Thick Crescent Iced Sub-Conductors Spacing Influence on the Aerodynamic Properties

2013 ◽  
Vol 419 ◽  
pp. 62-66
Author(s):  
Li Jun Ma ◽  
Shu Ying Hao ◽  
Qi Chang Zhang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Wake Flow ◽  
Ice Thickness ◽  
Aerodynamic Coefficient ◽  
Coefficient Variation ◽  
Moment Coefficient ◽  
Aerodynamic Properties

Using computational fluid dynamics software FLUENT analysis and calculation the aerodynamic coefficient of the 28mm ice thickness crescent iced quad-bundle conductors under different spacing. Studies show that aerodynamic coefficient of downwind sub-conductors affected by wake-flow, with the upwind sub-conductors there is always a big difference. With different spacing values, quad-bundle iced conductors in the wake-flow of different effects. Upwind sub-conductors, spacing values have nothing to do with the aerodynamic coefficient. Downwind sub-conductors, drag coefficient in the larger change significantly, moment coefficient variation is relatively small. Sub-conductors spacing has no effect on the lift coefficient.

scholarly journals STUDY OF MESH REFINEMENT ON THE AERODYNAMIC COEFFICIENTS FOR NACA2412 PROFILE WITH DIFFERENT ANGLE OF ATTACK AND k - w TURBULENCE MODEL

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Nícolas Lima Oliveira ◽  
Eric Vargas Loureiro ◽  
Patrícia Habib Hallak
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Lift Coefficient ◽  
Mesh Refinement ◽  
Angle Of Attack ◽  
Aerodynamic Coefficients ◽  
Computational Fluid Dynamics Cfd

This work presents the studies  obtained using OpenFOAM OpenSource Computational Fluid Dynamics (CFD) Software. Experiments were performed to predict lift coefficient and drag coefficient curves for the NACA2412 profile. Subsequently, the results obtained were compared with the results of the bibliography and discussed.

scholarly journals Hydrodynamic Analysis of Different Finger Positions in Swimming: A Computational Fluid Dynamics Approach

2015 ◽  
Vol 31 (1) ◽  
pp. 48-55 ◽  
Author(s):  
J. Paulo Vilas-Boas ◽  
Rui J. Ramos ◽  
Ricardo J. Fernandes ◽  
António J. Silva ◽  
Abel I. Rouboa ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Hydrodynamic Force ◽  
Lift Coefficient ◽  
Flow Speed ◽  
Cfd Analysis ◽  
Mean Flow ◽  
Hydrodynamic Analysis ◽  
Computational Fluid Dynamics Cfd

The aim of this research was to numerically clarify the effect of finger spreading and thumb abduction on the hydrodynamic force generated by the hand and forearm during swimming. A computational fluid dynamics (CFD) analysis of a realistic hand and forearm model obtained using a computer tomography scanner was conducted. A mean flow speed of 2 m·s−1was used to analyze the possible combinations of three finger positions (grouped, partially spread, totally spread), three thumb positions (adducted, partially abducted, totally abducted), three angles of attack (a = 0°, 45°, 90°), and four sweepback angles (y = 0°, 90°, 180°, 270°) to yield a total of 108 simulated situations. The values of the drag coefficient were observed to increase with the angle of attack for all sweepback angles and finger and thumb positions. For y = 0° and 180°, the model with the thumb adducted and with the little finger spread presented higher drag coefficient values for a = 45° and 90°. Lift coefficient values were observed to be very low at a = 0° and 90° for all of the sweepback angles and finger and thumb positions studied, although very similar values are obtained at a = 45°. For y = 0° and 180°, the effect of finger and thumb positions appears to be much most distinct, indicating that having the thumb slightly abducted and the fingers grouped is a preferable position at y = 180°, whereas at y = 0°, having the thumb adducted and fingers slightly spread yielded higher lift values. Results show that finger and thumb positioning in swimming is a determinant of the propulsive force produced during swimming; indeed, this force is dependent on the direction of the flow over the hand and forearm, which changes across the arm’s stroke.

