Numerical Wind Tunnel Research Articles

Robust design of NLF airfoils

A robust optimization design approach of natural laminar airfoils is developed in this paper. First, the non-uniform rational B-splines (NURBS) free form deformation method based on NURBS basis function is introduced to the airfoil parameterization. Second, aerodynamic characteristics are evaluated by solving Navier–Stokes equations, and the γ-Reθt¯ transition model coupling with shear-stress transport (SST) turbulent model is introduced to simulate boundary layer transition. A numerical simulation of transition flow around NLF0416 airfoil is conducted to test the code. The comparison between numerical simulation results and wind tunnel test data approves the validity and applicability of the present transition model. Third, the optimization system is set up, which uses the separated particle swarm optimization (SPSO) as search algorithm and combines the Kriging models as surrogate model during optimization. The system is applied to carry out robust design about the uncertainty of lift coefficient and Mach number for NASA NLF-0115 airfoil. The data of optimized airfoil aerodynamic characteristics indicates that the optimized airfoil can maintain laminar flow stably in an uncertain range and has a wider range of low drag.

Numerical simulation and wind tunnel measurements on a tricycle wheel sub-system

The drag of an isolated rotating wheel subsystem including its accessories (tyre, suspension, A-arms and fender) of a tricycle vehicle has been studied both numerically and experimentally. The objective of this study is to validate the numerical model developed in order to optimise a generic wheel subsystem through drag analysis. The CAD model of the wheel subsystem was created in CATIA-v5 and the numerical simulations were carried out using the Star CCM+ commercial CFD package. The resulting numerical model was validated experimentally by comparing with the drag and pressure coefficient measured in a large subsonic closed-loop wind tunnel. Different mesh topologies and turbulent models were tested. The final model developed shows less than 3% of drag discrepancy vs. experimental results. Two aerodynamic shapes of A-arms are then designed to perform drag reduction on the wheel subsystem. Numerical simulations show a significant drag reduction up to 20% compared with the original wheel subsystem.

Distribution Rule Analysis and Research of Wind Loads of Stadium by Numerical Simulation

The most of Long-span stadium roofs are complex surface, the load norms cannot put forward the design requirements clearly in frequently. Determine wind loads need to use other means for help, while the numerical wind tunnel is one of the commonly be used to research methods in recent years. This paper introduces about the numerical simulation method of a long-span stadium roof surface wind pressure distribution , and based on FLUENT platform, a gymnasium as an example, the shear stress transport k - ω model (referred to as the SST k - ω model) on the roof surface wind pressure distribution of numerical wind tunnel simulation, analysis stadium roof surface pressure distribution law based on different wind directions.

Large eddy simulation of the wind turbine wake characteristics in the numerical wind tunnel model

Large Eddy Simulation of NREL Phase VI wind turbine was performed in a virtual wind tunnel (24.4m×36.6m) in order to achieve a better understanding of the turbine wake characteristics. For this purpose, ANSYS-Fluent package was used to run the simulation using the dynamic Smagorinsky-Lilly model. For the purpose of validation, the pressure distribution at different span-wise sections along the turbine blade and the power produced by the wind turbine were compared with the published experimental results for the NREL phase VI rotor tested in the NASA wind tunnel with the same dimensions as in the model and a good agreement was found between the two. The airflow immediately behind the wind turbine was observed to be a system of intense and stable rotating helical vortices, which determined the dynamics of the far-wake. The system of vortices in the near-wake became unstable and broke down due to wake instability at a distance of five rotor diameters downstream of the wind turbine. This was defined as the boundary between the near- and far-wake regions. The collapsed spiral wake was found to spread in all directions in the far-wake resulting in the formation of the two pairs of counter-rotating vortices which caused the gradual increase of turbulence in these regions. The turbulence intensity in the wake was observed to increase immediately behind the turbine with a maximum of 12.12% at a distance of three rotor diameters downstream of the turbine, after which a gradual decrease in the turbulence intensity was observed in the near-wake regions due to wake instability. However, in the far-wake regions, due to counter-rotating vortices formed by the wake instability, the turbulence intensity showed a tendency to increase intensity. Finally the time-averaged wake velocities from the LES, with and without the blockage corrections, were compared with WAsP and a comparatively good agreement for the axial velocity predictions was observed in the far-wake.

