Gas Dynamics Engineering Whitepaper

Supersonic Laval Nozzle Dynamics & Boundary Layer Slag Ejection

In ultra-high power laser cutting (20kW–60kW) of thick structural plates (30mm–80mm), standard conical nozzles produce normal shock waves at the plate entrance, dissipating dynamic gas pressure and allowing molten slag to re-adhere to the lower kerf. ACTCNC de Laval convergent-divergent supersonic nozzles accelerate assist gas to Mach 1.5–2.2, maintaining parallel high-momentum jet streams through deep kerf slots.

1. Conventional Conical Nozzles vs. ACTCNC Supersonic Laval Nozzles

Nozzle Architecture	Jet Exit Velocity	Shock Wave Formation	Gas Consumption Reduction	Bottom Dross Slag (50mm Plate)
ACTCNC Supersonic Laval Nozzle	Mach 1.8 – 2.2 (Supersonic)	Smooth Expansion (No Detached Shock)	Up to 35% Nitrogen Saved	Zero Dross (Direct Assembly Finish)
Standard Conical High-Pressure Nozzle	Mach 0.8 – 0.95 (Subsonic)	Severe Bow Shock at Surface	Baseline Consumption (100%)	Heavy Slag Beads (Requires Grinding)

2. Deep Kerf Boundary Layer Momentum Retention

By preventing premature gas jet expansion, the aerodynamic wall shear stress remains over 4x higher at the plate bottom exit, cleanly expelling heavy iron oxide and molten stainless steel pools.