Flame Transfer Function Measurement and Instability Frequency Prediction Using a Thermoacoustic Model

2009 ◽  
Author(s):  
Kyu Tae Kim ◽  
Hyung Ju Lee ◽  
Jong Guen Lee ◽  
Bryan D. Quay ◽  
Domenic Santavicca
Keyword(s):  
Transfer Function ◽  
Gas Turbine ◽  
Critical Role ◽  
Flame Length ◽  
Operating Conditions ◽  
Gas Turbine Combustor ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Turbulent Premixed Flame ◽  
Instability Frequency

The dynamic response of a turbulent premixed flame to an acoustic velocity perturbation was experimentally determined in a lean-premixed, swirl-stabilized, lab-scale gas turbine combustor. Fuel was injected far upstream of a choked inlet to eliminate equivalence ratio oscillations. A siren-type modulation device was used to provide acoustic perturbations at the forcing frequency of 100 ∼ 400 Hz. To measure global heat release rate, OH*, CH*, and CO2* chemiluminescence emissions were used. The two-microphone method was utilized to estimate inlet velocity fluctuations, and it was calibrated by direct measurements using a hot wire anemometer under cold-flow conditions. Gain of the flame transfer function (FTF) shows a low pass filter behavior, and it is well-fitted by a second-order model. Phase difference increases quasi-linearly with the forcing frequency. Using the n-τ formulation, gain and phase of FTF were incorporated into an analytic thermoacoustic model in order to predict instability frequencies and corresponding modal structures. Self-excited flame response measurements were also performed to verify eigenfrequencies predicted by the thermoacoustic model. Instability frequency predicted by the thermoacoustic model is supported by experimental results. Two instability frequency bands were measured in the investigated gas turbine combustor at all operating conditions: f ∼ 220 Hz and f ∼ 350 Hz. Results show that the self-excited instability frequency of f ∼ 220 Hz results from the fact that the flames amplify flow perturbations with f = 150 ∼ 250 Hz. This frequency range was observed in the flame transfer function measurements. The other instability frequency of f ∼ 350 Hz occurs because the whole combustion system has an eigenfrequency corresponding to the 1/4-wave eigenmode of the mixing section. This was analytically and experimentally demonstrated. Results also show that the flame length, LCH*max, plays a critical role in determining self-induced instability frequency.

Characterization of Forced Flame Response of Swirl-Stabilized Turbulent Lean-Premixed Flames in a Gas Turbine Combustor

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Kyu Tae Kim ◽  
Jong Guen Lee ◽  
Hyung Ju Lee ◽  
Bryan D. Quay ◽  
Domenic A. Santavicca
Keyword(s):  
Transfer Function ◽  
Natural Gas ◽  
Gas Turbine ◽  
Strouhal Number ◽  
Premixed Flames ◽  
Flame Length ◽  
Gas Turbine Combustor ◽  
Flame Response ◽  
Flame Shape ◽  
Flame Angle

Flame transfer function measurements of turbulent premixed flames are made in a model lean-premixed, swirl-stabilized, gas turbine combustor. OH∗, CH∗, and CO2∗ chemiluminescence emissions are measured to determine heat release oscillation from a whole flame, and the two-microphone technique is used to measure inlet velocity fluctuation. 2D CH∗ chemiluminescence imaging is used to characterize the flame shape: the flame length (LCH∗ max) and flame angle (α). Using H2-natural gas composite fuels, XH2=0.00–0.60, a very short flame is obtained and hydrogen enrichment of natural gas is found to have a significant impact on the flame structure and flame attachment points. For a pure natural gas flame, the flames exhibit a “V” structure, whereas H2-enriched natural gas flames have an “M” structure. Results show that the gain of M flames is much smaller than that of V flames. Similar to results of analytic and experimental investigations on the flame transfer function of laminar premixed flames, it shows that the dynamics of a turbulent premixed flame is governed by three relevant parameters: the Strouhal number (St=LCH∗ max/Lconv), the flame length (LCH∗ max), and the flame angle (α). Two flames with the same flame shape exhibit very similar forced responses, regardless of their inlet flow conditions. This is significant because the forced flame response of a highly turbulent, practical gas turbine combustor can be quantitatively generalized using the nondimensional parameters, which collapse all relevant input conditions into the flame shape and the Strouhal number.

Characterization of Forced Flame Response of Swirl-Stabilized Turbulent Lean-Premixed Flames in a Gas Turbine Combustor

2009 ◽  
Author(s):  
Kyu Tae Kim ◽  
Jong Guen Lee ◽  
Hyung Ju Lee ◽  
Bryan D. Quay ◽  
Domenic Santavicca
Keyword(s):  
Transfer Function ◽  
Natural Gas ◽  
Gas Turbine ◽  
Strouhal Number ◽  
Premixed Flames ◽  
Flame Length ◽  
Gas Turbine Combustor ◽  
Flame Response ◽  
Flame Shape ◽  
Flame Angle

