Design of Acoustic Liner in Small Gas Turbine Combustor Using One-Dimensional Impedance Models

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Daesik Kim ◽  
Seungchai Jung ◽  
Heeho Park
Keyword(s):  
Gas Turbine ◽  
Side Wall ◽  
Acoustic Energy ◽  
Gas Turbine Combustor ◽  
Design Guideline ◽  
Acoustic Damping ◽  
Thermoacoustic Instabilities ◽  
Acoustic Dissipation ◽  
Acoustic Liner ◽  
Bias Flow

The side-wall cooling liner in a gas turbine combustor serves main purposes—heat transfer and emission control. Additionally, it functions as a passive damper to attenuate thermoacoustic instabilities. The perforations in the liner mainly convert acoustic energy into kinetic energy through vortex shedding at the orifice rims. In the previous decades, several analytical and semi-empirical models have been proposed to predict the acoustic damping of the perforated liner. In the current study, a few of the models are considered to embody the transfer matrix method (TMM) for analyzing the acoustic dissipation in a concentric tube resonator with a perforated element and validated against experimental data in the literature. All models are shown to quantitatively appropriately predict the acoustic behavior under high bias flow velocity conditions. Then, the models are applied to maximize the damping performance in a realistic gas turbine combustor, which is under development. It is found that the ratio of the bias flow Mach number to the porosity can be used as a design guideline in choosing the optimal combination of the number and diameter of perforations in terms of acoustic damping.

Acoustic Energy Balance During the Onset, Growth and Saturation of Thermoacoustic Instabilities

2020 ◽  
Author(s):  
R. Gaudron ◽  
D. Yang ◽  
A. S. Morgans
Keyword(s):  
Energy Balance ◽  
Network Models ◽  
Acoustic Energy ◽  
Dimensionless Numbers ◽  
Weakly Nonlinear ◽  
Acoustic Damping ◽  
Thermoacoustic Instabilities ◽  
Wide Range ◽  
Acoustic Absorption Coefficient ◽  
Flame Describing Function

Abstract Thermoacoustic instabilities can occur in a wide range of combustors and are prejudicial since they can lead to increased mechanical fatigue or even catastrophic failure. A well-established formalism to predict the onset, growth and saturation of such instabilities is based on acoustic network models. This approach has been successfully employed to predict the frequency and amplitude of limit cycle oscillations in a variety of combustors. However, it does not provide any physical insight in terms of the acoustic energy balance of the system. On the other hand, Rayleigh’s criterion may be used to quantify the losses, sources and transfers of acoustic energy within and at the boundaries of a combustor. However, this approach is cumbersome for most applications because it requires computing volume and surface integrals and averaging over an oscillation cycle. In this work, a new methodology for studying the acoustic energy balance of a combustor during the onset, growth and saturation of thermoacoustic instabilities is proposed. The two cornerstones of this new framework are the acoustic absorption coefficient Δ and the cycle-to-cycle acoustic energy ratio λ, both of which do not require computing integrals. Used along with a suitable acoustic network model, where the flame frequency response is described using the weakly nonlinear Flame Describing Function (FDF) formalism, these two dimensionless numbers are shown to characterize: 1) the variation of acoustic energy stored within the combustor between two consecutive cycles, 2) the acoustic energy transfers occurring at the combustor’s boundaries and 3) the sources and sinks of acoustic energy located within the combustor. The acoustic energy balance of the well-documented Palies burner is then analyzed during the onset, growth and saturation of thermoacoustic instabilities using this new methodology. It is demonstrated that this new approach allows a deeper understanding of the physical mechanisms at play. For instance, it is possible to determine when the flame acts as an acoustic energy source or sink, where acoustic damping is generated, and if acoustic energy is transmitted through the boundaries of the burner.

Comparison of Experimental and Numerical Results Concerning the Damping of Perforated Liners With Bias Flow

2008 ◽  
Author(s):  
Claus Heuwinkel ◽  
Lars Enghard ◽  
Ingo Ro¨hle ◽  
Bernd Mu¨hlbauer ◽  
Berthold Noll ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Collaborative Work ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Numerical Results ◽  
Stable Operation ◽  
Ambient Conditions ◽  
Thermoacoustic Instabilities ◽  
Bias Flow ◽  
Grazing Flow

Perforated liners with bias flow are integrated in the wall of gas turbine combustors to suppress thermoacoustic instabilities. The suppression of these unstable pressure oscillations is a requirement for the safe and stable operation of a gas turbine while applying new combustion concepts concerning more efficiency and cleanliness. Previous experiments have shown the high potential of perforated liners absorbing sound energy and therefore minimize combustion instabilities. In this collaborative work, the absorption properties of a liner are determined from both experimental measurements and numerical simulations. In both cases the analysis is based on acoustic pressure data recorded at several axial positions upstream and downstream of the liner. In the experiments this data is acquired by microphone measurements and in the simulation it is numerically calculated applying a three dimensional compressible URANS approach. The dissipation coefficient of the liner is identified for plane wave propagation at ambient conditions while a grazing flow is present in the duct. Parameters are the bias flow velocity and the amplitude of the incident sound wave. Comparing the results of the highly accurate experiments and the simulation reveals the abilities and limits of the numerical approach to model the absorption effect. The results are in very good agreement for the case without bias flow. However, the discrepancy between the experimental and numerical results is increasing while a bias flow is present.

scholarly journals NUMERICAL INVESTIGATION OF THE ACOUSTIC DAMPING OF PLANE ACOUSTIC WAVES BY PERFORATED LINERS WITH BIAS FLOW

