Pub Date : 2026-07-01Epub Date: 2026-02-09DOI: 10.1016/j.ast.2026.111850
Xinrui Zhou , Hairun Xie , Bokai Li , Jing Wang , Qineng Wang , Yonghe Zhang
Topology optimization is crucial for enhancing structural performance and reducing costs in fields such as aerospace, automotive, and civil engineering. However, traditional methods face exponentially growing computational costs as mesh resolution increases. Meanwhile, existing generative models often rely on image-based representations, which limits their adaptability to components at different resolutions. To overcome these limitations, we propose NG-TO (Neural Compression-based Generative Topology Optimization), an implicit generative method that integrates neural compression with diffusion models. Our framework first encodes topologies into a compact, resolution-invariant latent space. A diffusion model then operates within this space to generate new designs that comply with specified physical constraints. Evaluations in multi-resolution and out-of-distribution scenarios demonstrate the model’s capability for resolution-free encoding and constraint satisfaction, establishing a high-performance paradigm for spacecraft structural design.
{"title":"An implicit generative topology optimization method based on neural compression and diffusion models","authors":"Xinrui Zhou , Hairun Xie , Bokai Li , Jing Wang , Qineng Wang , Yonghe Zhang","doi":"10.1016/j.ast.2026.111850","DOIUrl":"10.1016/j.ast.2026.111850","url":null,"abstract":"<div><div>Topology optimization is crucial for enhancing structural performance and reducing costs in fields such as aerospace, automotive, and civil engineering. However, traditional methods face exponentially growing computational costs as mesh resolution increases. Meanwhile, existing generative models often rely on image-based representations, which limits their adaptability to components at different resolutions. To overcome these limitations, we propose NG-TO (Neural Compression-based Generative Topology Optimization), an implicit generative method that integrates neural compression with diffusion models. Our framework first encodes topologies into a compact, resolution-invariant latent space. A diffusion model then operates within this space to generate new designs that comply with specified physical constraints. Evaluations in multi-resolution and out-of-distribution scenarios demonstrate the model’s capability for resolution-free encoding and constraint satisfaction, establishing a high-performance paradigm for spacecraft structural design.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111850"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-09DOI: 10.1016/j.ast.2026.111785
Afsaneh Kheirani , Ilyass Tabiai , David St-Onge
Indoor inspection and mapping missions in tunnels, industrial facilities, and subterranean environments require aerial platforms capable of long-duration operation in cluttered, humid, and navigation-denied conditions. While multirotor drones provide high maneuverability, their endurance and payload capacity are fundamentally limited by battery-powered lift. Small indoor lighter-than-air vehicles alleviate this constraint through buoyancy; however, at meter-scale volumes, envelope materials become a critical limitation, as they largely determine system mass, gas retention, durability, and resistance to handling and collisions. Commonly used films present persistent trade-offs: metallized polyester offers low gas permeability but limited mechanical robustness, whereas polyurethane is more durable but heavier and more permeable.
This work introduces and experimentally validates a lightweight composite envelope material based on low-density polyethylene combined with a fluoro-siloxane barrier coating. The proposed treatment significantly improves helium retention while preserving flexibility and resistance to handling. Mechanical and functional testing show that the coated material achieves substantially higher tear resistance than metallized polyester and improved durability compared to polyurethane, while remaining considerably lighter. A cylindrical airship fabricated from this membrane was deployed in a semi-autonomous underground mapping mission, demonstrating reduced helium leakage, stable performance in humid conditions, and multi-day operation. These results show that fluoro-siloxane-coated polyethylene enables lightweight, durable, and gas-efficient envelopes, supporting persistent indoor operation of small lighter-than-air aerial platforms.
