1. 2010 ESRDC Team Meeting Operation and Modeling of Turbogenerators Hsing-Pang Liu Center for Electromechanics, University of Texas at Austin Ruixian Fang Department of Mechanical Engineering, University of South Carolina June 3, 2010

2. Operation Basis and Modeling Goal Gas turbines are primarily used for jet aircraft propulsion and power generation. Operation of gas turbines is based on thermodynamics principles and constitutive relations of heat transfer and fluid mechanics. The goal of ESRDC gas turbine modeling effort is to perform transient dynamic modeling and simulation of generic gas turbines.

3. Initial Effort Contact various UT ESRDC team personnel to find out what has been done on the gas turbine modeling in the past Obtain technical information on gas turbine design, modeling, simulation, and testing through literature search Search existing gas turbine modeling/simulation software for potential use in electric ship power generation application Download several identified gas turbine modeling software for free trial and evaluation

5. Developed by Netherlands National Aerospace Laboratory NLR

6. Any gas turbine configuration

7. Steady-state and transient off-design simulations

8. GSP LE (Light Edition) downloaded for evaluation

9. “GasTurb 11”

10. Developed by Dr. Joachim Kurzke (retired from Germany’s aircraft engine manufacturer MTU Aero Engines)

11. Simulates most common types of gas turbines for propulsion and for power generation

12. Simulates transient operation of gas turbines

13. Component maps offered in GasTurb are all taken from open literature

14. Supports modeling of engines based on a limited amount of information

15. Entry -level version downloaded for evaluation

16. Numerical Propulsion System Simulation “NPSS”

17. Originally developed by NASA Glenn Research Center and its industrial/government partners for military jet engine applications and space transportation

18. A consortium was later created to ensure continued development and enhancement

19. Latest version of NPSS 2.2.1 has been released for commercial distribution

20. Steady-state and transient off-design performance prediction

21. NIST (National Institute of Standards and Technology) compliant thermodynamic gas-properties package

23. Developed by Visual Solutions Inc.

24. Steady-state and transient behavior

25. Downloaded for evaluation

26. “GT PRO”

27. Developed by THERMOFLOW

28. Gas turbine combined cycle design program (mainly for gas turbine power plants)

29. “GPAL Gas Turbine Simulators”

30. Developed by Gas Path Analysis Limited

31. Single-shaft gas turbine (used in power generator)

32. Two-shaft gas turbine operating with a free power turbine (used in mechanical drive applications)

33. “Flowmaster V7.7 Gas Turbine”

34. Developed by Flowmaster

36. First version of GSP developed by inheriting features from DYNGEN, combined with improved stability and speed of numerical iteration processes

37. Implemented in object-oriented Borland Delphi environment in 1996

39. Air and gas properties thermodynamically averaged over the flow cross-sectional areas at inlet and exit of each component module

40. A pre-defined design point is calculated first from a set of design point data

41. For “off-design” modeling, deviation from the design point is calculated by solving a set of non-linear differential equations, which include conservation of mass, momentum, and energy for all components

43. Another Thermodynamic Simulation Code (Cycle-Tempo) A thermodynamic simulation code developed by Delft University of Technology (Netherlands) A program for thermodynamic modeling and optimization of systems for production of electricity, heat, and refrigeration Capable of modeling steady-state behavior of generic gas turbine engines (NOT transient dynamic gas turbine simulation) Well-documented and relatively simple Used to build a gas turbine engine model to predict the steady-state performance at the engine’s design point Compare the steady-state results, at engine’s design point, predicted by “Cycle-Tempo” with those predicted by other commercial software

45. Selected by US Navy to power IPS EDM, DDG 1000, and Littoral Combat Ship (LCS)

46. Selected by UK MOD to power Royal Navy’s future all-electric aircraft carrier

47. A multi-spool engine and is composed of intermediate-pressure and high-pressure compressors (IPC and HPC) and high-pressure, intermediate-pressure, and free-power turbines (HPT, IPT, FPT)

49. Compare results predicted by “Cycle-Tempo“ and “GSP”

52. MT30 Steady-State Performance at Design Point(Predicted by Cycle-Tempo)

53. MT30 Steady-State Performance at Design Point(Predicted by GSP)

55. Outlet air pressure = 5.79 bar (Cycle-Tempo), 5.79 bar (GSP)

57. Outlet air pressure = 24.32 bar (Cycle-Tempo), 24.32 bar (GSP)

59. Inlet air pressure = 23.59 bar (Cycle-Tempo), 23.59 bar (GSP)

60. Outlet air temperature = 916.43oC (Cycle-Tempo), 915.84oC (GSP)

61. Outlet air pressure = 9.545 bar (Cycle-Tempo), 9.531 bar (GSP)

63. Outlet air pressure = 4.301 bar (Cycle-Tempo), 4.290 bar (GSP)

65. Outlet air pressure = 1.013 bar (Cycle-Tempo), 1.014 bar (GSP)

66. Power output = 35937 kW (Cycle-Tempo), 35660 kW (GSP)No difference as large as 1%

69. Component maps are not used, but instead, scale factors are calculated for scaling of the maps during subsequent off-design calculations

