Passive scalar interface in a spatially evolving mixing layer (A. Attili and D. Denker)

Quartz nozzle sampling (D. Felsmann)

Dissipation element analysis of a planar diffusion flame (D. Denker)

Turbulent/non-turbulent interface in a temporally evolving jet (D. Denker)

Dissipation elements crossing a flame front (D. Denker and B. Hentschel)

Particle laden flow (E. Varea)

Turbulent flame surface in non-premixed methane jet flame (D. Denker)

DNS of primary break up (M. Bode)

Diffusion flame in a slot Bunsen burner (S. Kruse)

Various quantities in spatially evolving jet diffusion flame (D. Denker)

Slowly Propagating Flames under Microgravity

Under gravitational conditions, buoyancy can strongly influence burning characteristics of a slowly propagating flames. The gravitational force can lead to a deformation of the initially spherical flame shape, which makes the determination of laminar flame speed, a fundamental metric of a combustible mixture, quite challenging. The upward motion of buoyant flames induces a complex flow resulting in flames with mushroom-like shapes. Therefore, the validity of the existing flame speed extraction techniques for slowly propagating flames is unclear. Consequently, the accuracy of the experimental data obtained under normal gravity should be addressed. By suppressing the effect of buoyant flame motion under microgravity, laminar flame speeds can be extracted accurately. The comparison of flame speed data obtained with and without gravitational forces will lead to the development of novel post-processing routines for buoyant flames.

Typical Schlieren images of diethoxymethane/air flames non-affected (left) and affected (right) by buoyancy.

Experiments are carried out under microgravity conditions obtained:

  • during parabolic flights on board the Airbus A310 ZERO-G. Periods of 22 s of weightlessness condition under 10-2 g are achieved during those flights. This project is conducted together with CNRS-ICARE laboratory in France.
  • in the Drop Tower facility in Bremen, providing high-quality conditions of weightlessness for about 4.7 s.

Airbus A310 ZERO-G - source: (left) and an inside view of the Bremen Drop Tower - source: Zarm (right).