An Acoustic-Energy Method for Estimating the Onset of Acoustic Instabilities in Premixed Gas-Turbine Combustors

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Z. M. Ibrahim ◽  
F. A. Williams ◽  
S. G. Buckley ◽  
C. Z. Twardochleb
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Classical Method ◽  
Stability Index ◽  
Operating Conditions ◽  
Acoustic Energy ◽  
Linear Amplification ◽  
Gas Turbine Combustors ◽  
Acoustic Instabilities ◽  
Oscillatory Combustion

For given acoustic frequencies of premixed gas-turbine combustors, a classical method not currently in use is explored for assessing whether acoustically driven oscillatory combustion will occur. The method involves cataloging linear amplification and attenuation mechanisms and estimating magnitudes of their rates. Linear approximations to nonlinear mechanisms are included in an effort to obtain a reasonably complete description. A stability index is defined such that oscillation is predicted to occur when the value of the index exceeds unity. The method is tested on the basis of new experiments and experimental data available in literature. Moderate success is achieved in rationalizing these experimental results. The objective of the method is to enable quick and inexpensive decisions to be made for a wide variety of potential design configurations and operating conditions, without the complexity of computational fluid dynamics. The approach therefore may complement other approaches already in use.

A Method for Estimating the Onset of Acoustic Instabilities in Premixed Gas-Turbine Combustors

2007 ◽  
Author(s):  
Z. M. Ibrahim ◽  
F. A. Williams ◽  
S. G. Buckley ◽  
C. Z. Twardochleb
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Gas Turbine ◽  
Classical Method ◽  
Stability Index ◽  
Operating Conditions ◽  
Linear Amplification ◽  
Gas Turbine Combustors ◽  
Acoustic Instabilities ◽  
Oscillatory Combustion

For given acoustic frequencies of premixed gas-turbine combustors, a classical method not currently in use is explored for assessing whether acoustically driven oscillatory combustion will occur. The method involves cataloging linear amplification and attenuation mechanisms and estimating magnitudes of their rates. Linear approximations to nonlinear mechanisms are included in an effort to obtain a reasonably complete description. A stability index is defined such that oscillation is predicted to occur when the value of the index exceeds unity. The method is tested on the basis of new experiments and experimental data available in the literature. Moderate success is achieved in rationalizing these experimental results. The objective of the method is to enable quick and inexpensive decisions to be made for a wide variety of potential design configurations and operating conditions, without the complexity of computational fluid dynamics. The approach therefore may complement other approaches already in use.

A Critical Review of NOx Correlations for Gas Turbine Combustors

1975 ◽  
Author(s):  
D. A. Sullivan ◽  
P. A. Mas
Keyword(s):  
Experimental Data ◽  
Data Base ◽  
Gas Turbine ◽  
Critical Review ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Empirical Correlations ◽  
Gas Turbine Combustors ◽  
Semi Empirical ◽  
Adequate Data

The effect of inlet temperature, pressure, air flowrate and fuel-to-air ratio on NOx emissions from gas turbine combustors has received considerable attention in recent years. A number of semi-empirical and empirical correlations relating these variables to NOx emissions have appeared in the literature. They differ both in fundamental assumptions and in their predictions. In the present work, these simple NOx correlations are compared to each other and to experimental data. A review of existing experimental data shows that an adequate data base does not exist to evaluate properly the various NOx correlations. Recommendations are proposed to resolve this problem in the future.

scholarly journals The Design and Evaluation of a 14 Stage, 16:1 Pressure Ratio Compressor for an Industrial Gas Turbine

1996 ◽  
Author(s):  
Mohammad R. Saadatmand
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Rotor Blade ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Suction Surface ◽  
Design Intent ◽  
Flow Through ◽  
Industrial Gas Turbine

The aerodynamic design process leading to the production configuration of a 14 stage, 16:1 pressure ratio compressor for the Taurus 70 gas turbine is described. The performance of the compressor is measured and compared to the design intent. Overall compressor performance at the design condition was found to be close to design intent. Flow profiles measured by vane mounted instrumentation are presented and discussed. The flow through the first rotor blade has been modeled at different operating conditions using the Dawes (1987) three-dimensional viscous code and the results are compared to the experimental data. The CFD prediction agreed well with the experimental data across the blade span, including the pile up of the boundary layer on the corner of the hub and the suction surface. The rotor blade was also analyzed with different grid refinement and the results were compared with the test data.

