Dynamic Wind Response of Twin Tall Buildings Linked by a Skybridge

Lim Juntack 한국풍공학회 2019 한국풍공학회지 Vol.23 No.3

스카이브릿지로 연결된 쌍둥이 초고층건물은 두 가지 종류의 연동성-스카이브릿지로 인해 두 건물의 거동 동기화를 유발하는 구조적 연동성과 작용하는 풍하중의 높은 상관성으로 인한 공기역학적 연동성-이 나타난다. 단일 건물에 널리 적용되는 전통적인 풍력실험 방법으로는 이런 연동성과 영향들을 완벽히 파악할 수 없는 실정이다. 그런 이유로 보다 발전된 동적 풍응답 해석법이 요구된다. 이 논문은 스카이브릿지로 연결된 쌍둥이 건물에서 발생하는 구조적 및 공기역학적인 연동성을 다룰 수 있는 듀얼 풍력실험 방법을 자세히 다루었다. 제안된 방법을 적용하여 건물의 풍가속도에 대한 구조적 및 공기역학적 연동성의 영향을 평가하였다. 건물의 풍응답 산정에 스펙트럼 적분법과 백색 소음 근사법을 적용하였다. 실험 및 결과로 볼 때 동적 풍응답에 상당한 영향이 있음을 확인할 수 있었다. 여러 개의 풍력 측정센서를 활용한 풍력실험 기술은 구조적으로 연결된 초고층건물에 대한 풍동실험에 유용하게 사용될 것으로 판단된다. Twin tall buildings linked a skybridge involve two types of coupling: the structural coupling, developed by a skybridge, synchronizing the motions of vibration of the two building and the aerodynamic coupling resulting from high cross-correlations of the components of wind loading. From the wind engineering viewpoint, an understanding of these couplings and their impacts on the wind-induced response of the buildings can not be fully accounted for when using the traditional high-frequency force balance (HFFB) approach tailored for single tall buildings, and thus this requires utilization of advanced dynamic wind response analysis. This paper addresses the dual- HFFB approach accounting for correlated wind loading and structurally coupled response of twin buildings with a skybridge. The proposed method is subsequently used to investigate the effects of aerodynamic and structural couplings on the rooftop accelerations of the buildings. Spectral integration and white-noise approximation approaches are employed in calculations of the building responses. The presented results show significant effects of both the aerodynamic and structural couplings. The multi-HFFB technique would be useful for wind tunnel study of structurally connected tall buildings.

고속 비행체 공기흡입관 설계를 위한 저정밀도 공력-열-구조 연계해석

류동국,전형근,황인섭,김상호,이재우,김창완 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11

초음속 비행체의 경우 비행영역의 특성상 공력에 의한 열하중 및 압력하중이 크며, 이로 인해 비행체의 구조 설계시 공력하중 및 열 하중을 고려하여야 한다. 그러나 초기 설계 단계에서 전산유체해석을 활용하여 설계를 수행하기에는 계산 시간 등의 이유로 여러 가지 난점이 있다. 그러므로, 이 논문에서는 충격파 방정식 및 팽창파 방정식을 이용하는 저정밀도 해석도구를 개발하여 초음속 비행체의 공기 흡입관 형상을 바탕으로 저정밀도 공력해석을 수행하였다. 이후 공력해석 결과를 이용, 열해석을 통하여 비행체 표면의 열하중을 도출하였으며, 공력해석 및 열해석에서 도출한 값을 이용하여 공력-열-구조 연계해석을 수행하여, 주어진 비행 조건에서 비행체에 가해지는 하중을 도출하였다. In case of supersonic aircraft, there have strong thermal and pressure load because of flight condition, so these factors should be considered when designing the structure configuration. However, it is hard to run computational fluid dynamics(CFD) at conceptual design phase on account of some reasons, such as computing power and time. In this research, we developed low fidelity analysis tool using shockwave & Prandtl-Mayer expansion wave equation for doing low fidelity aerodynamic analysis on the basis of air-intake configuration. After that, using aerodynamic result, derived the thermal load. Then using aerodynamic & thermal analysis result, we conducted aerodynamic-thermal-structure coupled analysis to calculate load applied to aircraft.

Dynamic Wind Response of Twin Tall Buildings Linked by a Skybridge

임준택 한국풍공학회 2019 한국풍공학회지 Vol.23 No.3

Twin tall buildings linked a skybridge involve two types of coupling: the structural coupling, developed by a skybridge, synchronizing the motions of vibration of the two building and the aerodynamic coupling resulting from high cross-correlations of the components of wind loading. From the wind engineering viewpoint, an understanding of these couplings and their impacts on the wind-induced response of the buildings can not be fully accounted for when using the traditional high-frequency force balance (HFFB) approach tailored for single tall buildings, and thus this requires utilization of advanced dynamic wind response analysis. This paper addresses the dual-HFFB approach accounting for correlated wind loading and structurally coupled response of twin buildings with a skybridge. The proposed method is subsequently used to investigate the effects of aerodynamic and structural couplings on the rooftop accelerations of the buildings. Spectral integration and white-noise approximation approaches are employed in calculations of the building responses. The presented results show significant effects of both the aerodynamic and structural couplings. The multi-HFFB technique would be useful for wind tunnel study of structurally connected tall buildings.

