# Lift and Drag on an Airfoil

Topics: Airfoil, Aerodynamics, Drag equation Pages: 32 (5559 words) Published: October 10, 2012
Course Number and Name:
Me 646 Experimental Measurement & Data Analysis
Semester and Year:
Spring ‘12

Name of Lab Instructor:
Professor Goulet

Lab Section and Meeting Time:
Section 4 Thurs. 2:10 PM

Report Type:
Internal Report

Title of Experiment:
Aerodynamic Lab: Lift and Drag on an Airfoil
Date Experiment Performed:
03/29/2012

Date Report Submitted:
04/12/2012

Names of Group Members:

Michael Stevens

Abstract:
The Aerodynamics Lab: Lift and Drag on an Airfoil experiment examined the lift and drag on a NACA 0012 airfoil inside a wind tunnel. The objective of the experiment was to obtain information relating to the lift and drag of the airfoil, such as lift forces, lift coefficients, drag forces including its contributors, and drag coefficients. The data was analyzed using Matlab by two different methods, through pressure distributions, and through a force balance. Approximations of the lift and drag data to compare with the experiment results were attempted to test which methods were effective, or not effective. These approximations were conducted using a Javafoil simulation, and also using thin airfoil theory.

The lift forces calculated from the pressure distribution measurements were slightly higher than the directly measured forces from the force balance, however, the pressure distribution measurements followed the same trend as the force balance data. This represented a calibration error in the pressure distribution measurements. Calculations gave a maximum coefficient of lift of

. The drag data
showed that form drag was the largest contributor to total drag, with skin friction drag and induced drag having only small contributions. Javafoil simulations gave similar results of coefficients of lift for the given airfoil, of which closely matched the force balance data. It was determined that thin airfoil theory is only acceptable for a rough estimate at angles of attack of up to the stall angle, which was about 9° for the NACA 0012 airfoil. The NACA 0012 airfoil is a symmetrical airfoil with simple geometry. This makes the airfoil better for fabrication purposes, as well as for experimental calculations. However, for better design, airfoils that generate more lift due to their pure geometry would be better for use on lift seeking machines such as aircraft.

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Experimental Design:
The objective of the Aerodynamics Lab was to obtain a measurement of lift forces, drag forces, and other related criterion to an airfoil at different angles of attack inside a wind tunnel. The wind tunnel that was used for the experiment was the UNH ME student wind tunnel, and was set at a constant flow speed at 3 on the speed dial. The airfoil that was utilized for the experiment was a NACA 0012 airfoil, with a chord length 150mm, and span of 300mm. The airfoil was equipped with ten pressure taps on the top surface, and ten pressure taps on the bottom surface. For pressure measurements, these taps were each connected to a port on a manometer with water as the working fluid. In addition, a Pitot-static tube and a port exposed to atmospheric pressure were also connected to the manometer for pressure measurements. Attached to the airfoil was a TecQuipment AFA2 single lift and drag balance for measuring lift and drag force data directly.

Figure 1: Experimental setup of AFA2 indicating placement of protractor, model clamp, load cell, and airfoil.

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Figure 2: Experimental setup of manometer indicating placement of the manometer, airfoil, and Pitot-tube.

The first part of the experiment consisted of gathering pressure data from around the airfoil to generate a pressure distribution. With the airfoil and force balance set up in a manner similar to Figure 1, the airfoil was first adjusted to a 0° angle of attack via the protractor, then tightened in place with the model clamp. The wind tunnel was then turned on to a speed setting of 3. To measure the pressure...