Institute Of Mechanics,Chinese Academy of Sciences
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一种引射惰性气体阻燃的锅炉爆炸吹灰技术
No full text本发明公开了一种引射惰性气体阻燃的锅炉爆炸吹灰技术，包括氧气气瓶、乙炔气瓶、氮气气瓶、文丘里引射器、燃烧爆炸装置、电磁阀、弯头、三通接头、圆形直管、圆形连接管、螺栓和螺母。本发明利用氧气与乙炔在燃烧爆炸装置内爆炸产生的气流反向通过文丘里引射器时引射惰性气体氮气，减弱爆炸对气体输送管路和电磁阀的冲击，并且氮气能够阻断爆炸产生的回火面，阻止燃烧回火面向气瓶和电磁阀延伸，延长设备的使用寿命，提高爆炸吹灰系统的安全性
一种使用氨工质的混合动力超声速发动机
No full text本发明提供了一种使用氨工质的混合动力超声速发动机，其包括发动机本体以及匹配设置于所述发动机本体内的上的进气道、预冷器、燃料泵、压气机、燃料涡轮、燃烧室、喷管和电动机；喷管设置在燃烧室一侧，在燃烧室中燃烧产生的气流从喷管喷射出去；混合动力超声速发动机还包括设在发动机本体内的燃料电池和蓄电池。本发明通过对高速飞行时发动机吸入的来流空气进行燃料预冷，不仅大幅降低了压气机所需功率，还预热了燃料电池及燃烧室化学反应的反应物，一举多得，使得整套混合动力系统方案得以封闭；同时通过蓄电池燃料电池‑燃烧室内的氨燃料燃烧有机融合组成了混合动力系统，动力实现更加多样性，能满足飞行器在各个飞行阶段下的动力需求
一种电磁线圈炮发射速度的智能调控装置及方法
No full text本发明提供了一种电磁线圈炮发射速度的智能调控装置及方法，该装置包括电磁驱动加载机械系统、激光测速控制系统、电控开关控制系统、电容容量控制系统、智能变压器控制系统和电脑主机控制系统。该方法为：通过电脑主机编写程序，借助电容容量控制器和智能变压器控制器，对电容容量大小和充电电压进行调控；通过电控开关控制器和激光测速控制器来执行电脑主机的程序指令，对每个铜线圈放电时刻进行控制并对每个铜线圈加速后的磁性子弹速度进行测量；反复多次发射磁性子弹，记录各项数据并反馈至电脑主机。本发明装卸便捷、精准调控、操作智能、安全可靠，可自动调节智能化地加速弹丸至千米每秒量级，为高速碰撞动力学问题的研究奠定实验基础
Experimental research on radiation in expansion regions of hypervelocity flow
No full text随着临近空间高超声速飞行器速度的不断提升，气动物理效应逐渐凸显。一般认为，在马赫数大于10的超高速飞行中，气动辐射现象不可忽略，能够形成复杂的飞行器光环境，进而影响到飞行器热防护设计、目标特性和光学载荷性能。
长期以来，气动辐射研究主要集中于激波波后和头部驻点等压缩区。然而，近年来国外飞行试验数据显示，在飞行器的肩部等膨胀区域测到了超出预期的辐射功率。这一现象的可能原因包括：膨胀流动中的热化学反应模型精度不足，或存在尚未认知的辐射机制。因此，开展膨胀区辐射实验研究具有重要的科学价值和工程意义。
在地面实验条件下模拟膨胀区流动并开展辐射测量面临极大挑战，主要包括高焓气流的产生与维持、可控膨胀流动的实现、以及低温下较弱辐射光谱信号的精确时空分辨测量等关键问题。基于此，本研究以探索超高速膨胀区辐射机理为核心目标，发展了基于多型脉冲式设备的超高速流动辐射实验平台，开展了激波波后、模型绕流膨胀区和模型尾迹膨胀区的辐射量化测量，获得氮气和空气工质下定量辐射光谱，发现并分析了膨胀区辐射的特殊机制。具体研究内容和成果如下：
（1）在Φ800激波管上实现了对低速（4.7 km/s）、低压（20 Pa）氮气工况下激波波后非平衡区的定量光谱测量。在580–740 nm波段实现了10 W/(m3·sr·nm) 量级微弱辐射信号的绝对光谱辐射强度测量。分析表明，计算光谱在绝对强度和光谱形状特征上与实验光谱具有较好的一致性。基于实验光谱获得了非平衡区的振动-电子温度和平动-转动温度，结果显示，态-态模型计算结果较双温度模型更接近实验值，但计算值仍与实验结果有明显差距。
（2）基于JF-14激波风洞发展了模型绕流膨胀区辐射实验平台。采用头部半径25 mm的半圆柱钝头模型，测量了模型肩部膨胀区的宽波段辐射光谱。实验涵盖多种典型工况：氮气工况（激波速度3.25 km/s、压力200 Pa）以及空气工况（3.51 km/s、200 Pa和3.92 km/s、100 Pa），测点处气体静温范围为4000 K–6000 K。实验结果表明：氮气工况下，肩部膨胀区辐射以氮分子第一正带系为主要特征，计算光谱与实验光谱形状相近，光谱强度比实验高3–4倍。近壁区域观测到了520 nm附近氮原子谱线，应与氮分子预离解机制有关。空气工况中，发现了明显的连续谱辐射现象，呈现短波强、长波弱的特点，且光谱强度比计算预测值高一个量级以上。该现象对应的辐射机制不明，强度远超现有理论预测；分析讨论了黑体辐射、韧致辐射、氧原子光复合等潜在可能辐射机制，均难以解释该现象。
（3）基于二级轻气炮开展了模型尾迹膨胀区辐射测量。实验采用直径19 mm的球形模型，在4.57 km/s飞行速度和19.5 kPa实验舱气体压力条件下测量了尾迹不同区域辐射特征。氮气工况中，尾迹区实验辐射光谱比计算结果高约一个量级，根据实验光谱，结合光谱理论计算和量子化学分析，发现基于双温度模型的流场计算预测严重偏离实际情况，尾迹膨胀区存在显著的高振动能级过布居特征。此外还探索了空气工况，观察到尾迹辐射为连续谱辐射特征，指向了NO2化学发光机制。
总之，本文重点面向膨胀区辐射实验数据匮乏、理论模型不确定性大等现实挑战，发展了多类辐射实验平台，基于量化光谱数据，发现了膨胀区辐射特殊现象，探讨了多种可能辐射机制，为膨胀区辐射建模和应用奠定基础。</p
A new high-order RKDG method based on the TENO-THINC scheme for shock-capturing
No full textIn recent years, Runge-Kutta Discontinuous Galerkin (RKDG) methods have gained substantial attention in solving hyperbolic conservation laws, attributed to their high-order accuracy and adaptability to unstructured meshes. However, standard RKDG methods cannot capture discontinuities without oscillation unless they are supplemented with troubled cell indicators and limiters. Existing indicators, such as the total variation bounded (TVB) minmod indicator and the KXRCF indicator, typically depend on a critical parameter tied to the equation's solution, necessitating tuning for different cases. In terms of limiters, the popular limiters even fail to guarantee the high-order property in the smooth regions. The advent of Weighted Essentially Non-Oscillatory (WENO) schemes prompts the implementation of WENO limiters for RKDG methods, preserving high-order properties. However, WENO-family schemes exhibit significant numerical dissipation, potentially smearing small-scale flow structures. In this work, the Targeted Essentially