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Characteristics of aerodynamic force and flow structure behind single box girder under isolated slit control

Journal of Central South University 2022年第8期29卷 2542-2557页

作者： CHEN Guan-bin CHENWen-li Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin 150090China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090China

An isolated slit was placed in a single box girder to obtain passive leading-edge suction and trailing-edge jet flow to control the unsteady aerodynamic force and modify the flow *** Great Belt East Bridge was used as a physical model at a geometric scale of 1:*** tunnel experiments were conducted at an incoming airflow speed of 10 m/s,and the Reynolds number was calculated as 2.3×104 using the test model height and wind *** surface pressure distribution was measured,and the aerodynamic force acting on the test model with and without the isolated slit was calculated by integrating the pressure *** was found that the control using an isolated slit can dramatically decrease the fluctuating surface pressure distribution and aerodynamic *** analysis on the power spectral density of the lift force revealed that the isolated slit accelerated vortex ***,high-speed particle image velocimetry was used to investigate the wake flow structure behind the test model.A vortex separated from the upper surface was pushed to a lower location and the wake flow structure was modified by the isolated slit.A proper orthogonal decomposition(POD)of the flow field showed that the first two POD modes in the controlled case contributed less energy than those in the uncontrolled case,indicating that more energy was transferred to higher modes,and small-scale vortices had more energy.A secondary instability structure was found in the wake flow for a nondimensional jet momentum coefficient J of 0.0667.

关键词： single box girder isolated slit aerodynamic force proper orthogonal decomposition(POD)mode

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Time-varying nonlinear dynamics of a deploying piezoelectric laminated composite plate under aerodynamic force

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Acta Mechanica Sinica 2018年第2期34卷 303-314页

作者： S.F.Lu W.Zhang X.J.Song College of Science Inner Mongolia University of Technology College of Mechanical Engineering Beijing University of Technology

Using Reddy’s high-order shear theory for laminated plates and Hamilton’s principle, a nonlinear partial differential equation for the dynamics of a deploying cantilevered piezoelectric laminated composite plate, under the combined action of aerodynamic load and piezoelectric excitation, is introduced. Two-degree of freedom(DOF)nonlinear dynamic models for the time-varying coefficients describing the transverse vibration of the deploying laminate under the combined actions of a first-order aerodynamic force and piezoelectric excitation were obtained by selecting a suitable time-dependent modal function satisfying the displacement boundary conditions and applying second-order discretization using the Galerkin method. Using a numerical method, the time history curves of the deploying laminate were obtained, and its nonlinear dynamic characteristics,including extension speed and different piezoelectric excitations, were studied. The results suggest that the piezoelectric excitation has a clear effect on the change of the nonlinear dynamic characteristics of such piezoelectric laminated composite plates. The nonlinear vibration of the deploying cantilevered laminate can be effectively suppressed by choosing a suitable voltage and polarity.

关键词： Deploying piezoelectric laminated composite plate Time-varying nonlinear dynamics Third-order shear deformation plate theory Time-dependent modal function aerodynamic force

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Morphology Effects of Leading-edge Serrations on aerodynamic force Production： An Integrated Study Using PIV and force Measurements

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Journal of Bionic Engineering 2018年第4期15卷 661-672页

作者： Teruaki Ikeda Tetsuya UedA Toshiyuki Nakata Ryusuke NodA Hiroto Tanaka Takeo Fujii Hao Liu Graduate School of Engineering Chiba University 1-33 Yayoi-cho lnage-ku Chiba-shi Chiba 263-8522 Japan TERAL Inc. 230 Moriwake Miyuki-cho Fukuyama-shi Hiroshima 720-0003 Japan School of Engineering Tokyo Institute of Technology 2-12-10okayama Meguro-ku Tokyo 152-8550 Japan Shanghai Jiao Tong University and Chiba University International Cooperative Research Centre (SJTU-CU ICRC) Shanghai 200240 China

