REAL GAS EFFECTS IN HEATED GAS INFLATORS

Currently, almost all new vehicles are equipped with airbags. A common type of airbag inflator is the Heated Gas Inflator (HGI). These inflators are cylindrical shaped canisters that are filled to very high pressures with a gaseous mixture of fuel and air. The mixture is ignited from one or both ends of the cylinder. The resulting high temperatures from combustion heat the excess air, which is then used to inflate the airbag. Once the mixture is ignited large pressure waves form, traveling along the length of the tube. These waves, inherent to the design of the inflator, do not allow the use of a volume averaged assumption for the combustion chamber. Therefore, it is necessary to use a Computational Fluid Dynamics (CFD) code to model the dynamic nature of the inflator. Commercial CFD codes are readily available that could be used to model the HGI. Thes