P14414 Arborloo Wind Resistance Test Stand

1. P14414 Arborloo Wind Resistance Test Stand BACKGROUND What is an Arborloo? An arborloo is a simple and inexpensive sanitation system that consists of a pit latrine that allows for composting human waste into organic fertilizer. Arborloos provide a means of sanitation for rural communities where conventional water treatment plants are not present. These structures are easily destroyed by the hurricane force winds that can be experienced in these communities every year. • Project Objectives: • Design a test stand to determine the wind resistance of various scale model arborloo designs • Test stand should provide information about the forces experienced by an arborloo during a Class I hurricane • Test stand should allow for safe testing of various arborloo sizes, shapes, and materials • Team should create a set-up for testing, devise a test procedure, and provide recommendations for the optimal arborloo shape and design based on testing results Theory Design CD – Drag Coefficient The drag coefficient is a dimensionless parameter that characterizes an objects resistance to fluid flow and allows for direct comparison of aerodynamic effects on different shapes. For certain shapes, the Coefficient of Drag stays constant independent of Reynolds Number. In the case of the team’s first prototype, which can be treated as a flat plate, the CD will stay constant for all Re larger than 1000. The design for the test stand utilizes the existing equipment of the KGCOE wind tunnel. The team created a metal flange that bolted onto the pre-existing base plate. A shaft runs through the flange and is used to support the load cell and the arborloo model. This shaft can be adjusted up and down according to the size of the model to be tested. A collar with a set screw is welded to the bottom of the flange and will be used to lock the load cell shaft in place. This information will be collected and processed using a data acquisition system and a software program will output useful data to the user. For data collection, a pressure scanner device outputs signal to a pressure transducer that feeds data to the Data Acquisitions Unit (DAQ) for the pressure test while the load cell feeds data straight to the DAQ. Velocity Profile and Pressure Distribution of scale arborloo exposed to 95 mph winds • Velocity Profile and Pressure Distribution of full size arborloo exposed to 95 mph winds • CFD modeling software was used to confirm that using a wind tunnel would be an effective way to mimic Type I hurricanes. • Modeling in CFD proved that using this method was valid and tests in the wind tunnel could be performed. • That coefficient of drag can then be used to calculate force felt on a full size arborloo, using the same equation. RESULTS • Testing provided a variety of results. The most current results do not match predicted values of Drag Coefficient: • Predicted CD: 1.2 • Observed Values: 2.0 • The team believes the walls of the wind tunnel are affecting measured wind speed. This is not uncommon as boundary layer effects and blockage effects are weaknesses of wind tunnel testing. ACKNOWLEDGMENTS • Dr. Brian Thorn • Sarah Brownell • Pedro Cruz Dilone • Kevin Gebo • Prof. John Wellin From Left to Right: Katie Bentley(ME), Greg Hyde(IE), Lori Liebman(ME), Joe Rojano(ME), Ray Zheng(ME)