While the leading-edge serration in owls＇ wing is known to be responsible for low noise gliding and flapping flights, the findings on its aero-acoustic role have been diverse or even controversial. Here we present an experimental study of the morphological effects of leading-edge serrations on aerodynamic force production by utilizing owl-inspired, single-feather, clean and serrated wing models with different serration lengths and spacing, and by combining Particle Image Velocimetry （PIV） and force measurements. force measurements show that an increase in the length and density of the leading-edge serrations leads to a reduction in the lift coefficient and lift-to-drag ratio at Angles of Attack （AoAs）〈 15° whereas the clean and serrated wings achieve comparable aerodynamic performance at higher AoAs 〉 15°, which owl wings often reach in flight. Furthermore PIV visualization of the flow fluctuations demonstrates that the leading-edge serration-based mechanism is consistent in all serrated wing models in terms of passive control of the laminar-turbulent transition while at AoAs 〉 15° similar suction flow is present at leading edge resulting in a comparable aerodynamic performance to that of the clean wing. Our results indicate the robustness and usefulness of leading-edge serration-inspired devices for aero-acoustic control in biomimetic rotor designs.

关键词： biomimetic leading-edge serrations low-speed wind tunnel particle image velocimetry aerodynamic force lami-nar-turbulent transition

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SIMULATION STUDY OF aerodynamic force FOR HIGH-SPEED MAGNETICALLY-LEVITATED TRAINS

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Chinese Journal of Mechanical Engineering 2006年第2期19卷 226-232页

作者： LI Renxian LIU Yingqing ZHAI Wanming School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031 China National Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031 China

Based on Reynolds average Navier-Storkes equations of viscous incompressible fluid and k-ε two equations turbulent model, the aerodynamic forces of high-speed magnetically-levitated （maglev） trains in transverse and longitudinal wind are investigated by finite volume method. Near 80 calculation cases for 2D transverse wind fields and 20 cases for 3D longitudinal wind fields are analyzed. The aerodynamic side force, yawing, drag, lift and pitching moment for different types of maglev trains and a wheel/rail train are compared under the different wind speeds. The types of maglev train models for 2D transverse wind analysis included electromagnetic suspension （EMS） type train, electrodynamic suspension （EDS） type train, EMS type train with shelter wind wall in one side or two sides of guideway and the walls, which are in different height or/and different distances from train body. The situation of maglev train running on viaduct is also analyzed. For 3D longitudinal wind field analysis, the model with different sizes of air clearances beneath maglev train is examined for the different speeds. Calculation result shows that： ① Different transverse effects are shown in different types of maglev trains. ② The shelter wind wall can fairly decrease the transverse effect on the maglev trains. ③ When the shelter wall height is 2 m, there is minimum side force on the train. When the shelter wall height is 2.5 m, there is minimum yawing moment on the train. ④ When the distance between inside surfaces of the walls and center of guideway is 4.0 m, there is minimum transverse influence on the train. ⑤ The size of air clearance beneath train body has a small influence on aerodynamic drag of the train, but has a fairly large effect on aerodynamic lift and pitching moment of the train. ⑥ The calculating lift and pitching moment for maglev train models are minus values.

关键词： aerodynamic force Magnetically-levitated (maglev) train Stability Numerical analysis

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EFFECT OF UPSTREAM ROTOR ON aerodynamic force OF DOWNSTREAM STATOR BLADES

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Transactions of Nanjing University of Aeronautics and Astronautics 2006年第2期23卷 94-101页

作者：王志强胡骏王英锋赵勇南京航空航天大学能源与动力学院

To study the amplitude and the frequency of the aerodynamic force on stator blades, micro-sensors are embedded on the surface of stator blades of a low-speed single-stage axial compressor rig. The unsteady pressure distribution on stator blades is measured under the conditions of different axial spacing between the rotor and the stator, different rotating speeds and an extensive range of the mass flow. Amplitudes and frequencies of aerodynamic forces are analyzed by the Fourier transform. Experimental results show that under the effect of the rotor wake, the dominant frequencies of pressure fluctuations on stator blades are the rotor blade passing frequency （BPF） and its harmonics. The higher harmonics of the rotor BPF in the fore part of the suction side are more prominent than that in the other parts of the stator blade. Otherwise, fluctuations of the pressure and the aerodynamic force on stator blades vary with the mass flow, the rotating speed and the axial spacing between the rotor and the stator.

