| Dynamics of Supercritical Flows |
26 Aug 2012 |
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| Authors:
Bruce Chehroudi; Dustin Davis; Jeffrey Graham; Ann Karagozian; Ivett Leyva; Juan Rodriguez; Douglas Talley; Sophonias Teshome; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIR
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 | This research has concentrated on the characterization of mixing for typical liquid rocket injectors. The conditions of interest have encompassed subcritical to supercritical pressures with temperatures below and above the critical temperature, with and without an acoustic field. The project has been largely experimental in-house. A single shear coaxial injector element has been thoroughly studied. This type of injector element is commonly used in many rocket engines (e.g., Space Shuttle ... |
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| A Unified Approach on Combustion Instability in Cryogenic Liquid Rockets (Preprint) |
08 Dec 2008 |
23 pages |
| Authors:
Bruce Chehroudi; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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 | In this work, the author would like to portray a sketch of a unified physical picture to describe the coupling nature/strength between the chamber acoustics and the injectors. This new perspective is achieved through a physically intuitive argument combined with previously published test results for two popular injector designs, namely, coaxial and impinging jets. For the impinging-jets injectors, it is shown that the dynamic behavior of the dark-core (or breakup) ... |
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| Results on Subcritical One-Phase Coaxial Jet Spread Angles and Subcritical to Supercritical Acoustically Forced Coaxial Jet Dark Core Lengths (Preprint) |
25 Jun 2008 |
13 pages |
| Authors:
Douglas Talley; Juan I Rodriguez; Ivett A Leyva; Bruce Chehroudi; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An investigation of the behavior of N2 gas-gas shear coaxial jet spread angles in conjunction with a comprehensive N2 shear coaxial jet dark core length analysis is presented. For the one-phase coaxial jet spread angle study, a total of 6 cases, corresponding to different momentum flux ratios (MR's) at subcritical pressures are analyzed and compared to existing data. The measurements were extracted from 20 backlit images with the chamber to ... |
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| Effects of a Variable-Phase Transverse Acoustic Field on a Coaxial Injector at Subcritical and Near-Critical Conditions (Preprint) |
01-May-2008 |
12 pages |
| Authors:
Bruce Chehroudi; Douglas Talley; Juan I Rodriguez; Ivett A Leyva; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An experimental study that focuses on the effects of a variable transverse acoustic field on an N2 shear coaxial jet is presented. The coaxial jet is exposed to different acoustic conditions by varying the phase between two acoustic sources. The main objective of this investigation is to analyze the effect of transverse acoustic forcing with variable phase on the magnitude of the inner-jet dark-core length. The coaxial jet is exposed ... |
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| A Physical Hypothesis for the Combustion Instability in Cryogenic Liquid Rocket Engines (Preprint) |
21-Apr-2008 |
19 pages |
| Authors:
Bruce Chehroudi; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
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| In this work, the author would like to portray a sketch of a unified physical picture to describe the coupling nature/strength between the chamber acoustics and the injectors. This new perspective is achieved through a physically intuitive argument combined with previously published test results for two popular injector designs, namely, coaxial and impinging jets. For the impinging-jets injectors, it is shown that the dynamic behavior of the dark-core (or breakup) ... |
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| Preliminary Results on Coaxial Jet Spread Angles and the Effects of Variable Phase Transverse Acoustic Fields (Postprint) |
Jan 2008 |
16 pages |
| Authors:
Ivett A Leyva; Douglas Talley; Juan I Rodriguez; Bruce Chehroudi; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An experimental study on the jet spreading angle of N2 shear coaxial jets at sub-, near-, and supercritical pressures is presented. The jet spreading angle is an important parameter which characterizes the mixing between two flows forming a shear layer. The present results are compared with previous experimental data, CFD results, and theoretical predictions. The angle measurements are made directly from at least 20 backlit images. The shear coaxial injector ... |
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| Preliminary Results on Coaxial Jets Spread Angles and the Effects of Variable Phase Transverse Acoustic Fields (Preprint) |
21 AUG 2007 |
15 pages |
| Authors:
Ivett A. Leyva; Douglas Talley; Juan I. Rodriguez; Bruce Chehroudi; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An experimental study on the jet spreading angle of N2 shear coaxial jets at sub-, near-, and supercritical pressures is presented. The jet spreading angle is an important parameter which characterizes the mixing between two flows forming a shear layer. The present results are compared with previous experimental data, CFD results, and theoretical predictions. The angle measurements are made directly from at least 20 backlit images. The shear coaxial injector ... |
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| Dark Core Analysis of Coaxial Injectors at Sub-, Near-, and Supercritical Pressures in a Transverse Acoustic Field (Postprint) |
13 JUN 2007 |
19 pages |
| Authors:
Ivett A. Leyva; Douglas Talley; Bruce Chehroudi; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| An experimental study on the effects of an externally-imposed transverse acoustic field in a N2 shear coaxial jets at sub-, near-, and supercritical pressures is presented. Such fields and their interaction with the jets (i.e., breakup, mixing, etc.) are believed to play a critical role during combustion instabilities in liquid rocket engines. The shear coaxial injector used here is similar to those used in cryogenic liquid rockets. By using N2 ... |
