Pub Date : 2024-07-08DOI: 10.3390/aerospace11070559
Keon-Hyeong Lee, Min-Su Kim, Jeong-Yeol Choi, Kenneth H. Yu
A micro-pulse detonation engine (μPDE) was designed and installed to a direct-connect scramjet combustor of Pusan National University (PNU-DCSC). The active excitation on the scramjet combustor was experimentally studied using the μPDE operating at frequencies of 10–20 Hz. A vitiation air heater (VAH) was used to supply high-enthalpy vitiated air to the isolator and the scramjet combustor at a Mach number of 2.0, with a total temperature of 1600 K and a total pressure of 1.68 MPa. The exit of μPDE was located at the center of the cavity of the scramjet combustor. Active excitation was performed at equivalence ratios of 0.111 and 0.163, and characteristics were analyzed through Schlieren recording and bottom wall pressure measurement. As a result, when the detonation emitted from the μPDE entered the scramjet combustor, it instantly formed a shock train and moved forward within the scramjet combustor. The flame instantaneously changed from the cavity shear layer flame to the cavity flame. Through bottom wall pressure measurement, it was also observed that active excitation resulted in a significant pressure increase near the cavity compared to when active excitation was not performed. This revealed combustion characteristics, indicating improved combustion efficiency from the pressure increase in the scramjet combustor.
{"title":"An Experimental Investigation of Low-Frequency Active Excitation in Scramjet Combustor Using a Micro-Pulse Detonation Engine","authors":"Keon-Hyeong Lee, Min-Su Kim, Jeong-Yeol Choi, Kenneth H. Yu","doi":"10.3390/aerospace11070559","DOIUrl":"https://doi.org/10.3390/aerospace11070559","url":null,"abstract":"A micro-pulse detonation engine (μPDE) was designed and installed to a direct-connect scramjet combustor of Pusan National University (PNU-DCSC). The active excitation on the scramjet combustor was experimentally studied using the μPDE operating at frequencies of 10–20 Hz. A vitiation air heater (VAH) was used to supply high-enthalpy vitiated air to the isolator and the scramjet combustor at a Mach number of 2.0, with a total temperature of 1600 K and a total pressure of 1.68 MPa. The exit of μPDE was located at the center of the cavity of the scramjet combustor. Active excitation was performed at equivalence ratios of 0.111 and 0.163, and characteristics were analyzed through Schlieren recording and bottom wall pressure measurement. As a result, when the detonation emitted from the μPDE entered the scramjet combustor, it instantly formed a shock train and moved forward within the scramjet combustor. The flame instantaneously changed from the cavity shear layer flame to the cavity flame. Through bottom wall pressure measurement, it was also observed that active excitation resulted in a significant pressure increase near the cavity compared to when active excitation was not performed. This revealed combustion characteristics, indicating improved combustion efficiency from the pressure increase in the scramjet combustor.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 756","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141669367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-06DOI: 10.3390/aerospace11070558
Axing Xi, Yuanli Cai
To achieve the intelligent interception of different types of maneuvering evaders, based on deep reinforcement learning, a novel intelligent differential game guidance law is proposed in the continuous action domain. Different from traditional guidance laws, the proposed guidance law can avoid tedious manual settings and save cost efforts. First, the interception problem is transformed into the pursuit–evasion game problem, which is solved by zero-sum differential game theory. Next, the Nash equilibrium strategy is obtained through the Markov game process. To implement the proposed intelligent differential game guidance law, an actor–critic neural network based on deep deterministic policy gradient is constructed to calculate the saddle point of the differential game guidance problem. Then, a reward function is designed, which includes the tradeoffs among guidance accuracy, energy consumption, and interception time. Finally, compared with traditional methods, the interception accuracy of the proposed intelligent differential game guidance law is 99.2%, energy consumption is reduced by 47%, and simulation time is shortened by 1.58 s. All results reveal that the proposed intelligent differential game guidance law has better intelligent decision-making ability.
