1 Model Testing and Drag Reduction Technique Asi Bunyajitradulya (ABJ) 2145-392 Aerospace Engineering Laboratory II.

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Model Testing and Drag Reduction Technique

Asi Bunyajitradulya (ABJ)

2145-392 Aerospace Engineering Laboratory II

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In the design and development of engineering equipment:

Need certain data,

Not economical to build and test a life-size equipment right from the beginning,

Computer-Aided-Design/Engineering (CAD/CAE) helps in the initial design stage,

but it still requires verification from the testing.

Motivation

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Have you ever wonder?

From http://www.windtunnels.arc.nasa.gov/pics/12FT/12t2 From http://www.boeing.com

Model testing

Lift ~ O(100 N)

Real thing

Lift ~ O(100 tons)

?

Have you ever wonder how we can do that?

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How can we estimate the performance (e.g., lift and drag) of a life-size prototype with

the testing of a scaled model?

What underlying principle allows us to test a scaled-model and use the resulting data

to estimate the performance of a life-size prototype?

Dimensional analysis

Buckingham’s PI Theorem

Similarity

Background

Model Testing

Flow Visualization of Flow Past Delta Wing in A Wind Tunnel

Flow Visualization of Flow Past Delta Wing in A Wind Tunnel

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Lift and Drag, and Cl and Cd of An Airfoil,Dimensional Analysis and Model Testing

Drag and Drag Reduction Technique

From Van Dyke, M., 1982, An Album of Fluid Motion, Parabolic Press, Stanford.

Drag and Drag Reduction Technique

From Van Dyke, M., 1982, An Album of Fluid Motion, Parabolic Press, Stanford.

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Objectives

Investigate a drag reduction technique: e.g., trip wire technique

More specifically

Objective functional form:

V

)...,/,cylindercircular;Re;(

);;(

defc

cpxfy

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