{"title":"Vehicle envelope with lightweight ultrafilm for minimal leakage (VELUM)","authors":"Afsaneh Kheirani , Ilyass Tabiai , David St-Onge","doi":"10.1016/j.ast.2026.111785","DOIUrl":"10.1016/j.ast.2026.111785","url":null,"abstract":"<div><div>Indoor inspection and mapping missions in tunnels, industrial facilities, and subterranean environments require aerial platforms capable of long-duration operation in cluttered, humid, and navigation-denied conditions. While multirotor drones provide high maneuverability, their endurance and payload capacity are fundamentally limited by battery-powered lift. Small indoor lighter-than-air vehicles alleviate this constraint through buoyancy; however, at meter-scale volumes, envelope materials become a critical limitation, as they largely determine system mass, gas retention, durability, and resistance to handling and collisions. Commonly used films present persistent trade-offs: metallized polyester offers low gas permeability but limited mechanical robustness, whereas polyurethane is more durable but heavier and more permeable.</div><div>This work introduces and experimentally validates a lightweight composite envelope material based on low-density polyethylene combined with a fluoro-siloxane barrier coating. The proposed treatment significantly improves helium retention while preserving flexibility and resistance to handling. Mechanical and functional testing show that the coated material achieves substantially higher tear resistance than metallized polyester and improved durability compared to polyurethane, while remaining considerably lighter. A cylindrical airship fabricated from this membrane was deployed in a semi-autonomous underground mapping mission, demonstrating reduced helium leakage, stable performance in humid conditions, and multi-day operation. These results show that fluoro-siloxane-coated polyethylene enables lightweight, durable, and gas-efficient envelopes, supporting persistent indoor operation of small lighter-than-air aerial platforms.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111785"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-10DOI: 10.1016/j.ast.2026.111886
Qianyang Sun , Wenxuan Liu , Jun Wu , Dahai Zhang , Fangzhou Lu , Peifei Xu , Qingguo Fei
The gas rudder is a thrust vectoring device and withstand the direct impingement of high-temperature gases emitted by the engine. Significant temperature gradients exist between the regions exposed to the gases and other areas, resulting in considerable thermal stress within the gas rudder structure. To address the issue of temperature gradients and thermal stress in the rudder, this paper introduces a design method that features a dredging thermal protection structure (DTPS) with embedded high thermal conductivity materials. Numerical simulations were conducted to evaluate the effect of parameters of the DTPS, including the thickness and thermal conductivity of the dredging layer and thickness of the insulation layer, on temperature gradients and thermal stress. The results confirm that DTPS effectively reduces the temperature gradients in the gas rudder structure. The maximum tensile stress in the fiber direction of the composite panel of the flow deflector using DTPS was reduced by 57.8%.
{"title":"Design and characteristics of dredging thermal protection structure under high temperature gradient","authors":"Qianyang Sun , Wenxuan Liu , Jun Wu , Dahai Zhang , Fangzhou Lu , Peifei Xu , Qingguo Fei","doi":"10.1016/j.ast.2026.111886","DOIUrl":"10.1016/j.ast.2026.111886","url":null,"abstract":"<div><div>The gas rudder is a thrust vectoring device and withstand the direct impingement of high-temperature gases emitted by the engine. Significant temperature gradients exist between the regions exposed to the gases and other areas, resulting in considerable thermal stress within the gas rudder structure. To address the issue of temperature gradients and thermal stress in the rudder, this paper introduces a design method that features a dredging thermal protection structure (DTPS) with embedded high thermal conductivity materials. Numerical simulations were conducted to evaluate the effect of parameters of the DTPS, including the thickness and thermal conductivity of the dredging layer and thickness of the insulation layer, on temperature gradients and thermal stress. The results confirm that DTPS effectively reduces the temperature gradients in the gas rudder structure. The maximum tensile stress in the fiber direction of the composite panel of the flow deflector using DTPS was reduced by 57.8%.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111886"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146153334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-05DOI: 10.1016/j.ast.2026.111857
Xintao Zhang , Gang Sun , Lijuan Feng , Yongfeng Jin , Anran Ju
With the increasing diameter of high-bypass-ratio turbofan nacelles, reducing nacelle weight has become a critical design objective. Shortening the inlet length is an effective approach to achieve this goal but poses challenges under crosswind conditions due to flow separation and distortion risks. This study investigates the aerodynamic characteristics and optimization of short inlets subjected to crosswind. A distortion mechanism is revealed, showing that the coupling between the unsteady ground vortex and the diffuser flow is the key cause of flow instability and pressure distortion. Based on steady-state computational fluid dynamics analysis, a wall-velocity-based criterion is proposed for rapid engineering assessment of separation. A decoupled intuitive class shape transformation (DiCST) parameterization method is developed to independently control the fore-body and aft-body of the inlet, enhancing local shaping flexibility. Furthermore, a multi-objective optimization framework combining support vector machines with a genetic algorithm is established, transforming distortion evaluation into a flow-separation classification problem. The optimized short inlet achieves a length reduction of approximately 0.05 times the engine diameter in average while maintaining distortion within acceptable limits. Wind tunnel tests confirm that the optimized configuration suppresses flow separation effectively under crosswind conditions, validating the proposed design methodology.
