Article
Engineering, Multidisciplinary
Sujit Kumar, S. Narayanan
Summary: This study numerically investigates the aerodynamic characteristics of symmetric NACA airfoils at various thickness ratios, revealing lift/drag fluctuations at lower thickness ratios and proposing an empirical expression to predict lift and drag coefficients. The far-field acoustic measurements show that thicker airfoils emit lower acoustic emissions compared to thinner ones.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Engineering, Aerospace
Tong Shen, Zhan Tu, Daochun Li, Zi Kan, Jinwu Xiang
Summary: This study focuses on the aerodynamics of the bristled wings of the smallest flying insects. The research shows that as the wingspan of the insects decreases, the proportion of bristle area at the wingtip increases. Lift-based stroke is more effective than drag-based stroke in generating vertical force and aerodynamic efficiency. Bristled wings using the clap-and-fling mechanism can enhance both vertical force and efficiency, but bristle crossing mainly contributes to horizontal force and has little effect on vertical force augmentation.
Article
Engineering, Chemical
Hui Cai, Guoqing Miao
Summary: This study reported the flow pattern in a vertically vibrated, annular, and granular system, showing either laminar granular flow or turbulent granular flow in different vibration modes. The flow patterns were explained and identified using the Reynolds numbers of the granular system. The results revealed a property peculiar to the granular flow similar to, yet different from, viscous fluids.
Article
Mechanics
Jean-Baptiste R. G. Souppez, Patrick Bot, Ignazio Maria Viola
Summary: The study investigates the flow around a circular arc and its effects on forces. It is found that a leading-edge separation bubble is formed on the convex side of the arc, leading to boundary layer separation. The force crisis is associated with the suppressed relaminarization of the boundary layer, and the critical angle of attack exhibits a linear relationship with the Reynolds number.
Article
Engineering, Mechanical
Tingyun Yin, Giorgio Pavesi
Summary: In this study, the flow characteristics of a pitching hydrofoil were numerically investigated. The results showed that reducing the empirical coefficient in the turbulence model improved the prediction of hydraulic performance at high angles of attack. The dynamic behavior of the laminar separation bubble was strongly influenced by the pitching method and velocity.
JOURNAL OF FLUIDS AND STRUCTURES
(2022)
Article
Engineering, Geological
Hong Fang, Jianting Zhu, Jinrong Qiu, Yaoming Su, Di Xia
Summary: Using laminar or turbulent flow equations indiscriminately to describe groundwater flows in fracture networks may result in large errors. This study proposes a new method that separates laminar and turbulent flows in individual fractures to simulate steady-state groundwater flows in two- and three-dimensional fracture networks. The results show that using the laminar flow equation in all fractures overestimates groundwater flowrates, while using the turbulent flow equation underestimates them.
ENGINEERING GEOLOGY
(2022)
Article
Engineering, Marine
Hossein Jabbari, Ali Esmaeili, Shayan Rabizadeh
Summary: This study investigated the interaction of LSB formed on a full-span wing with ground clearance, and found that flying near the ground surface decreases the aerodynamic performance of the full-span wing in low Reynolds flow zone. Through numerical discussions, it was also revealed that at certain distances from the ground, the phase portrait curves exhibit an elliptical shape due to the bursting of the separation bubble.
Article
Mechanics
Kensuke Kusama, Takayuki Nagata, Masayuki Anyoji, Taku Nonomura, Keisuke Asai
Summary: Flow over a flat plate with a 5% thickness ratio is investigated using schlieren visualization in compressible low-Reynolds-number conditions. The results show that flow separates at the leading edge and forms laminar separation bubbles, with the position of the vortex shedding moving downstream as the Mach number increases. Additionally, the two-dimensional structure of generated vortices is maintained up to the trailing edge at a Mach number of 0.66, and the flow becomes stabilized with increasing Mach number.