저속 비행 3차원 유연날개 정적 공력-구조 연계해석

한형석,박주희,이나원,한철희,Han, Hyungseok,Park, Joohee,Lee, Nawon,Han, Cheolheui 항공우주시스템공학회 2015 항공우주시스템공학회지 Vol.9 No.2

태양광 고고도 장기체공형 무인기나 인간동력 항공기 등에 사용되는 높은 종횡비를 가진 유연날개는 공력 및 구조 상호작용으로 인하여, 구조적 비선형 처짐 및 양력감소 등의 문제가 발생한다. 본 연구에서는 저속 비행하는 높은 종횡비를 가진 날개의 단방향 공력-구조 연계해석을 수행하였다. XFOIL을 사용하여 공력천이현상을 포함한 저 레이놀즈수 익형 공력특성 자료 확보를 기반으로 3차원 양력선 이론을 사용하여 공력해석 연구를 수행했다. 구조해석은 상용소프트웨어 ANSYS를 사용하여 구조변형이나 응력해석 연구를 수행했다. 단방향 공력-구조 연계해석 결과를 바탕으로 인간동력 항공기 주 날개의 형상설계 연구를 수행했다.

헬리콥터 전기체의 제자리비행 선회 시뮬레이션

박세환,추연복,서동호,이덕주 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.11

Yawing 조종력 상실(Loss of yaw control effectiveness)은 헬리콥터 사고와 관련하여 가장 우려되는 요인 중 하나이다. 헬리콥터 사고율을 줄이기 위해서는 헬리콥터 yawing 움직임 및 꼬리로터 조종력 상실을 이해해야 한다. 제자리비행 선회 시뮬레이션은 이와 관련한 예비연구로서 적절한 주제라고 할 수 있다. 본 논문에서는, 공력-비행동역학 연계해석자를 이용하여 제자리비행 선회시 yawing 각속도와 heading 각도를 예측하였고, 예측 결과를 비행시험 데이터와 비교 및 검증하였다. 제자리비행시 꼬리로터의 콜렉티브 피치 트림값은 해석적 및 수치적 트림과정을 통해 구해졌으며, 제자리비행 선회시에는 트림값으로부터의 콜렉티브 피치 차이값이 입력 조건으로 주어졌다. Loss of yaw control effectiveness has been a primary concern regarding helicopter accidents. It is necessary to understand helicopter’s yawing motion and tail rotor control effectiveness to reduce the related helicopter accident rate. The hovering turn flight simulation is considered as an appropriate topic of the corresponding preliminary research. In the present paper, the coupled aerodynamics-flight dynamics solver was used to predict the yawing rate and heading angle during the hover turn flight, and the result was compared with the flight test data. The difference of tail rotor’s collective pitch angle from the trimmed angle was given as an input for hover turn while the trimmed tail rotor collective pitch angle for hover flight was calculated by analytic and numerical trim process.

Integrated Rocket Simulation of Internal and External Flow Dynamics in an e-Science Environment

고순흠,Sangho Han,김진호,김종암,문종배,Kum Won Cho,Yoonhee Kim 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.5

The internal and external flowfield variation of a launch vehicle has been simulated in an e-Science environment. To analyze the igniting process of a solid-rocket propellant, a fluid-structure interaction code has been developed using an ALE (arbitrary Lagrangian Eulerian) kinematical description and a staggered fluid-structure interaction algorithm. Also, unsteady motion of a detached rocket booster has been predicted by using an external flow analysis with an aerodynamic-dynamic coupled solver. A Korean e-Science environment designed for aerospace engineering, e-AIRS [15], supplies a user-friendly interface for such individual work and it can advance to an integrated rocket simulation of internal combustion and external flow variation by controlling the execution and data flow of two flow solvers. As a consequence, e-Science facilitates multi-disciplinary collaborative research, and makes individual work more convenient.

Aerodynamic loads and aeroelastic responses of large wind turbine tower-blade coupled structure in yaw condition

S.T. Ke,T.G. Wang,Y.J. Ge,Y. Tamura 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.6

An effective method to calculate aerodynamic loads and aeroelastic responses of large wind turbine tower-blade coupled structures in yaw condition is proposed. By a case study on a 5 MW large wind turbine, the finite element model of the wind turbine tower-blade coupled structure is established to obtain the modal information. The harmonic superposition method and modified blade-element momentum theory are used to calculate aerodynamic loads in yaw condition, in which the wind shear, tower shadow, tower-blade modal and aerodynamic interactions, and rotational effects are fully taken into account. The mode superposition method is used to calculate kinetic equation of wind turbine tower-blade coupled structure in time domain. The induced velocity and dynamic loads are updated through iterative loop, and the aeroelastic responses of large wind turbine tower-blade coupled system are then obtained. For completeness, the yaw effect and aeroelastic effect on aerodynamic loads and wind-induced responses are discussed in detail based on the calculating results.

