FAA Powerplant Written Practice Test

What is the function of the inlet guide vane assembly on an axial-flow compressor?

1. To increase air temperature

2. To direct air onto the first stage rotor blades

3. To balance engine thrust

4. To filter incoming air

The correct answer is: To direct air onto the first stage rotor blades

The inlet guide vane assembly in an axial-flow compressor is primarily designed to direct incoming air onto the first stage rotor blades at the optimal angle. This function is crucial for maintaining the efficiency of the compressor. By guiding the airflow properly, the inlet guide vanes help to maximize the amount of air that enters the compressor and ensures that the airflow has the correct velocity and direction when it hits the rotor blades. This optimization is vital for the effectiveness of the compressor in compressing the air for combustion. Inlet guide vanes do not increase air temperature; their main role is related to airflow management. They also do not serve to balance engine thrust or filter incoming air, as these functions are handled by different systems within the engine. Therefore, the correct understanding of the inlet guide vane assembly’s role in directing air onto the rotor blades helps highlight its importance in the overall performance of the axial-flow compressor.