{"title":"Deep Reinforcement Learning-Based Differential Game Guidance Law against Maneuvering Evaders","authors":"Axing Xi, Yuanli Cai","doi":"10.3390/aerospace11070558","DOIUrl":"https://doi.org/10.3390/aerospace11070558","url":null,"abstract":"To achieve the intelligent interception of different types of maneuvering evaders, based on deep reinforcement learning, a novel intelligent differential game guidance law is proposed in the continuous action domain. Different from traditional guidance laws, the proposed guidance law can avoid tedious manual settings and save cost efforts. First, the interception problem is transformed into the pursuit–evasion game problem, which is solved by zero-sum differential game theory. Next, the Nash equilibrium strategy is obtained through the Markov game process. To implement the proposed intelligent differential game guidance law, an actor–critic neural network based on deep deterministic policy gradient is constructed to calculate the saddle point of the differential game guidance problem. Then, a reward function is designed, which includes the tradeoffs among guidance accuracy, energy consumption, and interception time. Finally, compared with traditional methods, the interception accuracy of the proposed intelligent differential game guidance law is 99.2%, energy consumption is reduced by 47%, and simulation time is shortened by 1.58 s. All results reveal that the proposed intelligent differential game guidance law has better intelligent decision-making ability.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 36","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141672831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research presents the design and development of a near-space picosatellite platform intended to operate at high altitudes between 20–40 km above sea level. These picosatellites function similarly to orbital satellites but float and travel with the wind in the atmosphere instead of orbiting the Earth. The platform utilizes a super-pressure balloon to provide buoyancy, allowing the picosatellite to remain airborne and operational for several days to months, capable of flying around the world multiple times. This study focuses on the cost-effective design of high-altitude platforms, telecommunication systems, and energy consumption for the picosatellite, enabling it to communicate with ground stations from anywhere in the world while consuming low power. The use of common COTS (Commercial Off-The-Shelf) equipment aims to enhance accessibility for educational applications. This research gathered data from our previous studies for over 20 high-altitude platform flights, analyzed the necessary factors for whole system design, and developed a new prototype that has been successfully built and tested.
{"title":"Fly-around-the-World Near-Space Picosatellite for Cost-Effective School Space Projects","authors":"Pirada Techavijit, Polkit Sukchalerm, Natthapong Wongphuangfuthaworn, Sureepon Kiyapaet","doi":"10.3390/aerospace11070557","DOIUrl":"https://doi.org/10.3390/aerospace11070557","url":null,"abstract":"This research presents the design and development of a near-space picosatellite platform intended to operate at high altitudes between 20–40 km above sea level. These picosatellites function similarly to orbital satellites but float and travel with the wind in the atmosphere instead of orbiting the Earth. The platform utilizes a super-pressure balloon to provide buoyancy, allowing the picosatellite to remain airborne and operational for several days to months, capable of flying around the world multiple times. This study focuses on the cost-effective design of high-altitude platforms, telecommunication systems, and energy consumption for the picosatellite, enabling it to communicate with ground stations from anywhere in the world while consuming low power. The use of common COTS (Commercial Off-The-Shelf) equipment aims to enhance accessibility for educational applications. This research gathered data from our previous studies for over 20 high-altitude platform flights, analyzed the necessary factors for whole system design, and developed a new prototype that has been successfully built and tested.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 34","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141672312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3390/aerospace11070555
Shunfu Yang, Lu Gan, Tianyi Wang, Enze Zhu, Ling Yang, Hu Chen
This study introduces an advanced dual-mode compound attitude control framework for reusable launch vehicles (RLVs), underpinned by an enhanced particle swarm optimization (PSO) algorithm. This innovative strategy is tailored to meet the stringent demands for precision and robust anti-interference capabilities across the entire flight envelope of RLVs. The research commences with the formulation of a comprehensive attitude dynamics model and diverse heterogeneous actuator representations, meticulously crafted to reflect the distinct phases of RLV flight. Building upon this foundation, a synergistic control paradigm is engineered, integrating PID and fuzzy PID controllers and dynamically adjusting the inertia weights and learning factors of the PSO algorithm to achieve the balance between global and local optimization performance, complemented by a refined fitness evaluation function. The crux of the study is the application of an upgraded PSO algorithm to fine-tune the controllers’ weighting coefficients, culminating in an optimized dual-mode compound attitude control system. A series of comparative simulation analyses are thoroughly executed to appraise the system’s responsiveness, stability, precision, and resilience to interference. The simulation outcomes demonstrate an average reduction of 42.21% in step response overshoot, an 18.52% decrease in settling time, a 53.18% decline in steady-state error, a 56.80% drop in the maximum deviation value, a 55.82% improvement in recovery speed, and a 75.61% enhancement in tracking precision for the proposed controller. The findings clearly verify the superior performance of the proposed control system, affirming its contribution to the advancement of RLV attitude control. The proposed controller holds promising potential for real application in attitude control systems and is poised to augment the reliability and mission success rate of RLVs under intricate flight scenarios.