Numerical Simulation of Mean Wind Pressure on the Roof of Yantai Gymnasium

In order to determine the distribution of wind load on the roof, wind tunnel test and numerical simulation are both carried out. Then the distribution of mean wind pressure under different wind directions is obtained and the features of mean wind pressure are also analyzed. The datas show that wind pressure distribution of the roof is predominantly negative pressure; only a small area of windward side is positive pressure distribution. The peak of negative pressure appears at the roof ridge or windward long eaves, and varies as changes of wind direction. Meanwhile, the comparison between the results of the numerical simulation and wind tunnel test shows that the distribution law of both is almost the same, but in some areas that flow separation is serious, the error is larger. Then the reasons for the error are discussed.

Numerical Wind Tunnel Simulation of Wind Loads on a Solar Photovoltaic Power Generation Station

Aiming at the wind load evaluation in the mechanical structure design of solar photovoltaic power generation station with sun tracking, a numerical wind tunnel model was established based on the computational fluid dynamics theory and finite element method. The 8-level wind velocity was applied in the model considering the mal-condition of reef islands and Gobi desert where the solar photovoltaic power generation station usually installed. From the numerical simulation results, the influence of elevation angle of the solar cells on the wind load was presented. To decrease the maximum wind load on the power station, the gap between solar cells was proposed as air vent in this paper, which has been adopted in a prototype machine, and more than 20% of the equipment weight has been reduced.

The Influence of the Convective Terms Discretization Scheme on the Simulation Results of Architectural Numerical Wind Tunnel

The numerical simulation of construction is to obtain the desired accuracy. It depends on the theoretical basis of the calculator and selection of the various important factors in the actual operation. For this problem, this paper adopting the current code for the design of building structures as the comparison standard, using the FLUENT software, taking the numerical simulation results of a high building’s wind load shape coefficient of for example, discussing the influence of four kinds of the convective terms discretization scheme, respectively the first-order upwind, the second order upwind , power law and Quadratic upwind interpolation for convective kinematics, on the simulation results of architectural numerical wind tunnel, provides the reference for the rational use of numerical wind tunnel method.

The Selection of Pressure Velocity Coupling Algorithm in the Numerical Wind Tunnel of Arch Roof

using the FLUENT software, this paper taking the current code for the design of building structures as the comparison standard, have numerical wind tunnel simulation of the wind the surface wind pressure on arch roof. It focuses on the analysis of the effects of three kinds of pressure velocity coupling algorithm on the numerical simulation results, respectively SIMPLE, SIMPLEC, PISO, to provide a basis for the reasonable selection of algorithm.

Determination of the Average Wind Pressure of Circular Flat and Saddle Roof Building Based on the Numerical Wind Tunnel Method

For numerical wind tunnel method has the advantages of low cost, fast speed, the more comprehensive results, the paper using CFD knowledge and the FLUENT software, using RSM turbulence model, SIMPLE algorithm, simulation class D landform, to have numerical simulation of average wind pressure coefficient for of the circular planar and saddle roof building ,which the current code for the design of building structures did not give, to provide reference for determining the average wind pressure coefficient of the circular planar and saddle roof building .

The Turbulent Flow Model Selection for Numerical Wind Tunnel Simulation of the Low Layer Double Slope Roof

Using the FLUENT software, this paper taking the current code for the design of building structures as the comparison standard, have numerical wind tunnel simulation of the wind the surface wind pressure on low layer double slope roof. It focuses on the analysis of the effects of turbulence model selection on the numerical simulation results, such as Spalart-Allmaras、Standard k −ε、RNG k −ε、Realizable k −ε、Standard k −ω、SST k −ω and RSM, to provide a basis for the reasonable selection of turbulence models.

