Mechanisms for severe combustion instabilities induced by low-temperature fuel injection of an H2/O2rocket-type combustor

2022 ◽  
Author(s):  
Toru Ota ◽  
Hiroshi Terashima ◽  
Nobuyuki Oshima
Keyword(s):  
Low Temperature ◽  
Fuel Injection ◽  
Combustion Instabilities

scholarly journals An Experimental and Modeling Study of HCCI Combustion Using n-Heptane

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Hongsheng Guo ◽  
W. Stuart Neill ◽  
Wally Chippior ◽  
Hailin Li ◽  
Joshua D. Taylor
Keyword(s):  
Low Temperature ◽  
Internal Combustion Engines ◽  
Fuel Injection ◽  
Combustion Process ◽  
Injection System ◽  
Intake Manifold ◽  
Strong Impact ◽  
Oxides Of Nitrogen ◽  
Hcci Combustion ◽  
Modeling Study

Homogeneous charge compression ignition (HCCI) is an advanced low-temperature combustion technology being considered for internal combustion engines due to its potential for high fuel conversion efficiency and extremely low emissions of particulate matter and oxides of nitrogen (NOx). In its simplest form, HCCI combustion involves the auto-ignition of a homogeneous mixture of fuel, air, and diluents at low to moderate temperatures and high pressure. Previous research has indicated that fuel chemistry has a strong impact on HCCI combustion. This paper reports the preliminary results of an experimental and modeling study of HCCI combustion using n-heptane, a volatile hydrocarbon with well known fuel chemistry. A Co-operative Fuel Research (CFR) engine was modified by the addition of a port fuel injection system to produce a homogeneous fuel-air mixture in the intake manifold, which contributed to a stable and repeatable HCCI combustion process. Detailed experiments were performed to explore the effects of critical engine parameters such as intake temperature, compression ratio, air/fuel ratio, engine speed, turbocharging, and intake mixture throttling on HCCI combustion. The influence of these parameters on the phasing of the low-temperature reaction, main combustion stage, and negative temperature coefficient delay period are presented and discussed. A single-zone numerical simulation with detailed fuel chemistry was developed and validated. The simulations show good agreement with the experimental data and capture important combustion phase trends as engine parameters are varied.

Suppression of Instabilities in Gaseous Fuel High-Pressure Combustor Using Non-Coherent Oscillatory Fuel Injection

2003 ◽  
Author(s):  
D. Shcherbik ◽  
E. Lubarsky ◽  
Y. Neumeier ◽  
B. T. Zinn ◽  
K. McManus ◽  
...  
Keyword(s):  
High Pressure ◽  
Active Control ◽  
Fuel Injection ◽  
Injection Rate ◽  
Open Loop ◽  
Combustion Instabilities ◽  
Open Loop Control ◽  
Pressure Oscillations ◽  
Loop Control ◽  
Fuel Injection Rate

This paper describes the application of active, open loop, control in effective damping of severe combustion instabilities in a high pressure (i.e., around 520 psi) gas turbine combustor simulator. Active control was applied by harmonic modulation of the fuel injection rate into the combustor. The open-loop active control system consisted of a pressure sensor and a fast response actuating valve. To determine the dependence of the performance of the active control system upon the frequency, the fuel injection modulation frequency was varied between 300 and 420 Hz while the frequency of instability was around 375 Hz. These tests showed that the amplitude of the combustor pressure oscillations strongly depended upon the frequency of the open loop control. In fact, the amplitude of the combustor pressure oscillations varied ten fold over the range of investigated frequencies, indicating that applying the investigated open loop control approach at the appropriate frequency could effectively damp detrimental combustion instabilities. This was confirmed in subsequent tests in which initiation of open loop modulation of the fuel injection rate at a non resonant frequency of 300Hz during unstable operation with peak to peak instability amplitude of 114 psi and a frequency of 375Hz suppressed the instability to a level of 12 psi within approximately 0.2 sec (i.e., 75 periods). Analysis of the time dependence of the spectra of the pressure oscillations during suppression of the instability strongly suggested that the open loop fuel injection rate modulation effectively damped the instability by “breaking up” (or preventing the establishment of) the feedback loop between the reaction rate and combustor oscillations that drove the instability.

On the Relationship Between Fuel Injection Pressure and Two-Stage Ignition Behavior of Low Temperature Diesel Combustion

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
J. A. Bittle ◽  
T. J. Jacobs
Keyword(s):  
Low Temperature ◽  
Literature Review ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Low Temperature Combustion ◽  
Combustion Duration ◽  
Stage Combustion ◽  
Temperature Combustion ◽  
Fuel Injection Pressure ◽  
The Relationship

In previous work, it is reported that increased dilution at midrange injection pressures produces longer first stage combustion duration. There is also corresponding decreases in nitric oxide concentrations and smoke number with respect to a reference conventional combustion mode. Continuing this effort, the objective of this study is to investigate the effect of injection pressure on the first stage ignition duration under low temperature combustion (LTC) conditions. A sweep of injection pressure is performed and the resulting heat (energy) release profiles are examined. The ignition delay behavior is expected based on changing injection pressure, but the first stage ignition duration does not follow expected trends based on initial literature review. It is postulated that the influence of injection pressure on the local equivalence ratios is causing the observed behavior. The appropriate measurement and analysis tools are not available to the authors to confirm this postulation. A literature review of work investigating ignition conditions in low temperature combustion modes is used to support the postulation made in this study.