Computational Fluid Dynamics Simulations in Flow Past Arrays of Finite Plate: Marine Current Energy Harvesting Applications

2017 ◽  
Author(s):  
Bashar Attiya ◽  
I-Han Liu ◽  
Cosan Daskiran ◽  
Jacob Riglin ◽  
Alparslan Oztekin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Three Dimensional ◽  
Mean Value ◽  
Wake Flow ◽  
Corner Angle ◽  
Drag Forces ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Computational fluid dynamics simulations have been conducted for flows past two finite tandem plates at Reynolds number of 50,000. Large Eddy Simulations (LES) were employed in two and three-dimensional geometries to study the interference between tandem plate pair. In order to study the effects of plate corner angle on the flow field and drag forces, two different plate end corners, 90° and a sharp 45° corner angle, were also investigated. The switching from 90° to 45° corners complicate the flow pattern, increase the mean value of drag force and the fluctuations of the drag on the plate. As vortices shed from the upstream plate and reached close proximity to the face of the downstream plate, the vortex cores deformed highly. This behavior reduces the drag coefficient in the downstream plate. Drag coefficient was higher in the 45° case, for both the up and downstream plates by 5% and 10% respectively. Drag coefficient of downstream is recovered almost fully in the 45° case with just 3% difference from the upstream compared to 7% difference in 90° case. Lagrangian Coherent structures were identified and presented in a two-dimensional geometry. This gave a better understanding of the wake flow structure and their influence on the hydrodynamic loading on plates. Contours of vorticity fields and iso-surfaces of Q-criterion, and pressure distribution around the plates were also presented and discussed.

scholarly journals Aerodynamic study of three cars in tandem using computational fluid dynamics

2021 ◽  
Vol 15 (3) ◽  
pp. 8228-8240
Author(s):  
H. Abdul-Rahman ◽  
H. Moria ◽  
Mohammad Rasidi Mohammad Rasani
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Model Comparison ◽  
Cfd Simulation ◽  
Positive Impact ◽  
Lift Coefficient ◽  
Experimental Studies ◽  
Intelligent Transport System ◽  
Drag Coefficients

Aerodynamics of vehicles account for nearly 80% of fuel losses on the road. Today, the use of the Intelligent Transport System (ITS) allows vehicles to be guided at a distance close to each other and has been shown to help reduce the drag coefficients of the vehicles involved. In this article, the aim is to investigate the effect of distances between a three car platoons, to their drag and lift coefficients, using computational fluid dynamics. To that end, a computational fluid dynamics (CFD) simulation was first performed on a single case and platoon of two Ahmed car models using the STAR-CCM+ software, for validation with previous experimental studies. Significant drop in drag coefficients were observed on platoon models compared to a single model. Comparison between the k-w and k-e turbulence models for a two car platoon found that the k-w model more closely approximate the experimental results with errors of only 8.66% compared to 21.14% by k-e turbulence model. Further studies were undertaken to study the effects of various car gaps (0.5L, 1.0L and 1.5L; L = length of the car) to the aerodynamics of a three-car platoon using CFD simulation. Simulation results show that the lowest drag coefficient that impacts on vehicle fuel savings varies depending on the car's position. For the front car, the lowest drag coefficient (CD) can be seen for car gaps corresponding to X1 = 0.5L and X2 = 0.5L, where CD = 0.1217, while its lift coefficient (CL) was 0.0366 (X1 and X2 denoting first to second and second to third car distance respectively). For the middle car, the lowest drag coefficient occurred when X1 = 1.5L and X2 = 0.5L, which is 0.1397. The lift coefficient for this car was -0.0611. Meanwhile, for the last car, the lowest drag coefficient was observed when X1 = 0.5L and X2 = 1.5L, i.e. CD = 0.263. The lift coefficient for this car was 0.0452. In this study, the lowest drag coefficient yields the lowest lift coefficient. The study also found that for even X1 and X2 spacings, the drag coefficient increased steadily from the front to the last car, while the use of different spacings were found to decrease drag coefficient of the rear car compared to the front car and had a positive impact on platoon driving and fuel-saving.

