Gas Turbine Engine Control Systems Research Articles

A multi-input based full envelope acceleration schedule design method for gas turbine engine based on multilayer perceptron network

Acceleration schedule design is a crucial task in gas turbine engine (GTE) control system design as it dramatically influences the acceleration performance of GTE. The corrected parameter based (CPB) method is the traditional solution for acceleration schedule design, which is simple to implement but could not fully exploit GTE acceleration performance in full envelope. It even fails to prevent the GTE from exceeding its surge margin boundary in some envelope points. In this paper, aiming to improve full envelope acceleration performance of GTE, a novel multi-input based (MIB) method for high-precision acceleration schedule design is proposed. Firstly, the full envelope acceleration schedule (FEAS) design problem is represented, and the CPB method is realized as a baseline. Then, the proposed MIB method is formulated, which integrates a combined input selection (CIS) strategy and a multilayer perceptron (MLP) network. With a weighted integration loss function to evaluate sensors of GTE, the CIS strategy determines appropriate inputs to design a high-precision and robust FEAS. The MLP network is employed to further enhance the FEAS precision. Finally, effectiveness of the proposed method is verified through a series of simulations and flight data verification. Compared with the CPB, the simulation results of acceleration processes under random envelope points indicate that the high-precision MIB method significantly improves acceleration performance of GTE and reduces its possibility of violating the surge margin boundary. Acceleration performances of the two methods are further compared under 1000 random envelope points, and similar results show the effectiveness of the MIB. Moreover, the CIS strategy performs better than other input selection strategies and contributes to enhancing the FEAS design precision and robustness. The MLP network is more qualified to improve FEAS precision than other classical machine learning models.

Control Laws of the Aviation Gas Turbine Engine

The article is devoted to the solution of an important scientific and applied problem of improving the dynamic characteristics of an aviation engine and ensuring flight safety and the efficiency of aircraft operation, taking into account the properties of adaptive control of an aviation gas turbine engine: <structure><functioning><adaptation><development>. Based on the concept of creating perspective aviation engines with an increased level of control automation and with units operating at elevated temperatures and protected from high-energy electromagnetic radiation, the basic laws of controlling an aviation gas turbine engine in throttle modes, low-throttle mode, gas intake and discharge modes, and start-up mode are defined. To improve the working process of the engine, it is proposed to use the gas turbine engine control system as a mechatronic system based on the principle of adaptation. With the help of the Laplace transformation, the dynamic characteristics of the power plant were determined and the mathematical model of the power plant was investigated as a constructive aspect of the automatic control system. The gas turbine and the supersonic air manifold can to some extent be considered as independent control objects, replacing the connections between them with disturbing influences. For the control and limitation circuits, it is necessary to create control programs that calculate the values of the control parameters of the turbocharger rotor speed and gas temperature behind the turbine. Regulation of fuel consumption is carried out according to the derivative of the control parameters.

MoHydroLib: An HMU Library for Gas Turbine Control System with Modelica

Modelica is an open-source, object-oriented equation-based modeling language. It is suitable for describing sophisticated dynamic systems (symmetry/asymmetry) as it uses mathematical acausal equations to express physical characteristics. The hydraulic mechanical units (HMU) of gas turbine engine control systems couple the contents of mechanical, hydraulic, symmetry, and other multidisciplinary fields. This paper focuses on the Modelica description method of those HMU models. The content of this work is threefold: firstly, the division form of basic elements in HMU is defined, and the method for describing these element models with Modelica is proposed; secondly, the organization of the element models is defined by using the inheritance characteristics of Modelica, and a lightweight (small code scale) component model is designed; and finally, the causal/acausal connections are designed according to bond graph theory, and the elements and components are integrated into a prototype modeling library. In this paper, the modeling library is verified by comparing simulation results of five typical HMU subsystem models with commercial modeling and simulation software.

Design of <inline-formula> <tex-math notation="LaTeX">$H_\infty$ </tex-math> </inline-formula> Output Feedback Controller for Gas Turbine Engine Distributed Control With Random Packet Dropouts

The distributed control architecture is expected to dominate the gas turbine engine (GTE) control systems in future, in which the sensors and actuators are connected to the controllers via a network. Hence, the control problem of network-enabled high-performance distributed engine control (DEC) becomes important in modern gas turbine control systems. Due to the properties of the network, the packet dropouts must be considered. This study introduces a distributed control system architecture based on a networked cascade control system (NCCS). Typical turboshaft engine-distributed controllers are designed based on the NCCS framework with a $H_\infty $ output feedback under random packet-dropouts. The sufficient robust mean-stable conditions are derived via the Lyapunov stability theory and linear matrix inequality approach. In addition, the effectiveness of the presented method is illustrated through a series of simulations.

Logical-dynamical controllers for multiply connected technical objects (on examples of gas-turbine engines)

We propose a design structure and conception for a logical-dynamical controller for separate subsystems of a multiply connected automatic control system for a complex technical object. Basing on the discrete analysis of the movement of the multiply connected control object towards its equilibrium state, we synthesize a double logical algorithm forming a logically corrected signal taking into account the influence of natural cross interfaces inside the object. Using the simulation modeling of the proposed logical-dynamical multiply connected automatic control system for an aviation gas-turbine engine, we confirm the efficiency of the double logical control algorithm authority for a complex technical object functioning under conditions of parametric and functional indefiniteness.

