Front Variable Area Bypass Injector(Front-VABI) is a component of the Adaptive Cycle Engine(ACE) with important variable-cycle features. The performance of Front-VABI has a direct impact on the performance and stabili...Front Variable Area Bypass Injector(Front-VABI) is a component of the Adaptive Cycle Engine(ACE) with important variable-cycle features. The performance of Front-VABI has a direct impact on the performance and stability of ACE, but the current ACE performance model uses approximate models for Front-VABI performance calculation. In this work, a multi-fidelity simulation based on a de-coupled method is developed which delivers a more accurate calculation of the Front-VABI performance based on Computational Fluid Dynamics(CFD) simulation. This simulation method proposes a form of Front-VABI characteristic and its matching calculation method between it and the ACE performance model, constructs a coupling method between the(2-D) Front-VABI model and the(0-D) ACE performance model. The result shows, when ACE works in triple bypass mode, the approximate model cannot account for the effect of FrontVABI pressure loss on Core Driven Fan Stage(CDFS) design pressure ratio, and the calculated error of high-pressure turbine inlet total temperature is more than 40 K in mode transition condition(the transition operating condition between triple bypass mode and double bypass mode). In double bypass mode, the approximate model can better simulate the performance of FrontVABI by considering the local loss of area expansion. This method can be applied to the performance-optimized design of Front-VABI and the ACE control law design during mode transition.展开更多
The alternative working modes and flexible working states are the outstanding features of an adaptive cycle engine, with a proper control schedule design being the only way to exploit the performance of such an engine...The alternative working modes and flexible working states are the outstanding features of an adaptive cycle engine, with a proper control schedule design being the only way to exploit the performance of such an engine. However, unreasonable design in the control schedule causes not only performance deterioration but also serious aerodynamic stability problems. Thus, in this work,a hybrid optimization method that automatically chooses the working modes and identifies the optimal and smooth control schedules is proposed, by combining the differential evolution algorithm and the Latin hypercube sampling method. The control schedule architecture does not only optimize the engine steady-state performance under different working modes but also solves the control-schedule discontinuity problem, especially during mode transition. The optimal control schedules are continuous and almost monotonic, and hence are strongly suitable for a control system, and are designed for two different working conditions, i.e., supersonic and subsonic throttling,which proves that the proposed hybrid method applies to various working conditions. The evaluation demonstrates that the proposed control method optimizes the engine performance, the surge margin of the compression components, and the range of the thrust during throttling.展开更多
Accurate engine performance models are important for model-based performance evaluation of aero engine.The accuracy of the model often depends on engine component maps,so there is a need for a method that can accurate...Accurate engine performance models are important for model-based performance evaluation of aero engine.The accuracy of the model often depends on engine component maps,so there is a need for a method that can accurately correct the component maps of the model over a wide range.In this paper,a new method for modifying component maps is proposed,this method combines the correction of the scaling factors with the solution process of the off-design working point,and uses the adjustment of the variable geometric parameters of the engine to change the position of the working line,in order to obtain more correction results and guarantee high accuracy in a wider range.The method is validated by taking the main fan of the Adaptive Cycle Engine(ACE),an ideal power unit for a new generation of multi-purpose and ultra-wide working range aircraft,as an example.The results show that the maximum error between the corrected component maps and the target maps is less than 1%.New possibility for more precise component maps can be realized in this paper.展开更多
Traditional rural social-ecological systems(SES)share many features which are crucial for sus-tainable development.Eastern European countries such as Romania,are still rich in traditional cultural landscapes.However,t...Traditional rural social-ecological systems(SES)share many features which are crucial for sus-tainable development.Eastern European countries such as Romania,are still rich in traditional cultural landscapes.However,these landscapes are increasingly under internal(e.g.,people’s aspirations toward western socioeconomic ideals)and external(institutional changes,globalization of the commodity market,connectivity with other cultures)pressures.Therefore,understanding the ways how traditional SES navi-gated past and more recent changes is of crucial importance in getting insights about the future trajectory of these systems.Here,we present the rural SES from the Saxon region of Transylvania through the lens of institutional transitions which happened in the past century in this region.We show that the rural SES went through episodic collapses and renewals,their cyclic dynamic being related to the episodic chang-es of the higher level formal institutions.These episodic collapses and renewals created a social-ecolog-ical momentum for the sustainability of these SES.While we recognize that policy effectiveness depends on institutional stability(and institutions are unstable and prone to collapses),maintaining those social-ecological system properties which can assure navigation of societies through the challenges imposed by global changes should be in the heart of every governance system.Such properties includes wide extent of native vegetation,fertile soils,wide range of provisioning ecosystem services,genuine links between people and landscapes and knowledge about the social-ecological systems.These features could provide important capitals and memory elements for the(re)emergence of social-ecological systems(old or new).展开更多
基金funded by National Natural Science Foundation of China(Nos.51776010 and 91860205)National Science and Technology Major Project,China(No.2017-I0001-0001)。
文摘Front Variable Area Bypass Injector(Front-VABI) is a component of the Adaptive Cycle Engine(ACE) with important variable-cycle features. The performance of Front-VABI has a direct impact on the performance and stability of ACE, but the current ACE performance model uses approximate models for Front-VABI performance calculation. In this work, a multi-fidelity simulation based on a de-coupled method is developed which delivers a more accurate calculation of the Front-VABI performance based on Computational Fluid Dynamics(CFD) simulation. This simulation method proposes a form of Front-VABI characteristic and its matching calculation method between it and the ACE performance model, constructs a coupling method between the(2-D) Front-VABI model and the(0-D) ACE performance model. The result shows, when ACE works in triple bypass mode, the approximate model cannot account for the effect of FrontVABI pressure loss on Core Driven Fan Stage(CDFS) design pressure ratio, and the calculated error of high-pressure turbine inlet total temperature is more than 40 K in mode transition condition(the transition operating condition between triple bypass mode and double bypass mode). In double bypass mode, the approximate model can better simulate the performance of FrontVABI by considering the local loss of area expansion. This method can be applied to the performance-optimized design of Front-VABI and the ACE control law design during mode transition.
