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A polytropic process is a thermodynamic process that obeys the relation: = where p is the pressure , V is volume , n is the polytropic index , and C is a constant. The polytropic process equation describes expansion and compression processes which include heat transfer.
The compressor also has to pass the same flow as whatever uses the gas power, ie additional turbine stages for a single shaft engine or separate power turbines or a jet nozzle. This equal-flow requirement is alongside an equal pressure-ratio requirement, between overall compression and expansion ratios, and together they position the running ...
Stalling is the separation of flow from the compressor blade surface as shown in the Figure 6. At low flow rates the angle of attack increases over the critical or maximum angle that the aerodynamic profile can sustain, and due to this there occurs the flow separation on the suction side of the blades which is known as positive stalling. If the ...
There are many options for the motor that powers the compressor: Gas turbines power the axial and centrifugal flow compressors that are part of jet engines. Steam turbines or water turbines are possible for large compressors. Electric motors are cheap and quiet for static compressors.
The simplest inlet to a centrifugal compressor is typically a simple pipe. Depending upon its use/application inlets can be very complex. They may include other components such as an inlet throttle valve, a shrouded port, an annular duct (see Figure 1.1), a bifurcated duct, stationary guide vanes/airfoils used to straight or swirl flow (see Figure 1.1), movable guide vanes (used to vary pre ...
Thus for an incompressible inviscid fluid the specific internal energy is constant along the flow lines, also in a time-dependent flow. The pressure in an incompressible flow acts like a Lagrange multiplier , being the multiplier of the incompressible constraint in the energy equation, and consequently in incompressible flows it has no ...
It is a situation of separation of air flow at the aero-foil blades of the compressor. This phenomenon depending upon the blade-profile leads to reduced compression and drop in engine power. Positive stalling Flow separation occur on the suction side of the blade. Negative stalling Flow separation occur on the pressure side of the blade.
The velocity triangle [2] (Figure 2.) for the flow process within the stage represents the change in fluid velocity as it flows first in the stator or the fixed blades and then through the rotor or the moving blades. Due to the change in velocities there is a corresponding pressure change. Figure 2. Velocity Triangle for fluid flow in turbine