HOW COST EFFECTIVE IS YOUR V & V?

ABSTRACTThere are many reasons for verification and validation (V&V) including their use to mature a product and reduce the overall development costs. However, there are many V&V approaches that can be applied, from review through modeling, analysis and testing. How effective are these at finding issues with the product? How cost effective are they? Does it matter when the approaches are performed, or in what sequence? This paper examines the V&V approaches applied during the development of gas turbine engine control and monitoring systems. How cost effective are they? In some cases, it is a requirement of the certification process that certain verification approaches are used – but if an approach is not cost effective, would you also use it during development of the product?

H∞ Networked Cascade Control System Design for Turboshaft Engines with Random Packet Dropouts

The distributed control architecture becomes more and more important in future gas turbine engine control systems, in which the sensors and actuators will be connected to the controllers via a network. Therefore, the control problem of network-enabled high-performance distributed engine control (DEC) has come to play an important role in modern gas turbine control systems, while, due to the properties of the network, the packet dropouts must be considered. This study introduces a distributed control system architecture based on a networked cascade control system (NCCS). Typical turboshaft engine distributed controllers are designed based on the NCCS framework with H∞ state feedback under random packet dropouts. The sufficient robust stable conditions are derived via the Lyapunov stability theory and linear matrix inequality approach. Simulations illustrate the effectiveness of the presented method.

Stability Analysis for GE T700 Turboshaft Distributed Engine Control Systems

Future gas turbine engine control systems will be based on a distributed architecture in which the sensors and actuators will be connected to the controllers via a communication network. The performance of the distributed engine control (DEC) system is dependent on the network performance. The network-induced time delay may degrade the performance of the closed-loop systems and even destabilize the systems if the controllers are designed without considering the effects of the delay. This paper introduces a new method to estimate the maximum tolerance of the time delay for analysis of the stability of the GE T700 turboshaft engine DEC system. The sufficient conditions for stability are derived and dynamic output feedback controllers for the turboshaft engine are applied. Hardware-in-the-loop simulation illustrates the effectiveness of the presented method.

Using the «virtual engine» software in automatic control system of gas turbine engine

The paper presents the mathematical tools and virtual engine software used in digital automatic control systems of modern gas turbine engines (GTE). The software is based on a real-time fully variable thermogasdynamic engine model operating in onboard computers. The new approach makes it possible to control the engine by the parameters inaccessible for measurement due to the virtual engine software in the gas turbine engine control system. The engine fault tolerance improves. We synthesized the control loops of a bypass turbojet engine with a high bypass ratio according to critical parameters (engine thrust, gas temperature in the combustor, stall margin) determined by calculations. We propose a methodology of restoring information on inlet airflow data and values of control factors in case of failure of information channels. The quality of engine regulation improved considerably. The lifetime of the engine increased essentially in the context of varying its characteristics in operation. We developed a methodology of real-time identification of an onboard engine thermogasdynamic simulation model based on the reverse feedback approach.

Design of Distributed Engine Control Systems with Uncertain Delay.

Future gas turbine engine control systems will be based on distributed architecture, in which, the sensors and actuators will be connected to the controllers via a communication network. The performance of the distributed engine control (DEC) is dependent on the network performance. This study introduces a distributed control system architecture based on a networked cascade control system (NCCS). Typical turboshaft engine-distributed controllers are designed based on the NCCS framework with a H∞ output feedback under network-induced time delays and uncertain disturbances. The sufficient conditions for robust stability are derived via the Lyapunov stability theory and linear matrix inequality approach. Both numerical and hardware-in-loop simulations illustrate the effectiveness of the presented method.

Идентификация предсрывных явлений в компрессоре для использования в адаптивной системе управления авиационного газотурбинного двигателя

Идентификация предсрывных явлений в компрессоре для использования в адаптивной системе управления авиационного газотурбинного двигателя

Development of requirements for accuracy of inertia compensation in gas temperature control loop of gas turbine engine control systems with a channel selector

The influence of thermocouple inertia compensation errors on the quality of channels selecting in multidimensional gas turbine engine control systems is analyzed. Based on the results obtained, the requirements to the accuracy of inertia thermocouple compensator realization are formulated. The study was carried out by means of mathematical modeling.

1.2.3 Reducing Scrap & Rework

AbstractA complex system almost always remains uncertain late into its development. In gas turbine engine control systems at Rolls‐Royce, typically 50% of the development costs of the software can be spent on corrections and modifications (scrap & rework). The scrap & rework is caused by both the evolution of the system and risks in the design and implementation. The paper summarises over 10 years of research in measuring, managing and reducing scrap & rework.

