CERES :: Browsing by Author "Jafari, Soheil"

Browsing by Author "Jafari, Soheil"

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Open Access
Advanced constraints management strategy for real-time optimization of gas turbine engine transient performance
(MDPI, 2019-12-06) Nikolaidis, Theoklis; Jafari, Soheil; Li, Zhuo
Motivated by the growing technology of control and data processing as well as the increasingly complex designs of the new generation of gas turbine engines, a fully automatic control strategy that is capable of dealing with different aspects of operational and safety considerations is required to be implemented on gas turbine engines. An advanced practical control mode satisfaction method for the entire operating envelope of gas turbine engines is proposed in this paper to achieve the optimal transient performance for the engine. A constraint management strategy is developed to generate different controller settings for short-range fighters as well as long-range intercontinental aircraft engines at different operating conditions by utilizing a model predictive control approach. Then, the designed controller is tuned and modified with respect to different realistic considerations including the practicality, physical limitations, system dynamics, and computational efforts. The simulation results from a verified two-spool turbofan engine model and controller show that the proposed method is capable of maneuverability and/or fuel economy optimization indices while satisfying all the predefined constraints successfully. Based on the parameters, natural frequencies, and dynamic behavior of the system, a set of optimized weighting factors for different engine parameters is also proposed to achieve the optimal and safe operation for the engine at different flight conditions. The paper demonstrates the effects of the prediction length and control horizon; adding new constraints on the computational effort and the controller performance are also discussed in detail to confirm the effectiveness and practicality of the proposed approach in developing a fully automatic optimized real-time controller for gas turbine engines.
Open Access
Advanced control algorithm for FADEC systems in the next generation of turbofan engines to minimize emission levels
(MDPI, 2022-05-23) Aghasharifian Esfahan, Majid; Namazi, Mohammadmehdi; Nikolaidis, Theoklis; Jafari, Soheil
New propulsion systems in aircrafts must meet strict regulations and emission limitations. The Flightpath 2050 goals set by the Advisory Council for Aviation Research and Innovation in Europe (ACARE) include reductions of 75%, 90%, and 65% in CO2, NOx, and noise, respectively. These goals are not fully satisfied by marginal improvements in gas turbine technology or aircraft design. A novel control design procedure for the next generation of turbofan engines is proposed in this paper to improve Full Authority Digital Engine Control (FADEC) systems and reduce the emission levels to meet the Flightpath 2050 regulations. Hence, an Adaptive Network–based Fuzzy Inference System (ANFIS), nonlinear autoregressive network with exogenous inputs (NARX) techniques, and the block-structure Hammerstein–Wiener approach are used to develop a model for a turbofan engine. The Min–Max control structure is chosen as the most widely used practical control algorithm for gas turbine aero engines. The objective function is considered to minimize the emission level for the engine in a pre-defined maneuver while keeping the engine performance in different aspects. The Genetic Algorithm (GA) is applied to find the optimized control structure. The results confirm the effectiveness of the proposed approach in emission reduction for the next generation of turbofan engines.
Open Access
Advanced modelling and control of 5MW wind turbine using global optimization algorithms
(SAGE, 2018-10-29) Jafari, Soheil; Pishkenari, Mohsen Majidi; Sohrabi, Shahin; Feizarefi, Morteza
This article presents a methodological approach for controller gain tuning of wind turbines using global optimization algorithms. For this purpose, the wind turbine structural and aerodynamic modeling are first described and a complete model for a 5 MW wind turbine is developed as a case study based on a systematic modeling approach. The turbine control requirements are then described and classified using its power curve to generate an appropriate control structure for satisfying all turbine control modes simultaneously. Next, the controller gain tuning procedure is formulated as an engineering optimization problem where the command tracking error and minimum response time are defined as objective function indices and physical limitations (overspeed and oscillatory response) are considered as penalty functions. Taking the nonlinear nature of the turbine model and its controller into account, two meta-heuristic global optimization algorithms (Imperialist Competitive Algorithm and Differential Evolution) are used to deal with the defined objective functions where the mechanism of interaction between the defined problem and the used algorithms are presented in a flowchart feature. The results confirm that the proposed approach is satisfactory and both algorithms are able to achieve the optimized controller for the wind turbine.
