Article
Engineering, Aerospace
Diliana Friedewald
Summary: This research focuses on using systematic unsteady Reynolds-averaged Navier-Stokes simulations to study gust load analyses of transport aircraft in cruise flight conditions. The study found that amplitude effects decrease with lower Mach numbers or higher excitation frequencies. Nonlinear simulations predict lower maximum lift values and lower lift and moment derivatives compared to their linear counterparts for lower frequencies combined with large-amplitude excitations.
Article
Engineering, Aerospace
Anna M. Young, Amanda S. M. Smyth
Summary: The unsteady load response of an airfoil encountering a gust is often modeled using analytical transfer functions, with studies showing that the effects of camber and incidence are not negligible when there is a streamwise gust component. New experimental data for an airfoil with nonzero loading encountering a gust with both streamwise and transverse components were presented in this work.
Article
Engineering, Aerospace
Junjie Fu, Di Sun, Feng Qu, Junqiang Bai
Summary: This paper analyzes the transonic buffet of the supercritical airfoil and proposes a strategy to suppress this phenomenon. By introducing two-dimensional bumps in the shock motion region, the developed transonic buffet can be suppressed. The study also finds that a superior buffet suppression bump should be placed after the shock-induced boundary-layer separation point and have a carefully designed height.
Article
Engineering, Aerospace
Rozie Zangeneh
Summary: The study investigates shock and boundary-layer interactions in transonic airfoils and highlights the importance of variables like freestream Mach number, Reynolds number, and boundary-layer thickness in determining the flow characteristics. Simulation results show a correlation between separation length and unit Reynolds number, and an increase in bubble size with higher boundary-layer thickness. Additionally, the length of rear separation decreases with increasing Reynolds number at a given Mach number.
Article
Mechanics
Maurizio Quadrio, Alessandro Chiarini, Jacopo Banchetti, Davide Gatti, Antonio Memmolo, Sergio Pirozzoli
Summary: In this study, flow control for reducing turbulent skin-friction drag is applied to a transonic airfoil, resulting in improved aerodynamic performance. The control method involves inducing spanwise forcing on a portion of the suction side of the airfoil. This not only reduces friction locally, but also modifies shock waves, leading to increased lift and decreased drag. The findings suggest that skin-friction drag reduction can be used as a tool to improve the overall aerodynamics of complex flows.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Yinghe Qi, Hengyang Ye, Qiuqin Hu, Xiaoqin Zhi, Limin Qiu
Summary: This study established an Euler-Euler two-phase flow model and a droplet growth model to predict the spontaneous desublimation of trace water vapor in a transonic cryogenic wind tunnel. The model was validated and applied to study the two patterns of water vapor desublimation in the wind tunnel, providing insights into the impact on aerodynamic data.
Article
Engineering, Aerospace
Toma Miyake, Hiroshi Terashima
Summary: This numerical study investigates the behavior of a double transonic dip with a supercritical airfoil. A two-dimensional model of a wing section with two degrees of freedom is used for the analysis. The study successfully captures the unique behavior of the double transonic dip on the flutter boundary of the supercritical airfoil, which is different from the behavior of conventional symmetric airfoils. The analysis shows that the motion of the shock wave over the upper surface is significantly affected by the behavior of the boundary layer around the cambered aft region of the lower surface.
Article
Mechanics
Enrico Degregori, Jae Wook Kim
Summary: The research demonstrates that wavy leading edge airfoils are more effective than straight leading edge ones, with the smallest amplitude airfoil performing the best. Unsteadiness in flow plays a crucial role in the performance of airfoils in transonic flows at moderate and high angles of attack.
Article
Engineering, Aerospace
Qingdian Zhang, Hongwei Ma, Yafei Zhong, Junde Guo, Zhongqiang Xie
Summary: The airfoil probe is a typical instrument for measuring total pressure/temperature in turbomachinery research. It not only causes measurement error itself, but also generates extra flow loss, affecting the accuracy. This study investigates the effects of airfoil probes on the aerodynamic performance of a compressor cascade using RANS and high-fidelity methods. The inclusion of airfoil probes decreases load capacity and shock waves due to the streamwise vortex, but also leads to earlier flow transition and reduction of separation bubble and profile loss. However, the extra loss is generated and redistributed to the overall flow field. The separated flow at the junction of the end wall, blade, and probe's pipes worsens the measuring accuracy, and the shedding streamwise vortex generated by the probe's pipe is revealed by DDES, providing insights into complex fluid mechanisms.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Thermodynamics
Li Jiahe, Liu Yanming, Wang Jiang
Summary: A hybrid flow control method using suction and loaded leading edge (SLLE) has been proposed in this study to overcome the huge drag on an airfoil in transonic flow. The passive flow control technique of loaded leading edge structure and the active control of suction slot have achieved significant drag reduction and improved lift-drag ratio.