{"title":"Compound Attitude Control Strategy for Reusable Launch Vehicle Based on Improved Particle Swarm Optimization Algorithm","authors":"Shunfu Yang, Lu Gan, Tianyi Wang, Enze Zhu, Ling Yang, Hu Chen","doi":"10.3390/aerospace11070555","DOIUrl":"https://doi.org/10.3390/aerospace11070555","url":null,"abstract":"This study introduces an advanced dual-mode compound attitude control framework for reusable launch vehicles (RLVs), underpinned by an enhanced particle swarm optimization (PSO) algorithm. This innovative strategy is tailored to meet the stringent demands for precision and robust anti-interference capabilities across the entire flight envelope of RLVs. The research commences with the formulation of a comprehensive attitude dynamics model and diverse heterogeneous actuator representations, meticulously crafted to reflect the distinct phases of RLV flight. Building upon this foundation, a synergistic control paradigm is engineered, integrating PID and fuzzy PID controllers and dynamically adjusting the inertia weights and learning factors of the PSO algorithm to achieve the balance between global and local optimization performance, complemented by a refined fitness evaluation function. The crux of the study is the application of an upgraded PSO algorithm to fine-tune the controllers’ weighting coefficients, culminating in an optimized dual-mode compound attitude control system. A series of comparative simulation analyses are thoroughly executed to appraise the system’s responsiveness, stability, precision, and resilience to interference. The simulation outcomes demonstrate an average reduction of 42.21% in step response overshoot, an 18.52% decrease in settling time, a 53.18% decline in steady-state error, a 56.80% drop in the maximum deviation value, a 55.82% improvement in recovery speed, and a 75.61% enhancement in tracking precision for the proposed controller. The findings clearly verify the superior performance of the proposed control system, affirming its contribution to the advancement of RLV attitude control. The proposed controller holds promising potential for real application in attitude control systems and is poised to augment the reliability and mission success rate of RLVs under intricate flight scenarios.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 35","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141675948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3390/aerospace11070556
T. Horchler, S. Fechter, J. Hardi
Despite considerable research effort in the past 60 years, the occurrence of combustion instabilities in rocket engines is still not fully understood. While the physical mechanisms involved have been studied separately and are well understood in a controlled environment, the exact interaction of fluid dynamics, thermodynamics, chemical reactions, heat-release and acoustics, ultimately leading to instabilities, is not yet known. This paper focuses on the investigation of flame-acoustic interaction in a model combustion chamber using detached-eddy simulation (DES) methods. We present simulation results for a new load point of combustion chamber H from DLR Lampoldshausen and explore the flame response to resonant and non-resonant external excitation. In the first part of the paper, we use time-averaged results from a steady-state flow field without siren excitation to calculate the combustion chamber Helmholtz eigenmodes and compare them to the experimental results. The second part of the paper presents simulation results at a non-resonant excitation frequency. These results agree very well with the experimental results at the same condition, although the numerical simulation systematically overestimates the oscillation amplitudes. In the third part, we show that a simulation with resonant siren excitation can correctly reproduce the shift in eigenmode frequencies that is also seen in the experiments. Additionally, for this new load point, we confirm previous numerical results showing a strong influence of transversal excitation on the shape of the dense LOx cores. This work also proposes a bombing method for determining the resonant eigenmode frequencies based on an unexcited steady-state DES by simulating the decay of a strong artificial pressure pulse inside the combustion chamber.
