SALT RESEARCH
VENTILATION FANS
November 24, 2008
1. Air Handling System: Real-time model for an Institutional building:
http://livebuilding.queensu.ca/building_systems/heating_cooling_system/real_time_model
http://livebuilding.queensu.ca/building_systems/heating_cooling_system/air_handling
2. VERTICLE WIND TUNNELS
http://www.sky-chaser.com/skydive.htm
Used for sky-diving training and practice. This construction provides the same lift as the fan in the script.
Flying in the narrow updraft provides some special challenges to precision fying, especially holding a body position - Important for any skydiving discipline. For inexperienced jumpers, or first-timers, a VWT can give the feeling of freefall with the anxiety, fear-of-heights, and cost removed from the equation, to name a few. In a nutshell, a VWT works by creating a powerful updraft using a fan or propeller apparatus. This vertical wind is anywhere from 80 to 145 MPH, depending on the VWT capabilities and skill-level of the jumper. Instead of the jumper falling through the air at terminal velocity, in a VWT the air is moving, causing the jumper to hover (or "float") on that air stream. The updraft must be the same speed as the relative wind would be in free fall to reach equilibrium (equivalent to terminal airspeed).
Vertical wind tunnels have had many designs when they first started out. The original was invented by taking a large propeller, driven mainly by a diesel engine, to produce an updraft sufficient to "float" a jumper. An excellent example of this setup can be seen down below in the SUMMERFEST section where the HURRICANE I VWT is shown. Like the diagram above, the left schematic shows the setup of such a VWT. These are run outdoors, and feature a platform and padding / netting around the flight "chamber". A gearbox, clutch, and bevel-drive (90 degree gearing) mates the propeller to the engine, which develops at least 600 horsepower. The prop-wash enters a diffuser, to smooth out the airflow and distribute it evenly across the flight area. These VWT's operate at about 80 to 110-MPH, and most are portable units. These can be operated at theme parks, drop-zones, and the like. The disadvantages are exposure to the elements and low airspeeds.
A new and far-more advanced version of the VWT came out in the late 1990's with more engineering (Sky-Venture) for it's specific purpose, rather than just being downwind of a large, noisy, and turbulent propeller. This next design offers a higher airspeed, smoother airflow, and the ability to operate in any weather. The flight chamber is enclosed in a building, which also can include shops, gear, spectator, and training rooms. Instead of the air being blown into the chamber, it is removed from the top, creating a suction which draws air through a venturi and screen at the base of the unit. The eliminates almost all turbulence and allows a strong and steady airstream across the entire flight chamber. Usually 5 (or more) electric fans power the unit, each developing at least 150 horsepower. The exhaust vents to the atmosphere (open system, non-recirculating).
Also - To ease some suspicions - There is NO WAY a person in the chamber can reach the fans via the updraft, due to the shape of the tunnel throat at the top, and lower airspeed due to divergence. Many units have a new synchronous frequency drive to control the motors precisely and quickly change airspeeds. Airpeeds in these units range from 110 to 145-MPH, and can suit any skill level, from beginners to expert free-fliers. The disadvantages of the unit is lack of portability and initial construction costs. Also, although the unit can operate in any weather, temperature is not controlled as it is an open system.
VIDEO
Glimpse of NASA verticle spin tunnel fan:
Click on ‘view video’
http://www.nasa.gov/mission_pages/constellation/orion/orion-spintunnel.html
