F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
F01N1/00—Silencing apparatus characterised by method of silencing
F01N1/08—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling
F01N1/12—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling using spirally or helically shaped channels