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.

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.

Analysis of wind attack angle increments in wind tunnel tests for the aerodynamic coefficients of iced hangers

2019 ◽  
Vol 23 (4) ◽  
pp. 603-613 ◽  
Author(s):  
Pan Guo ◽  
Shengli Li ◽  
Dongwei Wang
Keyword(s):  
Quantitative Analysis ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Attack Angle ◽  
Calculation Error ◽  
Aerodynamic Coefficients ◽  
Aerodynamic Coefficient ◽  
Cable Structures ◽  
Accuracy Requirement ◽  
Preliminary Study

Wind attack angle increments are important inputs for the accurate and efficient wind tunnel test in analyzing the aerodynamic coefficients and Den Hartog galloping coefficients of iced cable structures. This research aims to investigate the interference of wind attack angle increments on the aerodynamic coefficients and Den Hartog galloping stability of iced hangers based on the aerodynamic coefficient theory and Den Hartog galloping theory, and by adopting the method of wind tunnel test. The analysis shows that considerable calculation error will be caused when directly using the conventional method during the processing and analysis of Den Hartog galloping for iced cable structures. The curve fitting of the aerodynamic coefficients of iced hangers in which their characteristics are better presented, for example, smooth-going characteristic, antisymmetric characteristics for lift coefficients, and symmetric characteristics for drag coefficients, can satisfy the accuracy requirement of the derivation of lift coefficients and can then be used to examine the Den Hartog galloping coefficients of iced hangers accurately. In cases where the wind attack angle increments are more than 3°, the wind attack angle that corresponds to the minimum value of the Den Hartog coefficients shows an offset. Meanwhile, distortions occur when determining the range of wind attack angles of Den Hartog galloping, and thus quantitative analysis cannot be conducted. These cases are only applicable to a preliminary study. The precision of the Den Hartog coefficients, which is solved in cases where the wind attack angle increments are not more than 3°, can meet the requirements for the Den Hartog galloping analysis. Results of this study can provide a reference for research on the galloping of iced hangers using the wind tunnel test.

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 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.

Galloping response of sector-shape iced eight bundle conductors

2020 ◽  
Vol 47 (10) ◽  
pp. 1201-1213
Author(s):  
Meng-qi Cai ◽  
Lin-shu Zhou ◽  
Qian Xu ◽  
Xiao-hui Yang ◽  
Xiao-hui Liu
Keyword(s):  
Transmission Lines ◽  
Theoretical Basis ◽  
Wind Tunnel Test ◽  
Dynamic Responses ◽  
Test Results ◽  
The Finite Element Method ◽  
Aerodynamic Coefficients ◽  
Aerodynamic Loads ◽  
Natural Modes ◽  
Wind Velocities

Wind tunnel test results of the aerodynamic coefficients of sector-shape iced eight bundle conductors varying with wind attack angles are presented. Then, by means of the user-defined cable elements, the aerodynamic loads are applied on the cable elements of each sub-conductor through the finite element method (FEM). In addition, the galloping responses of sector-shape iced eight bundle conductors are discussed. Finally, galloping responses, including dynamic responses (natural modes and frequencies), galloping orbits, and amplitudes of typical sector-shape iced eight bundle conductor transmission lines in the cases of different span lengths, wind velocities, and angles of wind attack are studied, respectively. These results provide useful references for a theoretical basis for the study of galloping and the technique of anti-galloping in cold regions.

scholarly journals Remote and Feedback Control of the Flap Angle in a Wind Tunnel Test Model by Optical Measurement

Aerospace ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 11
Author(s):  
Kazuhisa Chiba ◽  
Tatsuro Komatsu ◽  
Hiroyuki Kato ◽  
Kazuyuki Nakakita
Keyword(s):  
Feedback Control ◽  
Wind Tunnel ◽  
Optical Measurement ◽  
Wind Tunnel Test ◽  
Measurement Technology ◽  
Test Model ◽  
Measurement Equipment ◽  
Feedback Control System ◽  
Aerodynamic Coefficients ◽  
Japan Aerospace Exploration Agency

We have developed a remote and precise feedback control system using optical measurement technology to alter the angle of a flap, which is part of a wind tunnel test model, automatically and to earn the aerodynamic data efficiently. To rectify the wasteful circumstance that Japan Aerospace Exploration Agency (JAXA)’s low-turbulence wind tunnel stops ventilation every time to switch model configurations, we repaired hardware for remote operation and generated software for feedback control. As a result, we have accomplished a system that dramatically advances the efficiency of wind tunnel tests. Moreover, the system was able to consider the deformation of the model through optical measurement; the system controlled flap angles with errors less than the minimum resolution of optical measurement equipment. Consequently, we successfully grasped the nonlinearity of three aerodynamic coefficients C L , C D , and C M p that was impossible so far.

