Constant static pressure runner in an axial flow turbine

A method of maintaining substantially constant a pressure of a fluid flowing though a passage while changing an angular velocity of the fluid, the method comprising the steps of:

• flowing the fluid from a first end of the passage to a second end of the passage, said flowing of fluid being in a fluid transit area;
• changing an angular velocity of the fluid by providing a curved blade in said fluid transit area, said changing of said angular velocity causing a first pressure gradient;
• changing an axial velocity of the fluid by varying a magnitude of said fluid transit area from said first end to said second end of said rotor to provide a second pressure gradient which counteracts said first pressure gradient caused by said changing of said angular velocity by said curved blade, and to maintain a pressure of the fluid substantially constant along said curved blade.

An axial flow turbine comprising:

• a jacket;
• a rotor positioned inside said jacket and having a longitudinal central axis, an intake end and a discharge end, said rotor including a movable blade rotatable about said longitudinal central axis, said blade having a continuously varying angle of inclination providing means for angular acceleration of fluid in said jacket, said angular acceleration causing a first pressure gradient in the fluid, said rotor also including a rotor core, said rotor core and said jacket cooperating to define a fluid transit area, said fluid transit area having a cross-sectional area varying in magnitude from said intake end to said discharge end and providing means for changing an axial velocity of the fluid and forming a second pressure gradient which substantially counteracts said first pressure gradient caused by said angular acceleration, said fluid flows from said intake end to said discharge end and transfers energy from the fluid to said rotor.