The surroundings include everything external to the system,and the system is separated from the surroundings by the system boundaries.
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The successive stages are normally arranged side by side along a horizontal axis, constituting what is called an“axial flow" turbine.
The speed of the flow of the fluid,which in steam turbines is produced by a fall in pressure of the steam from the boiler.
A turbine is a rotary engine which is driven by a stream of fluid (liquid or gas) directed on to the blades of the stator (定子).
Molecular activity gives the rise to an apparent shear stress in gases which is more important than the cohesive forces and since molecular activity increases with temperature,the viscosity of a gas also increases with temperature.