Wind tunnel design
With the Mech-Net service, students can control the wind tunnels via remote panels. They can turn the wind tunnel on and off, control motor speed with loop feedback to enter a desired velocity, and adjust the motor speed to obtain velocity. Users can remotely raise and lower the yarn streamer for the airfoils. Pressure transducers display data to the GUI.
Figure 2: Airfoil with yarn streamers in wind tunnel section
The hardware was designed in conjunction with NASA Glenn Research Center in Cleveland, Ohio, to provide ultra-low turbulence, straight-line (laminar) air flow, which permits true aerodynamic engineering and data acquisition and analysis. Flotek wind tunnels bring advanced aeronautic design principles to the high school and college laboratory. The largest model used is a Flotek 1440, which is a subsonic wind tunnel with a 12’ by 12” by 36” test section where air flow velocity can reach up to 90 mph. The tunnel is fitted with a 20-tube manometer for enhanced visual reference with a two-component balance beam for measuring drag and side forces.
Figure 3: Flotek 1440 with local LabVIEW display
LabVIEW software can display up to 16 real-time readings of pressure and velocity over the test object while controlling the angle of attack and fan revolutions per minute. An airfoil stepper motor controller allows for computer control of the airfoil angle of attack from a slide bar on the LabVIEW remote front panel. A separate program calibrates the airfoil angle of attack manual degree reading to the computer slide bar degree reading.
As a result, students can conduct comprehensive experiments remotely. Interactivity includes adjustable test section velocity and airfoil angle attack, real-time updates of data and setpoints, and an audio and video server to enhance realism. With a change of IP address, different airfoils can be selected, such as the National Advisory Committee for Aeronautics NACA 0015 (Symmetrical), NACA 2415 (Trainer), and NACA 4415 (High Lift Amphibious Aircraft). The pressure tappings in the airfoil are connected to pressure transducers to demonstrate lift versus angle of attack relationship and effect of stall on the upper surface airflow.
Figure 4: User client interface for control and display of pressure over airfoil in wind tunnel