基金funded by National Nature Science Foundation of China(Nos.51776010 and 91860205)supported by the Academic Excellence Foundation of BUAA for PhD Students,China。
文摘The alternative working modes and flexible working states are the outstanding features of an adaptive cycle engine, with a proper control schedule design being the only way to exploit the performance of such an engine. However, unreasonable design in the control schedule causes not only performance deterioration but also serious aerodynamic stability problems. Thus, in this work,a hybrid optimization method that automatically chooses the working modes and identifies the optimal and smooth control schedules is proposed, by combining the differential evolution algorithm and the Latin hypercube sampling method. The control schedule architecture does not only optimize the engine steady-state performance under different working modes but also solves the control-schedule discontinuity problem, especially during mode transition. The optimal control schedules are continuous and almost monotonic, and hence are strongly suitable for a control system, and are designed for two different working conditions, i.e., supersonic and subsonic throttling,which proves that the proposed hybrid method applies to various working conditions. The evaluation demonstrates that the proposed control method optimizes the engine performance, the surge margin of the compression components, and the range of the thrust during throttling.
基金funded by National Nature Science Foundation of China(NSFC)(Nos.51776010,and 91860205)the support from Collaborative Innovation Center of Advanced Aero-Engine,china。
文摘Accurate engine performance models are important for model-based performance evaluation of aero engine.The accuracy of the model often depends on engine component maps,so there is a need for a method that can accurately correct the component maps of the model over a wide range.In this paper,a new method for modifying component maps is proposed,this method combines the correction of the scaling factors with the solution process of the off-design working point,and uses the adjustment of the variable geometric parameters of the engine to change the position of the working line,in order to obtain more correction results and guarantee high accuracy in a wider range.The method is validated by taking the main fan of the Adaptive Cycle Engine(ACE),an ideal power unit for a new generation of multi-purpose and ultra-wide working range aircraft,as an example.The results show that the maximum error between the corrected component maps and the target maps is less than 1%.New possibility for more precise component maps can be realized in this paper.
基金The publication of this manuscript was supported by the EEA Financial Mechanism and the Romanian Ministry of Environment,Forests and Waters under the project“Mapping and assessment of ecosystem services in Natura 2000 sites of the Niraj-Tarnava Mica region”(Programme RO02,grant No.3458/19.05.2015 to Milvus Group)through Bálint Czúcz.BC was supported also by the Bolyai scholarship of the Hungarian Academy of Sciences.
文摘Traditional rural social-ecological systems(SES)share many features which are crucial for sus-tainable development.Eastern European countries such as Romania,are still rich in traditional cultural landscapes.However,these landscapes are increasingly under internal(e.g.,people’s aspirations toward western socioeconomic ideals)and external(institutional changes,globalization of the commodity market,connectivity with other cultures)pressures.Therefore,understanding the ways how traditional SES navi-gated past and more recent changes is of crucial importance in getting insights about the future trajectory of these systems.Here,we present the rural SES from the Saxon region of Transylvania through the lens of institutional transitions which happened in the past century in this region.We show that the rural SES went through episodic collapses and renewals,their cyclic dynamic being related to the episodic chang-es of the higher level formal institutions.These episodic collapses and renewals created a social-ecolog-ical momentum for the sustainability of these SES.While we recognize that policy effectiveness depends on institutional stability(and institutions are unstable and prone to collapses),maintaining those social-ecological system properties which can assure navigation of societies through the challenges imposed by global changes should be in the heart of every governance system.Such properties includes wide extent of native vegetation,fertile soils,wide range of provisioning ecosystem services,genuine links between people and landscapes and knowledge about the social-ecological systems.These features could provide important capitals and memory elements for the(re)emergence of social-ecological systems(old or new).