Open Access
Advanced optimization of gas turbine aero-engine transient performance using linkage-learning genetic algorithm: Part Ⅰ, Building blocks detection and optimization in runway
(Elsevier, 2020-08-15) Liu, Yinfeng; Jafari, Soheil; Nikolaidis, Theoklis
This paper proposes a Linkage Learning Genetic Algorithm (LLGA) based on the messy Genetic Algorithm (mGA) to optimize the Min-Max fuel controller performance in Gas Turbine Engine (GTE). For this purpose, a GTE fuel controller Simulink model based on the Min-Max selection strategy is firstly built. Then, the objective function that considers both performance indices (response time and fuel consumption) and penalty items (fluctuation, tracking error, overspeed and acceleration/deceleration) is established to quantify the controller performance. Next, the task to optimize the fuel controller is converted to find the optimization gains combination that could minimize the objective function while satisfying constraints and limitations. In order to reduce the optimization time and to avoid trapping in the local optimums, two kinds of building block detection methods including lower fitness value method and bigger fitness value change method are proposed to determine the most important bits which have more contribution on fitness value of the chromosomes. Then the procedures to apply LLGA in controller gains tuning are specified stepwise and the optimization results in runway condition are depicted subsequently. Finally, the comparison is made between the LLGA and the simple GA in GTE controller optimization to confirm the effectiveness of the proposed approach. The results show that the LLGA method can get better solution than simple GA within the same iterations or optimization time. The extension applications of the LLGA method in other flight conditions and the complete flight mission simulation will be carried out in part II
Open Access
Advanced optimization of gas turbine aero-engine transient performance using linkage-learning genetic algorithm: Part Ⅱ, Optimization in flight mission and controller gains correlation development
(Elsevier, 2020-08-15) Liu, Yinfeng; Jafari, Soheil; Nikolaidis, Theoklis
This paper proposes a Linkage Learning Genetic Algorithm (LLGA) based on the messy Genetic Algorithm (mGA) to optimize the Min-Max fuel controller performance in Gas Turbine Engine (GTE). For this purpose, a GTE fuel controller Simulink model based on the Min-Max selection strategy is firstly built. Then, the objective function that considers both performance indices (response time and fuel consumption) and penalty items (fluctuation, tracking error, overspeed and acceleration/deceleration) is established to quantify the controller performance. Next, the task to optimize the fuel controller is converted to find the optimization gains combination that could minimize the objective function while satisfying constraints and limitations. In order to reduce the optimization time and to avoid trapping in the local optimums, two kinds of building block detection methods including lower fitness value method and bigger fitness value change method are proposed to determine the most important bits which have more contribution on fitness value of the chromosomes. Then the procedures to apply LLGA in controller gains tuning are specified stepwise and the optimization results in runway condition are depicted subsequently. Finally, the comparison is made between the LLGA and the simple GA in GTE controller optimization to confirm the effectiveness of the proposed approach. The results show that the LLGA method can get better solution than simple GA within the same iterations or optimization time. The extension applications of the LLGA method in other flight conditions and the complete flight mission simulation will be carried out in part II
Open Access
Aircraft thermal management: Practices, technology, system architectures, future challenges, and opportunities
(Elsevier, 2021-11-12) van Heerden, Albert S. J.; Judt, David M.; Jafari, Soheil; Lawson, Craig P.; Nikolaidis, Theoklis; Bosak, D.
