1. Introduction to Engine Performance Simulation Standards
From the S-15 Committee for
Gas Turbine Performance Simulation Nomenclature and Interfaces
Last Revision: March 30, 2017

2. 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.

3. List of Aerospace Propulsion Committees

4. 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.

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

6. S-15 Document Family Tree
GTE Performance Presentation
AS681
Fortran
Object-Oriented
Station Numbering
AS755
AIR6508*
Nomenclature
AS6502
ARP5571
Interface
AS4191
ARP4868
ARP7998*
Day Types
AS210
Analysis/ Data Reduction
ARP1210
AIR5509
Real-Time Simulation
ARP4148
AIR4548
Genealogy/Family tree to help identify the relevant document
* New standards currently in development
Following pages provide a brief
summary of each document

7. 03/30/2017

8. 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:
Code Rating
55 MTO
50 TO
45 Max Cont
… …

9. 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.
One of the Most important document

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

11. 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 …

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

13. 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
...

14. 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:
Function Description
x4868set*(…) Sets the value of parameters,
x4868run(…) Executes the engine program,
x4868get*(…) Gets the value of parameters.
OO Model delivery Spec

15. -Provides nomenclature for Objects, Nodes, switches & variables, e.g.:
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.
Standard Object Names- Instantiated Object names & port names
Standard Variable Names
Standard Switches and Options
Common Error Reporting ESI Codes

16. 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.
Temperature
Hot Day
This is a cartoon picture!!!
Cold Day
Altitude

17. 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()
NIN
NOUT
TITLE
CASE
ZALT
ZDTAMB …
-AS4191 now replaces previous document ARP4191, which is cancelled.
Fortran Model delivery specifications

18. New Standards in Development
AIR6508 Unconventional Propulsion Cycles' Station Designation and Nomenclature
ARP7998 Shared Memory Interface for Gas Turbine Engine Performance Programs

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