Shrouded turbine blade design
The use of a shroud surrounding turbine blades to enhance the energy output creates a distribution of wind speeds in the plane of the blades. A unique class of such shrouds previously patented by the author creates zones of higher velocity near the tips. In order to take advantage of this new distribution of velocity, new principles of propeller design are required. One of the designs involves increasing the P/D ratio and the PHI in the outer portion of the blades. This solution works for liquids and gases.
1. A shrouded turbine blade, said shroud characterized by a zone of higher velocity flow in the area of the tip of the blade it surrounds and said shroud having a curved shape with its narrowest part of the convex side of the curve adjacent to the blade, comprising a section thickness and a chord length, comprising a space separation between the blade tip and the shroud, wherein a P/D ratio, defined by pitch (P) divided by diameter (D), starts to increase consistently from any starting point within 40-90% of the distance from the center to the periphery of the blade and maintains that increase to the periphery, wherein the P/D ratio of the blade central to the starting point is not consistent increasing, and a t/c ratio, defined as section thickness (t) divided by chord length (c), and thickness decrease from center to periphery of the blade, wherein a pitch angle increases near the tip of the blade.
2. The blade of claim 1 , wherein the P/D ratio at the tip is greater than 0.7.
3. The blade of claim 2 , wherein the ratio is greater than 1.0.
4. A shrouded turbine blade, said shroud characterized by a zone of higher velocity flow in the area of the tip of the blade it surrounds and said shroud having a curved shaped with its narrowest part of the curve adjacent to the blade, the shrouded turbine blade comprising a profile in accordance with the parameters set forth in Table 2, in any proportional value, with a deviation of 10% of the c/R and Phi values set forth in Table 2 for any r/R point, wherein r is a radial coordinate, R is the radius, and Phi is pitch.
5. A shrouded turbine blade, said shroud characterized by a zone of higher velocity flow in the area of the tip of the blade it surrounds and said shroud having a curved shape with its narrowest part of the convex side of the curve adjacent to the blade, the blade is a substantially 10-meter diameter blade with said shroud of substantially 1-meter chord length, in any proportional value having the maintenance of geometric similitude, the shrouded turbine blade comprising a profile in accordance with the parameters set forth in the columns of Table 1, defined as r being the radial coordinate, R the radius, c the chord length, D the diameter, t the section thickness, f the section camber, φ the geometric pitch angle, and P the pitch with a deviation of 10% of the value for any r/R point set forth in Table 1.
6. The blade of claim 5 with a center to which the blade is attached and revolves, wherein, in a liquid speed of 3 meters per second, a setting of revolutions per minute of the blades is at 25-30.
7. The blade of claim 5 , wherein a ratio of revolutions per minute to diameter at a 3-meter per second flow in a liquid is 2.2 to 3.2.
8. A shrouded turbine blade, said shroud characterized by a zone of higher velocity flow in the area of the tip of the blade it surrounds and said shroud having a curved shape with its narrowest part of the curve adjacent to the blade, comprising a section thickness and a chord length, comprising a space separation between the blade tip and the shroud, wherein the tip does not have a lowest Phi, defined as pitch angle, value in the length of the blade and a t/c ratio, defined as section thickness (t) divided by chord length (c), and thickness decrease from center to periphery of the blade, wherein the Phi value starts to increase at a point 60-90% of the length from the blade central to the periphery of the blade and does not consistently increase from center to the point.