These equations govern the power, efficiencies and other factors that contribute to the design of turbomachines.
As the name suggests these equations were formulated by Leonhard Euler in the eighteenth century.
Accordingly, the change of the angular momentum is equal to the sum of the external moments.
Since no pressure forces are created on cylindrical surfaces in the circumferential direction, it is possible to write:
Figures 'a' and 'b' show impellers with backward and forward-curved vanes respectively.
(1.13), Euler developed the equation for the pressure head created by an impeller: Yth : theoretical specific supply; Ht : theoretical head pressure; g: gravitational acceleration For the case of a Pelton turbine the static component of the head is zero, hence the equation reduces to: Euler’s pump and turbine equations can be used to predict the effect that changing the impeller geometry has on the head.
Qualitative estimations can be made from the impeller geometry about the performance of the turbine/pump.