Experiments are performed in an optically-accessible catalytic combustion chamber (see Fig. 1). The flow in the catalytic combustor can be either laminar or turbulent. Advanced laser‑based spectroscopic techniques are applied, in cooperation with the Combustion Diagnostics group, to map the species and temperature profiles along the streamwise plane of symmetry (see Fig. 2). In turbulent catalytic combustion, PIV is used to map the velocity field.

Two‑dimensional steady and transient elliptic fluid mechanical codes have been in‑house developed, which are capable of treating detailed heterogeneous and homogeneous chemical reaction schemes and all relevant heat transfer mechanism in the solid.

Analytical ignition criteria based on matched activation energy asymptotics are also derived.

Fig. 1: (a) Schematic of the high-pressure catalytic combustion test rig. The steam generator unit is used for simulating exhaust gas recycle. (b) Photograph of the test rig (top) and detail of the reactor under operation as seen through the side quartz windows.

Fig. 2: Optical setup for spontaneous Raman and laser induced fluorescence (LIF) measurements.

Recent studies

1)     Fuel-lean catalytic combustion of methane/air mixtures over platinum

Fig. 3: Comparison between measured (a) and predicted (b, c, d) maps of the OH radical in high‑pressure catalytic combustion of methane over platinum. The green arrows indicate the onset of homogeneous ignition. The predictions refer to different homogeneous chemical reaction mechanisms.

2)      Fuel-lean catalytic combustion of hydrogen/air mixtures over platinum

Fig. 4: Left graph: Comparison between measured (a) and predicted (b, c, d) maps of the OH radical in atmospheric pressure catalytic combustion of hydrogen over platinum. The predictions refer to different homogeneous chemical reaction mechanisms.

Right graph: Comparison between measured (symbols) and predicted (lines) transverse profiles of species mass fractions and temperature.

 3)   Turbulent catalytic combustion

Fig. 5: (a) PIV‑measured instantaneous vorticity maps in: (I) a non‑reacting isothermal channel flow with inlet Reynolds number of 30,000 and (II) in catalytic combustion flow with the same incoming Reynolds number. 

(b) Domains of flow laminarization in channel‑flow catalytic combustion in terms of inlet Reynolds number, wall temperature, and inlet turbulence intensity.

4)    Analytical ignition criteria in channel‑flow CST

Fig. 6: Left: analytical homogeneous ignition criterion in channel‑flow CST. Right: comparison of analytical and numerical solutions.