scholarly journals Parametric investigation of combustion instabilities in a single-element lean direct injection combustor

2018 ◽  
Vol 11 ◽  
pp. 175682771878585 ◽  
Author(s):  
Rohan M Gejji ◽  
Cheng Huang ◽  
Christopher Fugger ◽  
Changjin Yoon ◽  
William Anderson
Keyword(s):  
Air Temperature ◽  
Equivalence Ratio ◽  
Direct Injection ◽  
Longitudinal Mode ◽  
Chamber Pressure ◽  
Single Element ◽  
Combustion Dynamics ◽  
Lean Direct Injection ◽  
Fuel Nozzle ◽  
Measured Pressure

Self-excited combustion dynamics in a liquid-fueled lean direct injection combustor at high pressure (1 MPa) are described. Studied variables include combustor and air plenum length, inlet air temperature, equivalence ratio, fuel nozzle location, and fuel composition. Measured pressure oscillations were dependent on combustor geometry and ranged from about 1% of mean chamber pressure at low equivalence ratio, up to 20% at high equivalence ratio. In the most unstable cases, strong pressure modes were measured throughout the frequency spectrum including a band around 1.2–1.5 kHz representing the 4th longitudinal mode, and another band around 7 kHz. The oscillation amplitudes have a non-monotonic dependency on air temperature, and are affected by the placement of the fuel nozzle relative to the throat of the subsonic swirling air flow. The parametric survey provides a rich dataset suitable for validating high-fidelity simulations and their subsequent use in analyzing and interpreting the complex combustion dynamics.

Combustion Dynamics Behavior in a Single-Element Lean Direct Injection (LDI) Gas Turbine Combustor

2014 ◽  
Author(s):  
Cheng Huang ◽  
Rohan Gejji ◽  
William Anderson ◽  
Changjin Yoon ◽  
Venkateswaran Sankaran
Keyword(s):  
Gas Turbine ◽  
Direct Injection ◽  
Single Element ◽  
Gas Turbine Combustor ◽  
Combustion Dynamics ◽  
Lean Direct Injection

Combustion Dynamics in a Single-Element Lean Direct Injection Gas Turbine Combustor

2019 ◽  
Vol 192 (12) ◽  
pp. 2371-2398 ◽  
Author(s):  
Cheng Huang ◽  
Rohan Gejji ◽  
William Anderson ◽  
Changjin Yoon ◽  
Venkateswaran Sankaran
Keyword(s):  
Gas Turbine ◽  
Direct Injection ◽  
Single Element ◽  
Gas Turbine Combustor ◽  
Combustion Dynamics ◽  
Lean Direct Injection

Numerical Investigation of Combustion Instabilities in a Single-Element Lean Direct Inject Combustor Using Flamelet Based Approaches

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Saurabh Sudhir Patwardhan ◽  
Pravin Nakod ◽  
Stefano Orsino ◽  
Carlo Arguinzoni
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Direct Injection ◽  
Single Element ◽  
Combustion Instabilities ◽  
Gas Turbine Combustor ◽  
Combustion Dynamics ◽  
Lean Direct Injection ◽  
Combustion Models ◽  
Simulation Results

Abstract In this paper, high-fidelity large eddy simulations (LES) along with flamelet-based combustion models are assessed to predict combustion dynamics in low-emission gas turbine combustor. A model configuration of a single-element lean direct injection (LDI) combustor from Purdue University (Huang et al., 2014, “Combustion Dynamics Behavior in a Single-Element Lean Direct Injection (LDI) Gas Turbine Combustor,” 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Cleveland, OH, July 28–30.) is used for the validation of simulation results. Two combustion models based on the flamelet concept, i.e., steady diffusion flamelet (SDF) model and flamelet generated manifold (FGM) model are employed to predict combustion instabilities. Simulations are carried out for two equivalence ratios of φ = 0.6, and 0.4. The results in the form of mode shapes, peak to peak pressure amplitude and power spectrum density (PSD) are compared with the experimental data of Huang et al. (2014, “Combustion Dynamics Behavior in a Single-Element Lean Direct Injection (LDI) Gas Turbine Combustor,” 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Cleveland, OH, July 28–30.). The effect of variation in the time-step size hence acoustic courant number is studied. Further, two numerical solver options, i.e., pressure-based segregated solver and pressure-based coupled solver, are used to understand their effect on the solution convergence regarding the number of time-steps required to reach the limit cycle of the pressure oscillations. A truncated (half) domain simulation is performed by applying an appropriate acoustic impedance boundary condition at the truncated location. Overall, the simulation results compare well with the experimental data and trends are captured accurately in all simulations. It builds confidence in flamelet-based combustion models for the use in combustion instability modeling which is traditionally done using finite rate chemistry models based on reduced kinetics.

