What process occurs when airflow is directed into the diffuser in a centrifugal type compressor?

In a centrifugal type compressor, the primary function of the diffuser is to convert kinetic energy (velocity) of the air into pressure energy, which is essential for effective compression. When airflow enters the diffuser, it is already being compressed and accelerated by the rotating impeller. As the air passes through the diffuser, its speed decreases, and as a result, the pressure increases due to the conservation of energy principle.

This process is critical because the goal of the compressor is to ensure that the air is at the appropriate pressure and flow rate before it enters the combustion chamber of a gas turbine. By successfully increasing the pressure, the compressor prepares the air for efficient mixing with fuel, leading to optimal combustion performance. This substantiates why the correct answer relates specifically to the compression and acceleration of the air for combustion purposes.