The Numerical Simulation of the Impact on the Hangzhou Bay Bridge Offshore Platform and the Sightseeing Tower

In this paper, the distribution of surface wind pressure and wind speed of Hangzhou bay bridge, offshore platform and sightseeing tower is numerically simulated based on Fluent. Two turbulence models, standard k ε model and Realizable k ε model, are used. The influence of the wind pressure distribution of the offshore platform and sightseeing tower by Hangzhou bay bridge is also analyzed. And the detailed comparison between numerical simulation and wind tunnel test is given. Results show that the impact of Hangzhou bay bridge on platform and sightseeing tower occurs mainly with the angle of the wind less than 450. When the angle of the wind is more than 450, the impact is little. The upper of the sightseeing tower does not almost suffer the effect of other buildings. The surface pressure of the platform changes from 5% to 15% between under bridge and under non-bridge condition. The surface pressure of sightseeing tower changes from 0.05% to 3%. The influence on the platform by the bridge is significant but not significant on the sightseeing tower. The simulation results of the tower and mast structure given by both standard k ε model and Realizable k ε model find that the windward side is ideal; the crosswind side is the best; the leeward side is less than ideal. By contrast, the Realizable k ε model is a closer correlation with wind tunnel test than standard k ε model.

The Numerical Simulation for Wind Pressure on the Roof of Rhombic Plane and Saddle-Shaped Building

The existing “structure load code” did not give wind load shape coeeficient of rhombic plane and saddle-shaped roof .On this issue, numerical wind tunnel method has significant advantages such as low cost,fasting,collecting more comprehensive results.Using information of CFD and the software of FLUENT, using RNG - turbulence model, simulating a landform rhombic plane, the paper had numerical simulation of average wind pressure coefficient for rhombic plane and saddle-shaped roof building. It focused the effect on the numerical simulation for bending-span ratio. Finally it provided reference for reasonably determining the average wind pressure coefficient of rhombic plane and saddle-shaped roof building.

On the optimal model configuration for aerodynamic modeling of open cargo railway train

This study is concerned with the optimal model configuration for aerodynamic modeling of long open cargo railway trains. Frontal air drag of several train configurations was studied using numerical modeling and physical i.e. wind tunnel testing of 1:40 scale railcar models in a range of cross-wind angles. In a long train, the locomotive and the last railcar influence the aerodynamic characteristics of the first three and the last three railcars only. Aerodynamic performance of all other railcars in the long train is similar and can be represented by two inner-train railcars only. A model train configuration combining the shortest computation time with the lowest experimental error was determined from numerical modeling and this was then used for wind tunnel testing. It has been shown that, for long open cargo railway trains the model consisting of six railcars with two streamlined bodies is the optimal configuration, with both the numerical modeling and wind tunnel testing results in good agreement.

Investigation of Aerodynamic Parameters of a Hybrid Airship

The aerodynamic parameters of a preliminary winged-hull airship design are investigated. The research methodology involved the use of numerical simulation and wind tunnel testing. The aerodynamic parameters of the design are first computed using a commercial CFD code. The force and moment coefficients are then measured on a scaled model in the IIUM low speed wind tunnel. The experimental results generally agree with the CFD predicted data. Addition of a wing to conventional airship increases the lift substantially with a reasonable increase in drag. The longitudinal and directional stabilities were found to be statically stable, however, both the conventional airship and the hybrid airship were found to have poor rolling stability. CFD simulations show that modifications to the wing placement and its dihedral have strong positive effect on the rolling stability.

Numerical Simulation and Experimental Verification of Butterfly Porous Fences

In this paper, the domestic and foreign research progress of numerical simulation on the porous fence is introduced briefly, and a numerical model is established to simulate the flow characteristics behind the butterfly porous fence through the FLUENT software. The comparison results found good agreement between the numerical model and wind tunnel experimental data with an error of 7.8% in the wind reduction ratio, indicating the present numerical model can be used to undertake study on butterfly and non-planar porous fences. The effect of porosity on the flow characteristics behind the butterfly porous fence have been evaluated using the present model to determine an optimum porosity for sheltering effect of an isolated porous fence. As a result, the butterfly porous fences with a range of porosity from 0.27 to 0.32 seem to have a better shelter effect among the studied porosities, and all the wind reduction ratios approach to 60%.

