🔍 Key Concepts

• Typical airflow distribution in gas turbines (how much air is for combustion vs. cooling/sealing/secondary air) • Role of excess air in controlling turbine temperatures and protecting turbine blades • Why only a portion of compressor discharge air actually mixes with fuel in the combustor

💭 Think About

• First, ask yourself: in a marine gas turbine, is MOST of the compressor air used directly for burning fuel, or is MOST of it used for cooling and other purposes? • Think about turbine blade temperature limits: does that push designers to use a relatively small or relatively large fraction of air in the actual combustion zone? • Eliminate any choice that would imply almost all the air is burned with fuel, leaving very little for cooling and dilution—does that sound realistic for a high‑temperature turbine?

✅ Before You Answer

• Be sure you understand that only a portion of the compressor air enters the primary combustion zone; the rest is for cooling, dilution, and sealing. • Estimate what “small fraction vs. majority” would mean in percentage terms and compare it to the choices. • Check which option seems most reasonable for the primary combustion air portion, given that the turbine must stay within safe metal temperature limits.