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Short Summary
Main recommendation: Build a pulsar pump, a water-driven pump with no moving parts that uses a trompe (a whirlpool that draws air into falling water) to supply bubbles to an airlift pump (a pipe where rising air bubbles carry water upward). The video recreates the device once described at the Alhambra in Granada, Spain, and shows it lifting water above its source. The pump's exact historical design remains uncertain, but its principle is demonstrated.
Key Points
- The pulsar pump has two stages: a trompe mixes air into a downward water stream, separates the air under pressure, and an airlift pump uses the bubbles to lift part of the water.
- Only a small fraction of the water passing through the device is actually pumped upward. The video estimates the output at under 5% of the total flow, so it requires a lot of water to raise a little.
- It is not a free-energy device. It temporarily stores energy from falling water in compressed air and then uses that energy to push water upward.
- The output is pulsed rather than continuous because air and water interact unevenly, making the system gurgly and hard to stabilize.
- Professor Caserès, a Spanish engineering professor, rebuilt the device more than a century after 1764 and presented results at a 1911 scientific congress in Granada, and recent historians have found his reconstruction plausible.
Details Worth Noting
- Concrete instructions:
- Build a free-surface basin at the top so the water starts from a clear, consistent level.
- Connect a vertical downpipe from the basin into a tee fitting so the falling stream swirls and draws in air. The video notes Caserès had the most success with a whirlpool to draw water and air downward.
- Direct the mixed flow into a separator tank with a sloped top, letting bubbles float up while only water exits on the side.
- Add a riser on the separator's outlet to create back pressure, so air stays under pressure and is forced up a discharge line instead of filling the separator.
- Route the discharge line upward above the inlet tank. Narrow pipes trap water between bubbles, letting buoyancy lift water to the top in pulses.
- Choose the downpipe diameter, which sets fluid velocity and how much air is drawn in, and the discharge pipe diameter, since an oversized pipe prevents bubbles from crowding enough to carry water.
- Set up a recirculation loop, as the presenter did with a bucket and pump below the table, since most of the flow passes through without being raised.
- The priest who first described the Alhambra pump in 1764 gave little detail on how air was introduced, so the exact original method is unknown.
- The device likely operated until the late 18th century, when a higher canal replaced it.
- Caserès argued the design avoids the fatigue and noise of hydraulic ram pumps near living quarters, since it has no valves or ram stroke.
Bottom Line
A pulsar pump shows that water can lift water with no moving parts, but it trades efficiency and stability for simplicity, and its practical value today lies mainly where efficiency is not critical.
