Steam Turbine Performance Modeling Via MATLAB Simulation Programming with Emphasis on Low Exhaust Pressure Conditions

Open Access
Meyer, Zechariah Daniel
Area of Honors:
Engineering Science
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Eric Robert White, Thesis Supervisor
  • Gary L Gray, Honors Advisor
  • Rankine
  • Turbine
  • Modeling
ARL has developed a turbine analysis FORTRAN program involving a closed-cycle Rankine system. It functions as a performance predictor by using turbine inlet pressure, turbine outlet pressure, turbine inlet temperature, turbine shaft rotational velocity, and geometric data to calculate torque, mass flow, and outlet temperature values. At low exhaust pressure conditions, the predictions for mass flow and torque are generally low compared to experimental data. To develop a modern, accurate turbine modeling tool usable for ARL in the future, the FORTRAN code was translated into MATLAB® and verified. A sensitivity analysis of the subroutines in the program was performed. Finally, simulation of experimental run data was performed and parameter/code modifications were tested to determine ways to improve the modeling system. A 4% increase in the input variable of turbine inlet pressure yielded accurate mass flow results and increased torque results. An increase of 0.0007” at the nozzle exit diameter and nozzle throat diameter parameters yielded accurate mass flow results and increased torque results from the program. Accounting for thermal expansion of the nozzle throat diameter yielded accurate mass flow results and increased torque results from the program. Recommendations were made to analyze the physical measurements used to determine inputs to the program, and to verify the validity of torque load assumptions that are used when actual torque cannot be directly measured.