Tool for the Integrated Dynamic Numerical Propulsion System Simulation (NPSS)/Turbine Engine Closed-Loop Transient Analysis (TTECTrA) User's Guide

The Tool for Turbine Engine Closed-Loop Transient Analysis (TTECTrA ver2) is a control design tool thatenables preliminary estimation of transient performance for models without requiring a full nonlinear controller to bedesigned. The program is compatible with subsonic engine models implemented in the MATLAB/Simulink (TheMathworks, Inc.) environment and Numerical Propulsion System Simulation (NPSS) framework. At a specified flightcondition, TTECTrA will design a closed-loop controller meeting user-defined requirements in a semi or fully automatedfashion. Multiple specifications may be provided, in which case TTECTrA will design one controller for each, producing acollection of controllers in a single run. Each resulting controller contains a setpoint map, a schedule of setpointcontroller gains, and limiters; all contributing to transient characteristics. The goal of the program is to providesteady-state engine designers with more immediate feedback on the transient engine performance earlier in the design cycle

Control Design for a Generic Commercial Aircraft Engine

This paper describes the control algorithms and control design process for a generic commercial aircraft engine simulation of a 40,000 lb thrust class, two spool, high bypass ratio turbofan engine. The aircraft engine is a complex nonlinear system designed to operate over an extreme range of environmental conditions, at temperatures from approximately -60 to 120+ F, and at altitudes from below sea level to 40,000 ft, posing multiple control design constraints. The objective of this paper is to provide the reader an overview of the control design process, design considerations, and justifications as to why the particular architecture and limits have been chosen. The controller architecture contains a gain-scheduled Proportional Integral controller along with logic to protect the aircraft engine from exceeding any limits. Simulation results illustrate that the closed loop system meets the Federal Aviation Administration s thrust response requirement

Overview of Intelligent Power Controller Development for the Deep Space Gateway

Intelligent, or autonomous, control of a spacecraft is an enabling technology that must be developed for deep space human exploration. NASAs current long term human space platform, the International Space Station, which is in Low Earth Orbit, is in almost continuous communication with ground based mission control. This allows near real-time control of all the vehicle core systems, including power, to be controlled by the ground. As focus shifts from Low Earth Orbit, communication time-lag and communication bandwidth limitations beyond geosynchronous orbit does not permit this type of operation. This presentation contains ongoing work at NASA to develop an architecture for autonomous power control and the vehicle manager which monitors, coordinates, and delegates to all the on-board subsystems to enable autonomous control of the complete spacecraft

Autonomous Power Control

Intelligent autonomous control of a spacecraft is an enabling technology that must be developed for deep space human exploration. NASA's current long term human space platform, the International Space Station which is in Low Earth Orbit, is in almost continuous communication with ground based mission control. This allows near realtime operation of all the vehicle core systems, including power, from the ground. As the focus shifts from Low Earth Orbit to deep space, challenges associated with communication time-lag and bandwidth limitations beyond geosynchronous orbit do not permit this type of ground based operation. These communication limitations motivate autonomous vehicle operations, including the vehicle subsystems such as power. This presentation will describe the ongoing development of an Autonomous Power Control (APC) system that can be used for a deep space exploration spacecraft. This work extends previous work on developing an autonomous power control which includes developing a control architecture for deep space vehicles, the use of software agents, and constructing a control simulation lab for demonstrating this capability. This presentation will begin with a discussion of the representative future power architectures that will be required for deep space exploration vehicles. The presentation then will describe how the power controller will integrate with the vehicle followed with a discussion of the autonomous power controller. Next it will describe the test setup used to evaluate the performance of the system and lastly show some of the test results. To develop the type of controller envisioned, it will be necessary to employ a detailed real-time simulation to evaluate its performance and ultimately verify its functionality

Sensor Data Qualification Technique Applied to Gas Turbine Engines

This paper applies a previously developed sensor data qualification technique to a commercial aircraft engine simulation known as the Commercial Modular Aero-Propulsion System Simulation 40,000 (C-MAPSS40k). The sensor data qualification technique is designed to detect, isolate, and accommodate faulty sensor measurements. It features sensor networks, which group various sensors together and relies on an empirically derived analytical model to relate the sensor measurements. Relationships between all member sensors of the network are analyzed to detect and isolate any faulty sensor within the network

Shock Position Control for Mode Transition in a Turbine Based Combined Cycle Engine Inlet Model