71. Uses the design point as a reference point

73. Transient effects included in GSP are rotor inertia, volume, heat soakage, and control system dynamics effects

75. corrected rotational speed (Nc)

76. pressure ratio (PR)

77. component efficiency (η)

78. Reynolds index

79. Component maps

80. Off-design performance is defined relativeto the design point and scaled proportionally

81. Pressure ratio and corrected mass flow are often used as map parameters

82. Three map input parameters are used to define the map operating point

83. Both steady state and transient simulation results can be plotted in component maps to assess component performance, such as compressor stall margin

84. For small differences (<25%), scaling usually does not add large errors; however, scaling for large difference will introduce large error margins

85. Component maps for specific engines are hard to obtain

87. Unscaled Generic Turbine Map(General Electric J85 Gas Turbine Engine)

89. representing a relation between pressure ratio and corrected mass flow

90. constantbeta lines are virtually perpendicular to the constant corrected speed curves in themaps

91. are equidistant, ranging between 0 and 1Two input parameters (i.e. beta parameter and speed parameter) can be used to find three output parameters (i.e., efficiency, pressure ratio, and corrected mass flow).

92. Unscaled Generic Compressor Map(Beta Parameter Included)

93. Unscaled Generic Turbine Map(Beta Parameter Included)

95. MOI of IP spool = 550 kg-m2

97. nominal rotational speed of IP = 7,500 rpm

98. nominal rotational speed of FPT = 3,600 rpm

99. A testing steady-state series off-design simulation was performed by investigating the relation between engine performance and fuel flow.

100. A manual fuel flow control was applied over a wide operating range by sweeping the fuel flow rate from the design-point value of 2.07 kg/s to a value of 0.6 kg/s.

102. MT30 Operating Lines in Scaled Free-Power Turbine Map (during An Off-Design Decreasing Fuel Flow Sweep)

103. A Transient Off-Design Simulation Input parameters are specified as functions of time, and the engine response to that input changes is then calculated. A testing transient simulation was carried out by using a manual fuel flow control to input an assumed time-dependent fuel flow rate (shown in the following figure).

104. Predicted MT30 Engine Transient Parameters Specific Fuel Consumption Airflow Rate High-Pressure Turbine Inlet Temperature Free-Power Turbine Output

107. Allows rapid adaptation to various configurations, rather than being dedicated to a specific engine

108. Implemented in Matlab-Simulink by using graphical user interface to reflect component-based architecture of the gas turbine model

109. Input is provided in files listing input variables, off-design component maps, control schedules, etc, and these files are accessed by any text file editor

110. Uses scalable maps, control functions and dimensionless parameters, for generic component models

111. Calculations performed on component level, using relations between component entry and exit gas properties based on component maps and thermodynamic equations

114. 29 Component-wise Gas Turbine VTB Model Gas Turbine Gas Turbine Simple-cycle 2-shaft 2 Stage compressor Intercooler Combustor Power Turbine Power turbine shaft speed feedback regulates fuel flow Six-phase Synchronous Generator Fuel Supply Heat Exchanger Combustor Low Pressure Compressor High Pressure Compressor Thermal Sink Note : compressors and turbines are characteristic curve based model. Power Turbine Gas Generator Turbine Intercooler Inlet Air Controllable resistive Load Starter Motor

115. Validation of VTB Gas Turbine Model Compare a single shaft VTB model results with GasTurb commercial simulation software Boundary conditions for the VTB model match those for GasTurb Compressor inlet conditions Air bleed Design point of shaft speed Etc. Results were compared Pressures and temperatures at the compressor exit port Turbine inlet/outlet ports Shaft power Compressor Map Turbine Map VTB Gasturb Fuel Combustor Component maps employed by GasTurb Bleeding design point (N = 11427rpm, Mass flow rate 21.018 kg/s). compressor Turbine inlet Note : Characteristic curves near design point were extracted and put into VTB model

116. Validation Results Comparison Design Point Compressor Outlet pressure error 2%, Outlet temperature error 9% Error caused by the assumption of ideal compression. Turbine Outlet pressure error 4% Outlet temperature error 8% Shaft power error 4% Note: GasTurb uses Generic fuel, while VTB assumes methane for these comparisons, we adjust the methane flow rate to match the compressor exhaust temperature. Off-Design Point Off-design validation Same engine settings. Different operating point. N = 9999 rpm - 10% below design point. Compressor Outlet temperature consistent with GasTurb Outlet pressure error 42% Error caused by the modeling method of the characteristic curve Turbine Outlet temperature error 15% Outlet pressure error 9% Shaft power error 8%