Introduction to Engine Performance Simulation Standards From the S-15 Committee for Gas Turbine Performance Simulation Nomenclature and Interfaces Last Revision: April 14, 2015

Mission Statement SAE International is a global body of scientists, engineers, and practitioners that advances self- propelled vehicle and system knowledge in a neutral forum for the benefit of society. 2

List of Aerospace Propulsion Committees 3

S-15 Technical Committee Gas Turbine Performance Simulation Nomenclature and Interfaces committee addresses: – All facets of engine performance monitoring/ testing/ analysis, – Including tools, processes, and methodologies, – Providing recommendations relative to the information contained in gas turbine engine performance data, – The format required to interface with users' computers and programs, and – Is relevant to airframers, engine manufacturers, the military, and NASA. 4

SAE Document types: AIR: Aerospace Information Report ("FYI") ARP: Aerospace Recommended Practice ("You should") AS: Aerospace Standard ("You shall") 5

S-15 Document Family Tree FortranObject- Oriented Station Numbering AS755 NomenclatureAS6502ARP5571 InterfaceAS4191ARP4868 GTE Performance Presentation AS681 Analysis/ Data Reduction ARP1210 AIR5509 Day Types AS210 Real-Time Simulation ARP4148 AIR4548 Following pages provide a brief summary of each document 6

04/14/2015 7

AIR4548 "Real-Time Modeling Methods for Gas Turbine Engine Performance" -Provides the description of 3 specific modeling methods: 1.Aero-thermodynamic - Simplified Non-linear Component-level cycle balance. 2.Piecewise linear - Whole engine process represented as variations about a baseline set of partial differential equations. 3. Transfer Function -Whole engine steady-state characterization supplemented by subsystem offsets and transient characteristics. 8

AIR5509 “Using Engine Test Data to Model Engine Performance” -Documents the process of matching an engine cycle model to test data and identifies common terminology to facilitate communication among all interested parties. -Provides definitions & description (including illustration) for: Data Acquisition Data Verification Data Reduction Data Analysis Performance Model adjustments & Data Match … 9

ARP1210 "Gas Turbine Engine Interface Test Data Reduction Computer Programs" -Provides general requirements for performance analysis programs: Program Input/Output User's Manual Units... 10

ARP4148 "Gas Turbine Engine Real Time Performance Model Presentation for Digital Computers" -Provides general requirements specific to real time model: Dynamic response Numerical stability Validity... 11

ARP4868 “Function-Based API for Gas Turbine Engine Performance Programs” -Specifies a set of functions and their expected behaviors that constitute a function based Application Program Interface (API). -Defines generic language independent functions. -Has appendices for specific implementations, currently C and Fortran. -Later revisions will add appendices for other languages. -Program Interface Functions replace the Fortran Common Blocks. Here is an example of interface & execution in subprogram mode: FunctionDescription x4868set*(…) Sets the value of parameters, x4868run(…) Executes the engine program, x4868get*(…) Gets the value of parameters. 12

ARP5571 “Gas Turbine Engine Performance Presentation and Nomenclature for Object-Oriented Computer Programs” -Provides nomenclature for Objects, Nodes, switches & variables, e.g.: Amb.MN CmpH.Nc TrbH.eff F030.Tt Pset.switchRC... -Provides structure for Error/Warning codes (ESI): The 8 or 9 digit integer includes the following information about the error/warning: severity, purpose, category & owner. 13

AS210 “Definition of Commonly Used Day Types (Atmospheric Ambient Temperature Characteristics Versus Pressure Altitude)” -Provides definitions (& plots) for “Hot Day”, “Tropical Day”, “Standard Day”, “Polar Day” and “Cold Day”... -Provides definitions for Altitude: Physical altitude, Geometric altitude, GPS altitude, Geopotential altitude, Pressure altitude. Altitude Temperature Hot Day Cold Day 14

AS4191 "Gas Turbine Engine Performance Presentation for Computer Programs Using FORTRAN" -Provides definition of "subroutine-mode" program interface with Fortran Common blocks. Example of one of the 6 Common Blocks: Minimum Input List for FIXIN Common Block: (1-6 out of 15): FIXIN() 1.NIN 2.NOUT 3.TITLE 4.CASE 5.ZALT 6.ZDTAMB … -AS4191 now replaces previous document ARP4191, which is cancelled. 15

AS681 "Gas Turbine Engine Performance Presentation for Computer Programs" -Provides definitions, general requirements and programming practices. Note that this document is program language independent. An example of requirements: Minimum list of program input variables: altitude, ambient temp, rating,... Minimum list of program output variables: thrust, power, fuel flow,... Rating code assignments. Example of ratings: CodeRating 55 MTO 50TO 45Max Cont …… 16

AS755 "Aircraft Propulsion System Performance Station Designation and Nomenclature" -Provides guidelines on Engine station designation. Stations are identified with a 3 (or more) digit number. Example: Station number: 160. The first digit: (1) is the stream, The second digit: (6) is the thermodynamic process, Third: (0) and optional fourth are intermediate stations. Station numbering is illustrated for several engine configurations: turbofan, turboprop,… -Also provides general performance parameter nomenclature: T41, P3, DTAMB, WF,... -AS755 now replaces previous document ARP755, which is cancelled. 17

S-15 Committee Contact Information Chairman: Keith Pattison SAE Staff representative: Rhonda Joseph (724)