scholarly journals Full-Span Flying Wing Wind Tunnel Test: A Body Freedom Flutter Study

Fluids ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 34
Author(s):  
Pengtao Shi ◽  
Jihai Liu ◽  
Yingsong Gu ◽  
Zhichun Yang ◽  
Pier Marzocca
Keyword(s):  
Wind Tunnel ◽  
Theoretical Analysis ◽  
Mass Balance ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Suspension System ◽  
The Body ◽  
Structural Dynamic ◽  
Flutter Speed ◽  
Theoretical Results

Aiming at the experimental test of the body freedom flutter for modern high aspect ratio flexible flying wing, this paper conducts a body freedom flutter wind tunnel test on a full-span flying wing flutter model. The research content is summarized as follows: (1) The full-span finite element model and aeroelastic model of an unmanned aerial vehicle for body freedom flutter wind tunnel test are established, and the structural dynamics and flutter characteristics of this vehicle are obtained through theoretical analysis. (2) Based on the preliminary theoretical analysis results, the design and manufacturing of this vehicle are completed, and the structural dynamic characteristics of the vehicle are identified through ground vibration test. Finally, the theoretical analysis model is updated and the corresponding flutter characteristics are obtained. (3) A novel quasi-free flying suspension system capable of releasing pitch, plunge and yaw degrees of freedom is designed and implemented in the wind tunnel flutter test. The influence of the nose mass balance on the flutter results is explored. The study shows that: (1) The test vehicle can exhibit body freedom flutter at low airspeeds, and the obtained flutter speed and damping characteristics are favorable for conducting the body freedom flutter wind tunnel test. (2) The designed suspension system can effectively release the degrees of freedom of pitch, plunge, and yaw. The flutter speed measured in the wind tunnel test is 9.72 m/s, and the flutter frequency is 2.18 Hz, which agree well with the theoretical results (with flutter speed of 9.49 m/s and flutter frequency of 2.03 Hz). (3) With the increasing of the mass balance at the nose, critical speed of body freedom flutter rises up and the flutter frequency gradually decreases, which also agree well with corresponding theoretical results.

scholarly journals Galloping Stability and Wind Tunnel Test of Iced Quad Bundled Conductors considering Wake Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xiaohui Liu ◽  
Ming Zou ◽  
Chuan Wu ◽  
Mengqi Cai ◽  
Guangyun Min ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Transmission Lines ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Aerodynamic Coefficients ◽  
Wake Effect ◽  
Aerodynamic Coefficient ◽  
Set Up ◽  
The Stability ◽  
Three Degrees Of Freedom

A new quad bundle conductor galloping model considering wake effect is proposed to solve the problem of different aerodynamic coefficients of each subconductor of iced quad bundle conductor. Based on the quasistatic theory, a new 3-DOF (three degrees of freedom) galloping model of iced quad bundle conductors is established, which can accurately reflect the energy transfer and galloping of quad bundle conductor in three directions. After a series of formula derivations, the conductor stability judgment formula is obtained. In the wind tunnel test, according to the actual engineering situation, different variables are set up to accurately simulate the galloping of iced quad bundle conductor under the wind, and the aerodynamic coefficient is obtained. Finally, according to the stability judgment formula of this paper, calculate the critical wind speed of conductor galloping through programming. The dates of wind tunnel test and calculation in this paper can be used in the antigalloping design of transmission lines.

scholarly journals Hypersonic Free Flight Investigation on Rudder Reflection of Aircraft

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 542
Author(s):  
Fei Xue ◽  
Yuchao Wang ◽  
Zenghui Jiang ◽  
Yinong Yang
Keyword(s):  
Wind Tunnel ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Model Matching ◽  
Free Flight ◽  
Control Effect ◽  
Time Curve ◽  
Hypersonic Wind Tunnel ◽  
Before And After ◽  
Ejection Mechanism