Prediction and Mitigation of Thermally Induced Creep Distortion in Gas Turbine Combustors

2007 ◽  
Author(s):  
Hany Rizkalla ◽  
Page Strohl ◽  
Peter Stuttaford
Keyword(s):  
Gas Turbine ◽  
Design Process ◽  
Optimal Operation ◽  
Operating Conditions ◽  
Thermal Loads ◽  
Thermally Induced ◽  
Part Load ◽  
Gas Turbine Combustors ◽  
Over Time ◽  
Load Conditions

In an effort to maximize efficiency and decrease emissions, modern gas turbine combustors are exposed to extreme operating conditions which if not accounted for during the design process, can lead to premature failure of the combustion components. Of interest to this article are some operating conditions that, in many instances can expose the gas turbine combustion chambers (liners) to asymmetric thermal loads. Highly asymmetric thermal loads at high temperatures can inflict severe distress on combustion liners attributing to thermal creep distortion and Thermo-Mechanical Fatigue (TMF). Modern low emission pre-mix combustion systems such as the Dry Low NOx (DLN) 2.6 in the GE F Class machines and PSM’s FlameSheet combustor employ firing curves that involve “staging” when the gas turbine is ramping up or down in load or is simply operating in part-load condition. During such staging process, the flame resides in only certain sectors of each combustor while the other sectors are cold, these part load conditions can cause high thermal gradients leading to high thermally induced stresses in the liners. High thermal stresses at high metal temperatures can induce severe visco-plastic (creep) geometric distortion in liners upon prolonged exposure to such conditions. Extreme thermally induced creep distortion can eventually lead to liners’ catastrophic failures due to buckling and/or rupture. Under mild circumstances permanent creep distortion of liners can lead to non-optimal combustion and hence attributing to non optimal operation of the gas turbine. Several means can be employed during the design process to avoid and/or account for creep distortion, some of which are discussed in this article. Although linear elastic analysis is usually used by design engineers to predict liner thermal deflection under part load conditions, it is important to note that even though the resulting stresses may be within the material’s elastic range, creep relaxation leading to permanent liner deformation may still occur over time causing non-optimal base load operation and degradation to the gas turbine efficiency. In most cases predicting thermally induced creep distortion over time can only be done using iterative numerical techniques such as FEA coupled with the material specimen creep testing. A case study involving a F class FlameSheet liner will be discussed and used for illustrative purposes. ANSYS non-linear creep FEA modeling was used to predict the creep deformation results over time using Haynes 230 specimen test data. The predicted numerical analytical results matched well with actual hardware characterized data, thus validating the analytical technique.

A Fully Non-Adiabatic Flamelet Generated Manifold Model for High Fidelity Modeling of Turbulent Combustion in Gas Turbine Like Conditions

2020 ◽  
Author(s):  
Rakesh Yadav ◽  
Ishan Verma ◽  
Abhijit Modak ◽  
Shaoping Li
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Turbulent Combustion ◽  
Gas Turbines ◽  
Turbulent Flame ◽  
Operating Conditions ◽  
High Fidelity ◽  
Mixture Density ◽  
Flamelet Generated Manifold ◽  
The Impact