The provision of adequate thermal management is becoming increasingly challenging on both military and civil aircraft. This is due to significant growth in the magnitude of onboard heat loads, but also because of their changing nature, such as the presence of more low-grade, high heat flux heat sources and the inability of some waste heat to be expelled as part of engine exhaust gases. The increase in the use of composites presents a further issue to address, as these materials are not as effective as metallic materials in transferring waste heat from the aircraft to the surrounding atmosphere. These thermal management challenges are so severe that they are becoming one of the major impediments to improving aircraft performance and efficiency. In this review, these challenges are expounded upon, along with possible solutions and opportunities from the literature. After introducing relevant factors from the ambient environment, the discussion of the challenges and opportunities is guided by a simple classification of the elements involved in thermal management systems. These elements comprise heat sources, heat acquisition mechanisms, thermal transport systems, heat rejection to sinks, and energy conversion and storage. Heat sources include both those from propulsion and airframe systems. Heat acquisition mechanisms are the means by which thermal energy is acquired from the sources. Thermal transport systems comprise cooling loops and thermodynamic cycles, along with their associated components and fluids, which move the heat from the source to the sinks over potentially large distances. The terminal aircraft heat sinks include atmospheric air, fuel, and the aircraft structure. In addition to the discussions on these different elements of thermal management systems, several topics of particular priority in aircraft thermal management research are deliberated upon in detail. These are thermal management for electrified propulsion aircraft, ultra-high bypass ratio geared turbofans, and high power airborne military systems; environmental control systems; power and thermal management systems; thermal management on supersonic transport aircraft; and novel modelling and simulation processes and tools for thermal management.
Open Access
Analysis of control-system strategy and design of a small modular reactor with different working fluids for electricity and hydrogen production as part of a decentralised mini grid
(MDPI, 2022-03-18) Gad-Briggs, Arnold; Osigwe, Emmanuel O.; Jafari, Soheil; Nikolaidis, Theoklis
Hydrogen is increasingly being viewed as a significant fuel for future industrial processes as it offers pathways to zero emission. The UK sees hydrogen as one of a handful of low-carbon solutions for transition to net zero. Currently, most hydrogen production is from steam reforming of natural gas or coal gasification, both of which involve the release of carbon dioxide. Hydrogen production from mini decentralised grids via a thermochemical process, coupled with electricity production, could offer favourable economics for small modular reactors (SMRs), whereby demand or grid management as a solution would include redirecting the power for hydrogen production when electricity demand is low. It also offers a clean-energy alternative to the aforementioned means. SMRs could offer favourable economics due to their flexible power system as part of the dual-output function. This study objective is to investigate the critical performance parameters associated with the nuclear power plant (NPP), the cycle working fluids, and control-system design for switching between electricity and hydrogen demand to support delivery as part of a mini grid system for a reactor power delivering up to approximately 600 MWth power. The novelty of the work is in the holistic parametric analysis undertaken using a novel in-house tool, which analyses the NPP using different working fluids, with a control function bolt-on at the offtake for hydrogen production. The results indicate that the flow conditions at the offtake can be maintained. The choice of working fluids affects the pressure component. However, the recuperator and heat-exchanger effectiveness are considered as efficiency-limiting factors for hydrogen production and electricity generation. As such, the benefit of high-technology heat exchangers cannot be underestimated. This is also true when deciding on the thermochemical process to bolt onto the plant. The temperature of the gas at the end of the pipeline should also be considered to ensure that the minimum temperature-requirement status for hydrogen production is met.
Open Access
A comparative analysis of nature-inspired optimization approaches to 2d geometric modelling for turbomachinery applications
(MDPI, 2013-09-18) Safari, Amir; Lemu, Hirpa G.; Jafari, Soheil; Assadi, Mohsen
A vast variety of population-based optimization techniques have been formulated in recent years for use in different engineering applications, most of which are inspired by natural processes taking place in our environment. However, the mathematical and statistical analysis of these algorithms is still lacking. This paper addresses a comparative performance analysis on some of the most important nature-inspired optimization algorithms with a different basis for the complex high-dimensional curve/surface fitting problems. As a case study, the point cloud of an in-hand gas turbine compressor blade measured by touch trigger probes is optimally fitted using B-spline curves. In order to determine the optimum number/location of a set of Bezier/NURBS control points for all segments of the airfoil profiles, five dissimilar population-based evolutionary and swarm optimization techniques are employed. To comprehensively peruse and to fairly compare the obtained results, parametric and nonparametric statistical evaluations as the mathematical study are presented before designing an experiment. Results illuminate a number of advantages/disadvantages of each optimization method for such complex geometries’ parameterization from several different points of view. In terms of application, the final appropriate parametric representation of geometries is an essential, significant component of aerodynamic profile optimization processes as well as reverse engineering purposes.