scholarly journals Numerical simulation of n-dodecane spray combustion based on OpenFOAM

2021 ◽  
Vol 39 (3) ◽  
pp. 539-548
Author(s):  
Wengang Li ◽  
Yinli Xiao ◽  
Yipin Lu ◽  
Zhibo Cao ◽  
Juan Wu
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Fuel Injection ◽  
Mixture Fraction ◽  
Spray Combustion ◽  
Combustion Model ◽  
Temperature Reaction ◽  
Penetration Length ◽  
Chemical Reaction Kinetics ◽  
Lift Off

For the purpose of providing the scientific insights to combustion characteristics of spray jet, numerical calculations of reacting and non-reacting spray cases are performed for ECN (engine combustion network) Spray A (n-dodecane spray combustion) which coupled finite chemistry combustion model PaSR and detailed chemical reaction kinetics based on OpenFOAM. The applicability and accuracy of the spray model is verified in the non-reacting spray case, and it is found that the predicted spray characteristics such as the penetration length of liquid and vapor and the mixture fraction are in good agreement with the test results. The two processes of low-temperature reaction and high-temperature ignition experienced by n-dodecane spray ignition are analyzed in reacting spray case, and it is found that the low-temperature reaction continues to exothermic before high-temperature ignition, and continues to proceed stably after high-temperature ignition, which promotes high-temperature ignition and flame stability. Finally, the effects of different fuel injection pressures on ignition delay time and flame lift-off length are studied.

Effect of Different Fuels On Combustion Instabilities in an Annular Combustors

2021 ◽  
Author(s):  
Preethi Rajendram Soundararajan ◽  
Vignat Guillaume ◽  
Daniel Durox ◽  
Antoine Renaud ◽  
Sebastien Candel
Keyword(s):  
Fuel Injection ◽  
Thermal Power ◽  
Time Lag ◽  
Liquid Fuels ◽  
Jet Engines ◽  
Combustion Instabilities ◽  
Describing Functions ◽  
Annular Combustor ◽  
Instability Map ◽  
Reference Map

Abstract Combustion instability in annular combustors of jet engines is a recurring issue. In the present study, the characteristics of instabilities for different fuels are investigated by combining the instability maps obtained in a laboratory-scale annular combustor equipped with multiple swirling spray injectors (MICCA-Spray) and flame describing functions (FDFs) from a single sector configuration (SICCA-Spray). Two types of liquid fuels are injected as hollow cone sprays: heptane, which is fairly volatile, and dodecane, which is less volatile. Experiments are also conducted with gaseous propane, premixed with air, which serves as a reference. An instability map is systematically drawn by varying the global equivalence ratio and thermal power. The data indicate that the amplitude and frequency of instabilities depend, for the same operating point, on the fuel injection conditions and fuel type. Overall trends show that premixed propane is unstable in a broad operating domain. Injection of liquid fuels induce changes in flame time lag that modify the unstable regions. For heptane, the instability map is closer to the propane reference map, whereas dodecane exhibits wider stable regions. An attempt is made to understand these features by examining the FDF, which gives the ratio of relative fluctuations in heat release rate to the relative fluctuations in velocity. The FDFs measured in a single sector configuration give access to gain and phase information that can be used to determine unstable bands and calculate an instability index guiding the interpretation of the differences in instabilities of the three fuels.

Numerical Simulation of Combustion Instabilities in a Lean Premixed Combustor With Finite Rate Chemistry

2003 ◽  
Author(s):  
David J. Cook ◽  
Heinz Pitsch ◽  
Norbert Peters
Keyword(s):  
Fuel Injection ◽  
Combustion Model ◽  
Analysis Tool ◽  
Computational Domain ◽  
Combustion Instabilities ◽  
Finite Rate ◽  
Flow Area ◽  
Lean Premixed ◽  
Dissipation Model ◽  
Computational Fluid Dynamics Cfd

Combustion instabilities in lean premixed gas turbine combustors remain a major limitation in decreasing NOx emissions. Computational Fluid Dynamics (CFD) has become an important design and analysis tool that is often used to predict thermoacoustic oscillations caused by these instabilities. Limitations to prediction accuracy are imposed by the choice of chemistry and combustion model. The focus of this study is to compare CFD calculations using Eddy Dissipation and Finite Rate Chemistry models to experimental data reported by Richards and Janus (1997) on the single-injector lean premixed DOE-NETL combustor. The computational domain consists of an annular swirl inlet, fuel injection, a can combustor, a plug for reduced flow area, and an exhaust plenum. The numerical calculations were done using a RANS solver. A 2D axisymmetric-swirl model with RANS turbulence model was employed. The Eddy Dissipation Model has become popular largely because of its robust performance. It is shown that this model does not predict combustion instabilities for the present case. On the other hand, the Finite Rate Chemistry Model is numerically stiff, but is capable of capturing the onset of combustion instabilities.

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