Pt7 denotes which quantity?

• A. local total pressure
• B. total pressure at station 7
• C. total inlet pressure
• D. total temperature at station 7

Answer: (B)

Pt7 represents the stagnation (total) pressure at a specific point in the engine flow, namely station 7. The symbol P_t means total pressure—the pressure the flow would have if it were brought to rest isentropically. The subscript 7 just identifies the exact location in the engine where that pressure is measured. So Pt7 is the total pressure at station 7, not a temperature and not the inlet pressure. In performance analysis, engineers look at how Pt changes from one station to another to assess pressure losses and overall cycle efficiency.