6.4.1 How Cost Effective is your V&V?

AbstractThere are many reasons for Verification and Validation (V&V) including their use to mature a product and reduce the overall development costs. However, there are many V&V approaches that can be applied, from review through modeling, analysis and testing. How effective are these at finding issues with the product? How cost effective are they? Does it matter when the approaches are performed, or in what sequence? This paper examines the Verification and Validation approaches applied during the development of gas turbine engine control and monitoring systems. How cost effective are they? In some cases it is a requirement of the Certification process that certain Verification approaches are used – but if an approach is not cost effective, would you also use it during development of the product?

Integrated Design of Feedback Controller and UIO: An LMI Solution

Fault diagnosis in a closed-loop gas turbine engine control system poses a great challenge since that the involved controller is to keep system stability, which desensitizes fault diagnostic performance. In this paper, a design algorithm that integrates various feedback controllers and unknown input observer (UIO) has been proposed. In this method, the controller has been considered as the state of an augmented model by combining the controller and the gas turbine model. Then the UIOs for fault detecting and isolating has been designed for this augmented model to obtain the parameters of the concerned controller and UIOs simultaneously. Moreover, this integrated design process has been formulated as linear matrix inequalities (LMIs). One notable feature of this algorithm is that the integrated design can weaken the effect of a feedback controller on output residual generator and maximize the robustness of UIO against unknown disturbances. Experimental results on a gas turbine engine illustrate the effectiveness and applicability of the proposed algorithm.

8.3.1 Certainty, Risk and Gambling in the Development of Complex Systems

AbstractOne of the few things certain about development of complex systems is the requirements for the system will remain uncertain late into the development program. Even though we recognize this, why do many programs assume that requirements will not change (gambling) or treat requirement change as a risk rather than a certainty? An analysis of gas turbine engine control systems requirements shows that typically 50% will change between Critical Design Review and Entry into Service. This requirements uncertainty manifests as technical risk to the programme. This paper evaluates the impact of not managing these uncertainties and describes how applying Systems Engineering principles can reduce this effect.Design iterations produce rework, and without technical risk management, ~50% of the effort will be wasted in producing unacceptable designs. In turn, correction of these errors will create more rework. This results in much iteration and cumulatively twice as much work is required to produce a mature design. With technical risk management, less than 10% of the design effort will result in rework, giving a mature product with far less iteration.Investigation into the source of the product development lifecycle problems indicates many escapes occur during requirements definition and review. Around twice as many changes are driven by errors in requirement definition by the developer, compared to customer‐driven requirements changes. In addition, many of these escapes are detected later in the product development lifecycle than they could have been found, resulting in further escalation of the cost of product development. This paper compares and contrasts the root causes for these escapes during system, software and hardware development and looks at the differences in consequences.The role of the Systems Engineer is critical in addressing these problems. In addition to effective elicitation of requirements from stakeholders, the Systems Engineer must manage volatility and apply robust design principles to protect against the impact of requirements changes. The Systems Engineer must flow requirements effectively from system to sub‐system, from sub‐systems to components and provide the “glue” that results in the integrated system being more than the sum of its parts.Some tools and techniques are presented to help Systems Engineers identify probable sources of uncertainty and provide effective mitigations. An approach is also presented for assessing the technical risk management “maturity” of a project, based upon ‘best practice’ approaches taken from those projects achieving low levels of engineering scrap and rework during their development phase.

On-line performance optimisation of aero engine control system

This paper is focused on on-line performance optimisation of gas turbine engine control systems. Practical problems of optimal engine control design and implementation are considered. An algorithm for on-line resolution of the engine control optimisation problem is proposed. The example of turbo-jet engine on-line specific fuel consumption minimisation is presented.

Distributed aero-engine control systems architecture selection using multi-objective optimisation

The cost of embedding intelligence into sensors and actuators directly has dramatically reduced over the past 10 years. This has led to the recent explosion of smart sensors and actuators available from manufacturers. Initially, these have been developed for the process control industries but increasingly applications in aerospace are being found. Integration of intelligent components is being carried out in an ad hoc manner by incorporating smart elements in inherently centralised architectures. This paper discusses the application of a multidisciplinary, multiobjective optimisation approach to a military gas turbine engine control system architecture design, where implementation benefits and penalties must be systematically evaluated.

Distributed Aero-Engine Control Systems Architecture Selection Using Multi-Objective Optimisation

Over the past 10 years the cost of embedding intelligence into sensors and actuators directly has dramatically reduced. This has led to the recent explosion of smart sensors and actuators available from manufacturers. Initially, these have been developed for the process control industries but increasingly applications in aerospace are being found. Integration of intelligent components is being done in an ad hoc manner by incorporating smart elements in inherently centralised architectures. This paper discusses the application of multi-disciplinary, multi-objective optimisation to a military gas turbine engine control system architecture design where implementation benefits need to be traded off against implementation penalties.

A new method of digital simulation for an aircraft gas turbine engine control system

An LD-9 aircraft gas turbine engine with its control system is simulated digitally by a new method, called the ‘method of spare parts’. The computer program of simulation possesses the main capabilities of a real engine altitude test facility and is called a ‘digital engine altitude simulator’. The results of simulation show that the capabilities of this new method are much better than that of the ordinary ‘method of block diagram’. The method can be used for modelling and simulating any type of gas turbine engines or industrial process control systems.