Remotely Controlled Wind Tunnel Experiments for STEM Education With LabVIEW and CompactRIO

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"By combining the powerful features of CompactRIO, FPGA technology, and the ability to access LabVIEW front panels remotely, the system was able to meet all of the customer’s desired goals."

- Stuart McFarlane, Viewpoint Systems, Inc.

The Challenge:
Developing a system to remotely access research-quality wind tunnels to conduct real-time, hands-on experiments with tight, closed-loop control.

The Solution:
Using NI LabVIEW software and the CompactRIO platform for data acquisition and control.

Author(s):
Stuart McFarlane - Viewpoint Systems, Inc.
Jack Gilbert - Mech-Net

GDJ was founded by Jack Gilbert, a former educator whose main goal is to bring science, technology, engineering, and math (STEM) concepts from theory into hands-on practice. Through Mech-Net, he wanted to start a new and innovative service to help schools and universities operate research-grade wind tunnels and engine stands via the Internet. While teaching at an aviation high school, he noticed the study of aerodynamics fascinated students. GDJ has developed equipment for educational purposes for a number of years. They operate their laboratory equipment with GUI software to control basic equipment functions.

Some institutions were able to purchase them for their programs, but the equipment was expensive and required frequent maintenance, which often made it cost-prohibitive. There were also space, noise, and safety concerns. To make it cost-effective, accessing the UI gives users the benefits without actually owning the physical hardware and provides multiple users simultaneous access.

The CompactRIO controller runs the entire application. LabVIEW Real-Time is used for the main loops and interfacing with the FPGA, which performs the control and data acquisition. Real-time, deterministic control using the LabVIEW FPGA Module allows for higher feedback rates, which significantly improves stability.

Rather than build the UI on the host computer, we designed it as part of the real-time application running on the CompactRIO. A thin LabVIEW client application is installed on the user’s host computer and, by specifying the remote IP address and system port in the host location, the user can connect to the system and “drive” it as though they are in the lab.

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 rpm. 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

The system is capable of remote Internet and intranet control, real-time data acquisition, data logging, and closed-loop control of the wind tunnel under operation. The system offers tight integration between the inputs, load, and control outputs and is embedded in a small control cabinet mounted on the stand.

Figure 4. NI cRIO-9074 Integrated System With an NI C Series I/O Module Mounted in the Control Cabinet on the Stand

By combining the powerful features of CompactRIO, FPGA technology, and the ability to access LabVIEW front panels remotely, the system was able to meet all of the customer’s desired goals. Only paying a small hourly fee to operate the equipment remotely makes this unique learning experience affordable to a much larger audience.

Author Information:
Stuart McFarlane
Viewpoint Systems, Inc.
800 West Metro Park
Rochester, NY 14623
Tel: (585) 475-9555
srm@viewpointusa.com

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