Underwater Propulsion: Evolution from Propellers to the No-Blade Era

When the first submarine attempted to dive underwater in the 17th century, people could hardly imagine how rapidly underwater propulsion technology would develop centuries later. From the initial simple propellers to today's no-blade propulsion systems, the evolution of underwater thrusters continues to reshape human understanding of underwater navigation.

The Propeller Era: Classics and Limitations

Traditional propeller thrusters have been the mainstay of underwater propulsion for over a century. While the principle of generating reactive force by rotating blades to push water seems simple, it actually involves complex fluid dynamics. However, as technology advanced, the limitations of propellers became apparent: narrow peak efficiency ranges, cavitation effects, and noise interference increasingly constrained their further application.

Pump-Jet Propulsion: The Choice for Stealth and Efficiency

To overcome the shortcomings of propellers, pump-jet thrusters emerged. This propulsion method accelerates water flow through rotors within ducts, combined with stator guidance, achieving higher propulsion efficiency and superior noise characteristics. Particularly in military applications, the low-noise advantage of pump-jet thrusters makes them the preferred choice for submarines. The latest adaptive pump-jet systems can even automatically adjust blade angles according to speed, maintaining optimal efficiency.

No-Blade Propulsion: Disruptive Innovation

The most revolutionary breakthrough comes from the emergence of no-blade propulsion technology. This approach mimics the propulsion methods of organisms like jellyfish, utilizing fluid elasticity to achieve silent propulsion. Another type of no-blade thruster employs magnetohydrodynamic (MHD) principles, accelerating seawater through electromagnetic fields to generate thrust, completely eliminating mechanical moving parts.

Diversification of Power Sources

Modern underwater thrusters also feature increasingly diverse power sources. Beyond traditional electric propulsion, new technologies like fuel cells and aluminum-water reaction energy sources continue to emerge. Particularly notable is the recent development of wave energy conversion technology, enabling underwater thrusters to directly harvest energy from the marine environment, theoretically achieving unlimited endurance.

Advances in Materials and Manufacturing

Breakthroughs in materials science have similarly propelled thruster development. From early cast iron and bronze to today's polymer composites and smart materials, thrusters have become lighter, stronger, and more corrosion-resistant. 3D printing technology has enabled the realization of complex blade curvature designs, further optimizing hydrodynamic performance.

Expansion of Application Scenarios

From initial ship propulsion to today's underwater robots, diving equipment, and ocean observation platforms, the application scenarios for underwater thrusters continue to expand. Across various fields including marine scientific research, resource exploration, ecological monitoring, and emergency rescue, different types of underwater thrusters are playing irreplaceable roles.

Looking ahead, with continuous breakthroughs in artificial intelligence, new materials, and energy technologies, underwater thrusters will develop towards greater efficiency, intelligence, and environmental sustainability. Perhaps in the near future, we will witness underwater thrusters that completely mimic biological swimming methods, or perpetual motion propulsion systems capable of autonomously harvesting energy from seawater. These innovations will continue to advance human exploration and utilization of the ocean, making the profound underwater world increasingly accessible.