609 風車設計開発のための数値風洞の研究(OS6-3.流体の数値計算手法と数値シミュレーション(3),OS・一般セッション講演)

609 風車設計開発のための数値風洞の研究(OS6-3.流体の数値計算手法と数値シミュレーション(3),OS・一般セッション講演)

Large eddy simulation of wind effects on a long-span complex roof structure

This paper presents a combined study of numerical simulations and wind tunnel tests for the determinations of wind effects on a long-span complex roof of the Shenzhen New Railway Station Building. The main objective of this study is to present an effective approach for the estimations of wind effects on a complex roof by computational fluid dynamics (CFD) techniques. A new inflow turbulence generator called the discretizing and synthesizing random flow generation (DSRFG) approach was applied to simulate inflow boundary conditions of a turbulent flow field. A new one-equation dynamic subgrid scale (SGS) model was adopted for the large eddy simulations (LES) of wind effects on the station building. The wind-induced pressures on the roof and turbulent flow fields around the station building were thus calculated based upon the DSRFG approach and the new SGS model integrated with the FLUENT software. In parallel with the numerical investigation, simultaneous pressure measurements on the entire station building were made in a boundary layer wind tunnel to determine the mean, fluctuating, and peak pressure coefficient distributions. The numerically predicted results were found to be consistent with the wind tunnel test data. The comparative study demonstrated that the recommended inflow turbulence generation technique and the new SGS model as well as the associated numerical treatments are useful tools for structural engineers to assess wind effects on long-span complex roofs and irregularly shaped buildings at the design stage.

Assessment of Roadway and Surrounding Configurations for Automotive Exhaust Dispersion Numerical Simulation and Wind Tunnel Experiment for Cross Wind Cases

Assessment of Roadway and Surrounding Configurations for Automotive Exhaust Dispersion Numerical Simulation and Wind Tunnel Experiment for Cross Wind Cases

Study on Wind-Resistant Design for Super High-Rise Building Envelop

A brief introduction of Nanchang International Financial mansion manometry test model was stated first, And based on the Fluent software platforms, Wind pressure on the surface of high-rise building with the influence of adjacent buildings is simulated by computation fluid dynamics (CFD) methods. The results show that the numerical wind tunnel to some extent, more in line with the measurement results, but the errors in some parts are still large, relevant results will provide references for the research and the engineering practice.

Research on Vortex-Induced Vibration Behavior of Steel Arch Bridge Hanger

A fluid-structure interaction numerical simulation technique based on CFD has been developed to study the vortex-induced vibration behavior of steel arch bridge hanger. Above all, wind acting on bridge hanger is simulated by using Flunet and then vortex-induced dynamic motion of hanger is solved by method in the User Defined Function (UDF). Finally hanger’s transient vibration in wind is achieved by dynamic mesh method provided by Fluent. Using this technique, the vortex-induced vibration behavior of hanger of the Nanjing Dashengguan Yangtze River Bridge is analyzed, including vibration amplitude, vibration-started wind speed and vortex shedding frequency. The study also considers influences of different section type (rectangle, chamfered rectangle and H) of hanger. The following conclusions are obtained. Firstly hanger of different section has different vibration behavior. Secondly vibration-started wind speed of different section hanger differs with each other. Thirdly relation between vibration amplitude and incoming wind speed varies obviously. At the same time, numerical results are compared with those of one wind tunnel test and the out coming is satisfied. Relation between vibration amplitude and wind speed in both numerical simulation and wind tunnel test is similar because vibration-started wind speed in numerical result has only 10% discrepancy with that in wind tunnel test while vibration amplitude’s discrepancy is only 15%. Consequently, analysis results show the reliability of this numerical simulation technique.