Active Control of Fuel Splits in Gas Turbine DLE Combustion Systems

2007 ◽  
Author(s):  
Ghenadie Bulat ◽  
Dorian Skipper ◽  
Robin McMillan ◽  
Khawar Syed
Keyword(s):  
Gas Turbine ◽  
Active Control ◽  
Control Algorithm ◽  
Pressure Fluctuations ◽  
Stability Limit ◽  
Operating Conditions ◽  
Direct Result ◽  
Operational Parameter ◽  
Engine Operation ◽  
The Impact

This paper presents a system for the active control of the fuel split within a two-stream Dry Low Emissions (DLE) gas turbine. The system adjusts the fuel split based upon the amplitude of combustor pressure fluctuations and burner metal temperature. The active control system, its implementation and its performance during engine tests on Siemens SGT-200 is described. The paper describes the active fuel split control algorithm. Engine test results are then presented for steady and transient loads with different rates of change of the engine operation temperature, including rapid load acceptance and load shedding. Additionally, cycling operating conditions were tested to evaluate the performance of the algorithm in typical island mode and mechanical drive applications. The active control algorithm was successful in providing stable and reliable control of the turbine allowing very low emissions levels to be attained without manual intervention. In fact it allows areas to be reached that until now were excluded. The impact of operational parameter changes (e.g. load change, ambient temperature, fuel composition etc.) on the engine operability proved the active control software’s ability to respond seamlessly. In addition, it prevented flameout and/or high pressure fluctuation while keeping burner temperatures within limits. Recorded emissions showed a reduction in NOx was achieved when the fuel split was controlled by the algorithm compared to standard operation. This was a direct result of the algorithm successfully identifying the lean stability limit and operating close to it.

scholarly journals Massively Parallel Large Eddy Simulation of Rotating Turbomachinery for Variable Speed Gas Turbine Engine Operation

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 703
Author(s):  
Nishan Jain ◽  
Luis Bravo ◽  
Dokyun Kim ◽  
Muthuvel Murugan ◽  
Anindya Ghoshal ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Large Scale ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Massively Parallel ◽  
Rotor Speed ◽  
Tip Leakage Flow ◽  
Engine Operation ◽  
Large Eddy ◽  
The Impact

Gas turbine engines are required to operate at both design and off-design conditions that can lead to strongly unsteady flow-fields and aerodynamic losses severely impacting performance. Addressing this problem requires effective use of computational fluid dynamics tools and emerging models that resolve the large scale fields in detail while accurately modeling the under-resolved scale dynamics. The objective of the current study is to conduct massively parallel large eddy simulations (LES) of rotating turbomachinery that handle the near-wall dynamics using accurate wall models at relevant operating conditions. The finite volume compressible CharLES solver was employed to conduct the simulations over moving grids generated through Voronoi-based unstructured cells. A grid sensitivity analysis was carried out first to establish reliable parameters and assess the quality of the results. LES simulations were then conducted to understand the impact of blade tip clearance and operating conditions on the stage performance. Variations in tip clearance of 3% and 16% chord were considered in the analysis. Other design points included operation at 100% rotor speed and off-design conditions at 75% and 50% of the rotor speed. The simulation results showed that the adiabatic efficiency improves dramatically with reduction in tip gap due to the decrease in tip leakage flow and the resulting flow structures. The analysis also showed that the internal flow becomes highly unsteady, undergoing massive separation, as the rotor speed deviates from the design point. This study demonstrates the capability of the framework to simulate highly turbulent unsteady flows in a rotating turbomachinery environment. The results provide much needed insight and massive data to investigate novel design concepts for the US Army Future Vertical Lift program.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

Uncertainty Analysis of Inflow Conditions on an HPT Gas Turbine Nozzle: Effect on Particle Deposition

2020 ◽  
Author(s):  
R. Friso ◽  
N. Casari ◽  
M. Pinelli ◽  
A. Suman ◽  
F. Montomoli
Keyword(s):  
Gas Turbine ◽  
Energy Efficient ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Operating Conditions ◽  
Wide Range ◽  
And Performance ◽  
Gas Turbine Nozzle ◽  
The Impact ◽  
Inflow Conditions

Abstract Gas turbines (GT) are often forced to operate in harsh environmental conditions. Therefore, the presence of particles in their flow-path is expected. With this regard, deposition is a problem that severely affects gas turbine operation. Components’ lifetime and performance can dramatically vary as a consequence of this phenomenon. Unfortunately, the operating conditions of the machine can vary in a wide range, and they cannot be treated as deterministic. Their stochastic variations greatly affect the forecasting of life and performance of the components. In this work, the main parameters considered affected by the uncertainty are the circumferential hot core location and the turbulence level at the inlet of the domain. A stochastic analysis is used to predict the degradation of a high-pressure-turbine (HPT) nozzle due to particulate ingestion. The GT’s component analyzed as a reference is the HPT nozzle of the Energy-Efficient Engine (E3). The uncertainty quantification technique used is the probabilistic collocation method (PCM). This work shows the impact of the operating conditions uncertainties on the performance and lifetime reduction due to deposition. Sobol indices are used to identify the most important parameter and its contribution to life. The present analysis enables to build confidence intervals on the deposit profile and on the residual creep-life of the vane.