Wind-sand coupling movement induced by strong typhoon and its influences on aerodynamic force distribution of the wind turbine

Shi-Tang Ke,Yifan Dong,Rongkuan Zhu,Tongguang Wang 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.4

The strong turbulence characteristic of typhoon not only will significantly change flow field characteristics surrounding the large-scale wind turbine and aerodynamic force distribution on surface, but also may cause morphological evolution of coast dune and thereby form sand storms. A 5MW horizontal-axis wind turbine in a wind power plant of southeastern coastal areas in China was chosen to investigate the distribution law of additional loads caused by wind-sand coupling movement of coast dune at landing of strong typhoons. Firstly, a mesoscale Weather Research and Forecasting (WRF) mode was introduced in for high spatial resolution simulation of typhoon “Megi”. Wind speed profile on the boundary layer of typhoon was gained through fitting based on nonlinear least squares and then it was integrated into the user-defined function (UDF) as an entry condition of small-scaled CFD numerical simulation. On this basis, a synchronous iterative modeling of wind field and sand particle combination was carried out by using a continuous phase and discrete phase. Influencing laws of typhoon and normal wind on moving characteristics of sand particles, equivalent pressure distribution mode of structural surface and characteristics of lift resistance coefficient were compared. Results demonstrated that: Compared with normal wind, mesoscale typhoon intensifies the 3D aerodynamic distribution mode on structural surface of wind turbine significantly. Different from wind loads, sand loads mainly impact on 30° ranges at two sides of the lower windward region on the tower. The ratio between sand loads and wind load reaches 3.937% and the maximum sand pressure coefficient is 0.09. The coupling impact effect of strong typhoon and large sand particles is more significant, in which the resistance coefficient of tower is increased by 9.80% to the maximum extent. The maximum resistance coefficient in typhoon field is 13.79% higher than that in the normal wind field.

Research on aerodynamic force and structural response of SLCT under wind-rain two-way coupling environment

Shitang Ke,Wenlin Yu,Yaojun Ge 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.4

Wind-resistant design of existing cooling tower structures overlooks the impacts of rainfall. However, rainstorm will influence aerodynamic force on the tower surface directly. Under this circumstance, the structural response of the super-large cooling tower (SLCT) will become more complicated, and then the stability and safety of SLCT will receive significant impact. In this paper, surrounding wind fields of the world highest (210 m) cooling tower in Northwest China under three typical wind velocities were simulated based on the wind-rain two-way coupling algorithm. Next, wind-rain coupling synchronous iteration calculations were conducted under 9 different wind speed-rainfall intensity combinations by adding the discrete phase model (DPM). On this basis, the influencing laws of different wind speed-rainfall intensity combinations on wind-driving rain, adhesive force of rain drops and rain pressure coefficients were discussed. The acting mechanisms of speed line, turbulence energy strength as well as running speed and trajectory of rain drops on structural surface in the wind-rain coupling field were disclosed. Moreover, the fitting formula of wind-rain coupling equivalent pressure coefficient of the cooling tower was proposed. A systematic contrast analysis on its 3D distribution pattern was carried out. Finally, coupling model of SLCT under different working conditions was constructed by combining the finite element method. Structural response, buckling stability and local stability of SLCT under different wind velocities and wind speed-rainfall intensity combinations were compared and analyzed. Major research conclusions can provide references to determine loads of similar SLCT accurately under extremely complicated working conditions.

Geometric Nonlinear Static Aeroelastic Characteristics Analysis of High-Aspect-Ratio Wing with Large Deformation

Junli Wang,Jinyang Li,Shuai Lei,Zhigui Ren,Yayin He 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.2

To explore the geometric nonlinearity of high-aspect-ratio wing due to large deformation, the aerodynamics were solved by Navier–Stokes governing equation based on the loose coupling method of CFD/CSD. Considering the large displacement stiffness matrix of wing structure, the Newton–Raphson method is used to solve the nonlinear elastic deformation of the structure. A geometrically nonlinear static aeroelastic coupling calculation program is developed. During the coupling process, an improved elastic approximation method was used to update the aerodynamic mesh, and the data exchange on the coupling interface was realized by a fixed-volume interpolation method. The reliability of the proposed method was verified by HIRENASD wing model. Finally, the effects of geometric nonlinear static aeroelasticity on longitudinal aerodynamic characteristics and stability of swept wing with high aspect ratio at different angles of attack are studied using this method. The results show that the lift direction of a high-aspect-ratio wing is significantly deformed under the influence of aerodynamic loads. The effective angle of attack of the wing decreases with the whole deformation, and the degree of decrease increases from the root to the tip. The significant flexural and torsional deformation will change the lift coefficient and drag coefficient of the wing and reduce the margin of the static stability of the wing.