scholarly journals ANALISIS AERODINAMIKA PADA BODI MOBIL HEMAT ENERGI LINTANG SAMUDRA MENGGUNAKAN METODE COMPUTATIONAL FLUID DYNAMICS

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Bagus Wahyu Prastyo ◽  
Imam Syafa’at ◽  
Muhammad Dzulfikar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Lift Coefficient

Aerodinamika kendaraan merupakan bentuk pergerakan aliran udara yang memberi pengaruh atau menyebabkan gaya kepada benda saat bergerak dengan kecepatan tertentu. Ada beberapa cara untuk mengetahui bentuk aerodinamika kendaraan. Pertama yaitu melakukan eksperimen dengan memasukkan kendaraan pada terowongan angin. Cara kedua yaitu menggunakan software CFD (Computational fluid dynamic). Dengan metode CFD peneliti dapat membuat berbagai bentuk desain tanpa mengeluarkan biaya tambahan. Penelitian ini bertujuan untuk mengetahui aerodinamika serta nilai Drag coefficient (CD) dan Lift coefficient (CL) pada bodi mobil Lintang Samudra. Simulasi dilakukan pada 4 kecepatan aliran udara yaitu 40, 50,60 dan 70 km/h. Simulasi menggunakan model turbulensi k-ɛ dengan intensitas 5%, model tersebut dipilih karena memiliki tingkat error terkecil terhadap validasi dari jurnal simulasi Bammidi dan Murty (2014) sebesar 0,13 %. Didapatkan hasil bodi Lintang Samudra 1 memiliki nilai CD = 0,07598 - 0,07025 dan CL=(-0,00800) – (-0,00837) Pada bodi Lintang Samudra 2 memiliki nilai CD = 0,072451 - 0,067020 dan CL = 0,001395 – 0,000949. Terdapat perbedaan bentuk aliran fluida pada bodi Lintang Samudra 1dan bodi Lintang Samudra 2. Jadi bodi kedua lebih aerodinamis dari bodi pertama. Kata kunci: aerodinamika, bodi, CFD, drag, lift.

scholarly journals Swimming Propulsion Forces Are Enhanced by a Small Finger Spread

2010 ◽  
Vol 26 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Daniel A. Marinho ◽  
Tiago M. Barbosa ◽  
Victor M. Reis ◽  
Per L. Kjendlie ◽  
Francisco B. Alves ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Force Production ◽  
Attack Angle ◽  
Propulsive Force ◽  
Drag And Lift ◽  
Back Angle ◽  
Dynamics Analyses

The main aim of this study was to investigate the effect of finger spread on the propulsive force production in swimming using computational fluid dynamics. Computer tomography scans of an Olympic swimmer hand were conducted. This procedure involved three models of the hand with differing finger spreads: fingers closed together (no spread), fingers with a small (0.32 cm) spread, and fingers with large (0.64 cm) spread. Steady-state computational fluid dynamics analyses were performed using the Fluent code. The measured forces on the hand models were decomposed into drag and lift coefficients. For hand models, angles of attack of 0°, 15°, 30°, 45°, 60°, 75°, and 90°, with a sweep back angle of 0°, were used for the calculations. The results showed that the model with a small spread between fingers presented higher values of drag coefficient than did the models with fingers closed and fingers with a large spread. One can note that the drag coefficient presented the highest values for an attack angle of 90° in the three hand models. The lift coefficient resembled a sinusoidal curve across the attack angle. The values for the lift coefficient presented few differences among the three models, for a given attack angle. These results suggested that fingers slightly spread could allow the hand to create more propulsive force during swimming.