Open Access
Compressor degradation management strategies for gas turbine aero-engine controller design
(MDPI, 2021-09-10) Sun, Xiaohuan; Jafari, Soheil; Fashandi, Seyed Alireza Miran; Nikolaidis, Theoklis
The Advisory Council for Aeronautics Research in Europe (ACARE) Flight Path 2050 focuses on ambitious and severe targets for the next generation of air travel systems (e.g., 75% reduction in CO2 emissions per passenger kilometre, a 90% reduction in NOx emissions, and a 65% reduction in the noise emissions of flying aircraft relative to the capabilities of typical new aircraft in 2000). Degradation is an inevitable phenomenon as aero-engines age with significant impacts on the engine performance, emissions level, and fuel consumption. The engine control system is a key element capable of coping with degradation consequences subject to the implementation of an advanced management strategy. This paper demonstrates a methodological approach for aero-engine controller adjustment to deal with degradation implications, such as emission levels and increased fuel consumption. For this purpose, a component level model for an aero-engine was first built and transformed to a block-structured Wiener model using a system identification approach. An industrial Min-Max control strategy was then developed to satisfy the steady state and transient limit protection requirements simultaneously while satisfying the physical limitation control modes, such as over-speed, surge, and over-temperature. Next, the effects of degradation on the engine performance and associated changes to the controller were analysed thoroughly to propose practical degradation management strategies based on a comprehensive scientometric analysis of the topic. The simulation results show that the proposed strategy was effective in restoring the degraded engine performance to the level of the clean engine while protecting the engine from physical limitations. The proposed adjustments in the control strategy reduced the fuel consumption and, as a result, the emission level and carbon footprint of the engine.
Open Access
Control requirements for future gas turbine-powered unmanned drones: JetQuads
(MDPI, 2018-12-19) Jafari, Soheil; Miran Fashandi, Seyed Alireza; Nikolaidis, Theoklis
The next generation of aerial robots will be utilized extensively in real-world applications for different purposes: Delivery, entertainment, inspection, health and safety, photography, search and rescue operations, fire detection, and use in hazardous and unreachable environments. Thus, dynamic modeling and control of drones will play a vital role in the growth phase of this cutting-edge technology. This paper presents a systematic approach for control mode identification of JetQuads (gas turbine-powered quads) that should be satisfied simultaneously to achieve a safe and optimal operation of the JetQuad. Using bond graphs as a powerful mechatronic tool, a modular model of a JetQuad including the gas turbine, electric starter, and the main body was developed and validated against publicly available data. Two practical scenarios for thrust variation as a function of time were defined to investigate the compatibility and robustness of the JetQuad. The simulation results of these scenarios confirmed the necessity of designing a compatibility control loop, a stability control loop, and physical limitation control loops for the safe and errorless operation of the system. A control structure with its associated control algorithm is also proposed to deal with future challenges in JetQuad control problems.
Open Access
Control surface freeplay effects investigation on airfoil's aero-elastic behavior in the sub-sonic regime
(MDPI, 2019-10-21) Jafari, Soheil; Feizarefi, Morteza; Pishkenari, Mohsen Majidi
One of the main limitations of linearity assumptions in airfoil’s aero-elastic problems is the inability to predict the system behavior after starting the instability. In reality, nonlinearities may prevent the amplitudes from going to infinity. This paper presents a methodological approach for predicting airfoil aero-elastic behavior to investigate the control surface freeplay effects on the state responses and the flutter speed. For this purpose, the airfoil structural model is firstly developed while using the Lagrange’s method. The aerodynamic model is then generated by utilizing the Theodorsen approach for lift and moment calculation and Jones approximation with P-method for unstable aerodynamic modelling. After that, the aero-elastic model is developed by combination of structural and aerodynamic models and a numerical integration method is used to extract the time responses in the state space. The flutter analysis has been completed by utilizing the P-method for the system without freeplay and by the time response approach for the system with freeplay. The results that were obtained from simulations confirm the effectiveness of the proposed method to predict the aero-elastic behavior and stability condition of a two-dimensional airfoil as well as to estimate the flutter speed with reasonable accuracy and low computational effort. Moreover, a sensitivity analysis of freeplay degree on time response results has been done and the results are discussed in detail. It is also showed that the control surface freeplay decreases the flutter speed. The results of the paper are also validated against publicly available data.
