Application of shape-based similarity query for aerodynamic optimization of wind tunnel primary nozzle

This paper presents the first results of a wide experimental investigation on the aerodynamics of a vertical axis wind turbine. Vertical axis wind turbines have recently received particular attention, as interesting alternative for small and micro generation applications. However, the complex fluid dynamic mechanisms occurring in these machines make the aerodynamic optimization of the rotors still an open issue and detailed experimental analyses are now highly recommended to convert improved flow field comprehensions into novel design techniques. The experiments were performed in the large-scale wind tunnel of the Politecnico di Milano (Italy), where real-scale wind turbines for micro generation can be tested in full similarity conditions. Open and closed wind tunnel configurations are considered in such a way to quantify the influence of model blockage for several operational conditions. Integral torque and thrust measurements, as well as detailed aerodynamic measurements were applied to characterize the 3D flow field downstream of the turbine. The local unsteady flow field and the streamwise turbulent component, both resolved in phase with the rotor position, were derived by hot wire measurements. The paper critically analyses the models and the correlations usually applied to correct the wind tunnel blockage effects. Results evidence that the presently available theoretical correction models does not provide accurate estimates of the blockage effect in the case of vertical axis wind turbines. The tip aerodynamic phenomena, in particular, seem to play a key role for the prediction of the turbine performance; large-scale unsteadiness is observed in that region and a simple flow model is used to explain the different flow features with respect to horizontal axis wind turbines.

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Flutter Performance of the Emergency Bridge with New-Type Cable-Girder

Mathematical Problems in Engineering ◽

10.1155/2019/1013025 ◽

2019 ◽

Vol 2019 ◽

pp. 1-14

Author(s):

Lei Yang ◽

Fei Shao ◽

Qian Xu ◽

Ke-bin Jiang

Keyword(s):

Wind Speed ◽

Wind Tunnel ◽

Analysis Program ◽

Aerodynamic Optimization ◽

Wind Resistance ◽

Optimal Scheme ◽

Critical Wind Speed ◽

Flutter Analysis ◽

New Type ◽

Optimization Schemes

Based on the proposed emergency bridge scheme, the flutter performance of the emergency bridge with the new-type cable-girder has been investigated through wind tunnel tests and numerical simulation analyses. Four aerodynamic optimization schemes have been developed in consideration of structure characteristics of the emergency bridge. The flutter performances of the aerodynamic optimization schemes have been investigated. The flutter derivatives of four aerodynamic optimization schemes have been analyzed. According to the results, the optimal scheme has been determined. Based on flutter theory of bridge, the differential equations of flutter of the emergency bridge with new-type cable-girder have been established. Iterative method has been used for solving the differential equations. The flutter analysis program has been compiled using the APDL language in ANSYS, and the bridge flutter critical wind speed of the optimal scheme has been determined by the program. The flutter analysis program has also been used to determine the bridge flutter critical wind speed of different wind-resistance cable schemes. The results indicate that the bridge flutter critical wind speed of the original emergency bridge scheme is lower than the flutter checking wind speed. The aerodynamic combined measurements of central-slotted and wind fairing are the optimal scheme, with the safety coefficients larger than 1.2 at the wind attack angles of −3°, 0°, and +3°. The bridge flutter critical wind speed of the optimal scheme has been determined using the flutter analysis program, and the numerical results agree well with the wind tunnel test results. The wind-resistance cable scheme of 90° is the optimal wind cable scheme, and the bridge flutter critical wind speed increased 31.4%. However, in consideration of the convenience in construction and the effectiveness in erection, the scheme of wind-resistance cable in the horizontal direction has been selected to be used in the emergency bridge with new-type cable-girder.