A dual flow-path inlet for a turbine based combined cycle (TBCC) propulsion system is to be tested in order to evaluate methodologies for performing a controlled inlet mode transition. Prior to experimental testing, simulation models are used to test, debug, and validate potential control algorithms which are designed to maintain shock position during inlet disturbances. One simulation package being used for testing is the High Mach Transient Engine Cycle Code simulation, known as HiTECC. This paper discusses the development of a mode transition schedule for the HiTECC simulation that is analogous to the development of inlet performance maps. Inlet performance maps, derived through experimental means, describe the performance and operability of the inlet as the splitter closes, switching power production from the turbine engine to the Dual Mode Scram Jet. With knowledge of the operability and performance tradeoffs, a closed loop system can be designed to optimize the performance of the inlet. This paper demonstrates the design of the closed loop control system and benefit with the implementation of a Proportional-Integral controller, an H-Infinity based controller, and a disturbance observer based controller; all of which avoid inlet unstart during a mode transition with a simulated disturbance that would lead to inlet unstart without closed loop control

Enhanced Engine Performance During Emergency Operation Using a Model-Based Engine Control Architecture

This paper discusses the design and application of model-based engine control (MBEC) for use during emergency operation of the aircraft. The MBEC methodology is applied to the Commercial Modular Aero-Propulsion System Simulation 40k (CMAPSS40k) and features an optimal tuner Kalman Filter (OTKF) to estimate unmeasured engine parameters, which can then be used for control. During an emergency scenario, normally-conservative engine operating limits may be relaxed to increase the performance of the engine and overall survivability of the aircraft; this comes at the cost of additional risk of an engine failure. The MBEC architecture offers the advantage of estimating key engine parameters that are not directly measureable. Estimating the unknown parameters allows for tighter control over these parameters, and on the level of risk the engine will operate at. This will allow the engine to achieve better performance than possible when operating to more conservative limits on a related, measurable parameter

Tool for Turbine Engine Closed-Loop Transient Analysis (TTECTrA) Users' Guide

The tool for turbine engine closed-loop transient analysis (TTECTrA) is a semi-automated control design tool for subsonic aircraft engine simulations. At a specific flight condition, TTECTrA produces a basic controller designed to meet user-defined goals and containing only the fundamental limiters that affect the transient performance of the engine. The purpose of this tool is to provide the user a preliminary estimate of the transient performance of an engine model without the need to design a full nonlinear controller

Dynamic Analysis for a Geared Turbofan Engine with Variable Area Fan Nozzle

Aggressive design goals have been set for future aero-propulsion systems with regards to fuel economy, noise, and emissions. To meet these challenging goals, advanced propulsion concepts are being explored and current operating margins are being re-evaluated to find additional concessions that can be made. One advanced propulsion concept being evaluated is a geared turbofan with a variable area fan nozzle (VAFN), developed by NASA. This engine features a small core, a fan driven by the low pressure turbine through a reduction gearbox, and a shape memory alloy (SMA)-actuated VAFN. The VAFN is designed to allow both a small exit area for efficient operation at cruise, while being able to open wider at high power conditions to reduce backpressure on the fan and ensure a safe level of stall margin is maintained. The VAFN is actuated via a SMA-based system instead of a conventional system to decrease overall weight of the system, however, SMA-based actuators respond relatively slowly, which introduces dynamic issues that are investigated in this work. This paper describes both a control system designed specifically for issues associated with SMAs, and dynamic analysis of the geared turbofan VAFN with the SMA actuators. Also, some future recommendations are provided for this type of propulsion system

Autonomous Power Controller for the NASA Gateway

Intelligent autonomous control of a spacecraft is an enabling technology that must be developed for deep space human exploration. NASA's current long term human space platform, the International Space Station which is in Low Earth Orbit, is in almost continuous communication with ground based mission control. This allows near real-time operation of all the vehicle core systems, including power, from the ground. As the focus shifts from Low Earth Orbit to deep space, challenges associated with communication time-lag and bandwidth limitations beyond geosynchronous orbit do not permit this type of ground based operation. These communication limitations motivate autonomous vehicle operations, including the vehicle subsystems such as power. This presentation will describe the ongoing development of an Autonomous Power Control (APC) system that can be used for a deep space exploration spacecraft. This work extends previous work on developing an autonomous power control which includes developing a control architecture for deep space vehicles, the use of software agents, and constructing a control simulation lab for demonstrating this capability. This presentation will begin with a discussion of the representative future power architectures that will be required for deep space exploration vehicles. The presentation then will describe how the power controller will integrate with the vehicle followed with a discussion of the autonomous power controller. Next it will describe the test setup used to evaluate the performance of the system and lastly show some of the test results. To develop the type of controller envisioned, it will be necessary to employ a detailed real-time simulation to evaluate its performance and ultimately verify its functionality