Open Access
Economic and environmental viability assessment of NASA’s turboelectric distribution propulsion
(Elsevier, 2020-06-29) Alrashed, Mosab; Nikolaidis, Theoklis; Pilidis, Pericles; Alrashed, Wael; Jafari, Soheil
The concept of turboelectric-distributed propulsion (TeDP) has become integral to engineering because of its ability to generate electricity. However, social science compels careful evaluations of TeDP’s environmental and economic impacts—out of caution, such elements must be taken up before TeDP is put into practice. Responding to this call, this research investigates TeDP’s economic and environmental viability with a case study of the National Aeronautics and Space Administration’s (NASA) proposal for a TeDP aircraft, N3-X, using technical aspects and real data integration. The economic assessment measures NASA’s N3-X economic added value for aviation manufacturing, operations, and investors as well as net present value, internal rate of return, and payback period. Meanwhile, the environmental assessment looks at carbon monoxide and dioxide and oxides of nitrogen. The economic and environmental evaluation results establish the viability of TeDP.
Open Access
The effect of emerging green market on green entrepreneurship and sustainable development in knowledge-based companies
(MDPI, 2018-07-04) Lotfi, Maryam; Yousefi, Akram; Jafari, Soheil
Environmental concerns, as well as consumers’ awareness of buying green or environmentally-friendly products, has a positive impact on the emergence of the green market. The emerging green market brings many opportunities in different fields. Today, the issue of green entrepreneurship and sustainable development aim at producing environmentally-friendly products. This is indeed welcomed in the emerging green market. The publicly available research studies that investigate how green entrepreneurship, sustainable development, and emerging green markets are interconnected with each other are limited. More specifically, the impact of the green market on green entrepreneurship and sustainable development has not yet been studied completely. Therefore, a comprehensive research model has been developed in this paper based on the literature. The developed model is then tested using IBM SPSS Statistics for Windows, Version 19. IBM Corp.: Armonk, NY, USA and Smart-PLS Version 2 based on the data collected via a survey from a sample of knowledge-based companies in the Science & Technology Park of Tehran University. The results of the research indicate a positive and significant effect of the emergence of the green market on green entrepreneurship and sustainable development in knowledge-based companies. Moreover, the impact of the green entrepreneurship structure on sustainable development has been studied and the result presents that green entrepreneurship has a positive and significant effect on sustainable development.
