The Tesla turbine is a bladeless turbine powered by fluid shear, invented by legendary scientist Nikola Tesla, patented in 1913. It is called a bladeless turbine because it applies the boundary layer effect rather than the traditional direct impact of a fluid on the turbine blades.
Tesla turbines consist of a set of smooth discs with nozzles on the disc that continuously blow air out towards the edges of the discs. This airflow adsorbs onto the disk due to fluid viscosity and the viscosity of the gas in the surface layer. When the airflow slows down and energy is applied to the disk, the gas moves in a spiral centripetal motion and discharges. Since the surface of the rotor is smooth and does not bulge, this design is extremely robust (ordinary turbines with blades can be imagined).
Tesla turbine 3D renderings
The principle of Tesla turbines is the boundary layer effect of the fluid, the fluid is affected by viscosity, will form a very thin boundary layer at the edge of the pipe wall or other objects, in the boundary layer, the flow rate of the fixed surface is 0, the farther away from the surface the greater the speed. Using this effect, it is possible to have a high-speed liquid drive a group of disks to rotate. Therefore, its efficiency is much higher than that of ordinary blade turbines.
The "bladeless" design of Tesla turbines
In the 1950s, Warren Rice tried to recreate Tesla's experiments. Before he retired, he completed the final testing of Tesla turbines and did a lot of laminar flow data analysis on multi-stage turbines. He declared that the design was extremely efficient (not the overall system efficiency after connecting the machines), and in 1991 published a report entitled "Tesla's Turbines", which made the following statement: With the correct use of the results of the analysis, the efficiency of rotor laminar flow use is very high, even more than 95%.
However, in order to achieve high rotor efficiency, the flow rate must be as small as possible, which means that the price of high efficiency is that there must be a sufficient number of turbo discs to form a huge rotor. Let's take a look at how Tesla turbines work through a short video, why such powerful mechanical properties are difficult to promote.
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Video source: Gem Tribe
Therefore, it seems unrealistic for Nikola Tesla to think that the 6-inch model has an efficiency of 97%. And we know that modern multi-stage blade turbines usually achieve 60% - 70% efficiency, while in practice large steam turbine generator sets often show more than 90% efficiency.
Tesla claimed in the patent that the device was patented for the use of fluids as a power medium to distinguish it from other fluid propulsion and compression devices. Until 2006, tesla turbines were not widely used for commercial purposes since their invention.
However, Tesla pumps have been commercially available since 1982 to transport corrosive, highly viscous, highly shear-sensitive fluids that contain solids or are difficult for other pumps to handle. Tesla itself has not received a large production contract. The main problem of his time was the lack of knowledge of materials science and the study of high-temperature materials. At that time, the best metallurgical techniques still could not prevent the turbo disc from twisting and deforming in operation.
Today, many amateur experiments in the field are already intentionally using Tesla turbines (steam is made from heat generated by fuel combustion, usually derived from the car's turbocharger or solar radiation) with compressed air or steam as the power source. The deformation problem of turbine discs has been partially solved, mainly thanks to the application of new materials, such as the use of carbon fiber to make turbine discs. A good example is that both PNGinc and International Turbo & Power have used carbon fiber materials in their Tesla turbine designs.