尽管在过去的 60 年中进行了大量的研究工作，但人们对火箭发动机燃烧不稳定性的发生仍不完全了解。虽然在受控环境下对相关物理机制进行了单独研究并有了很好的理解，但对流体动力学、热力学、化学反应、热释放和声学的确切相互作用，以及最终导致不稳定性的原因仍不得而知。本文重点研究了使用离散涡流模拟（DES）方法对模型燃烧室中火焰与声学相互作用的研究。我们展示了兰波尔德豪森德国航天中心燃烧室 H 新负载点的模拟结果，并探讨了火焰对共振和非共振外部激励的响应。在论文的第一部分，我们使用了没有汽笛激励的稳态流场的时间平均结果来计算燃烧室亥姆霍兹特征模态，并将其与实验结果进行比较。论文的第二部分介绍了非共振激励频率下的模拟结果。这些结果与相同条件下的实验结果非常吻合，尽管数值模拟系统地高估了振荡幅度。在第三部分中，我们展示了采用谐振警报器激励的模拟可以正确再现实验中出现的特征模态频率偏移。此外，对于这个新的负载点，我们证实了之前的数值结果，即横向激励对致密 LOx 磁芯形状的强烈影响。这项工作还提出了一种基于未激励稳态 DES 的轰炸方法，通过模拟燃烧室内强人工压力脉冲的衰减来确定共振特征模态频率。
{"title":"Numerical Investigation of Flame-Acoustic Interaction at Resonant and Non-Resonant Conditions in a Model Combustion Chamber","authors":"T. Horchler, S. Fechter, J. Hardi","doi":"10.3390/aerospace11070556","DOIUrl":"https://doi.org/10.3390/aerospace11070556","url":null,"abstract":"Despite considerable research effort in the past 60 years, the occurrence of combustion instabilities in rocket engines is still not fully understood. While the physical mechanisms involved have been studied separately and are well understood in a controlled environment, the exact interaction of fluid dynamics, thermodynamics, chemical reactions, heat-release and acoustics, ultimately leading to instabilities, is not yet known. This paper focuses on the investigation of flame-acoustic interaction in a model combustion chamber using detached-eddy simulation (DES) methods. We present simulation results for a new load point of combustion chamber H from DLR Lampoldshausen and explore the flame response to resonant and non-resonant external excitation. In the first part of the paper, we use time-averaged results from a steady-state flow field without siren excitation to calculate the combustion chamber Helmholtz eigenmodes and compare them to the experimental results. The second part of the paper presents simulation results at a non-resonant excitation frequency. These results agree very well with the experimental results at the same condition, although the numerical simulation systematically overestimates the oscillation amplitudes. In the third part, we show that a simulation with resonant siren excitation can correctly reproduce the shift in eigenmode frequencies that is also seen in the experiments. Additionally, for this new load point, we confirm previous numerical results showing a strong influence of transversal excitation on the shape of the dense LOx cores. This work also proposes a bombing method for determining the resonant eigenmode frequencies based on an unexcited steady-state DES by simulating the decay of a strong artificial pressure pulse inside the combustion chamber.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141674352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3390/aerospace11070554
Fei Zeng, Ruijia Sun, Zhenhua Chen, Yuang Liu, Weihua Yang
The architecture of aeroengine air-cooling system channels is notably intricate, with impingement heat transfer standing out as a critical process amidst the complexity. This study delves into the casing annular cavity’s structure, examining the influence of flow and structural parameters on heat transfer characteristics. Experimental findings have revealed a trend towards more uniform temperature distributions across the impingement target plate as the relative impingement distance (H/d) increases, under a constant impingement Reynolds number (Rej). Notably, an impingement angle (β) of 90° yields optimal heat transfer effects on the target surface. Furthermore, a higher impingement hole consistency (Is) correlates with a lower and more uniform temperature distribution across the target plate. Additionally, escalating the crossflow ratio (mc/m) results in a decline in the temperature at the impingement stagnation point and a corresponding rise in the heat transfer coefficient.
