Multivariable Sliding Mode Control Design for Aircraft Engines

Many control theories are used in controlling aircraft engines. However, the multivariablesliding mode control is not yet established in this application even though ithas a lot of potential in dealing with complex and nonlinear systems such as aircraftengines. Therefore, a guideline in developing multivariable sliding mode control law for an aircraft engine is presented in this thesis. The problem of chattering in thesliding mode control is suppressed by the use of the boundary layer method. The controllogic is tested by implementing NASA\u27s Commercial Modular Aero-PropulsionSystem Simulation 40k (C-MAPSS40k). Simulation results are analyzed and comparedto the results obtained from the baseline controller. The robust property of multivariable sliding mode control is also examined by altering the flight condition ofthe engin

Multivariable Sliding Mode Control Design for Aircraft Engines

Many control theories are used in controlling aircraft engines. However, the multivariablesliding mode control is not yet established in this application even though ithas a lot of potential in dealing with complex and nonlinear systems such as aircraftengines. Therefore, a guideline in developing multivariable sliding mode control law for an aircraft engine is presented in this thesis. The problem of chattering in thesliding mode control is suppressed by the use of the boundary layer method. The controllogic is tested by implementing NASA\u27s Commercial Modular Aero-PropulsionSystem Simulation 40k (C-MAPSS40k). Simulation results are analyzed and comparedto the results obtained from the baseline controller. The robust property of multivariable sliding mode control is also examined by altering the flight condition ofthe engin

Propulsion Control Technology Development in the United States A Historical Perspective

This paper presents a historical perspective of the advancement of control technologies for aircraft gas turbine engines. The paper primarily covers technology advances in the United States in the last 60 years (1940 to approximately 2002). The paper emphasizes the pioneering technologies that have been tested or implemented during this period, assimilating knowledge and experience from industry experts, including personal interviews with both current and retired experts. Since the first United States-built aircraft gas turbine engine was flown in 1942, engine control technology has evolved from a simple hydro-mechanical fuel metering valve to a full-authority digital electronic control system (FADEC) that is common to all modern aircraft propulsion systems. At the same time, control systems have provided engine diagnostic functions. Engine diagnostic capabilities have also evolved from pilot observation of engine gauges to the automated on-board diagnostic system that uses mathematical models to assess engine health and assist in post-flight troubleshooting and maintenance. Using system complexity and capability as a measure, we can break the historical development of control systems down to four phases: (1) the start-up phase (1942 to 1949), (2) the growth phase (1950 to 1969), (3) the electronic phase (1970 to 1989), and (4) the integration phase (1990 to 2002). In each phase, the state-of-the-art control technology is described and the engines that have become historical landmarks, from the control and diagnostic standpoint, are identified. Finally, a historical perspective of engine controls in the last 60 years is presented in terms of control system complexity, number of sensors, number of lines of software (or embedded code), and other factors

Design definition study of a NASA/Navy lift/cruise fan technology V/STOL airplane: Risk assessment addendum to the final report

An assessment of risk, in terms of delivery delays, cost overrun, and performance achievement, associated with the V/STOL technology airplane is presented. The risk is discussed in terms of weight, structure, aerodynamics, propulsion, mechanical drive, and flight controls. The analysis ensures that risks associated with the design and development of the airplane will be eliminated in the course of the program and a useful technology airplane that meets the predicted cost, schedule, and performance can be produced

F100 multivariable control synthesis program: Evaluation of a multivariable control using a real-time engine simulation

The design, evaluation, and testing of a practical, multivariable, linear quadratic regulator control for the F100 turbofan engine were accomplished. NASA evaluation of the multivariable control logic and implementation are covered. The evaluation utilized a real time, hybrid computer simulation of the engine. Results of the evaluation are presented, and recommendations concerning future engine testing of the control are made. Results indicated that the engine testing of the control should be conducted as planned

