Special Shaped Bodies of Revolution with Delay of Laminar-Turbulent Transition and their Applications in Clean Energy Technologies

Shapes with negative pressure gradients on their surfaces were proposed in order to avoid separation of the boundary layer. Wind tunnel tests have confirmed the absence of separation on some bodies of revolution similar to the trunks of aquatic animals. According to the Tollmin-Schlichting-Lin theory, the boundary-layer on a flat plate remains laminar for any frequencies of disturbances at small Reynolds numbers. Similar estimations have been done for a slender unseparated body of revolution and the relationship between critical values of the velocity, volume and length was proposed, which yields parameters of a minimal drag hull and allows estimating the maximum speed of aquatic animals. E.g., the dolphin’s body yields the critical value of the velocity 8.9m/s, the sailfish can ensure laminar flow pattern at speeds less than 41.8m/s. The proposed hulls could significantly reduce the drag of underwater vehicles, SWATH ships, airplanes, airships, cars, air and sea gliders, and bikes. The use of critical values of parameters allows developing the vehicles with the maximal commercial efficiency (weight-to-drag ratio) and the range. It was shown that hulls with sharp concave noses have no stagnation points, pressure and temperature peaks. In supersonic flows, they can reduce overheating of the noses. Such hulls penetrating into water have much lower loads on the noses. These special shaped bodies moving on the water surface cause much lower vertical velocities. They can ensure a low wave resistance of floating vehicles.