{"title":"Study on Heat Transfer Characteristics of Jet Impingement of Turbine Bending Surface","authors":"Fei Zeng, Ruijia Sun, Zhenhua Chen, Yuang Liu, Weihua Yang","doi":"10.3390/aerospace11070554","DOIUrl":"https://doi.org/10.3390/aerospace11070554","url":null,"abstract":"The architecture of aeroengine air-cooling system channels is notably intricate, with impingement heat transfer standing out as a critical process amidst the complexity. This study delves into the casing annular cavity’s structure, examining the influence of flow and structural parameters on heat transfer characteristics. Experimental findings have revealed a trend towards more uniform temperature distributions across the impingement target plate as the relative impingement distance (H/d) increases, under a constant impingement Reynolds number (Rej). Notably, an impingement angle (β) of 90° yields optimal heat transfer effects on the target surface. Furthermore, a higher impingement hole consistency (Is) correlates with a lower and more uniform temperature distribution across the target plate. Additionally, escalating the crossflow ratio (mc/m) results in a decline in the temperature at the impingement stagnation point and a corresponding rise in the heat transfer coefficient.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141674145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-04DOI: 10.3390/aerospace11070551
Estel Ferrer, J. A. Ruiz-de-Azua, Francesc Betorz, Josep Escrig
Distributed space systems are increasingly valued in the space industry, as they enhance mission performance through collaborative efforts and resource sharing among multiple heterogeneous satellites. Additionally, enabling autonomous and real-time satellite-to-satellite communications through Inter-Satellite Links (ISLs) can further increase the overall performance by allowing cooperation without relying on ground links and extensive coordination efforts among diverse stakeholders. Given the constrained resources available onboard satellites, a crucial element of achieving cost-effective and autonomous cooperation involves minimizing energy wastage resulting from unsuccessful or unnecessary communication. To address this challenge, satellites must anticipate their ISL opportunities or encounters with minimal resource utilization. Building upon prior publications, this work presents further insights into the use of supervised learning to enable satellites to forecast their encounters without relying on orbit propagation. In particular, a more realistic definition of satellite encounters, along with a versatile solution applicable to all polar low-Earth orbit satellites is implemented. Results show that the trained model can anticipate encounters for realistic and unseen data from an available data source with a balance accuracy of around 90% and six times faster when compared with the well-known Simplified General Perturbation 4 orbital model.