{"title":"Aerodynamic optimization strategy and experimental study on short inlet in crosswind conditions using decoupled intuitive class shape transformation curves","authors":"Xintao Zhang , Gang Sun , Lijuan Feng , Yongfeng Jin , Anran Ju","doi":"10.1016/j.ast.2026.111857","DOIUrl":"10.1016/j.ast.2026.111857","url":null,"abstract":"<div><div>With the increasing diameter of high-bypass-ratio turbofan nacelles, reducing nacelle weight has become a critical design objective. Shortening the inlet length is an effective approach to achieve this goal but poses challenges under crosswind conditions due to flow separation and distortion risks. This study investigates the aerodynamic characteristics and optimization of short inlets subjected to crosswind. A distortion mechanism is revealed, showing that the coupling between the unsteady ground vortex and the diffuser flow is the key cause of flow instability and pressure distortion. Based on steady-state computational fluid dynamics analysis, a wall-velocity-based criterion is proposed for rapid engineering assessment of separation. A decoupled intuitive class shape transformation (DiCST) parameterization method is developed to independently control the fore-body and aft-body of the inlet, enhancing local shaping flexibility. Furthermore, a multi-objective optimization framework combining support vector machines with a genetic algorithm is established, transforming distortion evaluation into a flow-separation classification problem. The optimized short inlet achieves a length reduction of approximately 0.05 times the engine diameter in average while maintaining distortion within acceptable limits. Wind tunnel tests confirm that the optimized configuration suppresses flow separation effectively under crosswind conditions, validating the proposed design methodology.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111857"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-07DOI: 10.1016/j.ast.2026.111867
X.F. Chen , W. Zhang , Y.F. Zhang
This study is the first to investigate the complex nonlinear dynamics of the blisk structure under both parametric, external and extreme random excitations. The extreme load is modeled by Lévy colored noise with heavy-tailed characteristics and temporal correlation. The amplitude-frequency response equations are derived using the averaging method. The amplitude-frequency response curves reveal the hardening nonlinearity and bistable characteristics of the blisk system under primary parametric resonance and 1:1 internal resonance. Notably, a low-frequency side peak in the response of the disk signifies energy transfer from the blade to the disk. Within the bistable region, Lévy colored noise induces the occurrence of stochastic switching between low- and high-amplitude oscillation states, as well as stochastic resonance. Importantly, larger noise intensities or shorter correlation times lead to persistent high-amplitude oscillations, which are observable through the time history and wavelet transform. This phenomenon may result in fatigue damage to the blisk structure and even exert a catastrophic impact on aircraft safety. Therefore, we introduce the mean first passage time and define a transition probability to quantify this state transition. The results demonstrate that greater noise intensity, shorter correlation time, or a smaller stability index markedly increase the likelihood of the catastrophic transition. The above findings can provide new theoretical support for the long-term stable operation, structural health monitoring, and fault diagnosis of aeroengines in extreme environments.
