Numerical investigation of ventilation efficiency in a Combat Arms training facility using computational fluid dynamics modelling

Abstract

Firing ranges critically depend on ventilation systems to minimize the exposure of personnel to ammunition refuse. A numerical analysis utilizing a computational fluid dynamics (CFD) method was used to simulate the ventilation system and predict airflow patterns within a 122-foot long, military firing range housing 21 firing stalls. The intent for this model was to identify back circulation causing firing emissions to entrain in occupied areas. Measured values at several locations within the facility were used for either input values in the model or for validation of the model solution. The analysis evaluated massless particles released at three heights to correspond with standing, kneeling, and prone firing positions. Additional predictions were completed using the recommended technical guidance for ventilation of small arms firing ranges to compare against flow dynamics of the current system. The results revealed particles circulating back behind the shooter and into the personnel occupied area. Lower supply air velocities correspond to more uniform flow and successful movement of particles downrange in the small arms firing range under investigation. The ventilation air velocity at the firing line recommended by the design guide was not achieved consistently despite the supply air velocity being set to design guide values. Overall, the results demonstrated that CFD models are useful aides for optimizing supply air velocities in current firing range facilities and for evaluating and developing design standards that provide the proper ventilation required for the health and safety of building occupants.