2012 ◽  
Vol 19 ◽  
pp. 6-17
Author(s):  
DAN ZHAO ◽  
ZHI YUAN ZHONG
Keyword(s):  
Frequency Domain ◽  
Real Time ◽  
Acoustic Waves ◽  
Method Of Lines ◽  
Single Layer ◽  
Numerical Results ◽  
Domain Model ◽  
Acoustic Energy ◽  
Acoustic Damping ◽  
Bias Flow

Perforated liners are extensively used in aero-engines and gas turbine combustors to suppress combustion instabilities. These liners, typically subjected to a low Mach number bias flow (a cooling flow through perforated holes), are fitted along the bounding walls of a combustor to convert acoustic energy into flow energy by generating vorticity at the rims of the perforated apertures. To investigate the acoustic damping of such liners with bias flow on plane acoustic waves, a time-domain numerical model is developed to compute acoustic wave propagation in a cylindrical duct with a single-layer liner attached. The damping mechanism of the liner is characterized in real-time by using a 'compliance', developed especially for this work. It is a rational function representation of the frequency-domain homogeneous compliance adapted from the Rayleigh conductivity of a single aperture with mean bias flow in the z-domain. The liner 'compliance' model is then incorporated into partial differential equations of the duct system, which are solved by using the method of lines. The numerical results are then evaluated by comparing with the numerical results of Eldredge and Dowling's frequency-domain model. Good agreement is observed. This confirms that the model and the approach developed are suitable for real-time characterizing the acoustic damping of perforated liners.

Effect of Flow Pulsations in Premixed, Swirl Stabilized Combustor

2014 ◽  
Author(s):  
Aayush K. Sharma ◽  
Uddalok Sen ◽  
Pallab Sinha Mahapatra ◽  
Swarnendu Sen ◽  
Achintya Mukhopadhyay
Keyword(s):  
Numerical Model ◽  
Gas Turbine ◽  
Formation Rate ◽  
Combustion Process ◽  
Product Formation ◽  
Primary Objective ◽  
Gas Turbine Combustor ◽  
Ansys Fluent ◽  
Thermoacoustic Instabilities ◽  
Product Formation Rate

In the present work, a numerical model has been developed using ANSYS Fluent 14.5 to simulate the combustion phenomenon in a partially premixed, swirl-stabilized, LPG-fueled gas turbine combustor. In a practical gas turbine combustor, pulsations in the flow at the air side cannot be avoided which can lead to thermoacoustic instabilities. The primary objective of the study is to numerically analyze the effect of such pulsations on the fluid flow and combustion process inside the combustor. Different parameters like static temperature, progress variable and product formation rate are compared at the outlet plane of the combustor. The effect of change in the parameters like amplitude and frequency of the sinusoidal air flow input has also been investigated in the present study. It is observed that the solution changes from periodic to quasi-periodic at a higher amplitude condition. The numerical model was qualitatively validated against experiments performed on a laboratory-scale premixed, swirl-stabilized, gas turbine combustor.

scholarly journals Robust Gas Turbine Combustor with Acoustic Liner

2012 ◽  
Vol 7 (1) ◽  
pp. 199-210 ◽  
Author(s):  
Kazufumi IKEDA ◽  
Keisuke MATSUYAMA ◽  
Masaharu NISHIMURA
Keyword(s):  
Gas Turbine ◽  
Gas Turbine Combustor ◽  
Acoustic Liner

Initial Growth and Development of Thermoacoustic Instabilities in a Gas Turbine Combustor

2018 ◽  
Author(s):  
Timothy M. Wabel ◽  
Mitchell Passarelli ◽  
J.D. M. Cirtwill ◽  
Pankaj Saini ◽  
Adam M. Steinberg ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Growth And Development ◽  
Initial Growth ◽  
Gas Turbine Combustor ◽  
Thermoacoustic Instabilities

Effect of Cooling Liner on Acoustic Energy Absorption and Flame Response

2010 ◽  
Author(s):  
Umesh Bhayaraju ◽  
Johannes Schmidt ◽  
Karthik Kashinath ◽  
Simone Hochgreb
Keyword(s):  
Transfer Function ◽  
Heat Release ◽  
Acoustic Waves ◽  
Bluff Body ◽  
Acoustic Energy ◽  
Combustion Instabilities ◽  
Acoustic Damping ◽  
Lean Combustion ◽  
Bias Flow ◽  
Flame Response

Gas turbine combustors with lean combustion injectors are prone to thermo-acoustic/combustion instabilities. Several passive techniques have been developed to control combustion instabilities, such as using Helmholtz resonators or viscous dampers using perforated liners that have potential for broadband acoustic damping. In this paper the role of single-walled cooling liners is considered in the damping of acoustic waves and on the flame transfer function in a sample bluff-body burner. Three liner geometries are considered: no bias flow (solid liner), normal effusion holes, and grazing effusion holes at 25° inclination. Cold flow experiments with speaker forcing are carried out to characterise the absorption properties of the liner and compared with an acoustic network model. The results show that whereas the bulk of the acoustic losses is due to the vortex recirculation zones, the liners contribute significantly to the absorption over a wide area of the frequency range. The flame transfer function gain is measured as a function of bias flow for a given operating condition of the burner. The experiments show that for the geometry considered, the global flame transfer function is little affected by cooling except in the case of the normal flow holes. Further analysis shows that whereas the total flame transfer function is not affected, the flame heat release becomes more spatially distributed along the axial length, and a 1D flame response shows distinct modes corresponding to the modal heat release locations.

Sign in / Sign up

Export Citation Format

Share Document