2.2 Moving blades
The moving blades of a turbine stage receive steam that has been accelerated in a nozzle or fixed blades and convert its kinetic energy into mechanical work on the turbine shaft.
The impingement of the steam on the blades produces a change in direction of motion of the steam which gives rise to a change in momentum and therefore to a force. Ideally, the angle through which the steam is turned is as near to 180° as possible. Figure 1.8 shows a typical velocity vector diagram in relation to the moving blade profile.
The manner by which the transfer of energy occurs in the moving blades is dependent upon whether the turbine is of an impulse or reaction type.