{"title":"Maintaining long-term stability of aeroengines under extreme environments: insights from a stochastic blisk model subjected to Lévy colored noise","authors":"X.F. Chen , W. Zhang , Y.F. Zhang","doi":"10.1016/j.ast.2026.111867","DOIUrl":"10.1016/j.ast.2026.111867","url":null,"abstract":"<div><div>This study is the first to investigate the complex nonlinear dynamics of the blisk structure under both parametric, external and extreme random excitations. The extreme load is modeled by Lévy colored noise with heavy-tailed characteristics and temporal correlation. The amplitude-frequency response equations are derived using the averaging method. The amplitude-frequency response curves reveal the hardening nonlinearity and bistable characteristics of the blisk system under primary parametric resonance and 1:1 internal resonance. Notably, a low-frequency side peak in the response of the disk signifies energy transfer from the blade to the disk. Within the bistable region, Lévy colored noise induces the occurrence of stochastic switching between low- and high-amplitude oscillation states, as well as stochastic resonance. Importantly, larger noise intensities or shorter correlation times lead to persistent high-amplitude oscillations, which are observable through the time history and wavelet transform. This phenomenon may result in fatigue damage to the blisk structure and even exert a catastrophic impact on aircraft safety. Therefore, we introduce the mean first passage time and define a transition probability to quantify this state transition. The results demonstrate that greater noise intensity, shorter correlation time, or a smaller stability index markedly increase the likelihood of the catastrophic transition. The above findings can provide new theoretical support for the long-term stable operation, structural health monitoring, and fault diagnosis of aeroengines in extreme environments.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111867"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-05DOI: 10.1016/j.ast.2026.111863
Jintao Hu , Min Chen , Jiyuan Zhang , Yihao Xu , Hailong Tang
Accurate state estimation is critical for performance optimization and reliability enhancement in modern turbine systems. Although traditional filtering methods have demonstrated strong performance in various applications, their effectiveness is limited in the presence of component performance dispersion, high-dimensional system dynamics, performance degradation and uncertain control inputs. This study proposes a variational inference-based state estimation framework for aero-engine systems to address challenges arising from multi-source uncertainty. Under the assumption of a known state-space model, a loss function based on the stochastic variational lower bound is constructed to enable joint optimization of state variables and model parameters. This allows for precise inference of component health states and reliable identification of fault-related features. In cases where the aero-engine system model is partially or completely unknown, a hierarchical variational framework is further introduced, incorporating stochastic differential equations to simultaneously infer system states and uncover underlying control dynamics. Simulation results demonstrate that the proposed method consistently outperforms traditional filtering algorithms under varying noise levels and model uncertainties. It effectively distinguishes between modeling errors and actual performance deviations of engine components, leading to improved diagnostic accuracy and robustness.
{"title":"State estimation and system model correction of aero-engines under multi-source uncertainty: A hierarchical variational inference approach","authors":"Jintao Hu , Min Chen , Jiyuan Zhang , Yihao Xu , Hailong Tang","doi":"10.1016/j.ast.2026.111863","DOIUrl":"10.1016/j.ast.2026.111863","url":null,"abstract":"<div><div>Accurate state estimation is critical for performance optimization and reliability enhancement in modern turbine systems. Although traditional filtering methods have demonstrated strong performance in various applications, their effectiveness is limited in the presence of component performance dispersion, high-dimensional system dynamics, performance degradation and uncertain control inputs. This study proposes a variational inference-based state estimation framework for aero-engine systems to address challenges arising from multi-source uncertainty. Under the assumption of a known state-space model, a loss function based on the stochastic variational lower bound is constructed to enable joint optimization of state variables and model parameters. This allows for precise inference of component health states and reliable identification of fault-related features. In cases where the aero-engine system model is partially or completely unknown, a hierarchical variational framework is further introduced, incorporating stochastic differential equations to simultaneously infer system states and uncover underlying control dynamics. Simulation results demonstrate that the proposed method consistently outperforms traditional filtering algorithms under varying noise levels and model uncertainties. It effectively distinguishes between modeling errors and actual performance deviations of engine components, leading to improved diagnostic accuracy and robustness.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111863"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The objective of this study is to propose a cross-flow fan for VTOL applications, evaluate its aerodynamic performance, and enhance its performance through a multi-objective optimization design method. Following an investigation into a three-dimensional CFD analysis approach for assessing the fan’s aerodynamic performance, a multi-objective optimization framework that simultaneously optimizes the rotor and casing by integrating CFD analysis and a deep neural network was developed and implemented. Based on CFD-derived performance metrics, the optimized fan demonstrated a thrust-shaft power ratio approximately 12.4 % lower than that of the original fan, while achieving a thrust increase of approximately 78.1 %. This substantial improvement in thrust was attributed to elevated flow velocity and flow rate at the fan outlet. Additionally, the thrust coefficient of the cross-flow fan was shown to be more than one order of magnitude greater than that of a conventional propeller fan. Performance validation using a scaled-down model further confirmed the effectiveness of the optimization method: although the thrust-shaft power ratio of the optimized fan was approximately 3.0 % lower than the original fan, its thrust increased by approximately 64.2 %. These findings underscore the potential of the proposed optimization approach not only for high-performance fan design but also for advancing the development of next-generation VTOL aircraft.