In order to study the control effect of the rudder surface of the hypersonic vehicle and the coupling dynamic characteristics of the rudder surface deflection and the flight attitude, a technical platform for the deflection and motion coupling of the aircraft rudder surface was designed. The platform ejection mechanism can launch the model into the wind tunnel flow field according to the preset attitude, and model can free flight without support interference. The innovative design of the model internal rudder partial system can guarantee the model to deflect the rudder surface in the free flight process, simulate the real steering process of the aircraft. By changing spring with different springs, the speed of the rudder surface can be changed. The dual optical path and image acquisition technology can capture the motion picture before and after the deflection of the rudder surface from two angles. After the image is matched by model matching, the six degrees of freedom parameter of the model can be changed with the time curve before and after the deflection of the rudder surface, and the area of the six freedom degree curve of the different state model is compared. In other words, the specific influence of dynamic rudder rotation on the motion of the model is known. The wind tunnel test of the model in the hypersonic wind tunnel of the 500 mm is carried out using this platform. The test results are highly repeatable, and the test platform technology is mature and reliable.

scholarly journals Desain dan Eksperimen Uji Getaran di Tanah dari Model Separuh Sayap Pesawat N219

WARTA ARDHIA ◽  
2017 ◽  
Vol 42 (3) ◽  
pp. 123
Author(s):  
Sayuti Syamsuar ◽  
Leonardo Gunawan ◽  
Martina Widiramdhani ◽  
Nina Kartika
Keyword(s):  
Wind Tunnel ◽  
Critical Phenomenon ◽  
Damping Ratio ◽  
Wind Tunnel Test ◽  
Ground Vibration ◽  
Parameter Analysis ◽  
Vibration Test ◽  
Software Analysis ◽  
Flutter Speed ◽  
Wing Model

Fenomena flutter merupakan salah satu fenomena yang kritis dan dapat membahayakan pesawat. Ketika, pesawat terbang semakin cepat dan mencapai kecepatan flutter, maka akan terjadi ketidakstabilan struktur. Oleh sebab itu, untuk menjamin keselamatan Pilot saat uji terbang, perlu dilakukan analisis awal pada kecepatan flutter. Uji terowongan angin selalu dilakukan untuk memvalidasi hasil dari analisis numerikal. Penelitian ini meliputi analisis program NASTRAN pada model separuh sayap pesawat N219 saat uji getaran di tanah. Prediksi kecepatan flutter secara analisis hampir sama dengan hasil uji terowongan angin. Parameter modus struktur yang ditemukan, seperti frekuensi natural, modus getar dan rasio redaman, dapat digunakan untuk analisis parameter flutter sebagai metoda analisis baru. [The Design and Experiment of Ground Vibration Test of N219 Aircraft Half Wing Model] Flutter phenomena is a critical phenomenon that can be dangerous for aircraft. When an aircraft fly faster until reach flutter speed, the structure will become unstable. Therefore, it is important to conduct preliminary analysis of flutter speed to ensure the safety of Pilot. Wind tunnel test is necessary to be conducted to validate numerical analysis results. This research consist of NASTRAN software analysis of half wing model of N219 aircraft for ground vibration test. The prediction of flutter speed which is obtained from software analysis is similar with the wind tunnel test result. It is found that the modus parameter of structure like natural frequency, modus of vibration and damping ratio can be used on the parameter analysis as a new analysis method.

The Stability Analysis of the Driving Rod of the Wind Tunnel Test Model Based on Workbench

2015 ◽  
Vol 799-800 ◽  
pp. 538-542
Author(s):  
Zi Yan Shao ◽  
Wen Jia Chen ◽  
Yong Jin Hu ◽  
Guan Jian Li
Keyword(s):  
Wind Tunnel ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Future Research ◽  
Response Analysis ◽  
Test Model ◽  
Main Research ◽  
Theoretical Support ◽  
Harmonic Response Analysis ◽  
The Stability

The ANSYS Workbench is used in this paper to analyse a kind of wind tunnel test model support platform with 5 degrees of freedom. The driving rod of the pitch motion is chosen as the main research project. By using static structural analysis, modal analysis and harmonic response analysis, a detailed analysis is made on the stress, deformation and frequency of the driving rod, and provides theoretical support for the future research on the stability of the institution.

