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"Turbojet engines"
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Gas turbine propulsion systems
\"'Gas Turbine Propulsion Systems in Aerospace & Defense' pulls together all of the systems and subsystems associated with gas turbine engines in aircraft and marine warship applications. The subject of engine (fuel) control has undergone major changes in the past 20 years due to the advent of the digital electronic control technology and therefore existing books on the subject are typically out of date with current methods. 'Gas Turbine Propulsion Systems in Aerospace & Defense' discusses the latest technologies in this area; including marine propulsion which is an emerging application area for the technology that involves some interesting modifications to aviation technologies. This book also fits well into the systems engineering focus of the Aerospace Series. Includes chapters on aircraft engine systems functional overview, marine propulsion systems, fuel control and power management systems, engine lubrication and scavenging systems, nacelle and ancillary systems, engine certification, unique engine systems and future developments in gas turbine propulsion systems Includes case studies of specific engines Includes applications within marine defence Accompanied by a book companion website featuring full colour images \"-- Provided by publisher.
Book
The Use of Ethanol as an Alternative Fuel for Small Turbojet Engines
The use of alternative fuels to traditional kerosene-based ones in turbo-jet engines is currently being widely explored and researched. However, the application of alternative fuels in the area of small turbojet engines with thrust ratings up to 2 kilo-newtons, which are used as auxiliary power units or to propel small aircraft or drones, is not as well researched. This paper explores the use of ethanol as a sustainable fuel and its effects on the operation of a small turbojet engine under laboratory conditions. Several concentrations of ethanol and JET A-1 mixtures are explored to study the effects of this fuel on the basic parameters of a small turbojet engine. The influence of the different concentrations of the mixture on the start-up process, speed of the engine, exhaust gas temperature, and compressor pressure are evaluated. The measurements shown in the article represent a pilot study, the results of which show that ethanol can be reliably used as an alternative fuel only when its concentration in a mixture with traditional fuel is lower than 40%, yielding positive effects on the operating temperatures and small negative effects on the speed or thrust of the engine.
Journal Article
The jet engine
\"The Jet Engine provides a complete, accessibledescription of the working and underlying principles of the gasturbine. Accessible, non-technical approach explaining the workings of jet engines, for readers of all levels. Full colour diagrams, cutaways and photographs throughout, written by RR specialists in all the respective fields, hugely popular and well-reviewed book, originally published in 2005 under Rolls Royce's own imprint\"-- Provided by publisher.
Book
Approach for fault prognosis using recurrent neural network
In general, fault prognosis research usually leads to the research of remaining useful life prediction and performance prediction (prediction of target feature), which can be regarded as a sequence learning problem. Considering the significant success achieved by the recurrent neural network in sequence learning problems such as precise timing, speech recognition, and so on, this paper proposes a novel approach for fault prognosis with the degradation sequence of equipment based on the recurrent neural network. Long short-term memory (LSTM) network is utilized due to its capability of learning long-term dependencies, which takes the concatenated feature and operation state indicator of the equipment as the input. Note that the indicator is a one-hot vector, and based on it, the remaining useful life can be estimated without any pre-defined threshold. The outputs of the LSTM networks are connected to a fully-connected layer to map the hidden state into the parameters of a Gaussian mixture model and a categorical distribution so that the predicted output sequence can be sampled from them. The performance of the proposed method is verified by the health monitoring data of aircraft turbofan engines. The result shows that the proposed approach is able to achieve significant performance whether in one-step prediction task, in long-term prediction task, or in remaining useful life prediction task.
Journal Article
Research on Hydrogen-Fueled Turbojet Engine Control Method Based on Model-Based Design
Due to the substantial disparities in physical attributes between hydrogen fuel and conventional fuels, the development of an efficient controller presents a formidable challenge. In this context, this paper delves into the utilization of a model-based design (MBD) methodology for the purpose of conceiving and enhancing control systems for hydrogen-fueled turbojet engines. The investigation commences by adopting an established physical model of a hydrogen-fueled turbojet engine and subsequently validates its performance through rigorous simulation exercises. Consequently, this research undertakes a systematic deconstruction of the design process into discrete sub-phases, thus facilitating a seamless progression from system requirement analysis to system verification. This approach engenders a concurrent design and optimization of the control system. The ultimate confirmation of the controller’s efficacy and reliability is achieved through exhaustive simulations and Hardware-In-the-Loop testing. The research findings not only serve to augment design efficiency and mitigate design expenditures, but also propose avenues for further performance ameliorations in the realm of hydrogen-fueled turbojet engines. The control system accuracy of MBD is compared with the experimental results, and under high hydrogen fuel flow conditions, the errors reach an extremely low level of 0.1%. This affords a novel design paradigm within the domain of aero-engine control.
