No of blade sets in reaction turbines

[chhitiz]

why do we need to have many sets of blades to utilize the gas pressure in reaction turbines properly? why not have just a set of comparatively wider blades?

 

[minger]

I assume by sets you're talking about stages. When it comes to stages, it all comes down to how much energy we can efficiently extract per stage. If we can get it all, then we'll just have one vane and one blade.

The preliminary turbine design is done without knowledge of blade shape or count. After the stage parameters and blade/gas angles are calculated, then we go back and try to find a shape and geometry.

Note that depending on your definition of "width" you could be decreasing the effective area through the turbine and reach a possibly unwanted choked condition.