scholarly journals Characterization of a Novel Porous Injector for Multi-Lean Direct Injection (M-LDI) Combustor

2017 ◽  
Author(s):  
Jianing Li ◽  
Umesh Bhayaraju ◽  
San-Mou Jeng
Keyword(s):  
Air Temperature ◽  
Mass Fraction ◽  
Direct Injection ◽  
Flame Temperature ◽  
Gaseous Fuel ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Porous Tube ◽  
Lean Direct Injection ◽  
Air Mixing

A generic novel injector was designed for multi-Lean Direct Injection (M-LDI) combustors. One of the drawbacks of the conventional pressure swirl and prefilming type airblast atomizers is the difficulty of obtaining a uniform symmetric spray under all operating conditions. Micro-channels are needed inside the injector for uniformly distributing the fuel. The problem of non-uniformity is magnified in smaller sized injectors. The non-uniform liquid sheet causes local fuel rich/lean zones leading to higher NOx emissions. To overcome these problems, a novel fuel injector was designed to improve the fuel delivery to the injector by using a porous stainless steel material with 30 μm porosity. The porous tube also acts as a prefilming surface. Liquid and gaseous fuels can be injected through the injector. In the present study, gaseous fuel was injected to investigate injector fuel-air mixing performance. The gaseous fuel was injected through a porous tube between two radial-radial swirling air streams to facilitate fuel-air mixing. The advantage of this injector is that it increases the contact surface area between the fuel-air at the fuel injection point. The increased contact area enhances fuel-air mixing. Fuel-air mixing and combustion studies were carried out for both gaseous and liquid fuel. Flame visualization, and emissions measurements were carried out inside the exit of the combustor. The measurements were carried out at atmospheric conditions under fuel lean conditions. Natural gas was used as a fuel in these experiments. Fuel-air mixing studies were carried out at different equivalence ratios with and without confinement. The mass fraction distributions were measured at different downstream locations from the injector exit. Flame characterization was carried out by chemiluminescence at different equivalence ratios and inlet air temperatures. Symmetry of the flame, flame length and heat release distribution were analyzed from the flame images. The effects of inlet air temperature and combustion flame temperature on emissions was studied. Emissions were corrected to 15% O2 concentration. NOx emissions increase with inlet air temperature and flame temperature. Effect of flame temperature on NOx concentration is more significant than effect of inlet air temperature. Fuel-air mixing profile was used to obtain mass fraction Probability Density Function (pdf). The pdfs were used for simulations in Chemkin Pro. The measured emissions concentrations at the exit of the injector was compared with simulations. In Chemkin model, a network model with several PSRs (perfectly stirred reactor) were utilized, followed by a mixer and a PFR (plug flow reactor). The comparison between the simulations and the experimental results was investigated.

Sector Tests of a Low NOx, Lean-Direct-Injection, Multipoint Integrated Module Combustor Concept

2002 ◽  
Author(s):  
Robert Tacina ◽  
Changlie Wey ◽  
Peter Laing ◽  
Adel Mansour
Keyword(s):  
Direct Injection ◽  
Pressure Ratio ◽  
Inlet Pressure ◽  
Inlet Temperature ◽  
Single Element ◽  
Nox Emissions ◽  
Fuel Injectors ◽  
Lean Direct Injection ◽  
Test Conditions ◽  
Engine Cycle

Results of a low-NOx combustor test with a 15° sector are presented. A multipoint, lean-direct injection concept is used. The configuration tested has 36 fuel injectors and fuel-air mixers in place of a dual annular arrangement of two conventional fuel injectors. An integrated-module approach is used for the construction where chemically etched laminates that are diffusion bonded, combine the fuel injectors, air swirlers and fuel manifold into a single element. Test conditions include inlet temperatures up to 866K, and inlet pressures up to 4825 kPa. The fuel used was Jet A. A correlation is developed relating the NOx emissions to the inlet temperature, inlet pressure, and fuel-air ratio. Using a hypothetical 55:1 pressure-ratio engine, cycle NOx emissions are estimated to be less than 40% of the 1996 ICAO standard.

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