JOURNAL OF THERMAL SCIENCE
(2023)
Article
Engineering, Aerospace
Yayun Shi, Shun He, Gaowei Cui, Gang Chen, Yan Liu
Summary: This study investigates the quenching of limit cycle oscillation (LCO) in a supercritical airfoil (NLR 7301) considering freeplay in transonic viscous flow. Computational Fluid Dynamics (CFD) based on Navier-Stokes equations is used to calculate transonic aerodynamic forces. A loosely coupled scheme with steady CFD and an efficient graphic method is developed to obtain the aerodynamic preload. The LCO quenching is observed based on nonlinear dynamic aeroelastic response obtained using a time marching approach.
CHINESE JOURNAL OF AERONAUTICS
(2023)
Article
Mechanics
Tapan K. K. Sengupta, Ardhendu Chakraborty, Arkadyuti Ghosh Roy, Aditi Sengupta, Prasannabalaji Sundaram
Summary: This study compares the effects of wall-heating and wall-cooling on shock-boundary layer interaction over an airfoil using implicit large eddy simulation. Results show that wall-heating reduces the oscillation frequency and strength of the shock wave, leading to higher fluctuations in flow features. Both heating and cooling result in a marginal increase in aerodynamic efficiency.
Article
Engineering, Mechanical
A. D'Aguanno, F. F. J. Schrijer, B. W. van Oudheusden
Summary: The study investigated the transonic buffet behavior of the supercritical airfoil OAT15A through experimental and numerical methods, revealing the main modes connected with buffet. The first three most energetic modes captured a majority of the fluctuating kinetic energy and displayed distinct characteristics from the buffet behavior.
EXPERIMENTS IN FLUIDS
(2021)
Article
Engineering, Aerospace
James G. Coder
Summary: Airfoils tested at low speeds and transonic conditions exhibit different surface pressure distributions and boundary-layer characteristics, leading to the development of a methodology to map transonic pressure gradients to equivalent low-speed airfoils. This method was successfully applied to design a low-speed, slotted, natural-laminar-flow airfoil, meeting design objectives and performing well down to a Reynolds number of 1 million.
JOURNAL OF AIRCRAFT
(2021)
Article
Nanoscience & Nanotechnology
Bing Han, Min Xu, Guoguang Chen, Tianxing Cai, Wenhu Wang, Shixi Guan
Summary: This study numerically investigates the transonic buffet phenomenon over a prescribed-pitching airfoil using a validated simulation approach. The results show that the lift fluctuations in the pitching case are larger than those in the fixed case, and the presence of shock wave interactions and boundary separation contribute to higher pressure and velocity fluctuation levels. The unsteady flow in the pitching case exhibits a more disordered pattern compared to the periodic shedding in the wake of the fixed case. The analysis also reveals strong interactions between the shock oscillations and Karman vortex structure.
Article
Acoustics
Sandip Chajjed, Mohammad Khalil, Dominique Poirel, Chris Pettit, Abhijit Sarkar
Summary: This paper reports the generalization of the Bayesian formulation of the flutter margin method, which improves the predictive performance by incorporating the joint prior of aeroelastic modal parameters. The improved algorithm reduces uncertainties in predicting flutter speed and can cut cost by reducing the number of flight tests.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Pascal Zeise, Bernhard Schweizer
Summary: Air ring bearings are an improved version of classical air bearings, providing better damping behavior and allowing operation above the linear threshold speed of instability. However, there is a risk of dangerous vibrations in certain rotor systems, which can be addressed by considering ring tilting effects.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Zbynek Sika, Jan Krivosej, Tomas Vyhlidal
Summary: This paper presents a novel design of a compact six degrees of freedom active vibration absorber with six identical eigenfrequencies. The objective is to completely suppress the vibration of a machine structure with six motion components. By utilizing a Stewart platform structure equipped with six active legs, a spatial unifrequency absorber with six identical eigenfrequencies is achieved. The design is optimized using a correction feedback and active delayed resonator feedback.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Kai Li, Yufeng Liu, Yuntong Dai, Yong Yu
Summary: This paper presents a novel light-powered self-oscillating liquid crystal elastomer (LCE) bow that can self-oscillate continuously and periodically under steady illumination. The dynamics of the LCE bow are theoretically investigated and numerical calculations predict its motion regimes. The suggested LCE bow offers potential advantages in terms of simple structure, customizable size, flexible regulation, and easy assembly.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Carmelo Rosario Vindigni, Giuseppe Mantegna, Calogero Orlando, Andrea Alaimo
Summary: In this study, a simple adaptive flutter suppression system is designed to increase the operative speed range of a wing-aileron aeroelastic plant. The system achieves almost strictly passivity by using a parallel feed-forward compensator implementation and the controller parameters are optimized using a population decline swarm optimization algorithm. Numerical simulations prove the effectiveness of the proposed simple adaptive flutter suppression architecture in different flight scenarios.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Nicco Ulbricht, Alain Boldini, Peng Zhang, Maurizio Porfiri