Abstract Flamelet Generated Manifold (FGM) has proven to be an efficient approach to model turbulent combustion across different regimes of combustion. The manifolds are generally created by solving laminar premixed or opposed flow configurations. Gas turbine combustors often involve many strong non-adiabatic events such as multiple temperature boundaries, quenching from cooling and effusion holes, conjugate heat transfer, soot radiation interaction, phase change from spray and the modulation of inlet conditions. The adiabatic assumption of the underlying flamelet generation in the FGM is, therefore, prone to errors in the prediction of flame speed, liner temperatures, and pollutant formation. In this work, a novel approach to generate fully non-adiabatic manifold is proposed and validated. The FGM manifold is created using a series of non-adiabatic flamelets, each flamelet is solved in one-dimensional physical space. The non-adiabatic flamelets are generated with an optimal combination of freely propagating and burner stabilized flames. This hybrid method of the flamelet configuration allows modeling large heat gain and loss without encountering any unrealistic temperature in the flamelet solution. Such fully non-adiabatic flamelets are then convoluted to generate a five-dimensional Non-adiabatic Flamelet Generated Manifold (NFGM) Probability Density Function (PDF.). The average properties such as temperature, mixture density, species concentration, rate of reaction, etc. from PDF are then coupled with the CFD solution. The non-adiabatic flamelets and corresponding NFGM is implemented into ANSYS Fluent software version 2020R1. This approach is validated first for canonical cases, followed by gas turbine like conditions of swirl stabilized methane fueled turbulent flame, developed at DLR Stuttgart as the PRECCINSTA combustor. The experimental data for this combustor is available for multiple operating conditions. A stable operating point (φ = 0.83, P = 30 kW) is chosen. The proposed nonadiabatic NFGM is used with Stress blended eddy simulation (SBES). The current NFGM-SBES results are compared with experimental data as well as the previously published works. The impact of modeling heat release in flamelet is used to analyze the M-shape versus V-shape flame transition and the peaks of the carbon monoxide in mixing shear layers. The findings from the current work, in terms of accuracy, validity and best practices while modeling NFGM-SBES are discussed and summarized. The improved results of NFGM compared to adiabatic FGM are encouraging and provides a potential high-fidelity tool for accurate, yet efficient modeling of turbulent combustion inside gas turbines.

Numerical and Experimental Analysis of the Temperature Distribution in a Hydrogen Fuelled Combustor for a 10 MW Gas Turbine

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Massimo Masi ◽  
Paolo Gobbato ◽  
Andrea Toffolo ◽  
Andrea Lazzaretto ◽  
Stefano Cocchi
Keyword(s):  
Temperature Distribution ◽  
Gas Turbine ◽  
High Performance ◽  
Turbine Blades ◽  
Steam Injection ◽  
Operating Conditions ◽  
Injection System ◽  
Reacting Flow ◽  
Cfd Model ◽  
Gas Turbine Combustors

Proper cooling of the hot components and an optimal temperature distribution at the turbine inlet are fundamental targets for gas turbine combustors. In particular, the temperature distribution at the combustor discharge is a critical issue for the durability of the turbine blades and the high performance of the engine. At present, CFD is a widely used tool to simulate the reacting flow inside gas turbine combustors. This paper presents a numerical analysis of a single can type combustor designed to be fed both with hydrogen and natural gas. The combustor also features a steam injection system to restrain the NOx pollutants. The simulations were carried out to quantify the effect of fuel type and steam injection on the temperature field. The CFD model employs a computationally low cost approach, thus the physical domain is meshed with a coarse grid. A full-scale test campaign was performed on the combustor: temperatures at the liner wall and the combustor outlet were acquired at different operating conditions. These experimental data, which are discussed, were used to evaluate the capability of the present CFD model to predict temperature values for combustor operation with different fuels and steam to fuel ratios.

The Use of Perforated Damping Liners in Aero Gas Turbine Combustion Systems

2011 ◽  
Author(s):  
Jochen Rupp ◽  
Jon Carrotte ◽  
Michael Macquisten
Keyword(s):  
Pressure Drop ◽  
Flow Field ◽  
Gas Turbine ◽  
Analytical Model ◽  
Operating Conditions ◽  
Acoustic Energy ◽  
Fuel Injector ◽  
Flame Tube ◽  
Gas Turbine Combustion ◽  
Combustion Systems

