Final answer:
Inlet Guide Vanes (IGVs) are adjustable vanes in gas turbine engines, positioned to optimize air flow and engine performance. At idle, IGVs are open to minimize air flow and prevent stalling. When power is added, they close to increase airflow and power output.
Step-by-step explanation:
IGV stands for Inlet Guide Vanes. These are mechanically adjustable vanes located at the inlet of a compresser in a gas turbine engine; they direct air flow onto the rotor blades at an angle that is optimal for the operating conditions. IGVs help in controlling the flow of air into the turbine, which is critical for maintaining the efficiency and performance of the engine.
At idle, IGVs are usually in a more open position, which allows for a minimal amount of air to flow into the compressor to prevent it from stalling. As power is added and the demand for compressed air increases, the IGVs move to a closed position to guide more air into the compressor for increased power production. IGVs are crucial for optimizing the engine's performance across different operating conditions.