Aerodynamic characteristics of tall buildings with porous double-skin façades: State of the art and future perspectives

Petar Škvorc,Hrvoje Kozmar 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.3

Double-skin façades (DSFs) have been increasingly implemented on tall buildings with the goal of improving building energy efficiency, natural ventilation and visual appearance. It is commonly known that wind and earthquakes represent major environmental load types impacting tall buildings. However, at this point, the aerodynamic characteristics of tall buildings equipped with porous façades are still relatively unknown, although it may be expected that the addition of porous outer skins will substantially affect the overall building aerodynamics. The scope of the present study is therefore to carefully review all the relevant parameters playing an important role in the aerodynamic characteristics of tall buildings with porous façades. Fluid flow and turbulence through porous surfaces were reviewed first with an emphasis on the wake and pressure drop behind perforated plates to analyze the phenomena of fundamental fluid mechanics relevant for porous surfaces. As the inflow characteristics predominantly dictate the aerodynamic characteristics of tall buildings, it is therefore useful to review major wind types, including the atmospheric boundary layer (ABL) and strong local winds, which have previously proved to cause major structural damage and failure. In order to be able to properly assess the aerodynamic loading of tall buildings with porous façades, it is necessary to understand the aerodynamic features of tall buildings with smooth surfaces. For this reason, the aerodynamic performance of smooth tall buildings was reviewed, as were the design features commonly adopted to mitigate adverse wind effects. The existing and rather sparse current knowledge of the aerodynamic characteristics of porous DSFs of high- and lowrise buildings is outlined. Based on the provided information, it is clear that a substantial amount of knowledge still needs to be acquired in the future in regard to various aerodynamic features of tall buildings with porous DSFs, particularly concerning wind loads, building energy efficiency, pedestrian wind comfort, renewable energy aspects, air pollution dispersion and dilution. It is expected that the optimal approach to advancing this topic is in combining field measurements, laboratory experiments and computational modeling.

다목적 공력성능향상을 위한 고속열차 전두부 최적형상의 공력 특성 검토

곽민호(Minho Kwak),윤수환(Suhwan Yun),박춘수(Choonsoo Park) 한국철도학회 2016 한국철도학회 학술발표대회논문집 Vol.2016 No.10

고속열차의 공기역학적 성능은 고속 주행에 지배적인 영향을 미치는 것으로 알려져 있다. 고속열차의 공력성능을 향상시키는 고속열차 전두부 형상의 최적설계를 수행하였다. 목적함수는 공기저항 저감, 강풍 안정성 향상, 터널 미기압파 저감으로 하여 2단계로 나누어 진행하였다. KTX 산천 열차의 형상을 바탕으로 공기저항 저감 최적설계를 먼저 수행한 후 강풍 안정성과 터널 미기압파 특성을 향상시키기 위한 다목적 최적설계를 수행하였다. 도출된 최적형상의 공력성능을 검토한 결과, 최적설계로 도출된 공력성능 변화율에 비해 전산수치해석을 통해 도출된 변화율이 비교적 더 크게 나타나는 것을 확인하였다. It is well known that Aerodynamic performances of high speed train take major effects on high speed running. Nose shape optimization of high speed train is done for the improvement of aerodynamic characteristics. The objective functions are the reduction of the aerodynamic drag, the improvement of the side wind stability, and the reduction of the micro-pressure wave at tunnel exits and two stages optimization is progressed. After the optimization for the aerodynamic drag reduction is performed based on KTXSancheon train shape, multi-objective optimization is conducted for the improvement of side wind stability and the micro-pressure wave. As a results of study for aerodynamic characteristics of optimized shapes, change ratios through optimization are lower than those through numerical simulations.

