Acoustic Sensitivities of Lean-Premixed Fuel Injectors in a Single Nozzle Rig

1999 ◽  
Vol 121 (3) ◽  
pp. 429-436 ◽  
Author(s):  
D. W. Kendrick ◽  
T. J. Anderson ◽  
W. A. Sowa ◽  
T. S. Snyder
Keyword(s):  
Mach Number ◽  
Bluff Body ◽  
Dynamical Behavior ◽  
Flame Stabilization ◽  
Acoustic Characteristics ◽  
Turbine Engine ◽  
Fuel Injectors ◽  
Acoustic Coupling ◽  
Lean Premixed ◽  
Exit Mach Number

An experimental and numerical investigation into the attenuation of combustion induced pressure oscillations in a single nozzle rig was undertaken at the United Technologies Research Center. Results from these investigations indicated a high combustor exit Mach number, similar to that used in a gas turbine engine, was required to correctly simulate the combustor dynamics and evaluate acoustic characteristics of lean premixed fuel injectors. Comparisons made between aerodynamically stabilized and bluff-body stabilized nozzles and the use of premixed and diffusion pilots showed that small levels of diffusion piloting behind a bluff-body yielded the best acoustic/emission performance. Their success is due to increased flame stabilization (superior anchoring ability), which reduced flame motion and thermal/acoustic coupling. For cases where diffusion piloting was not present, both designs exhibited similar dynamical behavior. Increases in the combustor exit Mach number and reductions in the inlet air temperature were shown to degrade acoustic performance of both nozzle designs. The bluff-body configuration with small levels of diffusion piloting, however, was found to be less sensitive to these changes when compared to its aerodynamic counterpart.

scholarly journals Acoustic Sensitivities of Lean-Premixed Fuel Injectors in a Single Nozzle Rig

1998 ◽  
Author(s):  
Donald W. Kendrick ◽  
Torger J. Anderson ◽  
William A. Sowa ◽  
Timothy S. Snyder
Keyword(s):  
Mach Number ◽  
Bluff Body ◽  
Dynamical Behavior ◽  
Flame Stabilization ◽  
Acoustic Characteristics ◽  
Turbine Engine ◽  
Fuel Injectors ◽  
Acoustic Coupling ◽  
Lean Premixed ◽  
Exit Mach Number

An experimental and numerical investigation into the attenuation of combustion induced pressure oscillations in a single nozzle rig was undertaken at the United Technologies Research Center. Results from these investigations indicated a high combustor exit Mach number, similar to that used in a gas turbine engine, was required to correctly simulate the combustor dynamics and evaluate acoustic characteristics of lean premixed fuel injectors. Comparisons made between aerodynamically stabilized and bluff-body stabilized nozzles and the use of premixed and diffusion pilots showed that small levels of diffusion piloting behind a bluff-body yielded the best acoustic/emission performance. Their success is due to increased flame stabilization (superior anchoring ability) which reduced flame motion and thermal/acoustic coupling. For cases where diffusion piloting was not present, both designs exhibited similar dynamical behavior. Increases in the combustor exit Mach number and reductions in the inlet air temperature were shown to degrade acoustic performance of both nozzle designs. The bluff-body configuration with small levels of diffusion piloting, however, was found to be less sensitive to these changes when compared to its aerodynamic counterpart.

scholarly journals Dynamics of lean premixed flames stabilized on a meso-scale bluff-body in an unconfined flow field

2018 ◽  
Vol 13 (6) ◽  
pp. 48 ◽  
Author(s):  
Yu Jeong Kim ◽  
Bok Jik Lee ◽  
Hong G. Im
Keyword(s):  
Bluff Body ◽  
Proper Time ◽  
Premixed Flames ◽  
Narrow Channel ◽  
Flame Stabilization ◽  
Inflow Velocity ◽  
Lean Premixed Flames ◽  
Lean Premixed ◽  
The Mean ◽  
Meso Scale

