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Aerospace Propulsion: Transverse Jet Control

Propulsion: Pulse Detonation Wave Engine Simulation

Alternative Fuels: Acoustically Coupled Droplet Combustion Control

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


(9/19/07) Juliett Davitian has won the 2007 AIAA Outstanding Aerospace Engineering M.S. Student Award.
Congratulations!

(06/07) Juliett Davitian has won the AE outstanding M.S. recipient award and Hann Mao has won the AE outstanding B.S. recipient award for 2007. Congratulations!

(06/06) Leo Alves has won the MAE outstanding PhD recipient award and Marcus George has won the AE outstanding MS recipient award for 2006. Congratulations!

(05/06) Ann Karagozian has completed chairing two studies for the Air Force.

(09/05) Juliett Davitian has won a three year NASA Graduate Student Research Program Fellowship, commencing in the Fall of 2005.

(5/05) Ann Karagozian has been appointed the Vice Chair of the Air Force Scientific Advisory Board.

(1/05) Srinivasan Dattarajan MS '02 , PhD '04 won the 2004 Best Student Presentation award from the AIAA Microgravity Technical Committee.

(5/12/04) Sevan Megerian Wins First Place at AIAA Student Conference, 2004.

(8/03) Lydia Treviño featured in UCLA Engineer—

(6/03) Robert Lobbia has received a special scholarship award from Aviation Week & Space Technology—the Next Century of Flight (NCF) award.


Click here for the latest group publications.


Researchers: Prof. Ann Karagozian, Prof. Robert M'Closkey, Prof. Luca Cortelezzi (McGill Univ.), Prof. Robert Kelly, Juliett Davitian (grad), Edson Rodriguez (grad), Cory Hendrickson (grad), Daniel Getsinger (grad)

Former Researchers: Sevan Megerian (grad), Leonardo Alves(grad), Marcus George (grad), Steve Shapiro (grad), Jonathan King (grad), Thierry Schuller (grad, Ecole Centrale de Paris), Robert Lobbia (undergrad), Stepan Shahinian (undergrad), Kristy Dalrymple (undergrad), Priya Sheth (undergrad), Rebekah Tanimoto (undergrad), Tom Berger (undergrad), Jeremy Ma (undergrad), Dr. Yen-Cheng Chen (postdoc)

Research Supported By:

 

National Science Foundation

and

NASA Dryden

 
 

Smoke visualization of the transverse jet with square wave forcing.

 
 

Jon King (right) and Steve Shapiro (left) photographing the mixing of a transerse jet with square wave forcing.

 
 

Shown above is 3D vortex element simulation of a pulsed transverse jet exposed to square wave excitation, with R = Uj / U∞ = 2.58, at a scaled frequency of 0.3 and duty cycle of 10%. (click image to run *.mpg movie file, 10MB)

This project involves examination of the fundamental features of the pulsed or acoustically excited transverse jet, a flowfield which may be applied to fuel injection as well as dilution air injection in gas turbine engines, and which can potentially be controlled via active means so as to improve engine efficiency and reduce emissions. Current activities involve: 1) experiments on gas phase jets in crossflow, including instability characterization and open and closed loop controlled acoustic excitation. 2) vortex element simulations of the unforced and forced jet in crossflow with a detailed examination of the evolution of the vortical structures associated with the jet. 3) development of control strategies for optimization of jet behavior. 4) linear stability analysis as well as full 3D Navier-Stokes simulations of reactive and non-reactive transverse jets.

The UCLA combustion laboratory's experiment setup for this project includes a low speed wind tunnel, and a range of alternative jet nozzles (both flush and elevated with respect to the lower tunnel wall). The data acquisition system allows for accurate system identification as well as open and closed loop control. A spectrum analyzer is used to extract frequency response of the input signal (speaker voltage) over the output signal (jet velocity). These Bode plots are used to create a plant model of the pulsed jet in crossflow. With the knowledge of the plant model an inverted model is used to create a compensator that gives a new compensated system Bode plot that is both flat in magnitude and matched in phase. The compensator allows us to explore different temporal waveforms (square wave, sine wave) for transverse jet forcing, with a range of operating conditions.  Optimization of jet forcing conditions to achieve desired flow features (penetration, spread, etc.) is also being explored.  More recent studies have focused on an exploration of transverse jet nearfield upstream shear layer instabilities, which vary significantly depending on the jet-to-crossflow velocity ratio R.  These studies are being conducted via gas phase experiments in the above-mentioned wind tunnel, via linear stability analysis (with discontinuous and continuous base flows for the transverse jet), and via full 3D transient Navier-Stokes simulations. 

