Wind load on irregular plan shaped tall building - a case study

Chakraborty, Souvik,Dalui, Sujit Kumar,Ahuja, Ashok Kumar Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.1

This paper presents the results of wind tunnel studies and numerical studies on a '+' plan shaped tall building. The experiment was carried out in an open circuit wind tunnel on a 1:300 scale rigid model. The mean wind pressure coefficients on all the surfaces were studied for wind incidence angle of $0^{\circ}$ and $45^{\circ}$. Certain faces were subjected to peculiar pressure distribution due to irregular formation of eddies caused by the separation of wind flow. Moreover, commercial CFD packages of ANSYS were used to demonstrate the flow pattern around the model and pressure distribution on various faces. k-${\varepsilon}$ and SST viscosity models were used for numerical study to simulate the wind flow. Although there are some differences on certain wall faces, the numerical result is having a good agreement with the experimental results for both wind incidence angle.

Wind load on irregular plan shaped tall building – a case study

Souvik Chakraborty,Sujit Kumar Dalui,Ashok Kuman Ahuja 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.1

This paper presents the results of wind tunnel studies and numerical studies on a '+' plan shaped tall building. The experiment was carried out in an open circuit wind tunnel on a 1:300 scale rigid model. The mean wind pressure coefficients on all the surfaces were studied for wind incidence angle of 0 and 45. Certain faces were subjected to peculiar pressure distribution due to irregular formation of eddies caused by the separation of wind flow. Moreover, commercial CFD packages of ANSYS were used to demonstrate the flow pattern around the model and pressure distribution on various faces. k-e and SST viscosity models were used for numerical study to simulate the wind flow. Although there are some differences on certain wall faces, the numerical result is having a good agreement with the experimental results for both wind incidence angle.

Experimental Investigation on the Wind-Induced Pressures on C-Shaped Buildings

Monalisa Mallick,Awadhesh Kumar,Kanhu Charan Patra 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.8

The present work focuses on the outcome of experimental investigation of pressure coefficients on different faces of C-shaped building models. An extensive experimentation was carried out to obtain a pressure coefficient over the surface of the models of varying configurations, corner curvature and angle of incidence between 0° to 180° at an interval of 30° in a subsonic open circuit wind tunnel. Four different configurations of C-shaped models of varying curvatures were tested. The models were made of perspex sheets. The recorded data of pressure at the located pressure tapings enabled determination of pressure coefficient and the study of the variation of pressure coefficient on the surfaces with wind angles and corner curvature. It has been observed that the pressure coefficient at a location on a surface varies significantly with the angle of incidence and the curvature of the surfaces. Also, the extent of maximum and minimum pressure zones have been found to change with the curvature and the wind direction.

Wind tunnel modeling of roof pressure and turbulence effects on the TTU test building

Bienkiewicz, Bogusz,Ham, Hee J. Techno-Press 2003 Wind and Structures, An International Journal (WAS Vol.6 No.2

The paper presents the results of 1:50 geometrical scale laboratory modeling of wind-induced point pressure on the roof of the Texas Tech University (TTU) test building. The nominal (prevalent at the TTU site) wind and two bounding (low and high turbulence) flows were simulated in a boundary-layer wind tunnel at Colorado State University. The results showed significant increase in the pressure peak and standard deviation with an increase in the flow turbulence. It was concluded that the roof mid-plane pressure sensitivity to the turbulence intensity was the cause of the previously reported field-laboratory mismatch of the fluctuating pressure, for wind normal and $30^{\circ}$-off normal to the building ridge. In addition, it was concluded that the cornering wind mismatch in the roof corner/edge regions could not be solely attributed to the wind-azimuth-independent discrepancy between the turbulence intensity of the approach field and laboratory flows.

Features of the flow over a finite length square prism on a wall at various incidence angles

Sohankar, A.,Esfeh, M. Kazemi,Pourjafari, H.,Alam, Md. Mahbub,Wang, Longjun Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.26 No.5

Wake characteristics of the flow over a finite square prism at different incidence angles were experimentally investigated using an open-loop wind tunnel. A finite square prism with a width D = 15 mm and a height H = 7D was vertically mounted on a horizontal flat plate. The Reynolds number was varied from $6.5{\times}10^3$ to $28.5{\times}10^3$ and the incidence angle ${\alpha}$ was changed from $0^{\circ}$ to $45^{\circ}$. The ratio of boundary layer thickness to the prism height was about ${\delta}/H=7%$. The time-averaged velocity, turbulence intensity and the vortex shedding frequency were obtained through a single-component hotwire probe. Power spectrum of the streamwise velocity fluctuations revealed that the tip and base vortices shed at the same frequency as that ofspanwise vortices. Furthermore, the results showed that the critical incidence angle corresponding to the maximum Strouhal number and minimum wake width occurs at ${\alpha}_{cr}=15^{\circ}$ which is equal to that reported for an infinite prism. There is a reduction in the size of the wake region along the height of the prism when moving away from the ground plane towards the free end.

