Effect of delay time on the combustion instability in a single-element combustor

2021 ◽  
Vol 178 ◽  
pp. 783-792
Author(s):  
Jinhyun Bae ◽  
Seokgyu Jeong ◽  
Youngbin Yoon
Keyword(s):  
Delay Time ◽  
Combustion Instability ◽  
Single Element

Combustion Instability with a Single-Element Swirl Injector

2007 ◽  
Vol 23 (5) ◽  
pp. 1102-1112 ◽  
Author(s):  
Kevin Miller ◽  
James Sisco ◽  
Nicholas Nugent ◽  
William Anderson
Keyword(s):  
Combustion Instability ◽  
Single Element ◽  
Swirl Injector

Large-Eddy Simulation of High-Frequency Combustion Instability in a Single-Element Atmospheric Combustor

2016 ◽  
Vol 32 (3) ◽  
pp. 628-645 ◽  
Author(s):  
Shingo Matsuyama ◽  
Dan Hori ◽  
Taro Shimizu ◽  
Shigeru Tachibana ◽  
Seiji Yoshida ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
High Frequency ◽  
Combustion Instability ◽  
Single Element ◽  
Eddy Simulation ◽  
Large Eddy

scholarly journals Combustion instability modeling using multi-mode flame transfer functions and a nonlinear Euler solver

2020 ◽  
Vol 12 ◽  
pp. 175682772095032
Author(s):  
Gowtham Manikanta Reddy Tamanampudi ◽  
Swanand Sardeshmukh ◽  
William Anderson ◽  
Cheng Huang
Keyword(s):  
Transfer Functions ◽  
Combustion Instability ◽  
Hybrid Approach ◽  
Scale Model ◽  
Single Element ◽  
High Fidelity ◽  
High Fidelity Simulation ◽  
Combustion Dynamics ◽  
Heat Addition ◽  
High Fidelity Simulations

Modern methods for predicting combustion dynamics in high-pressure combustors range from high-fidelity simulations of sub-scale model combustors, mostly for validation purposes or detailed investigations of physics, to linearized, acoustics-based analysis of full-scale practical combustors. Whereas the high-fidelity simulations presumably capture the detailed physics of mixing and heat addition, computational requirements preclude their application for practical design analysis. The linear models that are used during design typically use flame transfer functions that relate the unsteady heat addition [Formula: see text] to oscillations in velocity and pressure ([Formula: see text] and [Formula: see text]) that are obtained from the wave equation. These flame transfer functions can be empirically determined from measurements or derived from theory and analysis. This paper describes a hybrid approach that uses high-fidelity simulations to generate flame transfer functions along with nonlinear Euler CFD to predict the combustor flowfield. A model rocket combustor that presented a self-excited combustion instability with pressure oscillations on the order of 10% of mean pressure is used for demonstration. Spatially distributed flame transfer functions are extracted from a high-fidelity simulation of the combustor and then used in a nonlinear Euler CFD model of the combustor to verify the approach. It is shown that the reduced-fidelity model can reproduce the unsteady behavior of the single element combustor that was both measured in the experiment and predicted by a high-fidelity simulation reasonably well.

A standard for transmission electron spectroscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 530-531 ◽  
Author(s):  
Dennis Maher ◽  
David Joy ◽  
Peggy Mochel
Keyword(s):  
Thin Films ◽  
Electron Spectroscopy ◽  
Host Lattice ◽  
Single Element ◽  
Multicomponent Systems ◽  
Transmission Electron ◽  
Major Interest ◽  
Standard Specimens ◽  
Forms Of Carbon ◽  
Electron Energy Loss

A variety of standard specimens is needed in order to systematically investigate the instrumentation, specimen, data reduction and quantitation variables in electron energy-loss spectroscopy (EELS). Pure single element specimens (e.g. various forms of carbon) have received considerable attention to date but certain elements of interest cannot be prepared directly as thin films. Since studies of the first and second row elements in two- or multicomponent systems will be of considerable importance in microanalysis using EELS, there is a need for convenient standards containing these species. For many investigations a standard should contain the desired element, or elements, homogeneously dispersed through a suitable matrix and at an accurately known concentration. These conditions may be met by the technique of implantation.Silicon was chosen as the host lattice since its principal ionization energies, EL23 = 98 eV and Ek = 1843 eV, are well removed from the K-edges of most elements of major interest such as boron (Ek = 188 eV), carbon (Ek = 283 eV), nitrogen (Ek = 400 eV) and oxygen (Ek = 532 eV).

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

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