 

 

 

 

Publications:

  1. Transverse Jet Shear Layer Instabilities. Part II: Linear Analysis for Large Jet-to-Crossflow Velocity Ratios, Alves, L. S. de B., Kelly, R. E., and Karagozian, A. R., Journal of Fluid Mechanics, Vol. 602, pp. 383-401, 2008.

  2. Controlled Excitation of Transverse Jet Shear Layer Instabilities, Davitian, J., Hendrickson, C., Getsinger, D., M'Closkey, R. T.., and Karagozian, A. R., Western States Section/The Combustion Institute Spring Meeting, USC, Paper 08S-24, March, 2008.

  3. Strategic Control of Transverse Jet Flows, Davitian, J., Rodriguez, E., Hendrickson, C., M’Closkey, R. T., and Karagozian, A. R., 46th AIAA Aerospace Sciences Meeting, AIAA Paper AIAA-2008-0741, January, 2008.

  4. Transverse Jet Shear Layer Instabilities. Part I: Experimental Studies, Megerian, S., Davitian, J., Alves, L. S. de B., and Karagozian, A. R., Journal of Fluid Mechanics, Vol. 593, pp. 93-129, 2007.

  5. Local Stability Analysis of an Inviscid Transverse Jet, 3. Alves, L. S. de B., Kelly, R. E., and Karagozian, A. R., Journal of Fluid Mechanics, Vol. 581, pp. 401-418, 2007.

  6. Optimization of Controlled Jets in Crossflow, Shapiro, S., King, J., M'Closkey, R. T, and Karagozian, A. R., AIAA Journal, Vol. 44, No. 6, pp. 1292-1298, 2006.

  7. Linear Stability Analysis of Jets in Crossflow, Alves, L. S. de B., Kelly, R. E., and Karagozian, A. R., 43rd AIAA Aerospace Sciences Meeting, AIAA Paper AIAA-2005-1118, January, 2005.

  8. Evolution of Shear Layer Instabilities in the Transverse Jet, Megerian, S. and Karagozian, A. R., 43rd AIAA Aerospace Sciences Meeting, AIAA Paper AIAA-2005-0142, January, 2005.

  9. Control of Vorticity Generation in an Acoustically Excited Jet in Crossflow, Karagozian, A. R., Megerian, S., Alves, L, George, M., Kelly, R. E., and M'Closkey, R. T., 43rd AIAA Aerospace Sciences Meeting, Invited AIAA Paper 2005-0303, January, 2005 .

  10. Evolution of Shear Layer Instabilities in the Transverse Jet, Megerian, S. and Karagozian, A. R., AIAA Region VI Student Conference, UCLA, AIAA student paper, FIRST PLACE WINNER M.S. student division, April, 2004.

  11. Manipulation and Control of Transverse Jets, Karagozian, A. R., Cortelezzi, L., and Soldati, A., eds., CISM Courses and Lectures No. 439, Springer-Wein New York, 2003.

  12. Background on and Applications of Jets in Crossflow, in Manipulation and Control of Transverse Jets, Karagozian, A. R., CISM Courses and Lectures No. 439, Springer-Wein New York, 2003

  13. Jets Injected Normally into Compressible Crossflow, in Manipulation and Control of Transverse Jets, Karagozian, A. R., Wang, K. S. C., and Smith, O. I., CISM Courses and Lectures No. 439, Springer-Wein New York, 2003.

  14. Three-Dimensional Vortex Modeling of Unforced Transverse Jets, in Manipulation and Control of Transverse Jets, Cortelezzi, L. and Karagozian, A. R., CISM Courses and Lectures No. 439, Springer-Wein New York, 2003.

  15. Active Control of Jets in Crossflow, in Manipulation and Control of Transverse Jets, Karagozian, M'Closkey, R. T., King, J. M., Cortelezzi, L., and Karagozian, A. R., CISM Courses and Lectures No. 439, Springer-Wein New York, 2003.

  16. A Framework to Design Controllers for Engineering Applications of Transverse Jets, in Manipulation and Control of Transverse Jets, Cortelezzi, L., M’Closkey, R. T., and Karagozian, A. R., CISM Courses and Lectures No. 439, Springer-Wein New York, 2003

  17. The Actively Controlled Jet in Crossflow, R.T. M'Closkey, J. King, L. Cortelezzi, A.R. Karagozian, Journal of Fluid Mechanics, Vol. 452, No. 1, p. 325, February, 2002.

  18. On the Formation of the Counter-Rotating Vortex Pair in Transverse Jets, Cortelezzi, L. and Karagozian, A. R., Journal of Fluid Mechanics, Vol. 446, pp. 347-373, November, 2001.

  19. Actively Controlled Transverse Gas Injection, L. Cortelezzi, J. King, R. Lobbia, R.T. M'Closkey, A.R. Karagozian, IEEE Conference on Decision and Control, Invited Paper CDC00-INV4905, December, 2000.

 

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