# Stage loading

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{{Short description|Measure of load on turbomachinery stage}}

'''Stage Loading''' is a measure of the load on a [turbomachinery](/source/turbomachinery) stage, be it a part of a [compressor](/source/Gas_compressor), [fan](/source/Mechanical_fan) or [turbine](/source/turbine).

The parameter, which is non-dimensional, is defined as:

<math>L = \frac{gJ{\Delta}H}{U^2}</math><ref>{{Cite book |last=Walsh |first=Philip P |title=Gas Turbine Performance |last2=Fletcher |first2=Paul |date=1998 |publisher=Blackwell Science |isbn=0-632-06434-X |page= |pages=163,248|edition=2nd}}</ref>

where:
[Imperial Units](/source/Imperial_units) (SI Units)
        
<math>g</math>            acceleration of gravity                                ft/s/s (1.0)
          
<math>J</math>            mechanical equivalent of heat                      ft.lb/(s.hp) (1.0)       
     
<math>{\Delta}H</math>   change in specific enthalpy over stage         hp.s/lb (KW.s/Kg)

<math>U</math>           peripheral blade speed                                 ft/s (m/s)
                                     
Average stage loading has a very similar definition, where the number of stages, n, within the compressor, fan or turbine is used to provide an average value:

<math>L = \frac{gJ{\Delta}H}{nU^2}</math>

In this case the change in [enthalpy](/source/enthalpy) is across the whole unit, not just a stage. Similarly, the blade speed used is a mean for the whole device.

The above equation shows that if blade speed cannot be increased for, say, mechanical or [aerodynamic](/source/Aerodynamics) reasons, the number of stages has to be increased to get the
average stage loading back to an acceptable level, to obtain a satisfactory level of efficiency. The ideal average stage loading for a turbine is about 1.8.

==References==
{{reflist}}

Category:Turbomachinery

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Adapted from the Wikipedia article [Stage loading](https://en.wikipedia.org/wiki/Stage_loading) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Stage_loading?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.