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Energy Efficiency: Tranverse Jet Instabilities & Control

Advanced Propulsion: Detonations, ionized gases, and turbulent combustion

Alternative Fuels: Acoustically Coupled Droplet Combustion

Rocket Propulsion: Transcritical Coaxial Jet Instabilities


Hypersonic Flight Testing: Phoenix Testbed

Aerospace Safety: Hydrogen Leak Detection

Combustion Generated Air Pollutants: Lobed Fuel Injector

Hazardous waste Incineration: Resonant Dump Combustor

Aerospace Propulsion: In-flight Imaging of Transverse Jets

Rocket Propulsion: Transcritical Shear Coaxial Jets and Impinging Jet Instabilities

Researchers: Dr. Alex Schumaker (AFRL), Dr. Al Badakhshan (AFRL), Dr. Doug Talley (AFRL), Dr. John Benneluits, Dr. Rosa Padilla, Prof. Ann Karagozian, Dr. Mario Roa (AFRL)

Former Researchers: Dr. Dave Forliti (AFRL), Dr. Ivett Leyva (AFRL), Dr. Jeff Wegener (grad), Dr. Sophonias Teshome (grad), Dr. Juan Rodriguez (grad)

Research Supported By:




Air Force Office of Scientific Research


Jeffrey Wegener at the
EC-4 facility, AFRL/RQR

Acoustically coupled combustion instabilities can result in very large scale, potentially catastrophic pressure oscillations in a range of propulsion systems, including liquid rocket engines (LREs).  The present studies focus on coaxial jet flows, both non-reactive and reactive, operating in the transcritical regime, i.e., in the thermodynamic regime where no phase boundaries exist.  The experiments are being conducted in collaboration with researchers at the Air Force Research Laboratory (AFRL) Rocket Propulsion Division (RQR) at Edwards Air Force Base.  Coaxial injectors have proven to be among the most effective and simple means of delivering reactants in rocket combustion devices. Since injector flows are directly involved in reactive processes inside combustors, it is crucial to understand how they contribute to and are affected by the physical mechanisms that lead to combustion instabilities.

The present projects involve a systematic study of externally applied acoustic oscillations on coaxial jet flows at the AFRL/RQR. For the past several years, UCLA EPRL graduate students have conducted these experiments, under the supervision of senior AFRL researchers, in the cryogenic supercritical Combustion Stability Lab (EC-4). These studies have involved non-reactive nitrogen coaxial jets operating in subcritical and transcritical conditions, and more recently have involved LOX/GH2 and will involve LOX/kerosene testing in a parallel reactive facility in EC-4.


  1. The Response of Cryogenic H2/O2 Coaxial Jet Flames to Acoustic Disturbances, David J. Forliti, Alireza Badakhshan, Jeffrey Wegener, Ivett A. Leyva, and Doug G. Talley, 53rd AIAA Aerospace Sciences Meeting, AIAA SciTech, (AIAA 2015-1607)

  2. Receptivity of a Cryogenic Coaxial Gas-Liquid Jet to Acoustic Disturbances, Jeffrey L. Wegener, David J. Forliti, Ivett A. Leyva, and Doug G. Talley, 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Propulsion and Energy Forum, (AIAA 2014-3487)

  3. Cryogenic High-Pressure Shear-Coaxial Jets Exposed to Transverse Acoustic Forcing, Teshome, S., Leyva, I. A., Talley, D., and Karagozian, A. R., Paper AIAA-2012-1265, 50th AIAA Aerospace Sciences Meeting, Nashville, TN, January 9-12, 2012.

  4. Preliminary results on coaxial jet spread angles and the effects of variable phase transverse acoustic fields, I.A. Leyva, J. I. Rodriguez, B. Chehroudi, and D. Talley, 46th AIAA Aerospace Sciences Meeting & Exhibit, Paper AIAA-2008-0950, January 2008.

  5. Effects of a variable-phase transverse acoustic field on a coaxial injector at subcritical and near-critical conditions, J. I. Rodriguez, I.A. Leyva, B. Chehroudi, and D. Talley, ILASS Americas, 21st Annual Conference on Liquid Atomization and Spray Systems.


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