Impact of Impeller Casing Treatment on the Acoustics of a Small High Speed Centrifugal Compressor

2018 ◽  
Author(s):  
Sidharath Sharma ◽  
Jorge García-Tíscar ◽  
John M. Allport ◽  
Martyn L. Jupp ◽  
Ambrose K. Nickson
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Fluctuations ◽  
Operating Conditions ◽  
Aerodynamic Noise ◽  
Noise Sources ◽  
Casing Treatment ◽  
Active Research ◽  
Ported Shroud ◽  
The Impact

Ported shroud casing treatment is widely used to delay the onset of surge and thereby enhancing the aerodynamic stability of a centrifugal compressor by recirculating the low momentum fluid in the blade passage. Performance losses associated with the use of recirculation casing treatment are well established in the literature and this is an area of active research. The other, less researched aspect of the casing treatment is its impact on the acoustics of the compressor. This work investigates the impact of ported shroud casing treatment on the acoustic characteristics of the compressor. The flow in two compressor configurations viz. with and without casing treatment operating at the design operating conditions of an iso-speed line are numerically modelled and validated with experimental data from gas stand measurements. The pressure fluctuations calculated as the flow solution are used to compute the spectral signatures at multiple locations to investigate the acoustic phenomenon associated with each configuration. Propagation of the frequency content through the ducts has been estimated with the aid of method of characteristics to enhance the content coming from the compressor. Expected tonal aerodynamic noise sources such as monopole (buzz-saw tones) and dipole (Blade Pass Frequency) are clearly identified in the acoustic spectra of the two configurations. The comparison of two configurations shows higher overall levels and tonal content in the case of a compressor with ported shroud operating at design conditions due to the presence of ‘mid-tones’.

Demonstration of Active Control of Combustion Instabilities on a Full-Scale Gas Turbine Combustor

2001 ◽  
Author(s):  
C. E. Johnson ◽  
Y. Neumeier ◽  
M. Neumaier ◽  
B. T. Zinn ◽  
D. D. Darling ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Active Control ◽  
Fast Response ◽  
Dominant Mode ◽  
Broadband Noise ◽  
Full Scale ◽  
Operating Conditions ◽  
Combustion Instabilities ◽  
Gas Turbine Combustor ◽  
Airflow Distribution

This paper presents the results of an investigation of active control of combustion instabilities in a natural gas, high-pressure, full-scale gas turbine combustor that was retrofitted with an Active Control System (ACS). The combustor test rig simulates the geometry, inlet airflow distribution, and pressurization of a can-type combustor that exhibits dynamic flame instabilities at some off-design operating conditions. Two essential features of the investigated ACS are 1) a real-time mode observer that identified the frequencies, amplitudes and phases of the dominant modes in the pressure signal and 2) a fast response servo valve that can modulate a large portion of the gaseous fuel. Two active control configurations were studied. In the first configuration, the actuator was mounted on one of two premixed fuel stages, and in the second configuration it was mounted on the inlet to the stabilizing diffusion stage. In both configurations, the ACS damped combustion instabilities, attenuating the dominant mode by up to 15dB and reducing the overall broadband noise by 30-40%. NOx emissions were also reduced by approximately 10% when control was applied. Finally, this study demonstrated the importance of having a fast multiple-mode observer when dealing with complex combustion processes with inherently large time delays.

scholarly journals Darmstadt Rotor No. 2, II: Design of Leaning Rotor Blades

2003 ◽  
Vol 9 (6) ◽  
pp. 385-391
Author(s):  
Jörg Bergner ◽  
Dietmar K. Hennecke ◽  
Martin Hoeger ◽  
Karl Engel
Keyword(s):  
Mechanical Stability ◽  
Three Dimensional ◽  
Stability Limit ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Structural Constraints ◽  
Transonic Compressor ◽  
Aero Engines ◽  
The Impact

For Darmstadt University of Technology's axial singlestage transonic compressor rig, a new three-dimensional aft-swept rotor was designed and manufactured at MTU Aero Engines in Munich, Germany. The application of carbon fiber–reinforced plastic made it possible to overcome structural constraints and therefore to further increase the amount of lean and sweep of the blade. The aim of the design was to improve the mechanical stability at operation that is close to stall.To avoid the hazard of rubbing at the blade tip, which is found especially at off-design operating conditions close to the stability limit of the compression system, aft-sweep was introduced together with excessive backward lean.This article reports an investigation of the impact of various amounts of lean on the aerodynamic behavior of the compressor stage on the basis of steady-state Navier-Stokes simulations. The results indicate that high backward lean promotes an undesirable redistribution of mass flow and gives rise to a basic change in the shock pattern, whereas a forward-leaning geometry results in the development of a highly back-swept shock front. However, the disadvantage is a decrease in shock strength and efficiency.