Summary: The quantification of fluid-structure interactions in marine structures is crucial for their design and optimization. In this study, an analytical solution for the free vibration of a bidirectional composite in contact with a fluid is proposed. By imposing continuity conditions and boundary conditions, the coupled fluid-structure problem is solved and applied to sandwich structures in naval construction, offering insights into the effects of water on mode shapes and through-the-thickness profiles of displacement and stress.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Shahram Hadian Jazi, Mostafa Hadian, Keivan Torabi
Summary: Non-uniformity and damage are the main focus in studying vibrations of beam elements. An exact closed-form explicit solution for the transverse displacement of a nonuniform multi-cracked beam is introduced using generalized functions and distributional derivative concepts. By introducing non-dimensional parameters, the motion equation and its closed-form solution are obtained based on four fundamental functions. The impact of crack count, location, intensity, and boundary conditions on natural frequency and mode shape is evaluated through numerical study.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Eugenio Tramacere, Marius Pakstys, Renato Galluzzi, Nicola Amati, Andrea Tonoli, Torbjoern A. Lembke
Summary: This paper proposes the experimental stabilization of electrodynamic maglev systems by means of passive components, providing key technological support for the Hyperloop concept of high-speed and sustainable transportation.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Pengfei Deng, Xing Tan, He Li
Summary: In this paper, the authors improve the surface morphology method and study the bit-rock interaction model between the rock and the PDC bit, taking into account the impact of blade shape and cutter arrangement. They establish a dynamic model for a deep drilling system equipped with an arbitrary shape PDC bit and propose a stability prediction method. The results show that the shape of the blades and arrangement of the cutters on the PDC bit significantly affect the nonlinear vibration of the drilling system.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Salvador Rodriguez-Blanco, Javier Gonzalez-Monge, Carlos Martel
Summary: In modern LPT designs, the simultaneous presence of forced response and flutter in different operation regimes is unavoidable. Recent evidence suggests that the traditional linear superposition method may be overly conservative. This study examines the flutter and forced response interaction in a realistic low pressure turbine rotor and confirms that the actual response is much smaller than that predicted by linear superposition.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Kabilan Baskaran, Nur Syafiqah Jamaluddin, Alper Celik, Djamel Rezgui, Mahdi Azarpeyvand
Summary: This study investigates the impact of the number of blades on the aeroacoustic characteristics and aerodynamic performance of propellers used in urban air mobility vehicles. The results show that different blade numbers exhibit distinct noise levels, providing valuable insights for further research on propeller noise and aerodynamic performance.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Yongbo Peng, Peifang Sun
Summary: This study focuses on the reliability-based design optimization (RBDO) of the tuned mass-damper-inerter (TMDI) system under non-stationary excitations. The performance of the optimized TMDI system is evaluated using probability density evolution analysis. The results demonstrate the technical advantages of TMDI, including high vibration mitigation performance, considerable mass reduction, and less stroke demand.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Guanfu Lin, Zhong-Rong Lu, Jike Liu, Li Wang
Summary: Vision-based measurement is an emerging method that enables full-field measurement with non-contact and high spatial resolution capabilities. This paper presents a single-camera method for measuring out-of-plane vibration of plate structures using motion-parametric homography to capture image variation and displacement response.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Bronislaw Czaplewski, Mateusz Bocian, John H. G. Macdonald
Summary: Despite two decades of study, there is currently no model that can quantitatively explain pedestrian-generated lateral forces. This research proposes a foot placement control law based on empirical data to calibrate and generalize the rigid-leg inverted pendulum model (IPM) for predicting lateral structural stability.
JOURNAL OF SOUND AND VIBRATION
(2024)
Article
Acoustics
Justine Carpentier, Jean-Hugh Thomas, Charles Pezerat
Summary: This paper proposes an improved method for the identification of vibration sources on a car window using the corrected force analysis technique. By redefining inverse methods in polar coordinates, more accurate results can be obtained.
JOURNAL OF SOUND AND VIBRATION
(2024)