Journal Article
Performance and Emissions Assessment of a Micro-Turbojet Engine Fueled with Jet A and Blends of Propanol, Butanol, Pentanol, Hexanol, Heptanol, and Octanol
This study examines the impact of alcohol blends on the performance and emissions of aviation micro-turbojet engines. Thus, propanol, butanol, pentanol, hexanol, heptanol, and octanol were tested at 10%, 20%, and 30% concentrations and mixed with Jet A, as well as with an additional 5% heptanol blend to preserve base fuel properties, to fuel a JetCat P80 micro-turbojet. Physicochemical properties such as density, viscosity, and elemental composition were analyzed before engine testing. Carbon dioxide (CO2) emissions from 1 kg of fuel combustion varied, with propanol yielding the lowest at 3.02 kg CO2 per kg of fuel and octanol yielding the highest at 3.22 kg CO2 per kg of fuel. The following results were obtained: alcohol blends lowered exhaust gas temperature by up to 7.5% at idle and intermediate thrust but slightly increased it at maximum power; fuel mass flow increased with alcohol concentration, peaking at 20.4% above Jet A for 30% propanol; and thrust varied from −4.92% to +7.4%. While specific fuel consumption increased by up to 12.8% for propanol, thermal efficiency declined by 1.8–5.6% and combustion efficiency remained within ±2% of Jet A. Butanol and octanol emerged as viable alternatives, balancing emissions reduction and efficiency. The results emphasize the need for an optimal trade-off between environmental impact and engine performance.
Journal Article
Robust Control of Small Turbojet Engines
Modern turbojet engines mainly use computerized digital engine control systems. This opens the way for application of advanced algorithms aimed at increasing their operational efficiency and safety. The theory of robust control is a set of methods known for good results in complex control tasks, making them ideal candidates for application in the current turbojet engine control units. Different methodologies in the design of robust controllers, utilizing a small turbojet engine with variable exhaust nozzle designated as iSTC-21v, were therefore investigated in the article. The resulting controllers were evaluated for efficiency in laboratory conditions. The aim was to find a suitable approach and design method for robust controllers, taking into account the limitations and specifics of a real turbojet engine and its hardware, contrary to most studies which have used only simulated environments. The article shows the most effective approach in the design of robust controllers and the resulting speed controllers for a class of small turbojet engines, which can be applied in a discrete digital control environment.
Journal Article
Study on the biparametrical transudations circuits with distributed parameters
This paper highlights the methods of resenting mode in the transudation with distributed parameters. The transient parameters of the power supply were analyzed. It was discovered that resonance is provided in a small range of movement of the moving component of the sensor in known turbofan engines, indicating that the known techniques of sustaining the resonance mode are flawed. Further study should focus on developing novel methods for preserving resonance mode over the entire range of change of the converted value, general principles of turbojet engine construction, and a complete examination of their resonant circuits, according to the findings.
Journal Article
Off-equilibrium linearisation-based nonlinear control of turbojet enginese with sum-of-squares programming
In conventional linear parameter-varying (LPV) modelling and gain scheduling control design for turbojet engines, the linearisation is performed at a set of equilibrium points, and the validity of such LPV models is ensured near the equilibria. However, the linear model can only provide an approximate description of the engine’s state when the system operates away from equilibrium. In this paper, it is suggested that such linearisation should be carried out not only at equilibrium states but also in transient (off-equilibrium) operating regimes. This will result in a global approximation to the system states whether equilibrium or off-equilibrium. Theoretically, the transient control performance can be improved by introducing such an off-equilibrium linearisation-based control procedure. Subsequently, a gain scheduling control procedure based on off-equilibrium linearisation models is proposed by using sum-of-squares (SOS) programming, which, compared with many convex programming methods, can provide less conservative results. The resulting off-equilibrium linearisation-based nonlinear control procedure with SOS programming can capture a wide range of transient engine dynamics with better accuracy, and further achieve better control performance.
Journal Article