关键词： blade-row interaction aerodynamic force compressor spectral feature

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Machine learning-assisted sparse observation assimilation for real-time aerodynamic field perception

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Science China(Technological Sciences) 2024年第5期67卷 1458-1469页

作者： ZHAO QingYu HUANG Jun GUO YuXin PAN YuXuan JI JingJing HUANG YongAn State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Accurate aerodynamic distribution perception and real-time flight state evaluation are crucial for flight safety,e.g.,stall ***,the observations are usually sparse due to limitations in sensor mounting space and cost,and a reconstruction technology is urgently ***,a machine learning-assisted assimilation method based on sparse observations has been *** from the traditional reconstruction methods focusing on boundary condition correction,the proposed method formulates the flow field pressure distribution as a linear superposition of flow field modes,thereby forming a real-time reconstruction pattern that combines offline modal extraction using computational fluid dynamics(CFD)with real-time determination of modal weights using a neural *** this study,CFD simulations were conducted under 800different operating conditions for common modal extraction and model *** weights of these modes were determined online based on merely five observations for reconstructing the full pressure field.A pressure reconstruction with a relative error of 6.1%and a mean square error of 0.003 was achieved within the prescribed condition *** computational cost was just2 ms for each reconstruction run,significantly faster than the 20 min required by the classical reconstruction ensemble transform Kalman *** also showed that the method maintains almost the same accuracy amidst 1.5%measurement *** practical examples,shock waves and the change of lift coefficient were analyzed using the proposed method,providing remarkable evidence for the capability of the method in supporting stall *** validate the method’s effectiveness and explore its potential in real-time and accurate monitoring of an aircraft.

关键词： aerodynamic force sparse observation neural networks pressure field reconstruction

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Effects of axial gap and nozzle distribution on aerodynamic forces of a supersonic partial-admission turbine

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Chinese Journal of Aeronautics 2017年第6期30卷 1844-1853页

作者： Jinpeng JIANG Jiawen LI Guobiao CAI Jue WANG Qiyan LIN School of Astronautics Beihang University Beijing 100083 China System Engineering Division China Academy of Launch Vehicle Technology Beijing 100076 China Beijing Aerospace Propulsion Institute Beijing 100076 China

The turbine in an LH2/LOX rocket engine is designed as a two-stage supersonic partialadmission turbine. Three-dimensional steady and unsteady simulations were conducted to analyze turbine performance and aerodynamic forces on rotor blades. Different configurations were employed to investigate the effects of the axial gap and nozzle distribution on the predicted performance and aerodynamic forces. Rotor blades experience unsteady aerodynamic forces because of the partial admission. aerodynamic forces show periodicity in the admission region, and are close to zero after leaving the admission region. The unsteady forces in frequency domain indicate that components exist in a wide frequency region, and the admission passing frequency is *** multiples of the rotational frequency which are multiples of the nozzle number in a fulladmission turbine are notable components. Results show that the turbine efficiency decreases as the axial gap between nozzles and the 1 st stage rotor（rotor 1） increases. Fluctuation of the circumferential aerodynamic force on rotor 1 blades decreases with the axial gap increasing. The turbine efficiency decreases as the circumferential spacing between nozzles increases. Fluctuations of the circumferential and axial aerodynamic forces increase as the circumferential spacing increases. As for the non-equidistant nozzle distribution, it produces similar turbine performance and amplitudefrequency characteristics of forces to those of the normal configuration, when the mean spacing is equal to that of the normal case.