Open Access
Exchange rate analysis for ultra high bypass ratio geared turbofan engines
(MDPI, 2020-11-09) Nikolaidis, Theoklis; Jafari, Soheil; Bosak, David; Pilidis, Pericles
This paper investigates the impact of thermal management methods on the design point and synthesis exchange rates of an ultra-high bypass ratio geared turbofan engine. In a typical thermal management system, where heat is managed by means of heat exchangers that transfer engine waste heat into oil, air, or fuel. However, the utilization of air–oil and fuel–oil heat exchangers has an adverse impact on engine performance. This paper investigates the impact on and engine’s specific fuel consumption and summarizes it into common exchange rates for different thermal management configurations. The results show that any pressure loss in the bypass duct results in a severe specific fuel consumption penalty (an increase of 1% pressure loss in the bypass duct causes a 2% specific fuel consumption increase at cruise conditions). In addition, quite severe is the impact of extracting air from the gas path, particularly when the bleed location is in the bypass duct or the high-pressure compressor. It is also found that the utilization of a fuel–oil heat exchanger improves the specific fuel consumption at a higher rate than an air–oil heat exchanger. For the performance characteristics of the examined engine, the specific fuel consumption benefit with the former is 1.33%, while for the latter it is 0.38%
Open Access
Filament wound pipes optimization platform development: a methodological approach
(Elsevier, 2022-07-13) Rafiee, Roham; Shahzadi, Reza; Jafari, Soheil
A multi-objective and multi-level optimization procedure is developed for obtaining optimal structural design of filament wound composite pipes in oil and gas industries. At the first stage, regulated design constraints are identified. Required computational tools for predicting structural properties of the composite pipes are developed and validated through experimental study. Then, the pipe design procedure is formulated as an engineering optimization problem where a hybrid design-optimization platform is developed to deal with that. The platform integrates multi-objective genetic algorithm on level 1 with a premutation-based direct search approach on level 2. It is aimed to minimize the cost of the pipe while maximum values for other structural properties are expected. Manufacturing limitations are also taken into account as the constraints in addition to design requirements.
Open Access
Framework for integrated dynamic thermal simulation of future civil transport aircraft
(AIAA, 2020-01-05) van Heerden, Albert S. J.; Judt, David M.; Lawson, Craig P.; Jafari, Soheil; Nikolaidis, Theoklis; Bosak, David
The development of increasingly more electric systems and ultra high bypass ratio turbofan engines for civil transport aircraft is projected to bring forth critical challenges regarding thermal management. To address these, it is required that the thermal behavior of the complete propulsion-airframe unit is studied in an integrated manner. To this purpose, a simulation framework for performing integrated thermal and performance analyses of the engines, airframe, and airframe systems, is presented. The framework was specifically devised to test novel integrated thermal management solutions for future civil aircraft. In this paper, the discussion focuses mainly on the thermal modeling of the wing and fuel. A highly flexible approach for creating wing thermal models by means of assembling generic thermal compartments is introduced. To demonstrate some of the capabilities, a case study is provided that involves thermal analysis of a single-aisle airplane with ultra high bypass ratio engines. Results are provided for fuel temperatures across flights in standard, hot, and cold days and for different airframe materials. Engine heat sink temperatures and input power to the engine gearboxes, both important parameters needed to design thermal management systems, are also presented.
Open Access
Fuzzy controller structures investigation for future gas turbine aero-engines
(MDPI, 2021-02-22) Mohammadi Doulabi Fard, Seyed Jalal; Jafari, Soheil
The Advisory Council for Aeronautics Research in Europe (ACARE) Flight Path 2050 focuses on ambitious and severe targets for the next generation of air travel systems (e.g., 75% reduction in CO2 emissions per passenger kilometer, a 90% reduction in NOx emissions, and 65% reduction in noise emission of flying aircraft relative to the capabilities of typical new aircraft in 2000). In order to meet these requirements, aircraft engines should work very close to their operating limits. Therefore, the importance of advanced control strategies to satisfy all engine control modes simultaneously while protecting them from malfunctions and physical damages is being more crucial these days. In the last three decades, fuzzy controllers (FCs) have been proposed as a high potential solution for performance improvement of the next generation of aircraft engines. Based on an analytic review, this paper divides the trend of FCs design into two main lines including pure FCs (PFC) and min–max FCs (MMFC). These two main architectures are then designed, implemented on hardware, and applied in a case study to analyze the advantages and disadvantages of each structure. The analysis of hardware-in-the-loop (HIL) simulation results shows that the pure FC structure would be a high potential candidate for maneuverability and response time indices improvement (e.g., military applications); while min–max FC architecture has a great potential for future civil aero-engines where the fuel consumption and steady-state responses are more important. The simulation results are also compared with those of industrial min–max controllers to confirm the feasibility and reliability of the fuzzy controllers for real-world application. The results of this paper propose a general roadmap for fuzzy controllers’ structure selection for new and next generation of aircraft engines.
