Mixing Enhancement in Compressible Flows and Detonation Dynamics
Graduate Students: Daniel Alessandri (M. S.’ 93), Barbara Berger (Visiting Researcher CNRS, France, 1995)
Collaborators: Prof. Eli K. Dabora, University of Connecticut, Prof. James C. Hermanson, Worcester Polytechnic Institute
Project Summary
In this research effort, we are investigating the levels of mixing enhancement achievable when non-uniform composition (and density) jets and vortices interact with weak shock waves. Experiments involve planar imaging of Mie and Rayleigh scattering of the laser illuminated flow field downstream of shock interaction. The flow configurations studied so far include: (1) turbulent axisymmetric jet interacting with weak normal shock waves (Ms = 1.1 – 1.5) and (2) compressible vortex pairs colliding head-on with weak normal shock waves. Sample images from each are shown below. Additionally, interactions of multiple detonations are investigated experimentally to device new ways of anchoring oblique detonation waves in supersonic streams.
Shock-jet and Shock-vortex ring Interactions
  
Interaction of weak normal shock waves with a turbulent jet. Images from upper left corner clockwise: (1) Turbulent helium jet Red = 25,600, (2) Ms = 1.25, (x-x o )/d = 30.6, (3) Ms = 1.46, (x-x o )/d = 30.6, (4) Ms = 1.46, (x-xo )/d = 45.9 |
 
Rayleigh images of a propane vortex pair (left) and a propane vortex pair colliding head-on with a weak normal shock wave (right). Shock location is indicated by the arrow. |
Interaction of Periodically Generated Cylindrical Detonations
  
Framing pictures of successively initiated detonations in a stichiometric mixture of C2H2/O2 at 40 kPa to simulate pulsed initiation of cylindrical (or spherical) detonations in a hypersonic stream at different frequencies: 1.2×105 Hz (left),1.6×105 Hz (center),2.4×105 Hz (right). |
Framing pictures of successively initiated detonations in a stichiometric mixture of C2H2/O2 at 40 kPa to simulate pulsed initiation of cylindrical (or spherical) detonations in a hypersonic stream at different frequencies: 1.2×105 Hz (left),1.6×105 Hz (center),2.4×105 Hz (right).
Publications
Cetegen, B.M., Crary, L.F. and Dabora, E.K., “The interaction of periodically generated cylindrical detonations in a stimulated hypersonic flow”, Transactions of the Combustion Institute Vol. 28, 2000
Hermanson, J. C. and Cetegen, B. M., “Interaction of non-homogeneous axisymmetric turbulent jets with weak normal shock waves”, Physics of Fluids, Vol. 12 (5) pp.1210-1225, 2000
Hermanson, J. C. and Cetegen, B. M., “Mixing augmentation during interaction of weak shock waves with non-homogeneous turbulent jets”, Proceedings of the Twenty-seventh Symposium (International) on Combustion, pp. 2047-2053, The Combustion Institute, (1998)
Cetegen, B. M. and Hermanson, J. C., “Mixing Characteristics of Compressible Vortex Rings Interacting with Normal Shock Waves”, Combustion & Flame, Vol 100, pp.232-240, 1995.
Alessandri, D. S. and Cetegen, B. M., “Experiments on mixing enhancement in non-homogeneous axisymmetric jets swept by weak shock waves” Shock Waves @ Marseille IV,Editors: R. Brun and L. Z. Dumitrescu, pp. 331-336 Springer-Verlag, 1995.