Ocean current power generating apparatus using dual-duct with boundary layer control effect

1. An ocean current power generating apparatus using dual-duct with boundary layer control effect, comprising:

at least one power generating unit, comprising:

a turbine having a shaft box;

an inner duct, being a hollow structure or filled with foam material therein, wherein the turbine is located inside the inner duct, and an outer diameter of an inflow side of the inner duct is less than an outer diameter of an outflow side of the inner duct; and

an outer duct, being a single-piece structure without a hollow therein, wherein the outflow side of the inner duct is located inside the outer duct, an outer diameter of an inflow side of the outer duct is less than an outer diameter of an outflow side of the outer duct, and the boundary layer control effect for the inner duct is generated due to a gap existed between the outflow side of the inner duct and the outer duct.

2. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 1 , wherein the outer duct is a single-plate structure.

3. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 1 , wherein the inflow side of the inner duct is located inside the outer duct, outside the outer duct or aligned with the inflow side of the outer duct.

4. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 1 , wherein a distance between the outflow side of the inner duct and the outer duct is less than a distance between the inflow side of the inner duct and the outer duct.

5. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 1 , further comprising a plurality of support struts connecting to the shaft box and the inner duct, connecting to the inner duct and the outer duct, and connecting to the shaft box and the outer duct.

6. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 1 , further comprising a connecting part, wherein a quantity of the at least one power generating unit is two, and the connecting part is connected to the outer ducts of the power generating units.

7. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 6 , further comprising a platform connecting to the power generating units.

8. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 7 , wherein the platform comprises a tail wing part, a lateral wing part and a center body, a back end of the center body is connected to the tail wing part, and the lateral wing part is located at a middle section of the center body and connected to the power generating units.

9. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 8 , wherein the center body is a hollow structure or filled with foam material therein.

10. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 1 , further comprises a hub part and a plurality of blades, the hub part is connected to the shaft box, and the blades are connected to the hub part.

11. The ocean current power generating apparatus using dual-duct with boundary layer control effect of claim 10 , further comprising a power generator, a mechanical seal and a gearbox disposed inside the shaft box, wherein the turbine is connected to the power generator through the mechanical seal and the gearbox.