Theory and Evaluation of Auxiliary Combustion (Torch) Chambers

The theory for the design of an auxiliary naturally aspirated, combustion (torch) chamber relates the generation of combustion turbulence, intensity of turbulence, torch chamber volume and orifice diameter to the basic combustion process. Sample calculations show how to compute the thickness of the combustion wave, the characteristic time of turbulence required to complete the combustion in a given time interval, the optimum torch chamber volume and the orifice diameter.

Engine tests show that a significant reduction in HC and NOx emission levels can be achieved through the use of a torch ignition system. The combination of torch chamber geometry and torch nozzle orientation provides a control over the burn rate, rate of pressure rise, flame induced turbulence and swirl. Based on the data from the nozzles tested, the use of a swirling turbulent flame generated near the exhaust valve appears to be the most promising form of torch ignition.