This paper considers the use of perforated porous liners for the absorption of acoustic energy within aero style gas turbine combustion systems. The overall combustion system pressure drop means that the porous liner (or ‘damping skin’) is typically combined with a metering skin. This enables most of the mean pressure drop, across the flame tube, to occur across the metering skin with the porous liner being exposed to a much smaller pressure drop. In this way porous liners can potentially be designed to provide significant levels of acoustic damping, but other requirements (e.g. cooling, available space envelope etc) must also be considered as part of this design process. A passive damper assembly was incorporated within an experimental isothermal facility that simulated an aero-engine style flame tube geometry. The damper was therefore exposed to the complex flow field present within an engine environment (e.g. swirling efflux from a fuel injector, coolant film passing across the damper surface etc.). In addition, plane acoustic waves were generated using loudspeakers so that the flow field was subjected to unsteady pressure fluctuations. This enabled the performance of the damper, in terms of its ability to absorb acoustic energy, to be evaluated. To complement the experimental investigation a simplified 1D analytical model was also developed and validated against the experimental results. In this way not only was the performance of the acoustic damper evaluated, but also the fundamental processes responsible for this measured performance could be identified. Furthermore the validated analytical model also enabled a wide range of damping geometry to be assessed for a range of operating conditions. In this way damper geometry can be optimized (e.g. for a given space envelope) whilst the onset of non-linear absorption (and hence the potential to ingest hot gas) can also be identified.

scholarly journals Canonical Validation of a Modeling Strategy for Carbon Monoxide Emissions in Staged Operation of Gas Turbine Combustors

2020 ◽  
Vol 4 ◽  
pp. 161-175
Author(s):  
Noah Klarmann ◽  
Thomas Sattelmayer
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Combustion Model ◽  
Gas Turbine Combustors ◽  
Partial Load ◽  
Study Results ◽  
Fuel Staging ◽  
Staged Operation ◽  
Modeling Strategy

Canonical validation of a holistic modeling strategy for the prediction of CO emissions in staged operation of gas turbine combustors is subject of this study. Results from various validation cases are presented. Focus is on operating conditions that can be considered typical for modern, flexible gas turbines that meet the requirements of the upcoming new energy age. Reducing load in gas turbines is usually achieved by redistributing fuel referred to as fuel staging. Fuel-staged operation may lead to various mechanism like strong interaction of the flame with secondary air leading to quenching and elevated CO emissions and is - due to technical relevance - stressed in this work. In the recent past, our group published a new modeling strategy for the precise prediction of heat release distributions as well as CO emissions. An extension to the CO modeling strategy that is of high relevance for the introduced validation cases is addressed by this work. The first part of this study presents relevant aspects of the overall modelling strategy. Furthermore, a validation of the models is shown to demonstrate the ability of precisely predicting CO in two different multi-burner cases. Both validation cases feature a silo combustion chamber with 37 burners. The burner groups are switched off at partial load leading to intense interactions between hot and cold burners. Major improvement in comparison to CO predictions from the flamelet-based combustion model can be achieved as the modeling strategy is demonstrated to be capable of predicting global CO emissions accurately. Furthermore, the model’s precision in fuel staging scenarios are demonstrated and discussed.

THE EFFECTS OF BURNING ALTERNATIVE LIQUID FUELS IN GAS TURBINE COMBUSTORS ON THE OVERALL OPERATING CONDITIONS AND PERFORMANCE

2015 ◽  
Author(s):  
Gabriela de Castro Almeida ◽  
Washington Orlando Irrazabal Bohorquez ◽  
Marco Aurélio da Cunha Alves
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Gas Turbine Combustors ◽  
And Performance

Lean Blowout Research in a Generic Gas Turbine Combustor With High Optical Access

1993 ◽  
Author(s):  
G. J. Sturgess ◽  
D. Shouse
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Air Force ◽  
Operating Conditions ◽  
Test Facility ◽  
Turbine Engines ◽  
Flame Stability ◽  
Gas Turbine Engines ◽  
Gas Turbine Combustor ◽  
Lean Blowout

The U.S. Air Force is conducting a comprehensive research program aimed at improving the design and analysis capabilities for flame stability and lean blowout in the combustors of aircraft gas turbine engines. As part of this program, a simplified version of a generic gas turbine combustor is used. The intent is to provide an experimental data base against which lean blowout modeling might be evaluated and calibrated. The design features of the combustor and its instrumentation are highlighted, and the test facility is described. Lean blowout results for gaseous propane fuel are presented over a range of operating conditions at three different dome flow splits. Comparison of results with those of a simplified research combustor is also made. Lean blowout behavior is complex, so that simple phenomenological correlations of experimental data will not be general enough for use as design tools.

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