There are many strong endothermic chemical reactions achieved by super-high temperature

they need quickly quenching to avoid reverse reaction for obtaining substantial yield. Based on our experiments of CO2 pyrolysis by thermal plasma

where a non-conventional quenching was achieved with setting a converging nozzle at the exit of reactor to lead the pyrolysis gas at high speed into cooling tube

the reverse reaction CO+O=CO2 was unusually suppressed and very high CO2 conversion was achieved. To understand the mechanism of the novel quench phenomena

a CFD Simulation was carried out. It verified that a quenching rate of 107 K·s-1 could be expected

but the quench phenomena cannot be understood only by gas dynamics principle. A deep analysis on simulation revealed that converging nozzle resulted in viscous fluid strong rotating eddy in the cooling tube

it is the strong rotating eddy that enhance greatly both of the fluid entrainment into body jet and the forced heat transfer of the fluid at the cooling tube before entrainment.