Two-dimensional direct numerical simulations were conducted to investigate the dynamics of lean premixed flames stabilized on a meso-scale bluff-body in hydrogen-air and syngas-air mixtures. To eliminate the flow confinement effect due to the narrow channel, a larger domain size at twenty times the bluff-body dimension was used in the new simulations. Flame/flow dynamics were examined as the mean inflow velocity is incrementally raised until blow-off occurs. As the mean inflow velocity is increased, several distinct modes in the flame shape and fluctuation patterns were observed. In contrast to our previous study with a narrow channel, the onset of local extinction was observed during the asymmetric vortex shedding mode. Consequently, the flame stabilization and blow-off behavior was found to be dictated by the combined effects of the hot product gas pocket entrained into the extinction zone and the ability to auto-ignite the mixture within the given residence time corresponding to the lateral flame fluctuations. A proper time scale analysis is attempted to characterize the flame blow-off mechanism, which turns out to be consistent with the classic theory of Zukoski and Marble.

Effect of hydrogen enrichment on swirl/bluff-body lean premixed flame stabilization

2020 ◽  
Vol 45 (18) ◽  
pp. 10906-10919 ◽  
Author(s):  
Shilong Guo ◽  
Jinhua Wang ◽  
Weijie Zhang ◽  
Meng Zhang ◽  
Zuohua Huang
Keyword(s):  
Bluff Body ◽  
Flame Stabilization ◽  
Premixed Flame ◽  
Lean Premixed ◽  
Hydrogen Enrichment

scholarly journals Large Eddy Simulation of a Bluff Body Stabilized Lean Premixed Flame

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
A. Andreini ◽  
C. Bianchini ◽  
A. Innocenti
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Turbulent Combustion ◽  
Bluff Body ◽  
Sensitivity Study ◽  
Flame Stabilization ◽  
Combustion Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Lean Premixed

The present study is devoted to verify current capabilities of Large Eddy Simulation (LES) methodology in the modeling of lean premixed flames in the typical turbulent combustion regime of Dry LowNOxgas turbine combustors. A relatively simple reactive test case, presenting all main aspects of turbulent combustion interaction and flame stabilization of gas turbine lean premixed combustors, was chosen as an affordable test to evaluate the feasibility of the technique also in more complex test cases. A comparison between LES and RANS modeling approach is performed in order to discuss modeling requirements, possible gains, and computational overloads associated with the former. Such comparison comprehends a sensitivity study to mesh refinement and combustion model characteristic constants, computational costs, and robustness of the approach. In order to expand the overview on different methods simulations were performed with both commercial and open-source codes switching from quasi-2D to fully 3D computations.

Modeling of Turbulent Combustion Process and Lean Blow Out Using Combined Approach

2008 ◽  
Author(s):  
Yu. G. Kutsenko ◽  
S. F. Onegin ◽  
L. Y. Gomzikov
Keyword(s):  
Combustion Chamber ◽  
Bluff Body ◽  
Diffusion Flames ◽  
Premixed Flames ◽  
Combustion Process ◽  
Flame Stabilization ◽  
Combustion Model ◽  
Main Zone ◽  
Lean Premixed ◽  
No Emissions

Most of the modern combustor’s designs use staged concepts for reducing thermal NO emissions. Usually, a combustion process takes place inside the main zone, which uses very lean premixed fuel/air mixtures. A diffusion pilot zone supports combustion process inside a lean main zone. Thermal NO formation process takes place predominantly inside hot diffusion flame. So, operation modes of pilot and main zones must be arranged to provide low NO emissions of pilot zone and maintain flame stability inside the main zone simultaneously. In this paper a concept of new turbulent model combustion model is presented. This model allows to model diffusion and premixed flames and takes into account various physical processes, which lead to flame destabilization. The model uses an equation for reaction progress variable. In the frameworks of considered approach this equation has three source terms. These terms are responsible for different conditions of combustion process: diffusion flames, premixed flames and distributed reaction zones. A proposed model was widely validated for different types of combustion chambers such as: 1) Bluff-body flameholder (lean premixed combustion: modeling of lean blow out); 2) Conventional diffusion regime of combustion chamber of gas turbine engine (modeling of flame stabilization and NO emissions); 3) Combined combustion regime of combustion chamber: burning process is inside pilot diffusion and main premixed zones (NO emissions and lean blow out limits for several operational modes). These tests had shown a good agreement of experimentally obtained data with results of simulations.