Wind Tunnel Testing of Composite Wing Flutter Speed due to Control Surface Excitation

2013 ◽  
Vol 315 ◽  
pp. 359-363 ◽  
Author(s):  
Mahzan Muhammad Iyas ◽  
Muhamad Sallehuddin ◽  
Mat Ali Mohamed Sukri ◽  
Mansor Mohd Shuhaimi
Keyword(s):  
Wind Tunnel ◽  
Dynamic Instability ◽  
Wind Tunnel Test ◽  
Control Surface ◽  
Wind Tunnel Testing ◽  
Structural Stiffness ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Surface Excitation ◽  
Composite Wing

Flutter is a dynamic instability problem represents the interaction among aerodynamic forces and structural stiffness during flight. The study was conducted to investigate whether deflecting the control surface will affect the flutter speed and the flutter frequency. A wind tunnel test was performed using a flat plate wing made of composite material. It was found that by deflecting the control surface at 45°, the wing entered flutter state at wind speed of 28.1 m/s instead of 33.4 m/s. In addition, the flutter frequency also reduced from 224.52 Hz to 198.96 Hz. It was concluded that by deflecting the control surface, the wing experienced flutter at lower speed and frequency.

Composite Wing Flutter Speed and Frequency due to Variable Control Surface Deflection in Low Speed Wind Tunnel

2013 ◽  
Vol 390 ◽  
pp. 3-7
Author(s):  
Muhammad Iyas Mahzan ◽  
Sallehuddin Muhamad ◽  
Sa’ardin Abdul Aziz ◽  
Mohamed Sukri Mat Ali
Keyword(s):  
Wind Tunnel ◽  
Dynamic Instability ◽  
Wind Tunnel Test ◽  
Control Surface ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Surface Deflection ◽  
Relationship Of ◽  
Low Speed Wind Tunnel ◽  
The Relationship

Flutter is a dynamic instability problem represents the interaction among structural, aerodynamic, elastic and inertial forces and occurred when the energy is continuously transformed by the surrounding fluids to a flying structure in the form of kinetic energy. The study was conducted to investigate the relationship of the control surface deflection angle to the flutter speed and the flutter frequency. A wind tunnel test was performed using a flat plate wing made of composite material. It was found that by deflecting the control surface up to 45°, the flutter speed reduced almost linearly from 35.6 m/s to 22.7 m/s. The flutter frequency greatly reduced from 48 Hz without the control surface deflected to 34 Hz with the control surface deflected at 15°. After 15° deflection up to 45°, the flutter frequency reduced almost linearly.

Investigation of Wind-Resistance Reinforcement for a Sculpture

2011 ◽  
Vol 243-249 ◽  
pp. 5080-5084
Author(s):  
Yu Chun Li ◽  
Ke Feng Sun ◽  
Zhuang Wang ◽  
Zhi Yong Zhou
Keyword(s):  
Wind Tunnel ◽  
Theoretical Analysis ◽  
Structural Modification ◽  
Water Drop ◽  
Wind Tunnel Test ◽  
Special Structure ◽  
Wind Resistance ◽  
Existing Structures ◽  
Original Sculpture ◽  
Structural Engineers

The sculpture is a special structure. The wind-resistance issue of such a special structure is easily ignored by structural engineers. In this paper, the wind-resistance problem of a real sculpture ‘water-drop’ is investigated by wind tunnel test and theoretical analysis. The results show the original sculpture structure has severe wind-resistance defects. According to these defects, some reinforcing measures for the structure are put forward and put into execution. After the structural modification, the sculpture ‘water-drop’ has been hit by typhoon two times and now stands without any damage. Finally, a workflow is summarized for the wind-resistance appraisal and reinforcement of the existing structures.

