Bernoulli Levitation
Blow a big breath on a flat plate, instead of been ‘blow away’ the plate will come closer to you. Is it possible?
What?
Demonstrate the pressure change due to the change of fluid velocity (Bernoulli theory) and investigate the lift induced by the pressure difference.
How?
- The main components in this experiment are two circular plates. The airflow passes through these two plates. Observe for the lift force on the lower plate (the base plate) induced by the pressure difference.
- Hang a measured weight on the base plate.
- Turn on the fan and force the air blowing through pipe to the base plate.
- Repeat the above procedure and observe the payload on the base plate.
×Experiments demonstration
post-producing
Why?
Why the base plate can be sucked up with weight by blowing air on it? Why the payload can be as high as 1.5 kg?
×Think...
According to the Bernoulli theory, the velocity v, density ρ, height h, and pressure P of a fluid flow shall have the relation
pin+
In this system, the levels are equal (that is h內=h外) and v外=0. When the air speed is increased between these two plates, the pressure is decreased (lower than the atmospheric pressure). Now the pressure at outside the plates is greater than the pressure inside the plate, so the base plate is sucked up.
Qusetion
Is there any similar phenomenon in the real life can be explained by this principle?
×Discussion
post-producingTyphoon may lift up the roof; two ships can be sucked into each other if they get too close.
Reference
- C. Waltham, S. Bendall, and A. Kotlicki, Bernoulli levitation, Am. J. Phys. 71, 176 (2003).
- Halliday/Resnick/Walker, Foundamentals of Physics, 6th ed., Addison Wesley, 2001, U.S.A., Ch15.
Producer
v.1 Ya-Chen Li （李亞宸）, Tsung-Cean Tu （杜宗勳）
Experiment Materials
- 演示使用之送風機為市售吸塵器，並將排氣端當送風裝置即可。
- 教具本體用壓克力加工製成。
Advisor
Ching-Chi Chu （朱慶琪）
Written by
v.1 Tsung-Cean Tu （杜宗勳）, Ching-Chi Chu （朱慶琪）
