SCSC2003 Abstract S8546

Engine Flow Fence Actuator Sensitivity Analysis Using Mathematical Modeling & Computer Simulation

Engine Flow Fence Actuator Sensitivity Analysis Using Mathematical Modeling & Computer Simulation

Submitting Author: Mr. Oswald Harris


With the advent of super-fast personal computers and sophisticated simulation tools, mathematical modeling and computer simulation have become an extremely cost effective alternative of conducting static and dynamic analyses on complex gas turbine engine systems compared to actual hardware testing.

This paper describes the development of detailed mathematical models of the engine control components, and rotor system used on the United States Coast Guard, (USCG) HH65A helicopter fitted with LTS101-750B-2 engines (Reference 1). The models are subsequently utilized to conduct extensive investigation of the static and dynamic characteristics and stability properties of the rotor system, the engines and pneumatic controllers.

The results of the investigation are analyzed using Design for Six Sigma tools, (DFSS) to determine the effects of parameter variability of Customer Critical to Quality Requirements (CTQ's).

The control components consist of Honeywell Engines & Systems, Bendix, AL-B1 power turbine governors, TS-Y1 temperature compensators, DP-S1 main fuel controls, and the much maligned AV-P1 engine inlet flow fence actuator.

Basic principles of fluid dynamics, thermodynamics, and mechanical dynamics are used to derive equations of motion to describe the dynamics of each of the subsystems. These equations are solved using Matlab/Simulink available commercially from The MathWorks, Inc.

Each control component was calibrated as we do the actual control hardware against its Acceptance Test Plan (ATP). Successfully satisfying the ATP ensures that the component meets nominal standard of performance for production hardware suitable for field service. This is considered minimum standard of validation of the control component models.

In the case of the engine model it was validated against a limited set of engine data from a recent flight test data, and adequate correlation was exhibited (Reference 2).

Frequency response analyses done with the rotor model (Reference 3) established the dominant resonant frequencies of the main rotor, and the tail rotor to be wn = 4 Hz and 6 Hz respectively. These values match results previously published in an internal system development report (References 4).

The model was used to conduct parameter sensitivity analyses at various operating conditions to determine the main elements of the system that affects its steady state and transient performance.

The results from the analyses are presented and system component design recommendations are provided. The model also served to identify some unexpected design shortcomings that will influence subsequent component design.


1. Oswald G. Harris, Honeywell Engines & Systems, Report, “HH65A/LTS101-750B-2: AV-P1 Flow Fence Actuator Parameter Sensitivity Analysis,” May 24,2001.

2. Oswald G. Harris, Honeywell Engines & Systems, MEMO LTS-101-M003, "LTS101-750B-2 Model Validation," May 22, 2002.

3. Oswald G. Harris, Honeywell Engines & Systems, MEMO LTS-1-1-M002, “HH-65A Helicopter Rotor Model,” July 16, 1999.

4. Report No. 81-5309-5, LHTEC, “Drive Train Torsional Stability Verification Test Report for the HH-65A/T800 Demonstrator Program,” 10 October 1992.

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