关键词： aerodynamic force Axial gap Computational fluid dynam-ics (CFD) Nozzle distribution Partial admission Turbine

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Multi-objective aerodynamic shape optimization of a streamlined high-speed train using Kriging model

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第3期23卷 225-242页

作者： Le ZHANG Zhi-yuan DAI Tian LI Ji-ye ZHANG State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China

With continuous changes to energy-saving requirements,the task of train aerodynamic optimization becomes *** aerodynamic optimization of a high-speed train is carried out assuming the same shape of the head and tail cars,which ignores the combined effect of the two cars on aerodynamic *** streamlined structure of the train has different effects on the aerodynamics of the head and tail ***-depth study of these effects will help engineers improve their shape design *** on the surrogate model method,this paper studies the influence of five shape parameters of the streamlined area on the resistance of the head and tail cars and the lift force of the tail car of CRH380A,and compares the aerodynamic performance of the two optimization *** research results show that the optimization direction for reducing drag of the head car is opposite to that for reducing the drag and lift of the tail car,while the optimization directions for reducing both drag and lift for the tail car alone,are roughly the ***,the same shaped head and tail cars are problematic for improving aerodynamic *** optimization,the head car’s resistance,the tail car’s resistance,and the tail car’s lift of the train with the same shape of head and tail cars are reduced by 1.7%,0.5%,and 3.5%,*** train with different shapes had values decreased by 5.6%,1.4%,and 7.5%,*** optimization effect of the latter is more than twice that of the former.

关键词： High-speed train aerodynamic force Optimization Surrogate model Streamlined area

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Study of aerodynamic and inertial forces of a experimental and numerical methods

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Chinese Journal of Aeronautics 2022年第6期35卷 63-76页

作者： Xiaowu YANG Bifeng SONG Wenqing YANG Dong XUE Yang PEI Xinyu LANG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China National Key Laboratory of Science and Technology on aerodynamic Design and Research Northwestern Polytechnical UniversityXi’an 710072China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China

The force-generation mechanism of a dovelike flapping-wing micro air vehicle was studied by numerical simulation and *** obtain the real deformation pattern of the flapping wing,the digital image correlation technology was used to measure the dynamic deformation of the *** dynamic deformation data were subsequently interpolated and embedded into the CFD solver to account for the aeroelastic *** dynamic deformation data were further used to calculate the inertial forces by regarding the wing as a system of particles to take into account the wing *** temporal variation of the forces produced by the flapping wing was measured by a miniature load *** numerical results provide more flow details of the unsteady aerodynamics of the flapping wing in terms of vortex formation and *** calculated results of the inertial forces are analyzed and compared with the CFD results which represent the aerodynamic *** addition,the total forces,i.e.,the sum of the CFD result and inertial result,are compared with the experimental results,and an overall good agreement is obtained.

关键词： aerodynamic force CFD Digital image correlation Flapping-wing micro air vehicles Inertial force

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Effects of 3-D deformation of elastic wings on aerodynamic performance of an aircraft model

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Science China(Technological Sciences) 2023年第5期66卷 1365-1377页

作者： GUO QinFeng FENG SiYuan WANG JinJun Fluid Mechanics Key Laboratory of Education Ministry Beijing University of Aeronautics and AstronauticsBeijing 100191China

The wind tunnel experiment is conducted on a simplified aircraft model with rigid and two kinds of elastic wings to investigate the effect of wing 3-D deformation on the aircraft aerodynamic *** results show that two elastic wings exhibit different aerodynamic performances,which are classified as the lift-enhancement wing and the drag-reduction *** the liftenhancement wing,the stall angle is delayed from 8°to 15°with a corresponding lift increment of 64.3%compared with the rigid *** is shown that the lift enhancement of the aircraft model is accompanied by the torsional vibration mode of the wing,which results in the significant improvement of wing *** the drag-reduction wing,the aerodynamic performance is dominated by the time-averaged deformation,which couples the bending and *** wing twist reduces the effective angle of attack,as well as the frontal area,and contributes to the decreased wake ***,the bent wings function as barriers to the cross flow resulting in a reduction of lift-induced *** a result,the drag coefficient is reduced from 0.115 to 0.098 with a reduction of 14.8%at angle of attack of 12°.

关键词： wind tunnel experiment elastic wing aerodynamic force wing deformation wake flow field

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