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A Simple Educational Wind Tunnel Setup For Visualization Of Duct Flow Streamlines And Nozzle/Diffuser Boundary Layer Separation

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2008 Annual Conference & Exposition


Pittsburgh, Pennsylvania

Publication Date

June 22, 2008

Start Date

June 22, 2008

End Date

June 25, 2008



Conference Session

Fluid Mechanics Experiments and Laboratories

Tagged Division

Division Experimentation & Lab-Oriented Studies

Page Count


Page Numbers

13.102.1 - 13.102.11



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Paper Authors


B. Terry Beck Kansas State University

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Terry Beck is a Professor of Mechanical and Nuclear Engineering at Kansas State University
(KSU) and teaches courses in the fluid and thermal sciences. He conducts research in the
development and application of optical measurement techniques, including laser velocimetry and laser-based diagnostic testing for industrial applications. Dr. Beck received his B.S. (1971), M.S. (1974), and Ph.D. (1978) degrees in mechanical engineering from Oakland University.

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Brian Anderson Kansas State University

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Brian Anderson is a recent graduate and is currently a graduate student in the Mechanical and Nuclear Engineering Department at Kansas State University (KSU). He was team leader for the for the SAE Aero Design Competition in 2007 and has contributed significantly to previous wind tunnel lab development projects including the current smoke rake system.

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Mina Hosni Kansas State University

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Mina Hosni is a freshman in the the Mechanical and Nuclear Engineering Department at Kansas State University (KSU). She is working on the smoke rake flow visualization project in conjunction with the Campus Internship Program (CSI) at KSU.

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NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

A Simple Educational Wind Tunnel Setup for Visualization of Duct Flow Streamlines and Nozzle/Diffuser Boundary Layer Separation


Wind tunnel testing has long been an important component common to many introductory fluid mechanics and aerodynamics courses. Demonstrations of the basic physical mechanisms of viscous and pressure drag associated with the formation of drag forces on various aerodynamic shapes are readily conducted using standard electronic or mechanical balance hardware. Experimental measurements of lift, drag, pitching moment, and pressure distribution on small- scale models likewise play a significant role in supporting basic fluid mechanics theory in such introductory courses. Understanding these physical characteristics is very important to automotive aerodynamic design, for maximizing fuel economy, and in the teaching of basic principles of aerodynamic design as applied to aircraft. In addition to the more common use of the wind tunnel as a tool for investigation of the aerodynamics of sting-mounted test models, however, the wind tunnel as a whole provides the means to demonstrate several significant principles of fluid mechanics and the application of these principles to engineering design. One such recent application of the wind tunnel involved instrumenting the entire wind tunnel for pressure distribution measurements, to demonstrate ideal inviscid fluid flow behavior, as well to illustrate the relative importance of various sources of mechanical energy losses to wind tunnel design.

This paper presents the authors experience with modifying an Aerolab educational wind tunnel test facility for experimental work associated with an Undergraduate Campus Internship (CSI) mentoring program project. The purpose of this laboratory activity was to demonstrate characteristics of variable area duct flow and diffuser boundary layer separation using flow visualization by smoke injection. A simple modification to the test section region of the wind tunnel was made to conform to a converging and/or diverging (diffuser) duct flow configuration. This setup was used in conjunction with a special-purpose smoke rake injection system of our own design, and a relatively inexpensive low-power laser-based lighting system, for visualization of the associated air flow. The paper describes various ways of constructing and testing simple duct flows for the wind tunnel test section region using inexpensive materials, as well as the requirements for obtaining good quality flow visualization using smoke injection. The smoke visualization tests can potentially reveal the details of inviscid streamline flow for converging ducts or channels and the onset of boundary layer separation, along with various flow instabilities associated with discharge from a low-speed diverging (diffuser) duct outlet. The connection between diffuser and nozzle head loss behavior and boundary layer separation phenomena are also brought out in these experiments, and they should be adaptable to most educational wind tunnel laboratory test facilities.


The educational wind tunnel represents an important tool for introducing engineering students to basic experimental measurements of lift, drag, pitching moment, and pressure distribution (or

Beck, B. T., & Anderson, B., & Hosni, M. (2008, June), A Simple Educational Wind Tunnel Setup For Visualization Of Duct Flow Streamlines And Nozzle/Diffuser Boundary Layer Separation Paper presented at 2008 Annual Conference & Exposition, Pittsburgh, Pennsylvania. 10.18260/1-2--4191

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