The aerodynamics design of compressor is definitely required for the flow direction

which

however

isn′t considered in the definition of stagnation pressure.So

the limitation of stagnation pressure appears when describing the performance of unsteady flow in high load fan/compressor.In order to deal with this limitation

available stagnation pressure was presented to consider the influnence on working capability of small flow volume caused by its velocity value and flow direction.And

according to the design demand of flowing in fan/compressor

the concepts of available stagnation pressure and pressure difference coefficent were defined at the level of engneering aplication.The application of available stagnation pressure can reflect more effectively the influence of flow direction on unsteady flow field in turbomachinery

making the performance characters of flow field change more sensitive to the change of quality of flow field.So the available stagnation pressure is useful to analyze the unsteady flow field.