Papers by Keyword: Wind Tunnel Test

Abstract: The numerical investigations presented in this paper deal with wind tunnel testing scheme design for 1/4 scaled MIRA model including supporting system. Based on the structure of aerodynamic and aero-acoustic full scale wind tunnel, using computational fluid dynamics (CFD), focus on MIRA model and supporting system, the drag force of scaled models and supporting system were calculated. By comparing with the wind tunnel testing results and drag force coefficient of reference, it is certain that the wind tunnel testing scheme is available and effective and that the value calculated by CFD is in good agreement with experiments.

Abstract: In the present study, an experimental setup was made to measure the aerodynamic characteristics of vehicles on the bridge for different cases in a wind tunnel considering the aerodynamic interference. The influence of the wind turbulence, the vehicle interference, and the distance of vehicle from the windward edge of the deck on the aerodynamic coefficients of vehicles were investigated based on the experimental results. The measured results showed that the wind turbulence, the vehicle interference, and the vehicle distance from the windward edge significantly affected the aerodynamic coefficients of vehicles.

Abstract: The Shenzhen New Railway Station (SNRS) has roof dimensions of 450 m long and 408 m wide. This paper presents the results of wind loads acting on the large-span roof structure. In the wind tunnel test, wind-induced pressures including mean and fluctuating components were measured from the roof of a 1:200 scale SNRS model under suburban boundary layer wind flow configuration in a boundary layer wind tunnel of HD-2 at Hunan University. Based on the data obtained simultaneously from the wind tunnel tests, the distributions of the mean and fluctuating wind pressure coefficients and the characteristics of probability density functions of wind pressures of typical pressure taps were analyzed in detailed. The outcomes of the experimental study indicate that: (1) The maximum mean negative wind pressure coefficients on the roof occur at the windward leading edge region, where the maximum fluctuating wind pressure coefficients occur also in this region; (2) There are some differences of the maximum mean negative wind pressure coefficients and RMS wind pressure coefficients under conditions with different number of trains inside the station, but such effects on the overall pressure distributions on the whole roof are negligible; (3) There are clearly negative skewed distributions for some pressure taps at the windward leading roof edge and much longer negative tails are observed, which follow Non-Gaussian distributions. The results presented in this paper are expected to be of considerable interest and of use to researchers and professionals involved in designing complex long-span roof structures.

Abstract: Wind tunnel test of 1:500 rigid model of tall building with atrium was carried out. Based on the experimental results, characteristics of wind pressures on atrium facades and wind loads on the structure were investigated in detail. The results show that the formation of flow separation on the building top plays a critical role in the generation of wind pressures on the atrium facades. Meanwhile, wind pressure coefficient distributions on the atrium facades are found to be relatively uniform. Moreover, the horizontal and vertical correlations of pressure coefficient exhibit high at most locations on atrium facades. With the increasing of the opening ratio, the mean wind pressure coefficients first decreased and then stabilized, and the fluctuating wind pressure coefficients first decreased and then increased. A design guideline for the wind-resistant design of atrium facades was proposed, and the results predicted by the proposed guideline were in good agreement with those from the wind tunnel tests, indicating that the proposed guideline can be used in engineering applications. When the opening ratio is no more than 5.33%, the effect of the facade pressures within the atrium on the wind loads on the structure can be ignored. For such cases, the wind-resistant design for a tall building with atrium can refer to that of a similar shape tall building without atrium.

Abstract: One of the critical loads in engineering design is wind load, especially for high-rise structure or multi-story structure. In order to forecast the distribution of wind effects on structure, how to accurately predict the building surface wind pressure distribution is very important. Using the wind tunnel model test and numerical simulation calculation methods, the surface wind load on the mega-frame structure were comparatively analyzed and researched in this paper. The results show that combined the realized к-ε model with the standard wall function will not only satisfy the mega-frame structure surface wind pressure value requirement, but also provide complete wind filed around, which could provide meaningful information for further research on wind load.

Abstract: Most tall buildings are constructed in the prosperous center of large cities, where is inevitable to be surrounded by many interfering buildings. Wind interference effects among buildings should not be neglected. Therefore, it is necessary to investigate wind interference effects on such tall buildings. Based on the wind tunnel test of rigid model of a tall building, the wind pressure distribution on the building with interfering buildings around it has been researched, the contours of the mean and fluctuate wind pressure coefficients have also been presented. It has been found that shielding effect and channeling effect are significant in the wind interference effects on building. Wind pressure coefficients on side wall and leeward wall of a upstream building may be dramatically changed in case the wake boundary of the upstream building is interfered. The conclusions might be used as reference to structural design and plan.

Abstract: Wind tunnel tests of 1:100 rigid model of fish-shaped roof structures were carried out. The mean, fluctuating (RMS) and peak pressure coefficients, the local shape coefficient distributions on fish-shaped roofs were presented and discussed. It was found that negative pressures (suctions) occurred on the most areas on the roofs, and high negative pressure coefficients occurred on the eaves and cantilevered roof parts. When wind flows blew along the corridors under the roofs, the flows enhanced suctions on the surfaces of the roofs, and the suctions on the lower surface were greater than those on the upper surfaces, positive pressures occurred on that area after superposition of wind actions on the two sides. The roof eaves and regions above the corridors experienced the worst RMS pressure coefficients and the worst minimum pressure coefficients. The distribution characteristics of the worst RMS and minimum pressure coefficients were found to be quite similar to those of the mean pressure coefficients. The results obtained from the experimental investigation are expected to be useful in the wind-resistant design of complex roof structures in typhoon-prone regions.

Abstract: The Capture Trajectory System (CTS) is an advanced measurement method of the trajectory for store separation in wind tunnel test. According to the characteristics of good real-time, high reliability and a large amount of data processing in the CTS test, an open-architecture measurement & control system based on VXI bus and PMAC2 is proposed in this paper, and its overall scheme design, hardware composition and software structure are described. With IPC, embedded operator and PMAC2 applied, the three level microcomputer structure ensures the system has good real-time and accurate trajectory control. The hierarchical software and the modular design method make sure that the system has good portability, universality and extensibility.

Abstract: By the method of computational fluid dynamics (CFD), this paper calculates the aerodynamic parameters of one complex high-speed train model which adopts different support forms when the reference velocity is 70m/s under different operating conditions. It also analyses the support interference mechanism from the point of flow field structure. The results show that the distributed cylinder support form causes least interference on the model, while the single big cylinder support forms change the flow field structures much which leads to much change of the aerodynamic parameters of the model. The distributed cylinder support form can be applied as a good support form for the high-speed train wind tunnel tests.

Abstract: Based on mark points on the surface of bridge pneumatic model, adopting the DIC-Digital image correlation method to handle the pictures captured by CCD Video Camera in the high frequency get the displacement values of the mark points in the time series and thus obtaining the vibration forms of the bridge. The fundamental principles of the DIC-Digital image correlation method and its application were introduced in this paper and the reliability and stability of the method was testified by the comparison to the results measured by the laser displacement sensor