FLUID DYNAMICS RESEARCH
(2021)
Article
Engineering, Aerospace
Hua-feng Xu, Sheng-feng Zhao, Ming-yang Wang, Xiao-Ying Sheng, Ge Han, Xin-gen Lu
Summary: This study utilizes experimentally validated Large Eddy Simulation method and Dynamic Mode Decomposition analysis technique to investigate the unsteady flow characteristics on a compressor cascade under different Reynolds number conditions. The results show that at low Reynolds number, large-scale vortices dominate the flow, while at high Reynolds number, vortices become dispersed and smaller. The study also reveals the significant roles of Kelvin-Helmholtz instability and harmonic instability in the flow.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Mechanics
Reynolds Addo-Akoto, Jong-Seob Han, Jae-Hung Han
Summary: This study investigates the aerodynamic characteristics of flexible flapping wings in hover, considering the combined effects of aspect ratio, slack, and pitch angles. The results show that the flexibility of the wing can be indirectly altered by adjusting slack. An optimum aspect ratio range is observed depending on the flexibility, and the intensity of the leading-edge vortex decreases as slack increases. The shed trailing-edge vortices are found to be the key feature of twistable flexible wings, and negative wing twist plays a significant role in sustaining lift. The study also reveals the relationship between aspect ratio, wing flexibility, and the effective downwash area for lift enhancement.
Article
Mathematics, Applied
Jiri Holman, Jiri Furst
Summary: This article discusses the numerical simulation of flows transitioning from laminar to turbulent due to boundary layer separation, utilizing the Reynolds averaged Navier-Stokes equations with the EARSM model of turbulence and an algebraic model of bypass transition. The proposed method is tested on various cases of low-Reynolds subsonic transitional flows, including flows over different airfoil shapes.
JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
(2021)
Article
Engineering, Aerospace
Zhaolin Chen, Tianhang Xiao, Yan Wang, Ning Qin
Summary: This article investigates the dynamic characteristics of laminar separation bubbles associated with aerodynamic loads unsteadiness of a cambered thin airfoil during pitching-up motions at low Reynolds number flows. The study reveals that the shape and size of the separation bubbles evolve during pitching motion, affecting the airfoil's upper surface and eventually leading to a fully detached flow. Vortex merging is observed in the rear part of the turbulent separation bubbles at Reynolds number 30,000, with a delayed transition observed as incidence increases at Reynolds number 60,000.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING
(2021)
Article
Engineering, Civil
Wenyong Ma, Xiaobin Zhang, John Macdonald, Longqian Jin, Yuxue Li
Summary: This study investigates the aerodynamic characteristics of a circular cylinder in the critical Reynolds number range, revealing that reattachment only occurs along a certain length of the cylinder, inducing a strong three-dimensional flow state and corresponding aerodynamic force distribution. The reattachment also causes an unsteady variation in aerodynamic force, with the lift coefficient mainly dependent on the occurrence of a separation bubble and the motion of the reattachment point.
JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Vibhav Durgesh, Hamid Johari, Elifalet Garcia
Summary: The objective of this study is to investigate the impact of airfoil thickness and camber for canonical NACA airfoils at Reynolds numbers in the range of 2 x 10(4) <= Re-c <= 5 x 10(4) and to correlate the observed aerodynamic behavior with the flow patterns. The results showed that the airfoil thickness and camber significantly influence the aerodynamic performance and a strong dependence on the Reynolds number was observed. The symmetric NACA airfoils exhibited nonlinear lift behavior and abrupt changes in lift values at Reynolds numbers below 4 x 10(4), while the cambered airfoil performed better with some Reynolds number dependence.
JOURNAL OF VISUALIZATION
(2023)
Article
Engineering, Aerospace
Feng-Yuan Zuo
Summary: A study was conducted on ramp-induced planar shock-wave/turbulent-boundary-layer interactions at hypersonic conditions using numerical simulation. The aim was to investigate the effects of wall temperature and Reynolds number. The results showed that the Reynolds-averaged Navier-Stokes equations could accurately predict the main features of the interactions. Various flow cases were computed to examine the scaling of heat transfer at different wall temperatures. It was found that the interaction zone decreased as the wall was cooled, and a power law originally introduced by Back and Cuffel successfully collapsed the data.