Effect of internal angles between limbs of cross plan shaped tall building under wind load

Kumar, Debasish,Dalui, Sujit Kumar Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.24 No.2

The present study revealed comparison the pressure distribution on the surfaces of regular cross plan shaped building with angular cross plan shaped building which is being transformed from basic cross plan shaped building through the variation of internal angles between limbs by $15^{\circ}$ for various wind incidence angle from $0^{\circ}$ to $180^{\circ}$ at an interval of $30^{\circ}$. In order to maintain the area same the limbs sizes are slightly increased accordingly. Numerical analysis has been carried out to generate similar nature of flow condition as per IS: 875 (Part -III):1987 (a mean wind velocity of 10 m/s) by using computational fluid dynamics (CFD) with help of ANSYS CFX ($k-{\varepsilon}$ model). The variation of mean pressure coefficients, pressure distribution over the surface, flow pattern and force coefficient are evaluated for each cases and represented graphically to understand extent of nonconformities due to such angular modifications in plan. Finally regular cross shaped building results are compared with wind tunnel results obtained from similar '+' shaped building study with similar flow condition. Reduction in along wind force coefficients for angular crossed shaped building, observed for various skew angles leads to develop lesser along wind force on building compared to regular crossed shaped building and square plan shaped building. Interference effect within the internal faces are observed in particular faces of building for both cases, considerably. Significant deviation is noticed in wind induced responses for angular cross building compared to regular cross shaped building for different direction wind flow.

Effect of internal angles between limbs of cross plan shaped tall building under wind load

Debasish Kumar,Sujit Kumar Dalui 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.24 No.2

The present study revealed comparison the pressure distribution on the surfaces of regular cross plan shaped building with angular cross plan shaped building which is being transformed from basic cross plan shaped building through the variation of internal angles between limbs by 15 for various wind incidence angle from 0 to 180 at an interval of 30. In order to maintain the area same the limbs sizes are slightly increased accordingly. Numerical analysis has been carried out to generate similar nature of flow condition as per IS: 875 (Part –III):1987 (a mean wind velocity of 10 m/s) by using computational fluid dynamics (CFD) with help of ANSYS CFX (k-e model). The variation of mean pressure coefficients, pressure distribution over the surface, flow pattern and force coefficient are evaluated for each cases and represented graphically to understand extent of nonconformities due to such angular modifications in plan. Finally regular cross shaped building results are compared with wind tunnel results obtained from similar \'+\' shaped building study with similar flow condition. Reduction in along wind force coefficients for angular crossed shaped building, observed for various skew angles leads to develop lesser along wind force on building compared to regular crossed shaped building and square plan shaped building. Interference effect within the internal faces are observed in particular faces of building for both cases, considerably. Significant deviation is noticed in wind induced responses for angular cross building compared to regular cross shaped building for different direction wind flow.

Wind loading of a finite prism: aspect ratio, incidence and boundary layer thickness effects

Herman Heng,David Sumner 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.31 No.3

A systematic set of low-speed wind tunnel experiments was performed at Re = 6.5×104 and 1.1×105 to study the mean wind loading experienced by surface-mounted finite-height square prisms for different aspect ratios, incidence angles, and boundary layer thicknesses. The aspect ratio of the prism was varied from AR = 1 to 11 in small increments and the incidence angle was changed from α = 0° to 45° in increments of 1°. Two different boundary layer thicknesses were used: a thin boundary layer with δ/D = 0.8 and a thick boundary layer with δ/D = 2.0–2.2. The mean drag and lift coefficients were strong functions of AR, α, and δ/D, while the Strouhal number was mostly influenced by α. The critical incidence angle, at which the prism experiences minimum drag, maximum lift, and highest vortex shedding frequency, increased with AR, converged to a value of αc = 18° ± 2° once AR was sufficiently high, and was relatively insensitive to changes in δ/D. A local maximum value of mean drag coefficient was identified for higher-AR prisms at low α. The overall behaviour of the force coefficients and Strouhal number with AR suggests the possibility of three flow regimes.

NACA0012 익형에서 윙렛의 공력 특성에 대한 매개변수적 연구

조재범(Jaebeom Cho),김상재(Sangjae Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

In this research, the winglet attached to the NACA0012 airfoil is studied through wind tunnel experiments to analyze its aerodynamic characteristics with respect to the cant angle and incidence angle which are key design factors of the winglet. Additionally, split scimitar winglets characteristics are verified. Results show that the winglet model with a larger cant angle has a larger lift-to-drag ratio and a smaller size of pitching moment coefficient. The model with an incidence angle of 0° shows improvements of aerodynamic characteristics at the range of low angle of attack and one with an incidence angle of -4° does at the range of high angle of attack. The split scimitar winglet model has a larger lift-to-drag ratio and a smaller size of pitching moment coefficient than the reference of winglet model.

Wind induced pressure on 'Y' plan shape tall building

Sourav Mukherjee,Sujit Kumar Dalui,Souvik Chakraborty,Ashok Kumar Ahuja 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.5

This paper presents a comprehensive study of pressure developed on different faces of a 'Y' plan shape tall building using both numerical and experimental means. The experiment has been conducted in boundary layer wind tunnel located at Indian Institute of Technology Roorkee, India for flow condition corresponding to terrain category II of IS:875 (Part 3) – 1987, at a mean wind velocity of 10 m/s. Numerical study has been carried out under similar condition using computational fluid dynamics (CFD) package of ANSYS, namely ANSYS CFX. Two turbulence models, viz., k-ε and Shear Stress Transport (SST) have been used. Good conformity among the numerical and experimental results have been observed with SST model yielding results of higher magnitude. Peculiar pressure distribution on certain faces has been observed due to interference effect. Furthermore, flow pattern around the model has also been studied to explain the phenomenon occurring around the model.