Design and aerodynamic characteristic analysis of unfolding-bending bionic flapping-wing aircraft

Weiping Shao,Hui Zhang,Pengfei Zeng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

A bionic flapping-wing aircraft model is designed in this study to achieve unfolding-bending effect of a bird’s wings during flight, realize active unfolding-bending movement, and demonstrate rapid return characteristic of flapping-bending motion. We use the new method of ADAMS and XFlow cosimulation to analyze its aerodynamic characteristics and investigate effects of flutter frequency, air flow velocity, fuselage angle of attack, and aileron torsion angle on its aerodynamic characteristics. Results showed that increasing the flapping frequency can significantly improve aerodynamic characteristics, increasing the air flow velocity will reduce aerodynamic characteristics, decreasing the fuselage angle of attack will reduce peak lift and increase peak thrust, and increasing the aileron torsion angle will reduce the rising resistance and increase forward thrust. The analysis results showed the excellent aerodynamic characteristics of the model.

ANALYSIS OF AERODYNAMIC CHARACTERISTICS OF REAR WING MOUNTED ON FASTBACK TYPE VEHICLE

김평기,최원석,김규홍 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.5

The performance parameters of automobiles are mainly determined by aerodynamic characteristics such as lift and drag. To maximize vehicle performance, besides optimizing the vehicle itself, various aerodynamic devices can be used. To determine the efficiency of these devices, it is important to study how they affect the vehicle’s aerodynamic characteristics. This paper analyzes the effect of a rear wing on the aerodynamic characteristics of a fastback type vehicle using computational fluid dynamics (CFD). The DrivAer model is used to simulate the vehicle and an S1223 high-lift airfoil is selected as the rear wing. Several CFD cases are considered, in which the rear wing is positioned at different angles of attack and heights and the effects of these parameters on the lift and drag coefficients are studied. The results for low vehicle velocity show that CD and CL are increased by 14 and decreased by 72 counts, respectively. For higher vehicle velocity, CD variation shows not much difference, however, CL variation shows further decrease of 35 counts. Furthermore, the effect of these parameters on the flow characteristics is analyzed, enabling guidelines for the design of efficient rear wings for fastback type vehicles to be suggested.

Effect of Ice accretion on the aerodynamic characteristics of wind turbine blades

Aakhash Sundaresan,S. Arunvinthan,A.A. Pasha,S. Nadaraja Pillai 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.32 No.3

Cold regions with high air density and wind speed attract wind energy producers across the globe exhibiting its potential for wind exploitation. However, exposure of wind turbine blades to such cold conditions bring about devastating impacts like aerodynamic degradation, production loss and blade failures etc. A series of wind tunnel tests were performed to investigate the effect of icing on the aerodynamic properties of wind turbine blades. A baseline clean wing configuration along with four different ice accretion geometries were considered in this study. Aerodynamic force coefficients were obtained from the surface pressure measurements made over the test model using MPS4264 Simultaneous pressure scanner. 3D printed Ice templates featuring different ice geometries based on Icing Research Tunnel data is utilized. Aerodynamic characteristics of both the clean wing configuration and Ice accreted geometries were analysed over a wide range of angles of attack (α) ranging from 0o to 24o with an increment of 3o for three different Reynolds number in the order of 105. Results show a decrease in aerodynamic characteristics of the iced aerofoil when compared against the baseline clean wing configuration. The key flow field features such as point of separation, reattachment and formation of Laminar Separation Bubble (LSB) for different icing geometries and its influence on the aerodynamic characteristics are addressed. Additionally, attempts were made to understand the influence of Reynolds number on the iced-aerofoil aerodynamics.

지면효과익을 지나는 가/감속 유동의 공력특성에 관한 실험적 연구

김태호(Tae-Ho Kim),윤복현(Bok-Hyun Yoon),김희동(Heuy-Dong Kim),?村秀男(Hideo Kashimura) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based upon conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics cannot be satisfactorily resolved due to the wind tunnel blockage effects or string problems to support the test object. To do this, it is necessary to develop a novel simulator appropriate to the WIG aerodynamics. The objective of the present study is to clarify the aerodynamic characteristics of a new developed WIG simulator, which is able to imitate real WIG flow circumstances such as gradually decelerating and accelerating flows.

