Shocks are formed by merge of compression waves with each other and its magnitude is enhanced or declined by catching compression waves or expansion waves behind the shock respectively.

Airbag sensors and other components of the collision and shock is very sensitive, so we should try to avoid collision and impact, so as to avoid the sudden expansion of the airbag unnecessary.

At the region near the nozzle exit, a vibrating flow phenomenon is found, which is associated with the expansion waves and shock waves reflections inside the gas jet.