markstein number can be utilised as an indicator for laminar and turbulent flame front stability.
The current attempts to replace conventional fuels, such as kerosene, with alternative ones, obtrude their comparison in order to find the most appropriate substitute. Additionally, significant differences in the flame behaviour, which could be recognised through different combustion characteristics, can lead to modification of currently used gas turbine design. Even so, the experimental data of alternative fuels are scarce, especially at elevated pressure conditions.
So, the combustion characteristics, laminar burning velocity and Markstein number of kerosene Jet A-1 and several alternative fuels (GTL and GTL blends) are investigated experimentally in an explosion vessel. For this purpose an optical laser method is employed based on the Mie-scattering of the laser light by smoke particles. Within this experimental study the influence of three crucial parameters: initial temperature, initial pressure and mixture composition on the burning velocity and Markstein number are investigated. The experiments were performed at three different pressures 1, 2, 4bar; three different temperatures 100°C, 150°C, 200°C; and for a range of equivalence ratio 0.67–1.67. The observed results are compared and discussed in detail.
Adaptive NOx Control on Refinery Gas in Industrial Gas Turbines
Authors: Geipel Philipp , Bjerklund Erik , Persson Magnus , Carrera Arturo Manrique 
Published: July 2013

The current work explores the operation of an industrial gas turbine (25 MWe) unit working under variable NOx emission limits (from 75 to 120 mg/Nm3) and variable fuel composition. The latter is typical for flared streams in oil process industry (refineries/well operation/petrochemicals).
In the current case the nitrous oxides (NOx) emission limits are dependent on the mixing ratio of natural gas (NG, 89%vol. methane) and refinery gas (RG, 40% vol. H2, 56%vol. CH4, C4+) that is used as fuel for the engine. This mixture is process dependent and varies in matter of minutes from 100% NG to 100% RG. Siemens has faced this challenge by using a SGT-600 unit (25MWe) operating in non-premixed combustion mode with a novel water injection strategy, the adaptive water injection for the control of NOx.
The adaptive water injection for NOx control has been developed after evaluating different NOx control strategies. It consists of a closed loop, in which NOx emission measurements are used as the main control parameter, linked to a fixed parametric curve based on the compressor discharge pressure. Fast response times and fail–safe strategies have also been developed and tested under operating conditions of the GT. The water injection method could cope with the variation of load, fuel supply mixture and NOx limit without any flame instability problems. This is done while maintaining the optimal amount of water needed to achieve the emissions target. The robustness of the system has been satisfactory over the tested period and seems a viable solution.
Comparison of Nonlinear to Linear Thermoacoustic Stability Analysis of a Gas Turbine Combustion System
Authors: Krebs Werner , Krediet Harmen , Portillo Enrique , Hermeth Sebastian , Poinsot Thierry , Schimek Sebastian , Paschereit Oliver 
Published: July 2013

Gas turbines offer a high operational flexibility and a good turn down ratio to meet future requirements of power production. In this context stable operation over a wide range and for different blends of fuel is requested. Thermoacoustic stability assessment is crucial for accelerating the development and implementation of new combustion systems.
The results of nonlinear and linear thermoacoustic stability assessments are compared on basis of recent measurements of flame describing functions and thermoacoustic stability of a model swirl combustor operating in the fully turbulent regime. The different assessment methods are outlined. The linear thermoacoustic stability assessment yields growth rates of the thermoacoustic instability whereas the limit cycle amplitude is predicted by the nonlinear stability method.
It could be shown that the predicted limit cycle amplitudes correlate well with the growth rates of excitation obtained from linear modeling. Hence for screening the thermoacoustic stability of different design approaches a linear assessment may be sufficient while for detailed prediction of the dynamic pressure amplitude more efforts have to be spent on the nonlinear assessment including the analysis of the nonlinear flame response.
Correlations for Turbulent Flame Speed of Different Syngas Mixtures at High Pressure and Temperature
Authors: Daniele S. , Jansohn P. 
Published: July 2013

There is an obvious lack of data and understanding of the behavior of turbulent flames at high temperature and high pressure, especially concerning hydrogen containing fuels. Among the many relevant parameters, the turbulent flame speed “ST” is one of the most interesting for scientists and engineers.
This paper reports an experimental investigation of premixed syngas combustion at gas-turbine like conditions, with emphasis on the determination of ST/SL derived as global fuel consumption per unit time. Experiments at pressures up to 2.00 MPa, inlet temperatures and velocities up to 773K and 150 m/s respectively, u′/SL greater than 100 are presented. Comparison between different syngas mixtures and methane clearly show much higher ST/SL for the former fuel. It is shown that ST/SL is strongly dependent on preferential diffusive-thermal (PDT) effects, co-acting with hydrodynamic effects, even for very high u′/SL. ST/SL increases with rising hydrogen content in the fuel mixture and with pressure. A correlation for ST/SL valid for all investigated fuel mixtures, including methane, is proposed in terms of turbulence properties (turbulence intensity and integral length scale), combustion properties (laminar flame speed and laminar flame thickness) and operating conditions (pressure and inlet temperature). The correlation captures effects of preferential diffusive-thermal and hydrodynamic instabilities.
The Impact of Perforation Geometry on Acoustic Damping Attributes of a Perforated Liner With Bias Flow
Authors: Mazdeh Alireza , Kashani Reza 
Published: July 2013

