Rubens' Tube

Project Type: Applied Acoustics

Project Information

Project Description:

The task is to design and build a Rubens’ Tube, similar to the one demonstrated by Heinrich Rubens in 1904.  The Tube uses jets of fire to illustrate the physics of acoustic standing waves.  The Tube consists of a long pipe with a row of very small holes that serve as flame jets.  The pipe is closed at one end and has a loudspeaker mounted on the other end.  The pipe is pressurized with a flammable gas, like propane, to produce a row of flames with equal height.  Certain sound waves from the speaker will resonate with the length of the pipe to produce regions of high sound amplitude that appear to not move up or down the tube’s length.  With a little help from Bernoulli’s principles for gas flow, the flames appear taller along the regions of high sound amplitude.  The flames really get moving when music is involved and the resonances are much more complex than a single tone.

Level of Difficulty: Low


Heinrich Rubens, Bernoulli's equation, resonance, standing wave, node, antinode, closed-tube resonator, Helmholtz resonator, wavelength, acoustic velocity, fundamental frequency, harmonic frequencies


Rubens’ Tube project from John Bush at the Colorado School of Mines for the CSM Learning Partnership Program;

Informative video from the University of Utah’s Chemical Engineering Department;

Team Roles

Electrical Engineer (2) – The Electrical Engineers on the project are responsible for the audio system, which includes the design and construction of a solid-state power amplifier to drive the mid-range speaker.  The amplifier should be battery powered and accept a number of different inputs from portable music sources.

Mechanical Engineer (2) – The Mechanical Engineers on the project are responsible for the Tube’s design and construction, which includes critical hole spacing and flame jet tuning.  The Mechanical Engineers will design the gas feed system and certify it to be safe, leak free, and accurately regulated.  The Electrical and Mechanical Engineers must work together to design a high efficiency, leak-free interface between the speaker and the propane volume.

Physicist (2) – The Physicists on the project are responsible for selecting the Tube’s length by matching the mid-frequency range of popular music to the Tube’s set of useful harmonics.  Measurements of the standing flame period and the driving frequency will be used to calculate the acoustic wave speed in the air-propane mixture.

Computer Scientist (2) – The Computer Scientists on the project are responsible for instrumenting the Rubens’ Tube with pressure transducers to measure the oscillating pressure field for acoustic frequencies that produce clear standing waves.  Transducer information will be collected and displayed using LabVIEW, which includes the design and construction of a transducer interface and calibration network.

Designer (2) – The Rubens’ Tube is a popular and dramatic illustration of acoustic principles.  Designers on the project are responsible for developing a packaging system for the project so it can easily carried to a demonstration site, set up quickly, be shown to a group of people, then quickly dismantled and transported to a new destination using the fewest number of tools.

Journalist (1) – The Journalist documents the project’s progress on the website, communicates with the local media, and is responsible for a final report to the principal sponsors and Power Mountain Engineering.  The Journalist also works closely with the Multimedia Artist to provide video and graphic art displays for demonstrations that explain the project to the public.  The whole project is your project.

Multimedia Artist (1) – The Artist also documents the project’s progress on the website and works with the Journalist to maintain the project’s presence on social media.  Additionally, the Artist designs and organizes all public relations events to assure spectator safety and to enhance the community’s awareness of science and technology.  In this case, the display area must have still air, but be well ventilated to dispel carbon monoxide gas.  The whole project is your project.

Business Manager (1) – The Business Manager is responsible for reporting the project’s progress against a predetermined schedule, determines critical path items to completion, and tracks project spending to assure that costs remain within a fixed budget.  The Manager works with all team members to identify problems early and resolve them quickly.  The whole project is your project.

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