One-sixth scale model airbag modules have been used to investigate flow aspiration effects in passenger-side airbag modules. A similarity analysis between flows in the model and the prototype unit assures reasonable approximation of the actual flows. In the controlled flow environment of the model, flow visualization suggests that the underexpanded jet structure follows the universal relationship based on experimental data and shows that aspiration occurs through the aspiration holes. Detailed velocity measurements provide the ratio of the mass added to the discharged gas for a single firing. The same approaches can be applied in the design of full-scale airbag systems.