{"title":"Inter-Satellite Link Prediction with Supervised Learning: An Application in Polar Orbits","authors":"Estel Ferrer, J. A. Ruiz-de-Azua, Francesc Betorz, Josep Escrig","doi":"10.3390/aerospace11070551","DOIUrl":"https://doi.org/10.3390/aerospace11070551","url":null,"abstract":"Distributed space systems are increasingly valued in the space industry, as they enhance mission performance through collaborative efforts and resource sharing among multiple heterogeneous satellites. Additionally, enabling autonomous and real-time satellite-to-satellite communications through Inter-Satellite Links (ISLs) can further increase the overall performance by allowing cooperation without relying on ground links and extensive coordination efforts among diverse stakeholders. Given the constrained resources available onboard satellites, a crucial element of achieving cost-effective and autonomous cooperation involves minimizing energy wastage resulting from unsuccessful or unnecessary communication. To address this challenge, satellites must anticipate their ISL opportunities or encounters with minimal resource utilization. Building upon prior publications, this work presents further insights into the use of supervised learning to enable satellites to forecast their encounters without relying on orbit propagation. In particular, a more realistic definition of satellite encounters, along with a versatile solution applicable to all polar low-Earth orbit satellites is implemented. Results show that the trained model can anticipate encounters for realistic and unseen data from an available data source with a balance accuracy of around 90% and six times faster when compared with the well-known Simplified General Perturbation 4 orbital model.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141678374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The residual stress field induced by interference-fit riveting in aircraft panel structures significantly affects the fatigue performance around the rivet holes. Common residual stress analytical models often overlook the non-uniformity of interference between the rivet and the hole, which impacts the applicability of these models. Addressing this issue, an analytical model of residual stress around the rivet hole is proposed for a typical single-riveted structure based on the thick-walled cylinder theory and Lame’s equations, considering the non-uniform interference along the axis of the rivet hole. This novel model is then extended to multi-riveted structures in fuselage panels. Using vector synthesis, analytical models for single-row double-rivets and double-row quadruple-rivets configurations were derived. The established analytical models provide a three-dimensional characterization of the residual stress field in typical riveted structures. Finally, the accuracy of the model is verified through X-ray diffraction experiments and FEM simulation results.
飞机面板结构中的过盈配合铆接所引起的残余应力场会严重影响铆钉孔周围的疲劳性能。常见的残余应力分析模型通常会忽略铆钉与孔之间过盈量的不均匀性，这影响了这些模型的适用性。针对这一问题，基于厚壁圆柱体理论和 Lame 方程，考虑到沿铆钉孔轴线的非均匀干涉，为典型的单铆接结构提出了铆钉孔周围残余应力分析模型。然后将这一新颖模型扩展到机身面板中的多铆接结构。通过矢量合成，得出了单排双铆钉和双排四铆钉配置的分析模型。建立的分析模型提供了典型铆接结构中残余应力场的三维特征。最后，通过 X 射线衍射实验和有限元模拟结果验证了模型的准确性。
{"title":"Three-Dimensional Characterization of Residual Stress in Aircraft Riveted Panel Structures","authors":"Yonggang Kang, Huantian Xiao, Zihao Wang, Guomao Li, Yonggang Chen","doi":"10.3390/aerospace11070552","DOIUrl":"https://doi.org/10.3390/aerospace11070552","url":null,"abstract":"The residual stress field induced by interference-fit riveting in aircraft panel structures significantly affects the fatigue performance around the rivet holes. Common residual stress analytical models often overlook the non-uniformity of interference between the rivet and the hole, which impacts the applicability of these models. Addressing this issue, an analytical model of residual stress around the rivet hole is proposed for a typical single-riveted structure based on the thick-walled cylinder theory and Lame’s equations, considering the non-uniform interference along the axis of the rivet hole. This novel model is then extended to multi-riveted structures in fuselage panels. Using vector synthesis, analytical models for single-row double-rivets and double-row quadruple-rivets configurations were derived. The established analytical models provide a three-dimensional characterization of the residual stress field in typical riveted structures. Finally, the accuracy of the model is verified through X-ray diffraction experiments and FEM simulation results.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 35","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141678290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Conventional forward bleed slots reduce the hypersonic inlet starting Mach number but suffer from excessive flow leakage after restart. This paper proposes a novel reverse bleed slot design method for curved axisymmetric inlets of a solid-fuel scramjet. Leveraging the Kantrowitz criterion and detailed flow analysis, the method optimizes bleed slot placement, number, area, and angle. Results show superior aerodynamic performance by placing slots in the non-starting region of the internal compression section, considering both unstarted flow and separation bubble dynamics during restart. Each bleed slot area is calculated successively down-stream based on the Kantrowitz criterion. Finally, the effects of bleed slot angle have been extensively studied. The key inlet performance reaches its optimum at a slot angle of approximately 130°, achieving a significant reduction in the starting Mach number (from 4.80 to 3.65) and a 50% decrease in bleed flow rate compared to the forward slot design. This method demonstrates its feasibility and effectiveness, enabling substantial improvement in inlet starting performance with minimal flow loss.
