🔍 Key Concepts

• Secondary (compressor bleed) air paths and purposes in gas turbine engines • Temperature and material limits of turbine vs compressor sections • Which turbine (HP vs LP) is exposed to the highest gas temperatures in a twin‑spool engine

💭 Think About

• Think about where in the engine the gas temperature is highest and materials most in need of extra cooling air. • In a twin‑spool layout, which turbine is directly driving the high‑pressure compressor, and what does that imply about the temperature of the gas it first encounters? • Compare the cooling needs of compressor blades (handling compressed but relatively cooler air) versus turbine blades (directly exposed to combustion gases).

✅ Before You Answer

• Identify which section actually sees combustion gas temperature rather than just compressed air. • Confirm which turbine (HP or LP) is upstream, i.e., hit first by the hot gases leaving the combustor in a twin‑spool design. • Ask yourself: in which section would failure due to overheating of blades/vanes be most critical, requiring the most secondary air for cooling?