{"title":"Aerodynamic performance of a cross-flow fan for VTOL and its multi-objective optimization","authors":"Yasuyuki Nishi , Masafumi Fukuyama , Naofumi Saeki , Kotaro Ohashi , Takao Oku","doi":"10.1016/j.ast.2026.111872","DOIUrl":"10.1016/j.ast.2026.111872","url":null,"abstract":"<div><div>The objective of this study is to propose a cross-flow fan for VTOL applications, evaluate its aerodynamic performance, and enhance its performance through a multi-objective optimization design method. Following an investigation into a three-dimensional CFD analysis approach for assessing the fan’s aerodynamic performance, a multi-objective optimization framework that simultaneously optimizes the rotor and casing by integrating CFD analysis and a deep neural network was developed and implemented. Based on CFD-derived performance metrics, the optimized fan demonstrated a thrust-shaft power ratio approximately 12.4 % lower than that of the original fan, while achieving a thrust increase of approximately 78.1 %. This substantial improvement in thrust was attributed to elevated flow velocity and flow rate at the fan outlet. Additionally, the thrust coefficient of the cross-flow fan was shown to be more than one order of magnitude greater than that of a conventional propeller fan. Performance validation using a scaled-down model further confirmed the effectiveness of the optimization method: although the thrust-shaft power ratio of the optimized fan was approximately 3.0 % lower than the original fan, its thrust increased by approximately 64.2 %. These findings underscore the potential of the proposed optimization approach not only for high-performance fan design but also for advancing the development of next-generation VTOL aircraft.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111872"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-07DOI: 10.1016/j.ast.2026.111858
V. Rolland , B. Shoesmith , E. Timofeev
This paper modifies the semi-analytical model (the MOCMR model) of Mach reflection in axisymmetric wedge-generated supersonic flow by Shoesmith and Timofeev (Shock Waves 31, 945-957 (2021)) to predict Mach reflection configurations at the axis of symmetry in an overexpanded jet just downstream from the exit of a nozzle. The jet flow is considered to be a steady, inviscid flow of an ideal gas with constant specific heats. Similar to the original MOCMR model, the MOCMR model for jet flow is based on a number of flowfields solved using the method of characteristics, a Mach stream flowfield solved by quasi-one-dimensional relations, and the three-shock theory at the triple point. The modifications include the incorporation of the jet boundary instead of a wedge surface, the addition of the Prandtl-Meyer expansion fan resulting from the interaction of the reflected shock with the jet boundary, and the method to efficiently and accurately resolve very small Mach disks. The results for flowfield structure and Mach disk radius and location are extensively compared with the experimental and numerical ones available in the literature as well as with the inviscid numerical simulations using an in-house adaptive unstructured finite-volume flow solver. The influence of various model assumptions on accuracy is examined. The proposed model is demonstrated to produce results of similar accuracy using considerably less computational resources as compared to time-marching CFD simulations, at the same time directly providing quantities which are difficult to extract from CFD flowfields. The application of the developed model lends additional support to the conjecture that seemingly regular reflections observed at the axis of symmetry in some physical experiments are due to insufficient optical resolution to discern a very small Mach disk. Furthermore, parametric studies are conducted for a range of exit Mach numbers and nozzle pressure ratios and the influence of these parameters on Mach disk radius and the slip line is examined.