Flame transfer function measurements of turbulent premixed flames were made in a model lean premixed, swirl-stabilized, gas turbine combustor. OH*, CH*, and CO2* chemiluminescence emissions were measured to determine heat release oscillation from a whole flame, and the two-microphone technique was used to measure inlet velocity fluctuation. 2-D CH* chemiluminescence imaging was used to characterize the flame shape: the flame length (LCH* max) and flame angle (α). Using H2-natural gas composite fuels, XH2 = 0.00 ∼ 0.60, very short flame was obtained and hydrogen enrichment of natural gas had a significant impact on the flame structure and flame attachment points. For a pure natural gas flame, the flames exhibit a “V” structure, whereas H2-enriched natural gas flames have an “M” structure. Results show that the gain of “M” flames is much smaller than that of “V” flames. Similar to results of analytic and experimental investigations on the flame transfer function of laminar premixed flames, it shows that the dynamics of a turbulent premixed flame is governed by three relevant parameters: the Strouhal number (St = LCH* max / Lconv), the flame length (LCH* max), and the flame angle (α). Two flames with the same flame shape exhibit very similar forced responses, regardless of their inlet flow conditions. This is significant because the forced flame response of a highly turbulent, practical gas turbine combustor can be quantitatively generalized using the non-dimensional parameters which collapse all relevant input conditions into the flame shape and the Strouhal number.

ANALYSIS AND IMPROVEMENT TECHNIQUES FOR THE TRANSFER FUNCTION OF A PLANAR LOW - PASS FILTER

2016 ◽  
Vol 15 (12) ◽  
pp. 2579-2586
Author(s):  
Adina Racasan ◽  
Calin Munteanu ◽  
Vasile Topa ◽  
Claudia Pacurar ◽  
Claudia Hebedean
Keyword(s):  
Transfer Function ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass

scholarly journals IpDFT-Tuned Estimation Algorithms for PMUs: Overview and Performance Comparison

2021 ◽  
Vol 11 (5) ◽  
pp. 2318
Author(s):  
David Macii ◽  
Daniel Belega ◽  
Dario Petri
Keyword(s):  
Weighted Least Squares ◽  
Performance Comparison ◽  
Rate Of Change ◽  
Parameters Estimation ◽  
Operating Conditions ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Estimation Algorithms ◽  
Class Testing ◽  
Low Pass

The Interpolated Discrete Fourier Transform (IpDFT) is one of the most popular algorithms for Phasor Measurement Units (PMUs), due to its quite low computational complexity and its good accuracy in various operating conditions. However, the basic IpDFT algorithm can be used also as a preliminary estimator of the amplitude, phase, frequency and rate of change of frequency of voltage or current AC waveforms at times synchronized to the Universal Coordinated Time (UTC). Indeed, another cascaded algorithm can be used to refine the waveform parameters estimation. In this context, the main novelty of this work is a fair and extensive performance comparison of three different state-of-the-art IpDFT-tuned estimation algorithms for PMUs. The three algorithms are: (i) the so-called corrected IpDFT (IpDFTc), which is conceived to compensate for the effect of both the image of the fundamental tone and second-order harmonic; (ii) a frequency-tuned version of the Taylor Weighted Least-Squares (TWLS) algorithm, and (iii) the frequency Down-Conversion and low-pass Filtering (DCF) technique described also in the IEEE/IEC Standard 60255-118-1:2018. The simulation results obtained in the P Class and M Class testing conditions specified in the same Standard show that the IpDFTc algorithm is generally preferable under the effect of steady-state disturbances. On the contrary, the tuned TWLS estimator is usually the best solution when dynamic changes of amplitude, phase or frequency occur. In transient conditions (i.e., under the effect of amplitude or phase steps), the IpDFTc and the tuned TWLS algorithms do not clearly outperform one another. The DCF approach generally returns the worst results. However, its actual performances heavily depend on the adopted low-pass filter.

Combustion Characteristics of Small Size Gas Turbine Combustor Fueled by Biomass Gas Employing Flameless Combustion

2007 ◽  
Author(s):  
Masato Hiramatsu ◽  
Yoshifumi Nakashima ◽  
Sadamasa Adachi ◽  
Yudai Yamasaki ◽  
Shigehiko Kaneko
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Flameless Combustion ◽  
Engine Exhaust ◽  
Micro Gas Turbine

One approach to achieving 99% combustion efficiency (C.E.) and 10 ppmV or lower NOx (at 15%O2) in a micro gas turbine (MGT) combustor fueled by biomass gas at a variety of operating conditions is with the use of flameless combustion (FLC). This paper compares experimentally obtained results and CHEMKIN analysis conducted for the developed combustor. As a result, increase the number of stage of FLC combustion enlarges the MGT operation range with low-NOx emissions and high-C.E. The composition of fuel has a small effect on the characteristics of ignition in FLC. In addition, NOx in the engine exhaust is reduced by higher levels of CO2 in the fuel.