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Computational fluid dynamics based aerodynamic optimization of the wind tunnel primary nozzle

10.1063/1.4704229 ◽

2012 ◽

Author(s):

Kolář Jan ◽

Dvořák Václav

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Wind Tunnel ◽

Aerodynamic Optimization

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Ballasted track aerodynamic optimization by wind tunnel test and CFD simulation

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/0954409720960889 ◽

2020 ◽

pp. 095440972096088

Author(s):

Guoqing Jing ◽

Dong Ding ◽

Le Fang

Keyword(s):

Wind Tunnel ◽

High Speed ◽

Cfd Simulation ◽

Wind Tunnel Test ◽

Wind Pressure ◽

Aerodynamic Optimization ◽

Great Probability ◽

Sliding Mesh ◽

Ballasted Track ◽

Set Up

Ballast flight problem sets back high-speed railway development, which causing damages to train and rail. The present paper puts forward wind tunnel tests and CFD simulation to study ballast flight mechanisms and ballasted track aerodynamics. A 1:1 scale ballasted track model was set up to analyze ballast flight phenomena, where aerodynamics influencing factors and impacts on ballast bed were investigated. A numerical model of CRH3 train-ballast bed was built by combining the Realizable k- ϵ viscous model and sliding mesh technique. CFD model with the above method was used to investigate aerodynamic effects as well as the mechanism of ballast flight, thus providing the theoretical basis for optimizing ballast bed profile and preventing ballast flight. Results show that pressure distribution exhibits large value at the center of the ballasted track and decreases at track edge. The head, tail and bogie area of the train result in large fluctuation of wind pressure, which has a great probability of ballast flight. Appropriate countermeasures should be taken, such as reduce shoulder ballast height and crib ballast could be effective methods to decrease the probability of ballast flight.

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Wind Tunnel Test of Aerodynamic Optimization Measures for Flutter Stability of Super Long-span Bridge with Truss Girder

Journal of Highway and Transportation Research and Development (English Edition) ◽

10.1061/jhtrcq.0000064 ◽

2011 ◽

Vol 5 (2) ◽

pp. 49-54 ◽

Cited By ~ 1

Author(s):

Hongtao Xu ◽

Haili Liao ◽

Yong He ◽

Junjun Zou

Keyword(s):

Wind Tunnel ◽

Wind Tunnel Test ◽

Aerodynamic Optimization ◽

Long Span ◽

Long Span Bridge

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Aerodynamic Measurements on a Vertical Axis Wind Turbine in a Large Scale Wind Tunnel

Journal of Energy Resources Technology ◽

10.1115/1.4004360 ◽

2011 ◽

Vol 133 (3) ◽

Cited By ~ 47

Author(s):

L. Battisti ◽

L. Zanne ◽

S. Dell’Anna ◽

V. Dossena ◽

G. Persico ◽

...

Keyword(s):

Wind Tunnel ◽

Flow Field ◽

Wind Turbine ◽

Wind Turbines ◽

Large Scale ◽

Fluid Dynamic ◽

Vertical Axis ◽

Vertical Axis Wind Turbine ◽

Aerodynamic Optimization ◽

Vertical Axis Wind Turbines

This paper presents the first results of a wide experimental investigation on the aerodynamics of a vertical axis wind turbine. Vertical axis wind turbines have recently received particular attention, as interesting alternative for small and micro generation applications. However, the complex fluid dynamic mechanisms occurring in these machines make the aerodynamic optimization of the rotors still an open issue and detailed experimental analyses are now highly recommended to convert improved flow field comprehensions into novel design techniques. The experiments were performed in the large-scale wind tunnel of the Politecnico di Milano (Italy), where real-scale wind turbines for micro generation can be tested in full similarity conditions. Open and closed wind tunnel configurations are considered in such a way to quantify the influence of model blockage for several operational conditions. Integral torque and thrust measurements, as well as detailed aerodynamic measurements were carried out to characterize the 3D flow field downstream of the turbine. The local unsteady flow field and the streamwise turbulent component, both resolved in phase with the rotor position, were derived by hot wire measurements. The paper critically analyses the models and the correlations usually applied to correct the wind tunnel blockage effects. Results highlight that the presently available theoretical correction models do not provide accurate estimates of the blockage effect in the case of vertical axis wind turbines. The tip aerodynamic phenomena, in particular, seem to play a key role for the prediction of the turbine performance; large-scale unsteadiness is observed in that region and a simple flow model is used here to explain the different flow features with respect to horizontal axis wind turbines.

Download Full-text