Open Access
Gas turbine aero-engines real time on-board modelling: A review, research challenges, and exploring the future
(Elsevier, 2020-12-22) Wei, Zhiyuan; Zhang, Shuguang; Jafari, Soheil; Nikolaidis, Theoklis
On-board real time modelling for gas turbine aero-engines has been extensively used for engine performance improvement and reliability. This has been achieved by the utilization of on-board model for the engine's control and health management. This paper offers a historical review of on-board modelling applied on gas turbine engines and it also establishes its limitations, and consequently the challenges, which should be addressed to apply the on-board real time model to new and the next generation gas turbine aero-engines. For both applications, i.e. engine control and health management, claims and limitations are analysed via numerical simulation and publicly available data. Regarding the former, the methods for modelling clean and degraded engines are comprehensively covered. For the latter, the techniques for the component performance tracking and sensor/actuator diagnosis are critically reviewed. As an outcome of this systematic examination, two remaining research challenges have been identified: firstly, the requirement of a high-fidelity on-board modelling over the engine life cycle, especially for safety-critical control parameters during rapid transients; secondly, the dependability and reliability of on-board model, which is critical for the engine protection in case of on-board model failure. Multiple model-based on-board modelling and runtime assurance are proposed as potential solutions for the identified challenges and their potential and effectiveness are discussed in detail.
Open Access
Gas turbine engine transient performance and heat transfer effect modelling: a comprehensive review, research challenges, and exploring the future
(Elsevier, 2023-09-12) Yang, Yimin; Nikolaidis, Theoklis; Jafari, Soheil; Pilidis, Pericles
Gas turbine transient simulation is an important tool in analysing engine performance during changes in operating conditions. This paper provides a comprehensive review of the development of gas turbine transient simulation, heat transfer effect on transient performance and transient simulation platforms over the past 70 years. The paper highlights the various methods used for gas turbine overall transient simulation, including white box approach, black box approach and numerical approach, and the development of models for heat transfer effects, including heat soakage, tip clearance, and component characteristic changes. Besides, the development of gas turbine transient simulation platforms has been included. Challenges that need to be addressed to achieve more accurate simulations are identified. For white and black box approaches, complex engine dynamics phenomena and heat transfer effects urge the development of methodologies. For the numerical approach, the high computational and geometry demand for the full-size gas turbine transient model slows the CFD application in gas turbine overall transient simulation. For heat transfer effect simulation, the increasing complexity of engine structures and cooling techniques urges the development of a more realistic heat soakage model. The paper suggests that the white box approach can benefit from a method that accurately models several thermal dynamics. The black box methodologies should consider the heat transfer effect during the modelling and training. And more attention should be paid to the full-size gas turbine transient model development. Additionally, the paper recommends the development of a more complete heat transfer model that includes axial clearance effects, detailed combustor heat transfer models, and advanced component maps.
Open Access
Gas turbine performance studies for LH₂-fuelled engines.
(2021-08) Pena López, Álvaro; Nikolaidis, Theoklis; Jafari, Soheil
The aim of this Individual Research Project is to lay solid foundations for the investigation of liquid hydrogen utilisation in aero gas turbines employing Cranfield University’s Turbomatch software. To this day, including key components like heat exchangers is considerably limited in this software. As heat exchangers are believed to be vital in order to take advantage of the unique properties of liquid hydrogen, this thesis aims to create the possibility to carry out investigations in this field without depending on similar tools from outside Cranfield University. To do so, a code is created in Matlab to serve as a heat exchanger library in which key parameters like outlet temperatures, overall pressure drops or geometrical characteristics are calculated in a split second. This code is validated, and results obtained from it are shown, compared and discussed. Different engine configurations are modelled in Turbomatch (in which the location of the heat exchangers is varied from one model to the other). The outputs from the code are introduced in these Turbomatch models and simulations are run. Results from these simulations are plotted and analysed, highlighting the impact of these heat exchangers according to the location they are on. Finally, some conclusions are extracted from all of the above and recommendations for future researches are listed.