On Compressor Station Layout

2003 ◽  
Author(s):  
Rainer Kurz ◽  
Sebouh Ohanian ◽  
Matt Lubomirsky
Keyword(s):  
Gas Turbine ◽  
Electric Motor ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
General Context ◽  
Operational Flexibility ◽  
Gas Engine ◽  
Wide Range ◽  
The Individual ◽  
The Impact

This paper discusses issues that influence the decision on the arrangement of compressors and the type of equipment in gas pipeline compressor stations. Different concepts such as multiple small units versus single large units are considered, both regarding their impact on the individual station and the overall pipeline. The necessity of standby units is discussed. Various concepts for drivers (gas turbine, gas motor and electric motor) and compressors (centrifugal and reciprocating) are analyzed. The importance of considering all possible operating conditions is stressed. With the wide range of possible operating conditions for the pipeline in mind, the discussion will be brought into the general context of operational flexibility, availability, reliability, installation issues, remote control, and operability of gas turbine driven centrifugal compressors compared to other solutions such as electric motor driven compressors or gas engine driven reciprocating compressors. The impact of different concepts on emissions and fuel cost is discussed. Among the assumptions in this paper are the performance characteristics of the compressor. It will be outlined how these performance characteristics influence the conclusions.

scholarly journals Industrial Gas Turbine Performance: Compressor Fouling and On-Line Washing

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Uyioghosa Igie ◽  
Pericles Pilidis ◽  
Dimitrios Fouflias ◽  
Kenneth Ramsden ◽  
Panagiotis Laskaridis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Operating Conditions ◽  
Compressor Cascade ◽  
Compressor Blades ◽  
Turbine Performance ◽  
Industrial Gas Turbines ◽  
On Line ◽  
The Impact

Industrial gas turbines are susceptible to compressor fouling, which is the deposition and accretion of airborne particles or contaminants on the compressor blades. This paper demonstrates the blade aerodynamic effects of fouling through experimental compressor cascade tests and the accompanied engine performance degradation using turbomatch, an in-house gas turbine performance software. Similarly, on-line compressor washing is implemented taking into account typical operating conditions comparable with industry high pressure washing. The fouling study shows the changes in the individual stage maps of the compressor in this condition, the impact of degradation during part-load, influence of control variables, and the identification of key parameters to ascertain fouling levels. Applying demineralized water for 10 min, with a liquid-to-air ratio of 0.2%, the aerodynamic performance of the blade is shown to improve, however most of the cleaning effect occurred in the first 5 min. The most effectively washed part of the blade was the pressure side, in which most of the particles deposited during the accelerated fouling. The simulation of fouled and washed engine conditions indicates 30% recovery of the lost power due to washing.

Some Aspects of Modelling Compressor Behavior in Gas Turbine Performance Calculations

2000 ◽  
Author(s):  
Claus Riegler ◽  
Michael Bauer ◽  
Joachim Kurzke
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Order Effects ◽  
Specific Work ◽  
Performance Modelling ◽  
Engine Operation ◽  
Turbine Performance ◽  
Major Interest ◽  
Compressor Map ◽  
Bypass Ratio

Performance calculation procedures for gas turbine engines are usually based on the performance characteristics of the engine components, and especially the turbo components are of major interest. In this paper methods of modelling compressors in gas turbine performance calculations are discussed. The basic methodologies based on Mach number similarity are summarized briefly including some second order effects. Under extreme enginepartload conditions, as for example subidle or windmilling, the operating points in the compressor map are located in a region which is usually not covered by rig tests. In addition the parameters usually used in compressor maps are no longer appropriate. For these operating conditions a method is presented to extrapolate compressor maps towards very low spool speed down to the locked rotor. Instead of the efficiency more appropriate parameters as for example specific work or specific torque are suggested. A compressor map prepared with the proposed methods is presented and discussed. As another relevant topic the performance modelling of fans for low bypass ratio turbofans is covered. Due to the flow splitter downstream of such a fan the core and bypass stream may be throttled independently during engine operation and bypass ratio becomes a third independent parameter in the map. Because testing a fan on the rig for various bypass ratios is a very costly task, a simplified method has been developed which accounts for the effects of bypass ratio.

Application of Active Combustion Instability Control to a Heavy Duty Gas Turbine

1998 ◽  
Vol 120 (4) ◽  
pp. 721-726 ◽  
Author(s):  
J. R. Seume ◽  
N. Vortmeyer ◽  
W. Krause ◽  
J. Hermann ◽  
C.-C. Hantschk ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Instability ◽  
Pressure Fluctuations ◽  
Preventive Measure ◽  
Feedback System ◽  
Operating Conditions ◽  
Combustion Instabilities ◽  
Instability Control ◽  
Heavy Duty Gas Turbine

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 percent. 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.

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