{"title":"Design of Reverse Bleed Slot for Curved Axisymmetric Inlet Based on Kantrowitz Criterion and Flow Field Characteristics","authors":"Yongzhou Li, Di Sun, Xinhui Tian, Yiqi Yuan, Xisheng Luo, Kunyuan Zhang","doi":"10.3390/aerospace11070553","DOIUrl":"https://doi.org/10.3390/aerospace11070553","url":null,"abstract":"Conventional forward bleed slots reduce the hypersonic inlet starting Mach number but suffer from excessive flow leakage after restart. This paper proposes a novel reverse bleed slot design method for curved axisymmetric inlets of a solid-fuel scramjet. Leveraging the Kantrowitz criterion and detailed flow analysis, the method optimizes bleed slot placement, number, area, and angle. Results show superior aerodynamic performance by placing slots in the non-starting region of the internal compression section, considering both unstarted flow and separation bubble dynamics during restart. Each bleed slot area is calculated successively down-stream based on the Kantrowitz criterion. Finally, the effects of bleed slot angle have been extensively studied. The key inlet performance reaches its optimum at a slot angle of approximately 130°, achieving a significant reduction in the starting Mach number (from 4.80 to 3.65) and a 50% decrease in bleed flow rate compared to the forward slot design. This method demonstrates its feasibility and effectiveness, enabling substantial improvement in inlet starting performance with minimal flow loss.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 57","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141680118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-04DOI: 10.3390/aerospace11070550
Dongjian Su, Qingyu Lin, Hao Wang, Ruyi Tao
The coupling action of gas flow with propellant burning surface regression is the critical process in solid rocket motor (SRM), which has an important effect on the unsteady combustion, erosive burning, dynamic combustion and pressure fluctuation of propellants. The immersed boundary method (IBM) is used to deal with the dynamic boundary of the flow field caused by the burning surface regression, and the face offsetting method (FOM) is applied to track the regression of the burning surface. The combination of these two methods can realize the coupling simulation of gas flow and burning surface regression. In this paper, the mathematical model of the immersed boundary method for all the flow field boundaries and the coupling method of gas flow with the propellant burning surface regression are given. And the implementation method of the immersed boundary method for all boundary conditions in the non-viscous flow field is given. The internal flow fields of the motor with the end-slotted and end-burning propellant and another motor with the perforated cylindrical propellant, considering the erosive burning, are simulated. The numerical results show that IBM, combined with FOM, has effectively realized the simulation of gas flow coupled with the burning surface regression.
{"title":"Numerical Simulation of Gas Flow Coupled with Burning Surface Regression Based on Immersed Boundary Method and Face Offsetting Method","authors":"Dongjian Su, Qingyu Lin, Hao Wang, Ruyi Tao","doi":"10.3390/aerospace11070550","DOIUrl":"https://doi.org/10.3390/aerospace11070550","url":null,"abstract":"The coupling action of gas flow with propellant burning surface regression is the critical process in solid rocket motor (SRM), which has an important effect on the unsteady combustion, erosive burning, dynamic combustion and pressure fluctuation of propellants. The immersed boundary method (IBM) is used to deal with the dynamic boundary of the flow field caused by the burning surface regression, and the face offsetting method (FOM) is applied to track the regression of the burning surface. The combination of these two methods can realize the coupling simulation of gas flow and burning surface regression. In this paper, the mathematical model of the immersed boundary method for all the flow field boundaries and the coupling method of gas flow with the propellant burning surface regression are given. And the implementation method of the immersed boundary method for all boundary conditions in the non-viscous flow field is given. The internal flow fields of the motor with the end-slotted and end-burning propellant and another motor with the perforated cylindrical propellant, considering the erosive burning, are simulated. The numerical results show that IBM, combined with FOM, has effectively realized the simulation of gas flow coupled with the burning surface regression.","PeriodicalId":505273,"journal":{"name":"Aerospace","volume":" 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141677092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：