{"title":"A model of Mach reflection in axisymmetric steady overexpanded jets: Development and applications","authors":"V. Rolland , B. Shoesmith , E. Timofeev","doi":"10.1016/j.ast.2026.111858","DOIUrl":"10.1016/j.ast.2026.111858","url":null,"abstract":"<div><div>This paper modifies the semi-analytical model (the MOCMR model) of Mach reflection in axisymmetric wedge-generated supersonic flow by Shoesmith and Timofeev (Shock Waves 31, 945-957 (2021)) to predict Mach reflection configurations at the axis of symmetry in an overexpanded jet just downstream from the exit of a nozzle. The jet flow is considered to be a steady, inviscid flow of an ideal gas with constant specific heats. Similar to the original MOCMR model, the MOCMR model for jet flow is based on a number of flowfields solved using the method of characteristics, a Mach stream flowfield solved by quasi-one-dimensional relations, and the three-shock theory at the triple point. The modifications include the incorporation of the jet boundary instead of a wedge surface, the addition of the Prandtl-Meyer expansion fan resulting from the interaction of the reflected shock with the jet boundary, and the method to efficiently and accurately resolve very small Mach disks. The results for flowfield structure and Mach disk radius and location are extensively compared with the experimental and numerical ones available in the literature as well as with the inviscid numerical simulations using an in-house adaptive unstructured finite-volume flow solver. The influence of various model assumptions on accuracy is examined. The proposed model is demonstrated to produce results of similar accuracy using considerably less computational resources as compared to time-marching CFD simulations, at the same time directly providing quantities which are difficult to extract from CFD flowfields. The application of the developed model lends additional support to the conjecture that seemingly regular reflections observed at the axis of symmetry in some physical experiments are due to insufficient optical resolution to discern a very small Mach disk. Furthermore, parametric studies are conducted for a range of exit Mach numbers and nozzle pressure ratios and the influence of these parameters on Mach disk radius and the slip line is examined.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111858"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-04DOI: 10.1016/j.ast.2026.111788
Yao Jiang , Meibao Yao , Xueming Xiao , Huanfeng Zhao , Hutao Cui , Zexu Zhang
In a microgravity environment, modular self-reconfigurable robots can perform a range of on-orbit missions including solar-array deployment, serial-arm assembly, and failed-subsystem replacement, owing to their modular scalability and morphological versatility, tailored to mission-specific constraints and extended across these tasks. However, conventional cubic modules have rotational blind spots and pose-dependent interfaces that inflate alignment burden and trigger collisions and local deadlocks, especially for large-scale deployment. Due to the tight coupling of local motion feasibility in modular robotic systems, coupled with the connectivity and reachability requirements during reconfiguration, task allocation and decision sequencing for large-scale architecture are often NP-hard. To address these issues, we present an integrated reconfigurable hardware-algorithmic solution. Structurally, the concentric, nested spherical design with isotropic geometry and unified locking mechanism reduces sensitivity to pose alignment, mitigates collisions and deadlocks, and expands the reachable workspace. Algorithmically, reconfiguration planning is formulated as an integer programming problem, incorporating penalties to enforce connectivity and reachability constraints within a hierarchical framework. The top level determines the matching and reconfiguration sequence by the proposed Cross-correlation BFS-Tree Genetic Algorithm with Gaussian mutation (CBGA), and the lower level aims at path planning using the designed kinematics-aware parallel A*. Extensive simulation and experiments are conducted with varied number of modular robots. The results demonstrate that the proposed system maintains full connectivity and reachability while achieving rapid convergence with low relocation steps even for large-scale architecture. Such capability thereby establishes its practical viability for autonomous modular reconfiguration in on-orbit missions.