Preliminary Design Concepts for High Solidity Nozzle-Less Radial Inflow Gas Turbine for Small Capacity Gas Turbine Engine

2006 ◽  
Author(s):  
Chetan S. Mistry ◽  
S. A. Channiwala
Keyword(s):  
Mach Number ◽  
Gas Turbine ◽  
Velocity Ratio ◽  
Basic Program ◽  
Preliminary Design ◽  
Power Requirement ◽  
Turbine Engine ◽  
Design Concepts ◽  
Compact Size ◽  
Exit Mach Number

The present work for the design of nozzle-less radial inflow turbine begins with power requirement of 20 kW. Based on the available parameters like temperature, pressure and mass flow rate required for the design are obtained from cycle analysis initially preliminary design of rotor was developed and from the available loss models the efficiency of the turbine was found. After completion of the preliminary design of turbine, it was felt necessary to optimized the result for best efficiency accordingly an analytical study was undertaken to study the influence of different parameters like inlet absolute Mach number, relative exit Mach number, solidity, relative velocity ratio, hub to shroud radius ratio and rotational speed on efficiency. VISUAL BASIC program is developed to study the effect of different parameters on efficiency, for different speed conditions it can be observed that for same solidity and higher speed gives the compact size with less variation in losses and efficiency. The results obtained from analysis also suggest the value of higher solidity but in practical situation that will restrict the flow through runner that by increasing the losses and reducing the efficiency.

Dynamics of Non-Premixed Bluff Body-Stabilized Flames in Heated Air Flow

2010 ◽  
Author(s):  
Caleb Cross ◽  
Aimee Fricker ◽  
Dmitriy Shcherbik ◽  
Eugene Lubarsky ◽  
Ben T. Zinn ◽  
...  
Keyword(s):  
Heat Release ◽  
Vortex Shedding ◽  
High Speed ◽  
Bluff Body ◽  
Combustion Process ◽  
Flame Stabilization ◽  
Inlet Temperature ◽  
Fuel Injectors ◽  
Flame Holder ◽  
Process Heat

This paper describes a study of the fundamental flame dynamic processes that control bluff body-stabilized combustion of liquid fuel with low dilatation. Specifically, flame oscillations due to asymmetric vortex shedding downstream of a bluff body (i.e., the Be´nard/von-Ka´rma´n vortex street) were characterized in an effort to identify the fundamental processes that most affect the intensity of these oscillations. For this purpose, the spatial and temporal distributions of the combustion process heat release were characterized over a range of inlet velocities, temperatures, and overall fuel-air ratios in a single flame holder combustion channel with full optical access to the flame. A stream of hot preheated air was supplied to the bluff body using a preburner, and Jet-A fuel was injected across the heated gas stream from discrete fuel injectors integrated within the bluff body. The relative amplitudes, frequencies, and phase of the sinusoidal flame oscillations were characterized by Fourier analysis of high-speed movies of the flame. The amplitudes of the flame oscillations were generally found to increase with global equivalence ratio, reaching a maximum just before rich blowout. Comparison of the flame dynamics to the time-averaged spatial heat release distribution revealed that the intensity of the vortex shedding decreased as a larger fraction of the combustion process heat release occurred in the shear layers surrounding the recirculation zone of the bluff body. Furthermore, a complete transition of the vortex shedding and consequent flame stabilization from asymmetric to symmetric modes was clearly observed when the inlet temperature was reduced from 850°C to 400°C (and hence, significantly increasing the flame dilatation ratio from Tb/Tu ∼ 2.3 to 3.7).