Analysis of Vehicle Dynamic Equilibrium Points with 3-DOF Based on Genetic Algorithm

2014 ◽  
Vol 608-609 ◽  
pp. 721-725
Author(s):  
Rong Li ◽  
Wei Min Li
Keyword(s):  
Genetic Algorithm ◽  
Vehicle Dynamics ◽  
Optimization Design ◽  
Degrees Of Freedom ◽  
Dynamic Equilibrium ◽  
Equilibrium Points ◽  
Vehicle Handling ◽  
Dynamic Modification ◽  
The Stability ◽  
Three Degrees Of Freedom

To further study the stability of vehicle dynamics, a vehicle handling stability’s nonlinear model (including longitudinal, lateral and yaw movement three degrees of freedom) was established. Genetic algorithm was proposed for the vehicle dynamics system’s equilibrium points with 3-DOF. This algorithm solves the problem that cannot be solved through the traditional analytic algorithms and numerical methods. Comparing with the existing research results, the feasibility of solving the equilibrium point by the genetic algorithm is verified. It provides the theoretical foundation for dynamic modification and optimization design of powertrain.

Study on the Aerodynamic Characteristics and Galloping Instability of Conductors Covered with Sector-Shaped Ice by a Wind Tunnel Test

2020 ◽  
Vol 20 (06) ◽  
pp. 2040016
Author(s):  
Jia-Xiang Li ◽  
Jian Sun ◽  
Ye Ma ◽  
Shu-Hong Wang ◽  
Xing Fu
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Ice Thickness ◽  
Shape Parameters ◽  
Aerodynamic Coefficient ◽  
Wind Tunnel Tests ◽  
And Control

Conductors with sector-shaped ice are susceptible to galloping. To prevent and control galloping, it is necessary to study the conductor aerodynamic characteristics. Wind tunnel tests were performed to study the influence of two shape parameters (ice thickness and ice angle) of a conductor with sector-shaped ice on the aerodynamic characteristics considering the roughness of the surface. In addition, the unstable areas for galloping are discussed according to Den Hartog theory and Nigol theory. The results show that with increasing ice thickness, the aerodynamic coefficient curves fluctuate more strongly, and galloping tends to occur; with increasing ice angle, the unstable area becomes larger according to Nigol theory, and the increasing drag coefficient will suppress the unstable areas according to Den Hartog theory. With the increasing two shape parameters, the most affected ranges of the aerodynamic coefficient curves are 150–180∘.

The Aerodynamic Analysis for Iced Four Bundled Transmission Lines with Typical Crescent

2014 ◽  
Vol 8 (1) ◽  
pp. 84-89 ◽  
Author(s):  
Liu Yuejun ◽  
Tang Ai P. ◽  
Liu Ke T. ◽  
Tu Jie W.
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Transmission Lines ◽  
Angle Of Attack ◽  
Wind Tunnel Test ◽  
Simulation Method ◽  
Single Wire ◽  
Wind Tunnel Tests ◽  
Absolute Value ◽  
Aerodynamic Test

Despite the fact that the wind tunnel tests have been carried out on iced transmission lines subjected to wind load, it is not practical to do wind tunnel tests due to its high cost. This paper describes a detailed numerical simulation method that can be used to instead of wind tunnel tests. Based on the galloping mechanism of iced transmission lines, the aerodynamic test was simulated with the typical crescent super-large thickness iced four bundled conductors. One of the results highlighted in this study is that the wind angle of attack had significant influence on the aerodynamics of iced conductors. The Den-Hartog and O.Nigol coefficient were calculated to determine galloping of iced transmission lines, comparing with the reference of wind tunnel test in the Zhejiang university, the range of the wind angle of attack to the bundled conductor which can lead to gallop is larger than single wire, but the absolute value of amplitude is less than the single conductor, split conductor is more likely to gallop than single conductor.

Sign in / Sign up

Export Citation Format

Share Document