Aerodynamic Force Measurement Yezad Anklesaria Graduate Student Aerospace Engineering Office: Toomey Hall 212 GTA- ME 242 yhar56@mst.edu Wednesday 13 February 2013

Overview Objective Wind tunnels and experimental equipment Experimental setup, procedure and measurements Momentum equation and drag Wake Expected Results Examples Reference

Purpose of Experiment Gain experience with setting up and performing aerodynamic experiment Learn some basic concepts in aerodynamic force measurement Gain experience with flow visualization Gain hands-on experience with common instrumentation used in the aerodynamic experiments

Wind Tunnel

Types of Wind Tunnel Test Section Speed Closed loop Open loop Low speed wind tunnel (0.3 > M) High Speed wind tunnels (0.4 < M < 0.75) Transonic wind tunnel (0.75 < M < 1.2) Super sonic wind tunnels (1.2 < M < 5) Hypersonic wind tunnels Mach (5 < M < 15)

Experimental Setup

Pitot Tube Principle of Operation Bernoulli’s Equation Stagnation pressure = static pressure + dynamic pressure P1= Static Pressure V1= Velocity of Flow P0= Total pressure r = Density Total Pressure Velocity Static Pressure

Experimental Wing NACA 0015 Airfoil Max. thickness =2.24 Chord: c = 16 inch Span : b = 16 inch

Data Collection Atmospheric data (Temperature and Pressure) Airfoil at 0o and 2o Drag Lift Velocity at various height Airfoil at 2o and 20o flap deflection Flow Visualization

Momentum Equation General Form Of Momentum equation Integral form of momentum equation for steady inviscid flow with no body forces

Drag U = Velocity of flow at a given location U = Free Stream velocity  = Density Of fluid v = Velocity of fluid S = Area of the wing Cd = Coefficient of Drag

Wake Region A wake is the region of recirculating flow immediately behind a moving solid body, caused by the flow of surrounding fluid around the body. Wake flow is generally turbulent As with all wave forms, it spreads outward from the source until its energy is overcome or lost, usually by friction or dispersion.

5o Angle of Attack 10o Angle of Attack 15o Angle of Attack

Airfoil in Wind Tunnel

Expected Results Drag Calculation using momentum theory Graphical representation of drag

Expected Results Velocity deficit Flow visualization Plot Velocity deficit to show wake in flow field Flow visualization Describe flow at various setups of airfoil

Reference and Further Reading Fundamentals Of Aerodynamics J. D. Anderson Similarity Of flows, Pages (40-50) Chapter 1, section 1.8 Equation of Drag, Pages (127-133) Chapter 2, section 2.6 Pages (197-210) Chapter 3, section 3.3 Wind tunnels Pages (197-210) Chapter 3, section 3.3 Pitot Tube Pages (210-219) Chapter 3, section 3.4 History Of Wind Tunnels http://www.grc.nasa.gov/WWW/k-12/WindTunnel/history.html

Aerodynamic Testing Mercedes-Benz SLS AMG Development and Testing Wind tunnel http://www.youtube.com/watch?v=sV_6E1Lh7yo BMW Aerodynamic Testing http://www.youtube.com/watch?v=eszhVxE_9-8

Questions