基于喷雾冷却时液滴撞击壁面现象,本文采用CLSVOF(coupled level set and volume of fluid)方法对不同工况下单液滴撞壁过程进行数值模拟,获得了单液滴撞击热壁面动态特性;分析了初始速度、液滴直径等初始参数对液滴撞壁后的动态铺展规...基于喷雾冷却时液滴撞击壁面现象,本文采用CLSVOF(coupled level set and volume of fluid)方法对不同工况下单液滴撞壁过程进行数值模拟,获得了单液滴撞击热壁面动态特性;分析了初始速度、液滴直径等初始参数对液滴撞壁后的动态铺展规律以及壁面换热特性的影响规律,获得了上述参数变化时液滴铺展系数和热流密度的变化趋势;探讨了场协同效应、液滴内部气泡以及三线接触点对壁面换热的影响。碰壁现象的研究对于大型制冷机组室外机散热、高热流电子器件散热等领域优化与控制喷雾有重要意义。展开更多
How to measure the two-dimensional attitude angle of space target and achieve stable tracking and aiming has become an important problem. The self-collimation is often measured via one-dimensional motion of the object...How to measure the two-dimensional attitude angle of space target and achieve stable tracking and aiming has become an important problem. The self-collimation is often measured via one-dimensional motion of the object in space. This paper proposes a micro-angle measurement system based on self-collimation to obtain the two-dimensional angle information of moving objects in space, and a thrice reflecting optical path structure is built to improve the compactness of the system. First, by establishing a posture angle measurement and decomposition model, the two-dimensional deflection angle value of the reflecting mirror is derived from the rotation angle equation;Second, the self-collimating measurement process is simulated to show the relationship between the reflecting mirror rotation angle and the imaging spot distortion of detector;Third, a two-dimensional micro-angle experimental platform is established based on the Position Sensitive Detector(PSD). Finally, nonlinear error of PSD is improved by the cubic spline interpolation method. The case results show a 15% reduction in the angle error.展开更多
A prism-excited multilayer film Surface Plasmon Resonance(SPR)sensing structure of graphene-silver-graphenemeasured mediums is proposed to solve the unstablility and oxidization problem of metallic silver films for SP...A prism-excited multilayer film Surface Plasmon Resonance(SPR)sensing structure of graphene-silver-graphenemeasured mediums is proposed to solve the unstablility and oxidization problem of metallic silver films for SPR sensors.By adding a graphene layer,the poor stability and the oxidization problem of silver film are solved.The electromagnetic field and reflection mechanism of the multilayer film structure are theoretically analyzed.The characteristics of the different metal materials for SPR,the distinct silver film thickness,and different graphene layers are studied through experiments to optimize the sensor design.Compared with the gold film sensor,the sensitivity of the multilayer film sensor with graphene layer is improved.The designed SPR sensor is used to detect a sucrose solution with a concentration of 0%-64%,and its refractive index is 1.33 to 1.45,linear correlation coefficient is 0.9984.Good resonance effect and sensing characteristics are thus obtained.展开更多
文摘基于喷雾冷却时液滴撞击壁面现象,本文采用CLSVOF(coupled level set and volume of fluid)方法对不同工况下单液滴撞壁过程进行数值模拟,获得了单液滴撞击热壁面动态特性;分析了初始速度、液滴直径等初始参数对液滴撞壁后的动态铺展规律以及壁面换热特性的影响规律,获得了上述参数变化时液滴铺展系数和热流密度的变化趋势;探讨了场协同效应、液滴内部气泡以及三线接触点对壁面换热的影响。碰壁现象的研究对于大型制冷机组室外机散热、高热流电子器件散热等领域优化与控制喷雾有重要意义。
基金Supported by the National Natural Science Foundation of China (61701296, U1831133)the Natural Science Foundation of Shanghai (17ZR1443500)the Shanghai Aerospace Science and Engineering Fund (SAST2017-062)。
文摘How to measure the two-dimensional attitude angle of space target and achieve stable tracking and aiming has become an important problem. The self-collimation is often measured via one-dimensional motion of the object in space. This paper proposes a micro-angle measurement system based on self-collimation to obtain the two-dimensional angle information of moving objects in space, and a thrice reflecting optical path structure is built to improve the compactness of the system. First, by establishing a posture angle measurement and decomposition model, the two-dimensional deflection angle value of the reflecting mirror is derived from the rotation angle equation;Second, the self-collimating measurement process is simulated to show the relationship between the reflecting mirror rotation angle and the imaging spot distortion of detector;Third, a two-dimensional micro-angle experimental platform is established based on the Position Sensitive Detector(PSD). Finally, nonlinear error of PSD is improved by the cubic spline interpolation method. The case results show a 15% reduction in the angle error.
基金Supported by the National Natural Science Foundation of China(61701296)。
文摘A prism-excited multilayer film Surface Plasmon Resonance(SPR)sensing structure of graphene-silver-graphenemeasured mediums is proposed to solve the unstablility and oxidization problem of metallic silver films for SPR sensors.By adding a graphene layer,the poor stability and the oxidization problem of silver film are solved.The electromagnetic field and reflection mechanism of the multilayer film structure are theoretically analyzed.The characteristics of the different metal materials for SPR,the distinct silver film thickness,and different graphene layers are studied through experiments to optimize the sensor design.Compared with the gold film sensor,the sensitivity of the multilayer film sensor with graphene layer is improved.The designed SPR sensor is used to detect a sucrose solution with a concentration of 0%-64%,and its refractive index is 1.33 to 1.45,linear correlation coefficient is 0.9984.Good resonance effect and sensing characteristics are thus obtained.