Towards Improved Prediction of Aero-Engine Combustor Performance Using Large Eddy Simulations

2008 ◽  
Author(s):  
S. James ◽  
M. S. Anand ◽  
B. Sekar
Keyword(s):  
Gas Turbine ◽  
Radial Profile ◽  
Design Tool ◽  
Operating Conditions ◽  
Outlet Temperature ◽  
Gas Turbine Combustor ◽  
Systematic Assessment ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Aero Engine

The paper presents an assessment of large eddy simulation (LES) and conventional Reynolds averaged methods (RANS) for predicting aero-engine gas turbine combustor performance. The performance characteristic that is examined in detail is the radial burner outlet temperature (BOT) or fuel-air ratio profile. Several different combustor configurations, with variations in airflows, geometries, hole patterns and operating conditions are analyzed with both LES and RANS methods. It is seen that LES consistently produces a better match to radial profile as compared to RANS. To assess the predictive capability of LES as a design tool, pretest predictions of radial profile for a combustor configuration are also presented. Overall, the work presented indicates that LES is a more accurate tool and can be used with confidence to guide combustor design. This work is the first systematic assessment of LES versus RANS on industry-relevant aero-engine gas turbine combustors.

Towards the Multiobjective Optimisation of Gas Turbine Combustors

2006 ◽  
Author(s):  
S. G. Wyse ◽  
G. T. Parks ◽  
R. S. Cant
Keyword(s):  
Transfer Function ◽  
Tabu Search ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Design Space ◽  
Objective Functions ◽  
Multiobjective Optimisation ◽  
Gas Turbine Combustor ◽  
Linear Network ◽  
Good Design

Gas turbine combustor design entails multiple, and often contradictory, requirements for the designer to consider. Multiobjective optimisation on a low-fidelity linear-network-based code is suggested as a way of investigating the design space. The ability of the Tabu Search optimiser to minimise NOx and CO, as well as several acoustic objective functions, is investigated, and the resulting “good” design vectors presented. An analysis of the importance of the flame transfer function in the model is also given. The mass flow and the combustion chamber width and area are shown to be very important. The length of the plenum and the widths of the plenum exit and combustor exit also influence the design space.

scholarly journals Study of modular transfer function-based optieal low-pass filter evaluation model and experiment

2008 ◽  
Vol 57 (5) ◽  
pp. 2854
Author(s):  
Qi Xun-Jun ◽  
Lin Bin ◽  
Cao Xiang-Qun ◽  
Chen Yu-Qing
Keyword(s):  
Transfer Function ◽  
Evaluation Model ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass

Measurement of Flame Frequency Response Functions Under Exhaust Gas Recirculation Conditions

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Joseph Ranalli ◽  
Don Ferguson
Keyword(s):  
Transfer Function ◽  
Carbon Capture ◽  
Transfer Functions ◽  
Combustion Process ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Flame Response ◽  
Gas Recirculation

Exhaust gas recirculation has been proposed as a potential strategy for reducing the cost and efficiency penalty associated with postcombustion carbon capture. However, this approach may cause as-yet unresolved effects on the combustion process, including additional potential for the occurrence of thermoacoustic instabilities. Flame dynamics, characterized by the flame transfer function, were measured in traditional swirl stabilized and low-swirl injector combustor configurations, subject to exhaust gas circulation simulated by N2 and CO2 dilution. The flame transfer functions exhibited behavior consistent with a low-pass filter and showed phase dominated by delay. Flame transfer function frequencies were nondimensionalized using Strouhal number to highlight the convective nature of this delay. Dilution was observed to influence the dynamics primarily through its role in changing the size of the flame, indicating that it plays a similar role in determining the dynamics as changes in the equivalence ratio. Notchlike features in the flame transfer function were shown to be related to interference behaviors associated with the convective nature of the flame response. Some similarities between the two stabilization configurations proved limiting and generalization of the physical behaviors will require additional investigation.

Experimental and numerical study of flame structure and emissions in a micro gas turbine combustor

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Vedant Dwivedi ◽  
Srikanth Hari ◽  
S. M. Kumaran ◽  
B. V. S. S. S. Prasad ◽  
Vasudevan Raghavan
Keyword(s):  
Gas Turbine ◽  
Rural Areas ◽  
Gas Turbines ◽  
Alternative Fuels ◽  
Numerical Study ◽  
Operating Conditions ◽  
Emission Characteristics ◽  
Nitric Oxides ◽  
Gas Turbine Combustor ◽  
Micro Gas Turbine

Abstract Experimental and numerical study of flame and emission characteristics in a tubular micro gas turbine combustor is reported. Micro gas turbines are used for distributed power (DP) generation using alternative fuels in rural areas. The combustion and emission characteristics from the combustor have to be studied for proper design using different fuel types. In this study methane, representing fossil natural gas, and biogas, a renewable fuel that is a mixture of methane and carbon-dioxide, are used. Primary air flow (with swirl component) and secondary aeration have been varied. Experiments have been conducted to measure the exit temperatures. Turbulent reactive flow model is used to simulate the methane and biogas flames. Numerical results are validated against the experimental data. Parametric studies to reveal the effects of primary flow, secondary flow and swirl have been conducted and results are systematically presented. An analysis of nitric-oxides emission for different fuels and operating conditions has been presented subsequently.

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