Kap 4

-        Gas production

-        Gas gathering system.

-        Gas transmission (to boost the pressure)

-        Storage facilities

-        Gas processing

-        Transport

Turbine: transforms pressure and Ekin in usable work

Compressor: increase pressure  (reverse as turbine)

In the turbine goes high pressure and the end product in usable work

In the compressor comes low pressure and the end product is high pressure (you need mechanical energy/work to do this)

Reducing the gas volume increase the gas pressure (Piston for example)

Positive Displacement: higher pressure trough reducing volume

Dynamic:  increasing pressure trough lowering Ekin

Example: radial compressor

A gas Turbine is an engine that converts the thermal energy from fuel into useful power and mechanical energy trough the combustion process

Gas compressor, a combustor and a turbine

increased pressure, compression raises the temperature of the air, Increasing efficiency (higher air-to-fuel rate)

Consists of stator(diffuser) and rotor (impeller)

axial

radial

o Accelerates the air to increase its total pressure and velocity o The rotor blades are mounted on the disc o The discs are fitted onto the main shaft

o Converts the velocity increase gained in the rotor to a static pressure (correct only for subsonic flow)

o Accelerates the air to increase its total pressure and velocity o Rotor blades are mounted on disc o The discs are fitted onto the main shaft

o Converts the velocity increase gained in the rotor to a static pressure increase o Stationary stators are fitted into the compressor casing

s. 48 ( Pt = total pressure,  Ps = static pressure, Pi = velocity part)

decreases total pressure, gets work out of the fluid flow

Is a nozzle:

Pressure decreases, velocity increases

The air is accelerated by the rotor blades to increase its total pressure, temperature and velocity The air passes onto the adjacent row of stator vanes (divergent duct) that converts most of the kinetic energy into static pressure energy (correct only for subsonic flow)

maybe through the combustion process or maybe bc of the nozzle by increasing the volume

1.      Velocity diagram

2.      H-s diagram

3.      P-v diagram.

Velocity triangles represent the various components of velocities of the working fluid in turbomachine.

Absolute , relative, axial

Axial, radial, tangential

Destructive Force= Centrifugal Force (radial)

Effective Force= Aerodynamic force (tangial)

-        Frictional losses: A major portion of the loses is due to fluid friction in stationary and rotating blade passages

-        Incident losses: During the off-design conditions, the direction of the relative velocity of the fluid at inlet does not match with the inlet blade angle and therefore, fluid cannot enter the blade passage smoothly by gliding along the blade surface

-        Clearance and leakage losses: Certain minimum clearance are necessary between the rotor and the stator.

When angle of incidence of the air relative velocity is too high or too low

o Surge is the occurrence of backflow/reversible flow in axial or centrifugal compressor due to unstable operation such as stall

o Once stalled the airfoil losses the ability to compress the air down the engine o High pressure build up forcing the gas to flow backward to the front of the compressor/engine

o Surge puts strain on many parts of the compressor and can cause severe damage to the internal components

o The surge region, located on the left-hand side of the compressor map (known as the surge line)

Occurs when the compressor is operating at low discharge pressure and very high flowrates.

The compressor choke occur when the flow in the compressor reaches Mach 1 at the blade throat, a point where no more flow can pass through the compressor

Chock can cause a severe damage to the compressor components

The degree of degradation of steady-flow energy devices such as turbines, compressors, and nozzles is due to irreversibility effects (friction, aerodynamic, entropy increase, heat transfer to the surroundings etc.)

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