Non-Oscillatory (TENO) indicator [1] is utilized, which leverages the nonlinear weighting strategy of the TENO scheme to separate high-wavenumber physical fluctuations and genuine discontinuities from smooth regions with a unified set of parameters. For troubled cells, a novel limiter is proposed for structured meshes, which combines a TENO scheme for resolving high-wavenumber physical fluctuations and a novel non-polynomial Tangent of Hyperbola for the INterface Capturing (THINC) scheme for resolving genuine discontinuities with extremely low numerical dissipation. Furthermore, the shifting between the TENO and THINC schemes is based on a new boundary variation diminishing (BVD) strategy, which only relies on compact neighborhoods and is significantly simpler than its predecessors. Meanwhile, a new strategy is proposed to ensure the consistency of the new limiter applied for 1D and 2D cases. A set of 1D and 2D benchmark cases including strong shockwaves and a broad range of flow length scales is simulated with uniform meshes for 1D cases and structured quadrilateral meshes for 2D cases to demonstrate the performance of the new numerical scheme. The indicator does not activate any limiters in the accuracy test cases to ensure the high-order property of the whole numerica
Improving the energy performance of vortex pump based on whale optimization algorithm
No full textThis study introduced a multi-objective optimization framework for vortex pumps, utilizing the whale optimization algorithm (WOA) and Gaussian process regression (GPR) to enhance energy performance under various operating conditions. Initially, 12 design parameters were analysed using the Plackett-Burman test, identifying five critical hydraulic parameters. These parameters formed the basis for optimizing the pump's head and weighted efficiency. A surrogate model database was created using Latin hypercube sampling, and GPR facilitated the optimization process. The application of WOA resulted in a 1.94 m increase in head, a 1.72% rise in efficiency, and a 1.69% improvement in weighted efficiency. Entropy production and rigid vorticity analysis further showed a significant reduction in energy loss across pump components. This research offers a robust framework for the efficient and energy-saving design of vortex pumps
Aerodynamic control of evaporative self-assembly in colloidal droplets
No full textThe evaporation of colloidal droplets on solid surfaces frequently results in the undesirable "coffee ring effect", a well-known phenomenon that has attracted significant attention across various fields, including inkjet printing, micro/nano fabrication, and coatings, due to its adverse implications. Although several control strategies, such as heating, exist to mitigate the coffee ring effect, to develop a simple, efficient, and non-contact universal approach still remains a significant challenge. In this study, we present an innovative approach to enhance the interfacial evaporation of droplets by implementing actively controlled airflow. This airflow generates intense internal motion within the droplet, promoting a more uniform dispersion of colloidal particles. Simultaneously, it significantly increases the evaporation rate at the liquid-air interface, facilitating the capture of colloidal particles and their arrangement into well-organized crystal structures. In contrast to conventional methods, this approach does not necessitate any alterations to the substrate or liquid, thereby demonstrating broader applicability. We are optimistic that this advancement will positively influence the fabrication of high-quality, highperformance printed electronics