Effect of Suspension and Body Flexibility on Dynamic Behavior of Passenger Cars

2005 ◽  
Author(s):  
M. Durali ◽  
A. Kasaiezadeh ◽  
O. B. Nakhjavani
Keyword(s):  
Degrees Of Freedom ◽  
Safety Margin ◽  
Suspension System ◽  
The Body ◽  
Vehicle Dynamic ◽  
Vehicle Model ◽  
Passenger Cars ◽  
Element Analysis ◽  
Usual Practice ◽  
Vehicle Dynamic Model

The usual practice in vehicle dynamic modeling is to consider the body and suspension components as rigid elements. The question this paper is trying to answer is; how large the errors will be if flexibility of the components are not considered in vehicle dynamic model. The flexible vehicle model made for this study has 300000 elements which are generated using Super-element analysis in MSC/NASTRAN and made usable in MSC/ADAMS environment using Craig-Bampton theorem. The full vehicle model made in ADAMS has 200 degrees of freedom and includes all bushings, mechanism, power train, and suspension system. The model was used in simulating ride and handling behavior of the vehicle in several virtual road conditions. The results show that although a rigid car model will result errors in handling behavior, but these errors are all towards increased safety margin when used in design process. On the contrary using a rigid model in vibration and ride analyses of the car tend to suppress the vibrations, and a flexible model markedly affect the vibration modes of the body and the suspension system components

The prospect ahead

1971 ◽  
Vol 269 (1199) ◽  
pp. 545-554
Keyword(s):  
Wind Tunnel ◽  
Bluff Body ◽  
Wind Tunnel Test ◽  
Accurate Solution ◽  
The Body ◽  
Wind Tunnels ◽  
Dual Approach ◽  
Architectural Models ◽  
Wind Pressures ◽  
Large Wind

The exacting nature of the problems of architectural aerodynamics and some of the difficulties of obtaining an accurate solution to them from laboratory experiments are described. Among the latter is the uncertainty associated with scale effect, which requires for its resolution more observations of the flow patterns about, and measurements of the wind pressures on, actual buildings and structures. The possibility of constructing a special wind tunnel is also mentioned. A dual approach to aerodynamic research is advocated: such that work in large wind tunnels, with complicated architectural models and elaborate simulation of the atmospheric wind, proceed in parallel with investigations on a simpler scale. The latter should concentrate on fundamental aspects of bluff body flows; particularly their unsteady components, their interaction with shear and turbulence in the approaching stream, as well as their dependence on the shape of the body, on any vibration it may exhibit and on its interference with neighbouring bodies. Examples are given of some of the subtle and surprising features of such flows. The architect is invited to specify the accuracy he requires of aerodynamic data and is urged to regard the wind-tunnel test, with full representation of the atmospheric wind and its turbulent structure, as a routine element in the design process.

Analysis Based Optimization of Human Powered Vehicle Body

2015 ◽  
Vol 760 ◽  
pp. 123-128
Author(s):  
Dan Maniu Dușe ◽  
Alexandru Radu Ari
Keyword(s):  
Fluid Dynamics ◽  
Main Product ◽  
Urban Transportation ◽  
Wind Tunnel Test ◽  
The Body ◽  
Vehicle Body ◽  
Automotive Market ◽  
Air Resistance ◽  
Human Powered ◽  
Theoretical Results

The human powered vehicle market is not only a larger market per unit than the automotive market, but it is one in growth. The main product of this market is the classical bicycle, which is familiar around the globe, but mainly in the urban environment. The bicycle, which in this paper will be considered a human powered vehicle, is slowly gaining ground in the field of urban transportation solutions. This paper analyzes the possibility of optimizing the body of a human powered vehicle recumbent tricycle through continuous fluid dynamics. The vehicle is already designed and built, and is fully functional. The body of the vehicle comes as a necessity to give the operator protection from the elements, but the main reason is, to give the vehicle less air resistance. This would be a great benefit to the operator and the perceived comfort. Usually the aerodynamics analysis comprise of a wind tunnel test that confirms the theoretical results. This paper shows the evolution of the body of a human powered vehicle as it is optimized after identifying the turbulent areas in its shapes. After optimization, a body is obtained which will be proposed for implementing over the built vehicle.

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