Article
Engineering, Aerospace
K. Lindhorst, M. C. Haupt, P. Horst
Article
Engineering, Aerospace
K. Lindhorst, M. C. Haupt, P. Horst
AERONAUTICAL JOURNAL
(2016)
Article
Engineering, Aerospace
K. Sommerwerk, B. Michels, K. Lindhorst, M. C. Haupt, P. Horst
AEROSPACE SCIENCE AND TECHNOLOGY
(2016)
Editorial Material
Mechanics
M. Fassin, D. Kowollik, S. Wulfinghoff, S. Reese, M. Haupt
ARCHIVE OF APPLIED MECHANICS
(2016)
Article
Engineering, Multidisciplinary
K. Sommerwerk, M. Woidt, M. C. Haupt, P. Horst
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING
(2017)
Article
Engineering, Aerospace
Kay Sommerwerk, Ian Krukow, Matthias C. Haupt, Dieter Dinkler
JOURNAL OF AIRCRAFT
(2016)
Article
Engineering, Aerospace
Xiaoliang Gong, Stephan Bansmer, Christoph Strobach, Ralf Unger, Matthias Haupt
Article
Engineering, Aerospace
K. Lindhorst, M. C. Haupt, P. Horst
Article
Engineering, Multidisciplinary
D. Kowollik, V. Tini, S. Reese, M. Haupt
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING
(2013)
Article
Engineering, Aerospace
Felix Hoette, Torben Fiedler, Matthias C. Haupt, Paul Lungu, Christoph V. Sethe, Oskar J. Haidn
JOURNAL OF PROPULSION AND POWER
(2019)
Article
Engineering, Aerospace
Felix Hoette, Matthias C. Haupt
AEROSPACE SCIENCE AND TECHNOLOGY
(2020)
Article
Engineering, Mechanical
Felix Hoette, Christoph Sethe, Torben Fiedler, Matthias C. Haupt, Oskar J. Haidn, Michael Rohdenburg
INTERNATIONAL JOURNAL OF FATIGUE
(2020)
Article
Mechanics
Mohit Talele, Matthias Haupt, Michel van Tooren, Ali Elham
Summary: This paper presents a methodology for optimizing composite plate behavior in aerospace applications by concurrently optimizing stringers topology and fiber pattern in grid stiffened tow steered composite structures. The study shows that the Lagrange multiplier approach effectively couples stiffener and plate models, allowing for independent meshes of stringers and skin. The results demonstrate that steering does improve the behavior of stiffened plates.
COMPOSITE STRUCTURES
(2021)
Article
Computer Science, Interdisciplinary Applications
Simon Thel, Daniel Hahn, Matthias Haupt, Sebastian Heimbs
Summary: This research aims to maximize load alleviation in aircraft wings by exploiting the geometric nonlinearities of the inner wing structure. A topology optimization approach is proposed to find designs with the desired properties. The passive load alleviation is achieved through bending-torsion coupling, which reduces the aerodynamic forces. The proposed methodology has been successfully applied to two test cases, demonstrating its potential for designing new geometries with the desired nonlinear behavior.
STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION
(2022)
Article
Engineering, Aerospace
Maximilian Mueller, Malte Woidt, Matthias Haupt, Peter Horst
Article
Engineering, Mechanical
Xuyi Jia, Chunlin Gong, Wen Ji, Chunna Li
Summary: A flow sensing method for real-time forecast of flow field in FSI systems using structural deformation is proposed in this study. The method utilizes multilayer POD to improve accuracy and deep neural network to map mode coefficients. The results show that the proposed method performs accurately in flow properties forecasting and is suitable for FSI systems with complex flow structures.
JOURNAL OF FLUIDS AND STRUCTURES
(2024)
Article
Engineering, Mechanical
Paulo H. N. Silva, Gustavo R. S. Assi
Summary: This paper presents an experimental study of fluid-structure interaction, demonstrating that the controlled rotation of rods can reduce mean drag and fluctuating lift forces simultaneously. By using a multi-objective genetic algorithm, the optimum rotation speeds were found, resulting in a more significant reduction in objectives and energy consumption. The contribution of each rod depends on its angular position and the flow conditions generated by the upstream control rods. The study clarifies the physical principles of the phenomenon and paves the way for technological applications.
JOURNAL OF FLUIDS AND STRUCTURES
(2024)
Article
Engineering, Mechanical
Yacine Manal, Pascal Hemon
Summary: Synchronized unsteady wall pressure measurements were performed on a full-scale circular chimney subjected to natural wind. The analysis of the pressure distribution using bi-orthogonal decomposition was crucial for the success of the processing. The results showed that atmospheric turbulence plays a significant role in the unsteady pressure response on the chimney, generating high levels of RMS pressure.
JOURNAL OF FLUIDS AND STRUCTURES
(2024)
Article
Engineering, Mechanical
Hironori Takeda, Yusuke Asai, Shunichi Ishida, Yasutoshi Taniguchi, Takuya Terahara, Kenji Takizawa, Yohsuke Imai
Summary: Wrinkling and creasing of an elastic membrane in a shear flow can be influenced by shear rate and membrane thickness. The deformation type can be determined by mechanical and geometrical effects of the membrane thickness, based on the geometrical consistency of the capsule surface.
JOURNAL OF FLUIDS AND STRUCTURES
(2024)
