Papers by Keyword: Wind Tunnel Test

Abstract: For the continuously-varying dynamic pressure flutter test data in the high-speed wind tunnel; this paper analyzes the strengths and weaknesses of the data Processing Method in this field. The data selection and stacking mode is improved. A Butterworth IIR digital filter is used for digital filtering. The power spectral density function is computed by Fourier transform of the autocorrelation function. A pick-hold method is used to predict the flutter critical point. It is indicated that our method features high accuracy and efficiency by theoretical analysis and wind tunnel flutter test.

Abstract: A method of measuring wavefront distortion field is presented in this paper, which gets the OPD through measuring deviation displacement field induced by the beams from center of camera to the mark points crossing the flow field. The experiments of a trans-aerosphere vehicle model in 2 meter supersonic tunnel have demonstrated that the method of this paper can be used to measure the large field of wavefront distortion, and the structures of wavefront distortion generated by oblique shock waves of the vehicles head and wing are correct. This method is simple and provides a new way to measure and observe aero-optics phenomena.

Abstract: To effectively excite the all moving wing flutter model and limiting or quick locking model in case of bigger amplitude of the model, an excitation and limiting and locking device is designed for the high-speed wind tunnel flutter test model. This paper introduces the structure arrangement, control principle and strategy of this device. The wind tunnel flutter test indicates that this device can enhance the SNR of the test data, improve the boundary prediction precision of flutter, prevent the model from entering the flutter divergence state and protect the model and wind tunnel test equipment.

Abstract: Liujiaxia Bridge is a truss stiffening girder suspension bridge which span is 536m, and it is the narrowest suspension bridge with the same scale, so the problems of flutter stability are prominent. Results of wind tunnel test show that its critical velocity cannot meet the requirements without any aerodynamic measures. Based on above considerations, seven kinds of aerodynamic measures are proposed, respectively wind tunnel tests are conducted. The results show that the program, in which the upper central stable board is 1.12m high and the under central stable board is 1.28m high, can meet the requirements. The results of this study provide some references to solving the problem of wind-resistant stability of narrow deck suspension bridge.

Abstract: In order to investigate the aerodynamic interference effects between parallel bridges, the aerodynamic interference effects on aerostatic coefficients of double thin-walled hollow pier in the parallel continuous rigid frame bridges with high-pier and long-span were investigated in details by means of wind tunnel test. The tandem interval and side-by-side interval between the two piers and wind direction angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of twin piers. The test got aerostatic coefficients of 10 conditions. The research results have shown that the aerodynamic interference effects on aerostatic coefficients of double thin-walled hollow pier in parallel bridges can not be ignored. The tandem interval and side-by-side interval between the two piers and wind direction angles are important factors affecting interference effects. The drag coefficient, lateral force coefficient and torque coefficient are affected by these factors.

Abstract: Storm cause deformation and collapse of structure, endanger people's life and property security. In order to avoid or reduce the impact of wind load effectively, the paper mainly introduce wind tunnel test, numerical wind tunnel method, time domain analysis, frequency domain analysis and the research and application of domestic scholars.

Abstract: A series of wind tunnel aerodynamic experiments were conducted to investigate the wind loads on the low-rise buildings located around the hillside. The result shown, the steep roof slope may cause a separation bubble at the edge and the small separation shear layer reattached the roof just near the edge due to the steep slope of roof at the uphill side. At the downhill side, the mean pressures of the building with gently slope roof to be positive for most of them. The building seems to be covered by the hill separation bubble, and the approaching flow with negative inclination acting on the buildings. The surface pressures of low-rise buildings may not reflect the local shear layer behaviors, but they shown the acting results of the wake of the hill. The fluctuating pressures distribution at low-rise buildings located at hillside would slightly less than the ones without hill.

Abstract: With wind tunnel tests, simultaneous pressure measurements are made on 4 cylindrical roof models with different rise-span ratios and roof inclinations. Effects of these geometrical factors on wind pressure characteristics of the roofs are investigated, including mean pressure coefficients, RMS pressure coefficients, skewness, kurtosis, and probability distributions of wind pressure. Results show that the mean vertical wind force coefficient of high rise-span ratio roof is larger than that of the low rise-span ration roof; the mean pressure coefficient distribution of the low rise-span ratio roof is similar to that of RMS pressure coefficients and the skewness (or the kurtosis); the vortex center line occurs at the windward edge for the low rise-span ratio roof with inclination 0°, which occurs at the roof apex for the high rise-span ratio roof. The roof inclination has more effects on the low rise-span ratio roof, the vortex moves from the windward edge to the apex for the roof with inclination 7.2°when the wind flows from the low eave to the high eave. The distribution of the skewness is strongly correlative to that of the kurtosis. The probability distributions of the roof edges and corners deviate obviously from the Guass distribution. If this point is ignored, the peak suction pressure will be underestimated.

Abstract: The many low rise roof structures are sensitive to the effects of fluctuating wind load. In engineering design for the structures, spatiotemporally varying wind loads on the low rise roofs are modeled as equivalent static wind loads. In this paper, the equivalent static load of the large span roofs is formulated in terms of either a weighted combination of modal inertial load components, and the resonant and background load components that was obtained by the POD (Proper Orthogonal Decomposition) and LRC (Load –Response -Correlation) techniques.

Abstract: Aerodynamic drag reduction of commercial truck at high speed is one of the important ways to reduce its energy consumption. CFD simulation and wind tunnel tests are performed on a kind of commercial truck, to study the influence of the cab shape and different kinds of guide cowls on aerodynamic drag, and the impact mechanism was also analyzed. It shows that the cab shape will make great contributions to the aerodynamic drag while the truck travelling, and through improving the shape of cab, guiding the air flow passed, it can effectively reduce the aerodynamic drag and achieve energy saving.