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| Dark Core Analysis of Coaxial Injectors at Sub-, Near-, and Supercritical Pressures in a Transverse Acoustic Field (Preprint) |
13 JUN 2007 |
18 pages |
| Authors:
Ivett A. Leyva; Douglas Talley; Bruce Chehroudi; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An experimental study on the effects of an externally-imposed transverse acoustic field in a N2 shear coaxial jets at sub-, near-, and supercritical pressures is presented. Such fields and their interaction with the jets (i.e., breakup, mixing, etc.) are believed to play a critical role during combustion instabilities in liquid rocket engines. The shear coaxial injector used here is similar to those used in cryogenic liquid rockets. By using N2 ... |
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| Coaxial Jets at Supercritical Conditions in a Variable Transverse Acoustic Field (Preprint) |
24 MAY 2007 |
6 pages |
| Authors:
Ivett A. Leyva; Juan Rodriguez; Bruce Chehroudi; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An experimental study on the effects of the relative position of a coaxial jet with respect to an externally-imposed transverse acoustic field is presented. A thorough investigation on the effects of chamber pressure, outer to inner jet velocity ratio (VR), and outer to inner momentum flux ratio (MR) on a coaxial jet subject to a fixed transverse acoustic field has been completed by this group [1-3]. However, the jet was ... |
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| Dark Core Analysis of Coaxial Injectors at Sub-, Near-, and Supercritical Conditions in a Transverse Acoustic Field |
MAY 2007 |
12 pages |
| Authors:
Ivett A. Leyva; Bruce Chehroudi; Douglas Talley; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An experimental study on the effects of an externally-imposed transverse acoustic field in sub-, near-, and supercritical N2 coaxial jets is presented. Such fields and their interaction with the jets (i.e., breakup, mixing, etc.) is believed to play a critical role during combustion instabilities in liquid rocket engines. The shear coaxial injector used here is similar to those used in cryogenic liquid rockets. By using N2 as the working fluid, ... |
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| Supercritical and Transcritical Shear Flows in Microgravity: Experiments and Direct Numerical Simulations |
AUG 2006 |
314 pages |
| Authors:
Dustin W. Davis; Bruce Chehroudi; Douglas G. Talley; Josette Bellan; Nora Okong'o; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
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| Experiments and direct numerical simulations (DNS) were conducted on shear layers at subcritical to supercritical pressures. The experiments were performed on single-component coaxial jets, where the slower inner flow was liquid nitrogen, the faster outer flow was cold gaseous nitrogen, and the environment was room temperature gaseous nitrogen. The experiments were performed with and without the effects of transverse acoustic waves. Careful attention was given to measuring all the initial ... |
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| A Rocket-Like Coaxial Injector in an Acoustic Field Under Sub- and Supercritical Conditions |
03 JUL 2006 |
9 pages |
| Authors:
D. W. Davis; Bruce Chehroudi; Douglas G. Talley; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| An experimental investigation was undertaken under non-reacting condition to gain a physical understanding of the interaction of acoustic waves and a coaxial-jet injector similar to those used in cryogenic liquid rockets. Liquid nitrogen (the round inner jet) and gaseous nitrogen (the annular outer jet) were used under subcritical, near critical, and supercritical chamber pressures, with and without presence of an external acoustic field. High-speed imaging provided information on the dynamic ... |
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| Shear-Coaxial Jets from a Rocket-Like Injector in a Transverse Acoustic Field at High Pressures (POSTPRINT) |
12 JAN 2006 |
19 pages |
| Authors:
Dustin W. Davis; Bruce Chehroudi; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
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| In order to gain a better understanding of some of the underlying physics associated with the interaction of high-amplitude acoustic waves and a coaxial-jet injector similar to those used in cryogenic liquid rockets, a non-reacting-flow experimental investigation was conducted under sub-, near-, and supercritical chamber pressures, with and without acoustical excitation. Past research works on this subject have shown both the relevance and importance of geometrical changes in an injector's ... |
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| The Effects of Pressure and an Acoustic Field on a Cryogenic Coaxial Jet |
22 JUN 2004 |
23 pages |
| Authors:
Dustin Davis; Bruce Chehroudi; Doug Talley; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
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| OBJECTIVES: Document the nature of the acoustic wave/coaxial-jet injector interaction * Map a range of input variables * Explore application of the data and the findings for rocket combustion instability. MOTIVATION: Combustion instability has always been one of the most complex phenomena in liquid rocket engines * High amplitude and high frequency acoustic instabilities (screaming), can lead to local burnout of the combustion chamber walls and injector plates * APPROACH: ... |
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| Laser Ignition For Combustion Engines |
21 MAY 2004 |
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| Authors:
Bruce Chehroudi; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| With the advent of lasers in the 1960s, researcher and engineers discovered a new and powerful tool to investigate natural phenomena and improve technologically critical processes. Nowadays, applications of different lasers span quite broadly from diagnostics tools in science and engineering to biological and medical uses. In this article basic principles and applications of lasers for ignition of fuels are concisely reviewed from the engineering perspective. The objective is to ... |
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