In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measur...In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.展开更多
为实现对爆炸温度场的动态测量,针对爆炸温度场变化快、范围广、温度高、难以测量的问题,提出一种基于高速成像技术的爆炸温度场测温方法。基于辐射原理推导出高速成像系统的温度测量模型,建立高速相机图像灰度值和被爆炸温度之间的对...为实现对爆炸温度场的动态测量,针对爆炸温度场变化快、范围广、温度高、难以测量的问题,提出一种基于高速成像技术的爆炸温度场测温方法。基于辐射原理推导出高速成像系统的温度测量模型,建立高速相机图像灰度值和被爆炸温度之间的对应关系,得到可通过控制高速成像系统曝光时间和透光率2个参数控制测温范围的算法;搭建高速成像爆炸温度场测量系统,用最小二乘法对系统进行标定,标定结果显示:该建模方法在2200~2900℃区间平均误差为0.74%,在1850~2350℃区间平均误差为1.95%,能够满足爆炸温度场的测量需求。运用搭建的系统与红外测温仪分别进行375 g、750 g及1500 g 3种药量的温压弹爆炸温度测量对比实验,实验结果表明:该系统与红外测温仪之间的温度测量值最大偏差为3.31%,实现了高响应速率及高分辨率测量。展开更多
The measurement of position and attitude parameters for the isolated target from a highspeed aircraft is a great challenge in the field of wind tunnel simulation technology.In this paper,firstly, an image acquisition ...The measurement of position and attitude parameters for the isolated target from a highspeed aircraft is a great challenge in the field of wind tunnel simulation technology.In this paper,firstly, an image acquisition method for small high-speed targets with multi-dimensional movement in wind tunnel environment is proposed based on laser-aided vision technology.Combining with the trajectory simulation of the isolated model, the reasonably distributed laser stripes and selfluminous markers are utilized to capture clear images of the object.Then, after image processing,feature extraction, stereo correspondence and reconstruction, three-dimensional information of laser stripes and self-luminous markers are calculated.Besides, a pose solution method based on projected laser stripes and self-luminous markers is proposed.Finally, simulation experiments on measuring the position and attitude of high-speed rolling targets are conducted, as well as accuracy verification experiments.Experimental results indicate that the proposed method is feasible and efficient for measuring the pose parameters of rolling targets in wind tunnels.展开更多
基金Projects(51808563,51925808)supported by the National Natural Science Foundation of ChinaProject(KLWRTBMC18-03)supported by the Open Research Fund of the Key Laboratory of Wind Resistance Technology of Bridges of ChinaProject(2017YFB1201204)supported by the National Key R&D Program of China。
文摘In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.
文摘为实现对爆炸温度场的动态测量,针对爆炸温度场变化快、范围广、温度高、难以测量的问题,提出一种基于高速成像技术的爆炸温度场测温方法。基于辐射原理推导出高速成像系统的温度测量模型,建立高速相机图像灰度值和被爆炸温度之间的对应关系,得到可通过控制高速成像系统曝光时间和透光率2个参数控制测温范围的算法;搭建高速成像爆炸温度场测量系统,用最小二乘法对系统进行标定,标定结果显示:该建模方法在2200~2900℃区间平均误差为0.74%,在1850~2350℃区间平均误差为1.95%,能够满足爆炸温度场的测量需求。运用搭建的系统与红外测温仪分别进行375 g、750 g及1500 g 3种药量的温压弹爆炸温度测量对比实验,实验结果表明:该系统与红外测温仪之间的温度测量值最大偏差为3.31%,实现了高响应速率及高分辨率测量。
基金supported by the National Natural Science Foundation of China (Nos.51375075, 51227004)the Scientific Research Fund of Liaoning Provincial Education Department of China (No.L2013035)the Science Fund for Creative Research Groups of China (No.51321004)
文摘The measurement of position and attitude parameters for the isolated target from a highspeed aircraft is a great challenge in the field of wind tunnel simulation technology.In this paper,firstly, an image acquisition method for small high-speed targets with multi-dimensional movement in wind tunnel environment is proposed based on laser-aided vision technology.Combining with the trajectory simulation of the isolated model, the reasonably distributed laser stripes and selfluminous markers are utilized to capture clear images of the object.Then, after image processing,feature extraction, stereo correspondence and reconstruction, three-dimensional information of laser stripes and self-luminous markers are calculated.Besides, a pose solution method based on projected laser stripes and self-luminous markers is proposed.Finally, simulation experiments on measuring the position and attitude of high-speed rolling targets are conducted, as well as accuracy verification experiments.Experimental results indicate that the proposed method is feasible and efficient for measuring the pose parameters of rolling targets in wind tunnels.
