Schauberger
Many suggestions have already been made as to how losses in energy, pressure or velocity arising in the transport of liquids or gaseous media can be reduced. Thus for the purposes of inhibiting the formation of air-bubbles, which provoke an increase in the resistance to flow, a British Patent No. 409,528 for a pipe has been published, which is wound in a screw-form manner and its cross-sectional surfaces are formed by two arcs of a circle. From the British Patent No. 28,5343 of 1913 AD, the application of a pipe with an egg-shaped cross-section was made known, which was provided with flow-directing slats to inhibit the formation of vortices. In the U.S. Patent No. 1,655,197 as well as in the Schauberger - Swiss Patent No. 126637, cylindrical or conical pipes were proposed with the object of reducing friction by converting it into rotation, for which the pipe axis served as the rotational axis. Lastly, the Schauberger - Austrian Patent No. 28099 depicts the use of indented and twisted pipes. [The Energy Evolution - Harnessing Free Energy from Nature, Schauberger Patent 196680 - Pipe for Liquid and Gaseous Media]
Video of a method for making profiled tubes: https://www.facebook.com/reel/1707842203302390
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