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关键词： 复杂地形   高边坡   风机   湍流风场   大涡模拟  

摘要： 复杂地形风电机组建设时易形成高边坡地形,可能严重影响机组的发电量和疲劳寿命。以重庆市某复杂山地风电场为例,基于CDRFG(Consistent Discretizing Random Flow Generation)方法生成大气边界层湍流入口,采用大涡模拟技术重现高边坡复杂地形的湍流风场分布,并根据激光测风雷达和测风塔实测数据验证大涡模拟结果的准确性;对比分析了风机平台开挖导致的3种不同高边坡地形下,风机机位湍流风场的差异性,提出了风机平台开挖影响评估指标,深入分析了高边坡地形对风电机组发电效益和安全运行的影响。研究为复杂地形风机平台建设提供了科学保障。

关键词： 激波   Richtmyer-Meshkov不稳定性   气柱   射流   微喷射   环量  

摘要： 针对实际应用中激波与物质近表面杂质及孔洞等相互作用中的界面邻近效应,通过数值模拟开展了下游平面重-轻界面对激波诱导重气柱演化影响的简化机理研究。结果表明,激波冲击气柱形成的衍射和透射波系依次冲击下游界面,在气柱与下游界面之间形成来回反射的波系结构,这些波系不仅影响气柱的界面演化,而且在下游界面诱导产生射流。在不同的界面间距条件下,气柱外部衍射波系在下游界面的反射波系不同,这些反射波系及气柱内部聚焦波系冲击气柱右极点的先后顺序也存在差异。当界面间距较小时,气柱射流可以穿透气柱与下游界面之间的间隙流体,并与下游界面射流耦合,显著促进气柱射流的演化。随着界面间距的增大,射流耦合现象逐渐减弱,重气柱演化涡对抑制了气柱射流的发展。当界面间距进一步增大时,气柱射流又会因下游界面反射稀疏波系的拉伸作用而被促进。此外,在不同的界面间距条件下,下游界面的存在均对气柱界面宽度、高度的发展及环量沉积起到促进作用。

关键词： 初中物理   重力   二力平衡   力学   力的合成   浮力  

摘要： 浮力问题是初中物理力学部分的重难点,其综合性极强,涉及重力、力的合成、二力平衡、压力、压强、密度等诸多知识点。下面对浮力相关的考点进行梳理,以帮助同学们更好地理解和掌握浮力知识。

关键词： Hypersonic   Thermochemical non-equilibrium flow   Wall temperature effect  

摘要： During the re-entry of a hypersonic aircraft into the earth's atmosphere, the surrounding air experiences dissociation, ionization, and other complex chemical phenomena due to extreme temperature by shock wave. To ensure thermal safety, the thermochemical non-equilibrium effects resulting from real-gas behavior should be taken into account. In this paper, the characteristics of a double-cone hypersonic laminar flow, including distributions of wall pressure, heat flux, and species dissociation are numerically analyzed with incoming enthalpy of 9.65-21.77 MJ/kg. The thermochemical non-equilibrium flow at different enthalpy and wall temperatures is performed with two-temperature model and Park's seven chemical reaction model. It is found that the double-cone flow features complex shock-shock interactions to form triple points. The flow topology is further brought out from the analysis of streamlines. At the lowest incoming enthalpy with isothermal wall conditions, two foci points appear. While others highlight only one focal point. As the increment of incoming enthalpy, the heat flux and dissociation of nitrogen and oxygen also increase. An increasing wall temperature leads to a larger separation bubble and a lower value of heat flux and pressure peak, while massive dissociation occurs without obvious ionization under considered cases.

关键词： Hypersonic flow  

摘要： In response to the issue of different cold/hot jet differences caused by the hot jet effect under various incoming flow conditions，the impact of jet temperature on the interaction flow field and aerodynamic characteristics was studied by numerically by solving the three-dimensional multi-component Reynolds-averaged Navier-Stokes (RANS) equations to simulate the typical aircraft configuration's divert jet interaction flow field. The differences in cold/hot jet interaction under various incoming Mach numbers and flight altitude conditions were analyzed. The study showed that the impact of jet temperature on the interaction flow field exhibited a coupled influence mechanism of mass and energy fluxes. When the total enthalpy ratio was higher than 1，the influence of jet energy flux was more significant than the mass flux. Conversely， when the total enthalpy ratio was lower than 1， the influence of jet mass flux was more significant than the energy flux. As the incoming Mach number increased， the total enthalpy ratio decreased，and the influence of jet mass flux became more pronounced than that of energy flux，and the interaction flow field range of cold jets with large mass flux gradually exceeded that of hot jets，and the force interaction factor caused by cold jets gradually exceeded that of hot jets. As the flight altitude increased，the total enthalpy ratio was constant，and the proportion of influence of jet mass flux and energy flux kept unchanged，the qualitative rule of cold/hot jet interaction differences remained unchanged，but the reduction in incoming dynamic pressure resulted in an overall decreasing trend of the jet interaction force and moment，it also led to an overall decreasing trend in the difference between the force interaction factor and the shift amount of jet force center of cold and hot jets interaction. © 2025 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.

关键词： 以家庭为中心   老年衰弱者   照顾者   照顾能力   心理压力  

摘要： 探讨以家庭为中心的护理对衰弱老年人照顾者及心理压力的影响。方法 选取xx社区90例衰弱老年人及其主要照顾者为研究对象(2024年1月至8月期间),将其采用抽签的方法分为对照组(常规护理)和观察组(常规护理+以家庭为中心的护理),每组45例。采用相应的量表评估两组患者主要照顾者照顾能力、心理压力的情况,并进行比较。结果 两组患者干预1个月后在照顾能力测量表(FCTI)各维度方面的差异有统计学意义(P<0.05),其中观察组在适应照顾角色、应变及提供协助、调整个人生活及满足需求等维度的能力更好。两组患者干预1个月后在照顾者负担量表(ZBI)方面的评分的差异有统计学意义(P<0.05),其中观察组评分更低。结论 以家庭为中心的护理能够有效提升老年衰弱患者照顾者的照护能力,同时缓解其心理压力。