STIRLOCHARGER POWERED BY EXHAUST HEAT FOR HIGH EFFICIENCY COMBUSTION AND ELECTRIC GENERATION

Stirling engines have been in existence since the early 1900s, and have been of little study in the recent years. Stirling engines are low power, heat engines which work on the principle of a temperature differential between the hot and cold sides. This thesis will look into the integration of a Stirling engine onto a turbocompressor for automotive applications calling the device a Stirlocharger

Combustion process in a Two-Stroke, H2-DI Linear Generator Free-Piston Engine during starting

A two-stroke free piston engine (FPE) for the application of a linear generator (LG) has been developed. It is a direct injection, spark ignition engine fuelled by hydrogen. In the past, the starting strategy of the FPE was based on the crank slider engine. However, the requirement of a different strategy is inevitable since the LG-FPE has no flywheel and has variable compression ratio during motoring. In addition, without a flywheel the engine has no energy storage to maintain its inertia in case of a misfire during starting. The fuelling amount, fuel injection and ignition timing during starting of LG-FPE is different from a conventional crank-slider engine. Starting of the former is done by accelerating a total moving mass of Skg alternately via electrical commutation of the linear motor towards both ends of the cylinders' stroke until sustainable combustions are achieved. The main objective of this research is to empirically investigate and determine the optimum injection and ignition timing during motoring with combustion when starting the LG FPE. Intake airflow measurements were obtained using laminar flow element setup. This is to determine the initial setting for hydrogen fuelling at stoichiometric air-fuel ratio. The investigation was carried out by varying the start of fuel injection (SOF) at constant start of ignition (SOl) and fuel per cycle (FPC) during motoring with combustion experiments of LG-FPE. Next, the SOF and FPC are kept constant while varying the SOL Finally, the FPC was varied at constant SOF and SOl values. Combustion process analyses were done by focusing on the rate of heat release, mass fraction burned, and ignition lag and combustion duration. From these analyses the optimum settings for SOF were found to be at linear position of+25.0 mm for cylinder 1 and -25.0 mm for cylinder 2. Early SOF setting resulted in lower peak pressure and slower rate of heat release while the ignition lag and combustion duration is longer. Whereas, the optimum settings for the SOl were found to be at position +29.5 mm for cylinder I and -30.0 mm for cylinder 2. The SOl must be before the peak pressure of compression (i.e. before the piston reverses direction). The timing must provide sufficient time for the flame to develop so that the piston will be in opposing motion in time for the heat release rate and cylinder pressure to reach its maximum. By using hydrogen instead of CNG, the ignition lag is reduced by 66% while the combustion duration is 50% faster

High Energy Density Propulsion Systems and Small Engine Dynamometer

This study investigates all possible methods of powering small unmanned vehicles, provides reasoning for the propulsion system down select, and covers in detail the design and production of a dynamometer to confirm theoretical energy density calculations for small engines. Initial energy density calculations are based upon manufacturer data, pressure vessel theory, and ideal thermodynamic cycle efficiencies. Engine tests are conducted with a braking type dynamometer for constant load energy density tests, and show true energy densities in excess of 1400 WH/lb of fuel. Theory predicts lithium polymer, the present unmanned system energy storage device of choice, to have much lower energy densities than other conversion energy sources. Small engines designed for efficiency, instead of maximum power, would provide the most advantageous method for powering small unmanned vehicles because these engines have widely variable power output, loss of mass during flight, and generate rotational power directly. Theoretical predictions for the energy density of small engines has been verified through testing. Tested values up to 1400 WH/lb can be seen under proper operating conditions. The implementation of such a high energy density system will require a significant amount of follow-on design work to enable the engines to tolerate the higher temperatures of lean operation. Suggestions are proposed to enable a reliable, small -engine propulsion system in future work. Performance calculations show that a mature system is capable of month long flight times, and unrefueled circumnavigation of the globe.Mechanical & Aerospace Engineerin

Digital simulation of gas turbine performance

No abstract available