{"title":"Towards scalable on-orbit assembly: Reconfigurable hardware and algorithm design","authors":"Yao Jiang , Meibao Yao , Xueming Xiao , Huanfeng Zhao , Hutao Cui , Zexu Zhang","doi":"10.1016/j.ast.2026.111788","DOIUrl":"10.1016/j.ast.2026.111788","url":null,"abstract":"<div><div>In a microgravity environment, modular self-reconfigurable robots can perform a range of on-orbit missions including solar-array deployment, serial-arm assembly, and failed-subsystem replacement, owing to their modular scalability and morphological versatility, tailored to mission-specific constraints and extended across these tasks. However, conventional cubic modules have rotational blind spots and pose-dependent interfaces that inflate alignment burden and trigger collisions and local deadlocks, especially for large-scale deployment. Due to the tight coupling of local motion feasibility in modular robotic systems, coupled with the connectivity and reachability requirements during reconfiguration, task allocation and decision sequencing for large-scale architecture are often NP-hard. To address these issues, we present an integrated reconfigurable hardware-algorithmic solution. Structurally, the concentric, nested spherical design with isotropic geometry and unified locking mechanism reduces sensitivity to pose alignment, mitigates collisions and deadlocks, and expands the reachable workspace. Algorithmically, reconfiguration planning is formulated as an integer programming problem, incorporating penalties to enforce connectivity and reachability constraints within a hierarchical framework. The top level determines the matching and reconfiguration sequence by the proposed Cross-correlation BFS-Tree Genetic Algorithm with Gaussian mutation (CBGA), and the lower level aims at path planning using the designed kinematics-aware parallel A*. Extensive simulation and experiments are conducted with varied number of modular robots. The results demonstrate that the proposed system maintains full connectivity and reachability while achieving rapid convergence with low relocation steps even for large-scale architecture. Such capability thereby establishes its practical viability for autonomous modular reconfiguration in on-orbit missions.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111788"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Transpiration cooling is widely applied in hypersonic aircraft due to its high cooling effectiveness. However, shock impingement significantly degrades cooling effectiveness. Therefore, investigation on the influence of shock wave on transpiration cooling for porous flat plates under hypersonic conditions is essential. This study focuses on the effects of shock wave intensity and coolant injection rate on transpiration cooling effectiveness at Mach 6. The temperature of the porous plate is measured by infrared thermometry, while the flow-field is observed using schlieren and the Nano-tracer Planar Laser Scattering (NPLS) technology. Results indicate that the cooling effectiveness degrades with the increasing shock intensity. The coolant injection rate non-linearly influences cooling effectiveness, as higher rates enhance mainstream flow interaction and intensify heat exchange. With the injection rate increasing from 0.1% to 1.0%, the cost-effectiveness ratio drops by 88.5% and the thickness of turbulent boundary layer grows by 58.7%. The results indicate that the increased wall recovery temperature is the primary factor in the reduction of transpiration cooling effectiveness.
{"title":"Experimental investigation of shock wave effects on transpiration cooling for porous flat plate in hypersonic flow","authors":"Yishanchun Lu, Dundian Gang, Yuxin Zhao, Qi Mi, Yuan Feng, Zhiyao Yang, Shikang Chen","doi":"10.1016/j.ast.2026.111837","DOIUrl":"10.1016/j.ast.2026.111837","url":null,"abstract":"<div><div>Transpiration cooling is widely applied in hypersonic aircraft due to its high cooling effectiveness. However, shock impingement significantly degrades cooling effectiveness. Therefore, investigation on the influence of shock wave on transpiration cooling for porous flat plates under hypersonic conditions is essential. This study focuses on the effects of shock wave intensity and coolant injection rate on transpiration cooling effectiveness at Mach 6. The temperature of the porous plate is measured by infrared thermometry, while the flow-field is observed using schlieren and the Nano-tracer Planar Laser Scattering (NPLS) technology. Results indicate that the cooling effectiveness degrades with the increasing shock intensity. The coolant injection rate non-linearly influences cooling effectiveness, as higher rates enhance mainstream flow interaction and intensify heat exchange. With the injection rate increasing from 0.1% to 1.0%, the cost-effectiveness ratio drops by 88.5% and the thickness of turbulent boundary layer grows by 58.7%. The results indicate that the increased wall recovery temperature is the primary factor in the reduction of transpiration cooling effectiveness.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"174 ","pages":"Article 111837"},"PeriodicalIF":5.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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