me 425: aerodynamics - toufiquehasan.buet.ac.bd 2016-lecture 1.pdf · • ansys fluent (me, buet...

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ME425: Aerodynamics1

ME 425: Aerodynamics

Dr. A.B.M. Toufique Hasan

Associate Professor

Department of Mechanical Engineering, BUET

Term: July 2016

04 September 2016

Lecture-1: Introduction

http://teacher.buet.ac.bd/toufiquehasan/courses.php


Introduction

Aerodynamics is the study of dynamics of gaseous fluids (air/gas),

especially the atmospheric interaction with moving bodies.

This field of engineering deals with the aerodynamic forces namely lift and

drag and moments and the heat transfer rates acting on a vehicle in flight.

These mechanical parameters greatly depends on the pattern of flow

around the vehicle.

And the resultant flow pattern depends on the geometry of the vehicle

(shape of the airfoil: NACA, SC, RAE, ONERA, BGK, NLR, DRA, OAT…

…), its orientation with respect to undisturbed free stream (angle of

attack-AOA), and the speed (Mach No.) and altitude (density) at which

the vehicle is moving.

Multi-element airfoilWing

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Introduction contd…

Fig. Viscous Flow around a circular cylinder at Re~300 (CFD)

Fig. Laser-induced-fluorescence (LIF) flow visualizations of wake past a circular cylinder at Re~650Source: Journal of Fluid Mechanics 2005; pp-215-252

Fig. Vortex shedding in side-by-side cylindersJournal of Fluid Mechanics 2014; pp-552-576

Fig. Vortex shedding from a square cylinders at Re~90Journal of Fluid Mechanics 2007; pp-169-178

Re ~100

Vortex street



Fig. Flow past an airfoil

Fig. Separation bubble from SD7003 airfoil at Re=66000Journal of Fluid Mechanics 2009; pp-129-153

streamlines

Chord line

AOA

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The complete flight of a vehicle/object is mostly comprises of the following

matters:

• Aerodynamics

• Propulsion and Power

• Structural mechanics/dynamics

• Stability and control

Aerodynamics is the fundamental of aerospace engineering (aeronautics).

A great scope is available for propulsion technology (Jet propulsion and

rocketry) and structural dynamics.



The physics of aerodynamics can be learnt from

• Theoretical aerodynamics (governing equations, simplification, theoretical modeling etc.)

• Experimental aerodynamics (wind tunnel, flow visualization-PIV, LIF, Schlieren, instrumentation, measurements etc.). ME, BUET has subsonic and supersonic (M~2.0) wind tunnels.

• Computational aerodynamics (governing equations, numerical techniques, computational resources, CFD)

Since the powerful computers are available now-a-days, aerodynamicproblems are conveniently solved using CFD software, such as

• ANSYS FLUENT (ME, BUET has licence)

• ANSYS CFX

• FASTRAN

• STAR CCM+

• ADINA

This course (ME 425) will cover the basics of aerodynamics based ontheoretical approach (theoretical aerodynamics).

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Aerodynamics can be broadly classified to two groups-

1. External aerodynamics

2. Internal aerodynamics

External aerodynamics Internal aerodynamics

1. Helicopter

2. Civil aircraft/passenger aircraft

3. Cargo aircraft

4. Military aircraft (most advanced)

5. Rockets

6. UAV

7. Spaceships

8. Wind turbine

9. Racing car aerodynamics

10. High speed train aerodynamics

1. Rocket nozzle (C-D nozzle)

2. Compressor/turbine blade

3. Fan blade

4. Butterfly valve

5. Cascade

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Air Berlin B737-700

B767 climbing in moist air

Lufthansa B737-300

Airbus A380



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First Flight: December 15, 2009

The Boeing 787-8 Dreamliner is asuper-efficient airplane. It will bring theeconomics of large jet transports to themiddle of the market, using 20 percentless fuel than any other airplane of itssize.

Cockpit crew: 2

Seating: 210 -250 passengers

Range 14200 – 15200 Km

Engine (s) - Two GE GENX /Two RollsRoyce’s Trent 1000.

Cruise speed: 902 Kmph (Mach 0.85)

Dreamliner: world's first major airliner to

use composite materials for most of its

construction

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Lockheed Martin F-22A Raptor

A-10 Thunderbolt II

Avro Vulcan Bombar



Space Shuttle

Space Shuttle Main Engine

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Ariane 5 just after lift-off

Shock diamonds

Flow structure inside nozzle



Unmanned air vehicle (UAV)

Flying of bird

UAV is used for

• Remotely piloted

• Surveillance

• Detection of biological, chemical or

nuclear materials

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Vehicles with wing spans less than approximately 6m and massesless than 25 kg are usually considered as UAV.

UAV are either remotely piloted or autonomous with artificial intelligence.

Requirements for a typical low-altitude small UAV include

– Long flight duration at speeds between 20 and 100 km/h

– Cruise altitude 3 to 300 m

– Light weight

– All-weather capabilities

Because of recent availability of very small sensors, video camera, andcontrol hardware, systems as small as 15 cm with mass of 80 g, referredto as micro-air vehicle (MAV), are now possible for limited missions.



The most important parameter in fluid dynamics/aerodynamics is theReynolds number, Re which is the ratio of inertia force to viscous force.

Fig. Reynolds number range for flight vehicles*

* http://www.annualreviews.org/doi/pdf/10.1146/annurev.fluid.35.101101.161102

µ

ρVL=Re

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Fig. Variation of Reynolds numbers with speed across insects, micro-airvehicles, birds, Model airplanes, Human powered vehicles, aircraft, hang-gliders and lighter than air airships. Adapted from (Lissaman 1983)



NACA 0012

NACA 0015

NACA 0024

NACA 2414

BOEING 737 Root

Boeing 737 Midspan

Boeing 737 Outboard

RAE 2822 (SC)

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Course content

1. Aerodynamic forces-drag and lift

2. Inviscid incompressible flow to include potential function, stream function, circulation

3. Basic potential flows

4. Kutta-Joukowski theorem

5. Airfoil theory

6. Wing theory

7. Aircraft propulsion

8. Aircraft performance; static and special performance

9. Introduction to stability and control


Reference texts:

1. Fundamentals of Aerodynamics- J Anderson

2. Aerodynamics for Engineers- John J Bertin

3. Aerodynamics for Engineering Students - E. Lo Houghton and PW Carpenter

4. Introduction to Flight - J Anderson

5. Aircraft performance and Design - J Anderson

me 425: aerodynamics - toufiquehasan.buet.ac.bd 2016-lecture 1.pdf · • ansys fluent (me, buet...

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