What is the purpose of the diffuser vanes in a centrifugal compressor:

1.   ?    to convert pressure energy into kinetic energy
2.   ?    to increase the temperature of the gas and improve vaporisation of the
   fuel
   
3.   ?    To convert kinetic energy into pressure energy

Compressor blades are designed to

1.   ?    Provide a given pressure and velocity rise
   
2.   ?    Provide a constant flow over the engine speed range
   
3.   ?    Produce a steady pressure and velocity rise over the engine speed range
   

A compressor blade will stall when:

1.   ?    Pressure, velocity and rotational speed relationships are disturbed
2.   ?    When mass airflow and speed relationships are constant
3.   ?    ‘When the gas flow through the turbine falls below 0.4Mach