AME341bRF

AME341bRF - Final Report: Incompressible gas Dynamics: Wind...

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1 | P a g e Final Report: Incompressible gas Dynamics: Wind Tunnel Testing of Airfoils AME 341b: Mechoptronics II Michael Asfaw Abstract The purpose of the experiment is to correlate values with previous results and to see how an aircraft structure can be completely categorized by dimensionless grouping irrelevant of its size. Two Airfoils, a symmetric, NACA0010, and a cambered, SD7037, were placed in a wind tunnel section under two different steady air stream velocities. Lift and Drag forces were recorded by sensors within the airfoil supporting structure. These values were compared with the integral of the horizontal momentum defect to show dissimilarities for low angles of attack due to a high resolution of the Force Balance. The drag from momentum defect is then used to calculate and plot Coefficient of Lift versus angle of attack as well as obtain a polar plot ( C L as a function of C D ). These results were found to be different from what was expected due to boundary conditions and blockage effect which was a result of the insufficient size of the wind tunnel test chamber.
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2 | P a g e Nomenclature L Lift Force D Drag Force U o free stream velocity (inlet velocity) U w wake velocity ν a kinematic viscosity of air c Chord Length b span of airfoil (wing span) α angle of attack ( angle between incoming flow and chord line) C L coefficient of lift C D coefficient of drag ρ a density of air R e Reynolds number A Test section cross sectional area h width of airfoil test section S Platform area t time Introduction Just as its name suggests, a wind tunnel is a tube or tunnel that has man-made windblown through it at a certain speed. Scientists and engineers put a model of an airplane, or a test section of an airplane such as the airfoil, elevator, rudder, fin or the whole fuselage in the tunnel and then study the way air moves around the model. By investigating the motion of the streamlines and streak lines that form around the test section and recording dimensionless quantities such as Coefficient of lift and drag of, they get a pretty good idea of how a larger scale model such as an airplane of the same shape and control surface arrangement will probably fly. It is a lot easier, cheaper, and safer to build and test a model than to build and fly a real airplane. An illustration of how the wind tunnel works is displayed in Fig. 1; Figure 1: General schematic of a wind tunnel setup
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3 | P a g e An airfoil is vertically mounted in the test section with the load frame (force balance) as the supporting structure. Figure 2: Tunnel Schematic section showing a vertically place airfoil for better force measurements. It is beneficiary to mount the ai rfoil vertically because force of gravity (weight) won’t produce a unwanted moments due to uneven distribution of the airfoil weight when the angle of attack is changed. Wind tunnels work on the idea that a stationary model with air moving around it
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This note was uploaded on 05/09/2010 for the course AME 341BL taught by Professor Spedding during the Spring '08 term at USC.

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AME341bRF - Final Report: Incompressible gas Dynamics: Wind...

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