Circular Cylinder Exposed to Cross Flow Fluid Forces – Parameters of Influence – Limits of Numerical Models

2003 ◽  
Author(s):  
Christoph Reichel ◽  
Klaus Strohmeier
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Models ◽  
Lift Coefficient ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Rigid Cylinder ◽  
Fluid Forces ◽  
Wide Range ◽  
Dynamics Simulations

In many technical fields, e.g. heat exchangers, circular cylinders are involved in Fluid Structure Interaction (FSI) problems. Therefore correct frequency and magnitude of fluid forces, respectively Strouhal number, drag and lift coefficient are needed. If fluid forces are evaluated with Computational Fluid Dynamics (CFD), mostly flow around a rigid cylinder is used to verify model and numerical methods. Unfortunately experimental as well as numerical results show great variation, making verification and testing of models difficult. Reynolds number is regarded as main influencing parameter for a rigid cylinder in cross flow. Most of experimental deviations can be related to other parameters, which differ from experiment to experiment. In this paper such parameters are specified and it is shown, that a closer look is needed, if one really wants to verify a model. Besides experimental results, which can be found in literature, some parameters are investigated by numerical simulation. Like experiments CFD (Computational Fluid Dynamics) simulations show a huge bandwidth of results, even when the same turbulence model is used. Flow around cylinders separates over a wide range of Reynolds numbers. It will be demonstrated that, using CFD, large deviations in fluid forces can often be related to miscalculation of the point of separation.

Computational fluid dynamics study of human-induced wake and particle dispersion in indoor environment

2016 ◽  
Vol 26 (2) ◽  
pp. 185-198 ◽  
Author(s):  
Yao Tao ◽  
Kiao Inthavong ◽  
Jiyuan Tu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Indoor Environment ◽  
Particle Dispersion ◽  
The Body ◽  
Wake Flow ◽  
Time Step ◽  
Directed Flow ◽  
Stagnant Region ◽  
The Impact

The impact of human-induced wake flow and particle re-dispersion from floors in an indoor environment was investigated by performing computational fluid dynamics simulations with dynamic mesh of a moving manikin model in a confined room. The manikin motion was achieved by a dynamic layering mesh method to update new grids with each time step. Particle transport from the floors and its re-dispersion was tracked by a Lagrangian approach. A series of numerical simulations of three walking speeds were performed to compare the flow disturbance induced by the walking motion. The significant airflow patterns included: an upward-directed flow in front of the body combined with a high velocity downward-directed flow at the rear of the body; a stagnant region behind the gap between the legs and counter-rotating vortices in the wake region. The airflow momentum induced by the moving body disturbed PM2.5 particles that were initially at rest on the floor to lift and become re-suspended due to its interaction with the trailing wake. The residual flow disturbances after the manikin stopped moving continued to induce the particle to spread and deposit over time. The spatial and temporal characteristics of the particle dispersion and concentration showed that higher walking speed was conducive to reducing human's exposure to contaminants in breathing region.

Two-Dimensional Analysis of Tandem/Staggered Airfoils Using Computational Fluid Dynamics

2005 ◽  
Vol 33 (3) ◽  
pp. 195-207 ◽  
Author(s):  
Z. Husain ◽  
M. Z. Abdullah ◽  
T. C. Yap
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Dimensional Analysis ◽  
Lift Coefficient ◽  
Open Circuit ◽  
Computational Method ◽  
Two Dimensional ◽  
Optimum Position ◽  
Computational Fluid Dynamics Cfd

The two-dimensional analysis, using computational fluid dynamics (CFD), of tandem/staggered arranged airfoils of the canard and wing of an Eagle 150 aircraft and also the aerodynamic tests conducted in an open-circuit wind tunnel are presented in the paper. The wind tunnel tests were carried out at a speed of 38m/s in a test section of size 300 mm (width), 300 mm (height) and 600 mm (length), at Reynolds number 2.25 × 105. The tests were carried out with tandem and staggered placement of the airfoils in order to determine the optimum position of the wing with respect to the canard and also to determine the lift coefficient at various angles of attack. The CFD code FLUENT 5 was used to investigate the aerodynamic performance of a two-dimensional model to validate the wind tunnel results. The flow interaction was studied in the tandem and staggered arrangements in the wind tunnel as well as by the computational method. The k-ε turbulence model gave exceptionally good results.

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