Pulsar Pump: Water Lifting Without Moving Parts Inspired by Alhambra's Waterworks

On a hill above Granada, Grady Hillhouse examines the Alhambra's waterworks and builds a pulsar pump demonstration. The device uses air entrainment to lift water uphill without moving parts, blending history with practical fluid dynamics. The video situates the idea in Renaissance and later engineering, referencing a priest's 1764 account and a 1911 reconstruction by Professor Casaris, while showing how an acrylic scale model can visualize air-water interactions and energy transfer. It also discusses applications, challenges, and the sense of wonder at purely mechanical solutions drawn from flowing water.

Introduction and historical backdrop

On the hill above Granada, the Alhambra stands as a monumental reminder of medieval and Renaissance engineering. The video frames the challenge of supplying reliable water to a fortress city perched above rivers, and surveys how engineers diverted natural sources to cisterns, baths, and fountains. This context sets the stage for a deep dive into a remarkable device known as a pulsar pump, which appears to lift water with no moving parts.

Pulsar pump concept and historical context

The idea of a pump with no moving components captured Grady's imagination after seeing Primal Space's coverage of Alhambra's water-management ingenuity. The Alcazaba fortress, at the western tip of the complex, was reportedly supplied by a pump that could lift water using a moving-air mechanism. A priest observed it in 1764 and described it imperfectly, while a later Spanish professor, Casaris, attempted to recreate the device in 1911, presenting results at a Granada scientific congress. Historians find the reconstruction plausible, and the notion of a two-phase flow device that uses air to move water remains fascinating but contested.

The acrylic demonstration and setup

To explore the concept, Grady builds a scale demonstration using acrylic parts sponsored by Sin Cut Sin. The top basin provides a free surface and a clear energy input. Water falls through a vertical pipe into a T-fitting that entrains air, creating bubbles that travel with the water. The downward flow is intended to carry both water and air to a separator where air is removed, and water continues onward. This stage mirrors the tromp portion of the mechanism: entraining air in a water stream, then separating the air so it can be reused or applied for other purposes.

From tromp to pulsar pump

The setup transitions into what is called a pulsar pump, a combination of a tromp and an airlift pump. The air bubbles at the bottom of the pipe act like carriers, lifting water upward through a riser and out a discharge line. Because the pipe is narrow and the bubbles are buoyant, the system generates pulses rather than a steady flow. The result is water rising higher than its input level, demonstrating the core effect of lifting water with no moving parts by harnessing air-water interactions.

Fluid dynamics and practical considerations

The video emphasizes two important points: first, even though water is being moved upward, the system does not provide free energy. Energy is borrowed from the flowing water, stored momentarily in the form of compressed bubbles, and then released to lift some water back up. Second, two-phase flow is complex and sensitive to many variables, including pipe diameter, flow rate, back pressure, and the mix of air and water. Grady discusses how these factors influence the stability and efficiency of the device, and notes that real-world use would require careful tuning and understanding of the interplay between air entrainment and water transport.

Historical relevance and modern applications

Two-phase airlift systems have been used in wastewater treatment, dredging, and other environments where traditional impellers clog. Grady connects the pulsar pump concept to broader hydraulic ram principles and considers how historical ideas could inspire simple, robust solutions in modern engineering, especially where electricity or moving parts are undesirable. The video also remarks on the scarcity of information about pulsar pumps and suggests areas for future research, including potential thesis ideas for engineering students.

Conclusion and call for discussion

Grady reflects on the charm of turning natural forces into useful work and invites viewers to share thoughts on the plausibility, history, and potential modern applications of pulsar pumps. The video closes with appreciation for the unknowns surrounding the Alhambra device and encouragement to explore the old mechanically driven ideas that still hold value today.