Flow-blurring sprays and lean premixed prevaporized combustion

In a flow-blurring atomizer, atomizing air enters the gap between the liquid tube and the exit orifice and partly flows back into the liquid tube. The resulting bubbly two-phase mixture bursts as it leaves the orifice, producing a fine, well-dispersed spray at low air-to-liquid ratios.

The spray is injected into swirling primary air, evaporates and mixes in a premixing section, and burns as a lean premixed flame. The combustor is mapped for emissions and stability with diesel and ethanol.

MHRD SPARC project, 2019 – 2023

Combining the LIF and Mie signals from SLIPI gives the Sauter mean diameter across the whole plane, while PIV and phase-Doppler measurements provide droplet velocities and a point check on drop size.

Swirling air opens the spray, moves the larger drops outward and changes where fuel vapour is available to the flame, which is why spray–swirl interaction matters for LPP combustion.

Fuel

Diesel

Air-to-liquid ratio

4.5

Swirl air

200 SLPM

Equivalence ratio

φ = 0.73

Thermal power

≈ 12 kW

The flame burns blue and compact, with no visible soot, showing that the spray evaporates and premixes before reaching the flame. Diesel and ethanol both run with low NO_x.