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Applied Aerodynamics - I
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o Course Contents (Tentative)
Introductory Thoughts
Historical Perspective
Flow Similarity
Aerodynamic Coefficients
Sources of Aerodynamic Forces
Fundamental Equations & Principles
Inviscid & Incompressible Flow
Incompressible flow over Airfoil and Finite Wing
Wing Body Combination
Aircraft Performance
Applied Aerodynamics - I
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o Course Evaluation
Resources:
• Lecture & Slides
• Book: Fundamentals of Aerodynamics – 2010 - John D. Anderson
Aircraft Performance and Design – 1999 - John D. Anderson
Quizzes 20%
Assignment 5%
Mid-Term Exam 25%
Final Term Exam 50%
Introductory Thoughts
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o Aerodynamics
Introductory Thoughts
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o Preview
Read section ‘1.1 IMPORTANCE OF AERODYNAMICS’ from the book ‘Fundamentals of Aerodynamics’
What is fluid?
Hydrodynamics, Gas Dynamics and Aerodynamics?
Introductory Thoughts
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o Preview
Douglas DC-3, one of the most famous aircraft of all time, is a low-speed subsonic transport designed during
the 1930s
Without a knowledge of low-speed aerodynamics, this aircraft would have never existed
Introductory Thoughts
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o Preview
Boeing 707 opened high-speed subsonic flight to millions of passengers beginning in the late 1950s
Without a knowledge of high-speed subsonic aerodynamics, most of us would still be relegated to ground
transportation
Introductory Thoughts
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o Preview
The Bell X-1 became the first piloted airplane to fly faster than sound, a feat accomplished with Captain Chuck
Yeager at the controls on October 14, 1947
Without a knowledge of transonic aerodynamics (near, at, and just above the speed of sound), neither the X-1,
nor any other airplane, would have ever broken the sound barrier
Introductory Thoughts
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o Preview
Lockheed F-104 was the first supersonic airplane point-designed to fly at twice the speed of sound,
accomplished in the 1950s
Introductory Thoughts
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o Preview
Lockheed-Martin F-22 is a modern fighter aircraft designed for sustained supersonic flight
Without a knowledge of supersonic aerodynamics, these supersonic airplanes would not exist
Introductory Thoughts
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o Preview
An innovative new vehicle concept for high-speed subsonic flight is the blended wing body
Blended-wing-body promises to carry from 400 to 800 passengers over long distances with almost 30 percent
less fuel per seat-mile than a conventional jet transport
This would be a “renaissance” in long-haul transport
Introductory Thoughts
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o Preview
Primary objectives of studying aerodynamics:
• External Aerodynamics: The prediction of forces and moments on, and heat transfer to, bodies moving
through a fluid (usually air)
• Internal Aerodynamics: Determination of flows moving internally through ducts
Introductory Thoughts
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o Preview
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Streamlines
A moving fluid element traces out a fixed path in space. As long as the flow is steady (i.e., as long as it does not
fluctuate with time), this path is called a streamline of the flow
Drawing the streamlines of the flow field is an important way of visualizing the motion of the gas
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Shear Stress
The shear stress τ is the limiting form of the magnitude of the frictional force per unit area, where the area of
interest is perpendicular to the y axis
Shear stress acts tangentially along the streamline
Introductory Thoughts
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o Fundamental Aerodynamic Variables
Shear Stress
Value of the shear stress at a point on a streamline is proportional to the spatial rate of change of velocity
normal to the streamline at that point
For the flow, dV/dy is the velocity gradient
τ ∝ dV/dy
The constant of proportionality is defined as the viscosity coefficient (μ)
Introductory Thoughts
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o Units
Introductory Thoughts
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o Aerodynamic Forces and Moments
Aerodynamic forces and moments on the body are due to only two basic sources:
1. Pressure distribution
2. Shear stress distribution
No matter how complex the body shape may be, the aerodynamic forces and moments on the body are due
entirely to the above two basic sources
The only mechanisms nature has for communicating a force to a body moving through a fluid are pressure and
shear stress distributions on the body surface
Introductory Thoughts
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o Aerodynamic Forces and Moments
The net effect of the p and τ distributions integrated over the complete body surface is a resultant aerodynamic
force R and moment M on the body
The flow far away from the body is called the freestream, and hence V∞ is also called the freestream velocity
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o Aerodynamic Forces and Moments