Fundamental investigation on the micro-explosion of aluminum-lithium alloy particle
No full textThe aluminum-lithium (Al-Li) alloy particle is considered to be a promising alternative for conventional aluminum particles to enhance energy release in solid propellants, owing to its tendency to undergo micro- explosions during combustion processes. In this study, both laser-induced ignition/combustion experiments and reactive molecular dynamics (RMD) simulations were performed to comprehensively capture the complete micro-explosion sequence of Al-Li alloy particles under a high-pressure oxygen condition. In combustion experiments, higher heating rates and Li concentrations effectively increase the probability of micro-explosions and shorten both the ignition delay time and the combustion time of Al-Li alloy particles. Meanwhile, RMD results reveal the micro-explosion mechanism from atomic scale, highlighting that the aggregation, melting, boiling and growth of Li cluster are the prerequisites for micro-explosion. The competition of stresses in the outer shell and inner Li cluster determine the micro-explosion phenomenon. In addition, influences of heating rates and Li concentrations on the micro-explosion were well clarified and their dependence was summarized. A high heating rate provides more energy to atoms within the Al-Li alloy particle through reactions and collisions, thereby shortening the duration of the atomic diffusion stage before micro-explosion. Furthermore, a high Li concentration enhances the expansion stress of the Li cluster to shorten the cluster growth stage. This systematic study establishes a fundamental understanding of the intricate mechanisms governing the micro-explosion of Al-Li alloy particles, offering potential insights for guiding practical applications
Neutrophils exhibit flexible migration strategies and trail formation mechanisms on varying adhesive substrates
No full textSubstrate anchorage is essential for cell migration, and actin polymerization at cell front and myosin contractility at cell rear are known to govern cell forward movement. Yet their differential driving strategies for neutrophil migration on distinct adhesiveness substrates and their contributions to the migration-induced trail formation remain unclear. Here we explore the morphological changes, migration dynamics, and trail formation of neutrophils on ICAM-1 and PLL substrates, with a focus on the relationships among adhesive forces, traction forces, and out-of-plane forces. Results indicate that, on ICAM-1, neutrophil migration and trail formation rely on the coordinated interactions of Arp2/3 and myosin, along with biochemical regulation ( via Syk and calpain) of adhesion and de-adhesion. This pattern leads to traction forces being concentrated at relatively fewer adhesive sites, facilitating cell forward migration. On PLL, however, neutrophils primarily depend on Arp2/3-mediated actin polymerization, resulting in a broader distribution of traction forces and weaker adhesions, which allows for higher leading-edge migrating velocities. Elevated membrane tension and out-of-plane forces generated by bleb protrusions on PLL reduce the reliance on myosin-driven contraction at the trailing edge, enabling easier tail detachment through elastic recoil. This work highlights the differential impact of substrate adhesiveness on neutrophil migration and trail formation and dynamics, providing new insights into cell migration mechanisms and potential therapeutic targets for inflammatory and immune-related disorders