Gas Turbine Mach Number Control With Simplified Fuel System

2000 ◽  
Author(s):  
Graham J. Dadd ◽  
Kin K. Chan
Keyword(s):  
Mach Number ◽  
Control Method ◽  
Avoidance Performance ◽  
Test Bed ◽  
Pump System ◽  
Turbine Engine ◽  
Control Loops ◽  
Acceleration And Deceleration ◽  
Point Trajectories ◽  
Exit Mach Number

The compressor exit Mach number control theory presented here will enable improved control of transient compressor working point trajectories of a turbine engine. This will allow the steady working line to be raised towards the surge boundary with the advantage of increased thrust and reduced specific fuel consumption. This new control method can replace the rigid acceleration and deceleration limiters of the fuel control loop, and achieve superior surge avoidance performance. This paper documents the theoretical and practical study of Mach number controllers designed for implementation with a simplified fuel pump system and the subsequent testing of the controllers on an aero-engine in the sea level test bed in DERA Pyestock. The new controller incorporated two Mach number dynamic limiting control loops (one each for acceleration and deceleration) besides the NH controller. Several designs were tested successfully and demonstrated not only Mach number control from idle to full power, but also surge avoidance. Engine start control was also tested in the latest engine test.

Unsteady Non-Reacting and Reacting Flow Simulations of a Triangular Bluff-Body Flameholder

2019 ◽  
Author(s):  
Manoj Mannari ◽  
A. T. Sriram ◽  
Gursharanjit Singh ◽  
S. Ganesan
Keyword(s):  
Bluff Body ◽  
Stokes Equations ◽  
Velocity Profiles ◽  
Flame Stabilization ◽  
Navier Stokes ◽  
Reacting Flow ◽  
Turbine Engine ◽  
Flame Holder ◽  
Eddy Simulation ◽  
Flow Features

Abstract Triangular bluff-body flame-holders, commonly called v-gutters, are used in gas turbine engine afterburners for flame stabilization. Unsteady flow dynamics in the v-gutter wake plays an important role in phenomenon such as combustion instability. The objective of the present work is to simulate the flow features for flow past v-gutter with Unsteady Reynolds-Averaged Navier–Stokes equations (URANS) and Large Eddy Simulation (LES) approach using Eddy Dissipation Model (EDM) for turbulent combustion. Volvo’s bluff body flame-holder rig configuration has been used for the current study. Both non-reacting and reacting simulations have been carried out in commercial Computational Fluid Dynamics (CFD) code FLUENT. In the case of non-reacting flow, the structure of instantaneous velocity field of LES differs from URANS approach. The predicted velocity profiles with LES have shown good agreement with the experiment in most of the regions than URANS for the case of non-reacting flow. In the case of reacting flow, LES simulations have shown unsteady flame with eddy structures. In contrast, URANS simulations have shown more like a steady flame. Overall, the temperature and velocity profiles were better predicted by LES than by URANS approach. In addition, simulations were carried out with circular flame-holder in an annular duct. The oscillation characteristics were found to be more or less similar for both straight and circular flame-holder.

Computational and Experimental Analysis of a Compact Combustor Integrated into a JetCat P90 RXi

2021 ◽  
Author(s):  
Daniel Holobeny ◽  
Brian T. Bohan ◽  
Marc D. Polanka
Keyword(s):  
Bluff Body ◽  
Flame Stabilization ◽  
Inlet Temperature ◽  
Gas Temperature ◽  
Turbine Engine ◽  
Pressure Losses ◽  
Primary Zone ◽  
Sustained Operation ◽  
Mass Flow Rates ◽  
Stable Flame

Abstract Ultra Compact Combustors (UCC) look to reduce the overall combustor length and weight in modern gas turbine engines. Previously, a UCC achieved self-sustained operation at sub-idle speeds in a JetCat P90 RXi turbine engine with a length savings of 33% relative to the stock combustor. However, that combustor experienced flameout as reactions were pushed out of the primary zone before achieving mass flow rates at the engine's idle condition. A new combustor that utilized a bluff body flame stabilization with a larger combustor volume looked to keep reactions in the primary zone within the same axial dimensions. This design was investigated computationally for generalized flow patterns, pressure losses, exit temperature profiles, and reaction distributions at three engine power conditions. The computational results showed the validity of this new Ultra Compact Combustor, with a turbine inlet temperature of 1080 K and a pattern factor of 0.67 at the cruise condition. The combustor was then built and tested in the JetCat P90 RXi with rotating turbomachinery and gaseous propane fuel. The combustor maintained a stable flame from ignition through the 36,000 RPM idle condition. The engine ran self-sustained from 25,000 to 36,000 RPM with an average exit gas temperature of 980 K, which is comparable to the stock engine.

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