Engineering

Introduction:

Indoor Shooting RangeIndoor Shooting Range is an area provided with targets for the controlled practice of shooting. It usually have a back wall with a sloped earthen berm or bank, with reinforced baffles additionally situated along the roof and side walls. The smoke which comes out from the guns causes hazardous effects if inhaled. Ranges with proper ventilation pull smoke and lead particles away from the shooting line and discharge them from the building to reduce potential lead poisoning. 

 

Recirculating the Air at an Indoor Firing Range:

Filters can remove nearly all lead dust that passes through the HVAC system – depending on the type of filter, of course. Equally as important, however, is the ventilation system used at the range. Some traditional ranges use the effective pass through or “once” through ventilation system – taking 100% of supply air from outside. As such, these systems require 100% of air to be heated or cooled to the desired temperature, drastically increasing the cost of energy for the range. While the pass through HVAC systems still need filters and maintenance, the dangers posed to employees and shooters are far less prominent than those of the diluted or recirculated ventilation systems.

Because recirculating ventilation systems for indoor firing ranges in most climates are significantly more energy efficient than alternatives, it is far cheaper to maintain and has become common practice. While proper ventilation and filtration is imperative in all HVAC systems, the recirculating system in an indoor firing range poses particular challenges and risks and a greater threat to danger. Having the right filters in place can easily solve any issues before they become a problem. This will be the focus moving forward.

First and foremost, the air must be blowing from behind the shooting stations. Recommended rates of airflow vary from 50 to 100 feet per minute (fpm) (0.25 to 0.5) m/sec, the air flow should be visibly blowing all smoke and particles down range away from the shooters. In order to accomplish this effectively, the distribution of airflow must be equivalent across the entire line of shooters, with no obstructions in its path. This even distribution of air is known as laminar airflow, and it eliminates turbulent areas where particles and dust might drift back towards the shooters’ respiratory zone, otherwise called “backflow.”

 

Sample Analysis:

A sample CFD analysis is carried out to understand the behaviour of  airflow inside a shooting range room. 

The CFD studies for shooting range room were carried out using ANSYS- Fluent Solver. The Geometry for duct section and Room including the Bullet trap region were generated in CATIA V5-R21 as well as ANSYS-Design Modeler for 1:1 reference and resolving any ambiguity on the Flow domain side. 

The Geometry of the room contains 3 Air Handling Unit (AHU) and 1 Outlet. The total inlet mass flow rate through the all 3 AHU is 63,000 L/S. The Pressure Outlet condition is given to the Outlet for creating the suction.

 

Geometry of the Room:

Geometry

Meshed Model:

meshing

 Results:

Velocity Streamline:

STREAMLINES

 

Velocity Contour at Perforated Plate:

vc 1

 

 Velocity Contour at 1/4 Length of the Room:

vc 3

 

 Velocity Contour at mid of the Room:

vc 4

 

Velocity Contour just before the Exit:

vc 5

 Velocity Contour parallel to the floor at mid of the Room:

vc 6

 

 Velocity Contour parallel to the side wall at mid of the Room:

vc 8

Conclusion:

The flow simulation was carried out with different parameters and was validated with CFD prior to finalizing the Design.