Here is a simple design for a desktop open return wind tunnel. This unit is a good size for the classroom, STEM fair, or just playing around at home. The fan is fully adjustable and can produce wind velocities up to 15 mph through the test section. A cooling duct has been added to provide airflow in the electronics cabinet under the fan. Please remember when assembling the wind tunnel, the fan should be drawing air through the tube. The fan is held in place with friction and 3-inch sheet metal screws. Please be careful not to over tighten the screws and pull the fan into the housing. The fan should be flush with the outside. The test sector is created with a 4-inch diameter by 12-inch long acrylic tube. All the pieces can be assembled without glue, but the tolerances are tight, so slight adjustments maybe required. Adding a smoke generator is a great way to visualize the aerodynamic flow of your test item. The electric system operates with 120V AC and all items can be purchased on Amazon.

Fan https://www.amazon.com/AC-Infinity-Cooling-Ventilation-Projects/dp/B004YTSB7C/ref=asc_df_B004YTSB7C?tag=bingshoppinga-20&linkCode=df0&hvadid=80882875798354&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584482455301957&psc=1

IEC 320 C14 Socket (Power Connector) https://www.amazon.com/AMAZECO-Screw-Mount-IEC320-Socket/dp/B01N2T2N1W/ref=sr_1_23?crid=85NRBHRXT3X2&keywords=2pc+power+connector+with+spring+cover&qid=1649889744&s=industrial&sprefix=2+pc+power+connector+with+spring+cover%2Cindustrial%2C186&sr=1-23

Toggle Switch https://www.amazon.com/DaierTek-125VAC-Waterproof-Automotive-Aircraft/dp/B07T6YNRZS/ref=sr_1_3?crid=KPFBNVQPS383&keywords=daiertek+safety+cover+toggle+switch&qid=1649889823&sprefix=daiertek+safety%2Caps%2C97&sr=8-3

Motor Control Module https://www.amazon.com/HiLetgo-Control-Regulator-50-220V-Adjustable/dp/B00LODGP2E/ref=sr_1_1_sspa?crid=YV35KS41RQ8Y&keywords=hiletgo+2000w+pwm+ac+motor+speed+control&qid=1649889881&sprefix=hiletgo+200%2Caps%2C103&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzSU1YMDc4R0g2WUtJJmVuY3J5cHRlZElkPUEwMzIyMjQ1WEhBMklHNzdZOUxBJmVuY3J5cHRlZEFkSWQ9QTAzOTY0NzUyRFE4UDRZWTVNVzgwJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Test section Tube 12" length (OD 3.937 inches, 5/64 (2mm) wall thickness) #15139-12" https://www.amazon.com/FixtureDisplays-Clear-Acrylic-Diameter-15139-36/dp/B086KVC9C9/ref=sr_1_3?crid=3DP6E2H22UZFB&keywords=fixturedisplay%2Bclear%2Bacrylic%2Btube%2B4%2Binch%2Btube&qid=1649890023&sprefix=fixturedisplay%2Bclear%2Bacrylic%2Btube%2B4%2Binch%2Btube%2Caps%2C112&sr=8-3&th=1

Smoke Generator https://www.amazon.com/LVH-Kitchen-Portable-Smoker-Smoke/dp/B08XTH9GQX/ref=sr_1_1_sspa?crid=6W3DCGDRUEIA&keywords=lvh+kitchen+portable+smoker+smoke+gun&qid=1649890236&sprefix=LVH+kitchen+Po%2Caps%2C92&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExOERSVlBRVERWSzJaJmVuY3J5cHRlZElkPUEwOTM2MDIwMk1XWDI0SlkyMlA0WiZlbmNyeXB0ZWRBZElkPUEwMDcyODU0M0ROQUNCRUdRU1VTRyZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=