Acoustic damping properties of perforated liners are highly dependent on a number of variables which can be categorized as “flow variables” such as the extent and Mach number of grazing flow as well as bias flow and “geometric variable” such as the shape of the hole which can be rectangular, cylindrical, conical with diverging or converging nozzle, thickness to radius ratio, radius to hole spacing ratio and hole orientation which can be normal to or inclined with respect to the perforated plate. Many of these variables were not incorporated in previous studies.
Theoretical and empirical approaches have provided the foundation for understanding the damping properties of liners but they are based on certain simplifying assumptions making them inadequate in addressing the more realistic conditions encountered in industrial applications. These limitations have highlighted the importance of numerical methods for studying damping behavior of liners. Acoustic attributes of perforated plates (mainly in terms of impedance which is a frequency-dependent complex quantity) as a function of non-dimensional variables like Reynolds, Strouhal, Mach, and Helmholtz numbers have been studied by various researchers, including the authors, using a variety of numerical tools starting from the simple 1D network scheme based on linear acoustics and the wall compliance concept introduced by Howe all the way to the computationally intensive Large-Eddy Simulations (LES) and Scaled Adaptive Simulation (SAS) reconstructing the full unsteady turbulent structures. Although the impacts of some geometry variations such as hole inclination angle and diameter, in conjunction with various fluid dynamic parameters, have been investigated using 1D network tools, the focus of LES has been mainly on analysis of a single circular hole with periodic boundary conditions as the representation of multi-perforation (assuming the perforations are spaced far enough from each other so that there is no interaction between neighboring holes). There is certainly a need for thorough investigation of the acoustics impact of these geometric parameters as well as shape of the holes using LES.
In an on-going research we are extending the numerical modeling work on characterizing the acoustic damping attributes of a perforation, beyond the current state of the art, by including the geometric variables including hole size, shape, orientation, and radius to thickness ratio, amongst others, in the study. In this paper, following a short review of the research conducted in the recent past for comprehension of the acoustic-vortex interaction mechanism in perforated liners resulting in acoustic absorption, we present the findings on the impact of thickness/radius ratio on the acoustic damping attribute of a perforation. The verification of the CFD results are done by comparing the data with analytical solutions.
Chemical Kinetic Modeling of Ignition and Emissions From Natural Gas and LNG Fueled Gas Turbines
Authors: Gokulakrishnan P. , Fuller C. C. , Joklik R. G. , Klassen M. S. 
Published: July 2013

Single digit NOx emission targets as part of gas turbine design criteria require highly accurate modeling of the various NOx formation pathways. The concept of lean, premixed combustion is adopted in various gas turbine combustor designs, which achieves lower NOx levels by primarily lowering the flame temperature. At these conditions, the post-flame thermal-NOx pathway contribution to the total NOx can be relatively small compared to that from the prompt-NOx and the N2O-route, which are enhanced by the super-equilibrium radical pathway at the flame front. In addition, new sources of natural gas fuel (e.g., imported LNG) with widely varying chemical compositions including higher order hydrocarbon components, impact flame stability, lean blow-out limits and emissions in existing lean premixed combustion systems. Also, the presence of higher order hydrocarbons can increase the risk of flashback induced by autoignition in the premixing section of the combustor.
In this work a detailed chemical kinetic model was developed for natural gas fuels that consist of CH4, C2H6, C3H8, nC4H10, iC4H10, and small amounts of nC5H12, iC5H12 and nC6H14 in order to predict ignition behavior at typical gas turbine premixing conditions and to predict CO and NOx emissions at lean premixed combustion conditions. The model was validated for different NOx-pathways using low and high pressure laminar premixed flame data. The model was also extended to include a vitiated kinetic scheme to account for the influence of exhaust gas recirculation on fuel oxidation. The model was employed in a chemical reactor network to simulate a laboratory scale lean premixed combustion system to predict CO and NOx. The current kinetic mechanism demonstrates good predictive capability for NOx emissions at lower temperatures typical of practical lean premixed combustion systems.