Selection of Stator-Rotor Combinations

How to Execute Conservation of Rothalpy ?? Enthalpy Kinetic Energy Velocity Vector Field Fluid Dynamics Generation of Change in rate of angular momentum (An Action) Shaft Torque is the final need as Reaction Who Will take the Reaction ???

Basic Rules for Design of An Ideal Turbine Flow Path Created highest usable form of a resource. Creation of initial velocity/kinetic energy using Stator. X1 (Impulse)+X2(Reaction)+(1-X1-X2)(centripetal) Y1 (Radial)+(1-Y1 )(Axial) Design of Flow Path using Conservation of rothalpy. Design blade cascade using conservation of mass and momentum. A design of an Ideal Machine ….. Each stage can do finite amount of action….!!! Many stages are needed to complete the action….

Flow in Stator-Rotor Inter stage Gaps

Geometrical Details along the Third Direction True flow through a turbo-machinery is three-dimensional. Flow and tangential flow velocities are very important for better operation of a turbo-machine. The third component, which is normal to flow and tangential directions is in general of no use. This direction can better represented as blade height direction.

Third Direction of an Axial Flow Turbo-Machines The third direction in an axial flow machine is the radial direction. The direction of Centrifugal forces! Strong centrifugal forces are exerted on blades & fluid in radial direction. The centrifugal field distorts the flow velocity profiles considerably. Fluid particles tend to move outwards rather than passing along cylindrical stream surfaces as classically assumed. Particularly in tall blade (low hub: tip) ratio designs. An approach known as the radial equilibrium method, widely used for three-dimensional design calculations in a an axial flow machine.

Radial Equilibrium Theory of Turbo-machines P M V Subbarao Professor Mechanical Engineering Department A Model for Stable Operation of A Machine A guiding equation for distribution of load along blade length ….

Radial Variation of Blade Geometry

Radial Equilibrium Theory Assumes that flow is in radial equilibrium before and after a blade row. Radial adjustment takes place through the row. More important for Axial Flow Machines.

Radial Equilibrium Analysis The centrifugal force = (rrdrdq)w2r Vq = rw The centrifugal force is The pressure force on the element

If the two forces are the only ones acting (viscous and other effects neglected), the particle will move at constant radius if:

Equilibrium Condition for A Rotating Fluid A mechanical equilibrium of a fluid elements demands thermodynamic equilibrium. The fluid must be facilitated to adjust radially as per the requirements. This process of radial adjustment of fluid parcels is well assumed to be isentropic. The radial variation of whirl velocity should be according to above equation. How to implement on a machine?

Implementation of Radial Equilibrium Stagnation enthalpy should conserve, as there are not interactions with rotor at inlet or exit.

Radial component of velocity should be constant (zero) along radial direction for radial equilibrium of flow.

Constant in a turbo-machine along meridoinal Plane Stagnation enthalpy is Constant in a turbo-machine along radial direction at intake and discharge.

Twisted Blades for Large Turbines