지면효과익을 지나는 가/감속 유동의 공력특성에 관한 수치해석적 연구

오대근,윤복현,김태호 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-

Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG(Wing In Ground Effect) aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based upon conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics cannot be satisfactorily resolved due to the wind tunnel blockage effects or string problems to support the test object. To overcome the problems, it is necessary to develop a novel simulator appropriate to the WIG aerodynamics. The lift increased in accelerating and decelerating flows without the Reynolds number, and the increase degree appeared remarkably as an dimensionless acceleration coefficient increased.

주거환기용 시로코홴의 내부모터 형상에 따른 공력특성 연구

차경훈(K.H. Cha),김진혁(J.H. Kim),김광용(K.Y. Kim) 한국전산유체공학회 2011 한국전산유체공학회지 Vol.16 No.4

Aerodynamic characteristics depending on the shape of an internal motor in a small-size sirocco fan for residential ventilation have been investigated. For the aerodynamic analyses of the sirocco fan, three-dimensional Reynolds-averaged Navier-Stokes equations are solved with the shear stress transport model for turbulence closure. The flow analyses are performed on hexahedral grids using a finite-volume solver. The validation of the numerical results at steady-state is performed by comparing with experimental data for the pressure and efficiency. In order to investigate the aerodynamic characteristics depending on shape of an internal motor in a sirocco fan, the reference shape is analyzed compared to the case without internal motor. Additionally, two shape parameters, height and width of the internal motor in a sirocco fan, are tested to investigate their effects on the aerodynamic characteristics. The results show that the shape of the internal motor in a sirocco fan is an important factor to improve the aerodynamic performances.

주거환기용 시로코홴의 내부모터 형상에 따른 공력특성 연구

차경훈(K.H. Cha),김진혁(J.H. Kim),김광용(K.Y. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5

Aerodynamic characteristics depending on the shape of an internal motor in a small-size sirocco fan for residential ventilation have been investigated. For the aerodynamic analyses of the sirocco fan, three-dimensional Reynolds-averaged Navier-Stokes equations are solved with the shear stress transport model for turbulence closure. The flow analyses are performed on hexahedral grids using a finite-volume solver. The validation of the numerical results at steady-state is performed by comparing with experimental data for the pressure and efficiency. In order to investigate the aerodynamic characteristics depending on shape of an internal motor in a sirocco fan, the reference shape is analyzed compared to the case without internal motor. Additionally, two shape parameters, height and width of the internal motor in a sirocco fan, are tested to investigate their effects on the aerodynamic characteristics. The results show that the shape of the internal motor in a sirocco fan is an important factor to improve the aerodynamic performances.

A Study on the Aerodynamic Characteristics of a Joined-wing Aircraft with Variation of Wing Configurations

Kidong Kim,Jisung Jang The Society for Aerospace System Engineering 2023 International Journal of Aerospace System Engineer Vol.10 No.1

The present study was attempted to investigate flow interference effects and the aerodynamic characteristics of the front and rear wings of a joined-wing aircraft by changing the configuration variables. The study was performed using a computational fluid dynamics(CFD) tool to demonstrate forward flight and analyze aerodynamic characteristics. A total of 9 configurations were analyzed with variations on the position, height, dihedral angle, incidence angle, twist angle, sweepback angle, and wing area ratio of the front and rear wings while the fuselage was fixed. The quantities of aerodynamic coefficients were confirmed in accordance with joined-wing configurations. The closer the front and rear wings were located, the greater the flow interference effects tended. Interestingly, the rear wing did not any configuration change, the lift coefficient of the rear wing was decreased when adjusted to increase the incidence angle of the front wing. The phenomenon was appeared due to an effective angle of attack alteration of the rear wing resulting from the flow interference by the front wing configurations.