Teaching Gas Turbine Performance
Gas turbine performance needs to be taught with a clear focus on its practical applications. When teaching this subject, it is tempting to start with the simplest gas turbine configuration - the turbojet. However, this type of engine has not been relevant to aircraft propulsion for many decades. The two-spool turboshaft engines used in helicopters are much more pertinent. The theory of their gas generator is applicable to the most common jet engine, the turbofan.
In practical performance work, the use of computer programs is currently standard; nobody uses the equations usually taught at university, even though they must be covered in introductory courses. Many versions of these are not applicable to modern high-temperature, high-pressure ratio engines, and their superficial use can lead to erroneous conclusions. Equations with constant isentropic exponents or those which neglect dissociation in combustion calculations or heat soakage in transient simulation are examples. Extensive exercises with oversimplified correlations should be discouraged.
However, the use of software has its own challenges because it is perceived by newcomers merely as a black box. One goal of teaching should be de-mystifying the black box, using the software in a targeted way, asking the right questions, checking the results for plausibility, and recognizing incorrect or dubious results. Specialized gas turbine performance programs, developed at universities or commercially, can be of great help if they go beyond presenting numbers. The results of parametric studies, presented in eye-catching graphs, can tell a lot more about what is important. Temperature and enthalpy - entropy diagrams that are true to scale are helpful. In addition, Sankey Diagrams, used to visualize the flow of energy in an engine, can illustrate the results of design and off-design studies very effectively.
Read more about my view about practice-relevant teaching of gas turbine performance in the paper I have presented at the GPPS conference in September 2025 in Shanghai, China, see GPPS-TC-2025-0109.
I presented three tutorials on the basics of gas turbine performance at the recent ASME Turbo Expo conferences in London (2024), Memphis (2025), and Milan (2026). All of the tutorials were well attended.
Gas Turbine Performance Basics
Aircraft Engine Thrust Management
The following tutorial is gonna be helpful if you want to simulate engine starting and windmilling with a 0-D performance program.
All the tutorials are licensed under Attribution 4.0 International (CC BY 4.0) See: https://creativecommons.org/licenses/by/4.0/legalcode