共查询到19条相似文献,搜索用时 93 毫秒
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喷射式空调系统的实验与数值模拟研究 总被引:2,自引:2,他引:0
利用二维轴对称,真实气体模型对喷射式制冷空调系统的喷射器进行CFD计算。搭建喷射式空调实验系统,进行喷射式空调实验,验证CFD模型的可行性。利用验证的CFD模型,进行实验工况以外的数值计算,得到了喷射器在不同发生条件、蒸发条件和冷凝条件下的性能变化。在喷射器结构确定,其它条件不变时,发生温度tg必须要在一定范围内,71℃≤tg≤95℃,喷射器才能正常运行。在计算条件下,蒸发温度te越高,喷射器的性能越好。冷凝温度tc要在一定范围内:20℃≤tc≤40℃,喷射器才能正常工作。当冷凝压力低于临界压力时,喷射器的性能表现出恒能力特性。 相似文献
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本文基于人教版高中《 物理·必修2》中“ 实验: 验证机械能守恒定律”一节内容, 利用气垫导轨改进课
本中的实验, 验证了弹力参与做功时的系统机械能守恒. 此改进有益于加深学生对机械能守恒定律的全面理解 相似文献
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在自旋交换光泵过程中,多种参数可能会影响到最终可获得的超极化气体氙-129核自旋极化度.通过低场(0.002 T)核磁共振(NMR)系统研究了连续流动工作模式的自旋交换光泵过程,当混合工作气体流量为0.3 SLPM和0.5 SLPM时,实验测量得到最佳光泵泡工作温度;对于同位素富集和自然丰度的氙-129气体,核自旋极化度的建立时间分别为15 min和22 min.由于混合工作气体的压力以及组分会导致铷原子吸收线的频移和展宽,并且影响到其线型,实验通过低场NMR系统测量确定了用于自旋交换光泵的最佳激光工作波长.低场NMR测量为获得具有高核自旋极化度的超极化气体氙-129,并且能够用于人体肺部MRI研究提供了实验依据. 相似文献
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为研究多喷管超声速引射器在有二次流情况下的性能,采用模拟器产生给定总温和总压的模拟二次流,在多喷管超声速引射器实验台上进行了一系列实验。重点考察了多喷管引射器的性能以及一次流总压和喷管安装构型对其性能的影响。实验结果表明:多喷管超声速引射器可保证二次流在设计工况下正常工作;二次流的加入大大减小了一次流的总压损失;较低的一次流总压具有更好的压力匹配性能,但引射增压能力也有所降低;合理的喷管安装构型可同时提高引射增压能力和压力匹配能力。提出了将二次流作为“助推器”,以帮助多喷管引射器在较低工况下实现启动的方案,在不增加系统复杂度的前提下提高了引射器的压力匹配能力。 相似文献
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基于红外光谱分析的小温差物体距离估计 总被引:1,自引:0,他引:1
基于辐射传输特性的目标距离估计作为一项典型的被动测距技术,是目前光电对抗领域的一个研究热点。在测距过程中无需向外界发射能量,使得这种探测方式极大地增强了导弹或无人机的隐身能力和突防能力。针对现有被动测距系统不适用于对迎面而来目标物体实施被动距离估计的不足,提出了一种改进的小温差目标距离估计方法。在引入了信号传递函数概念的基础上,明确了当前算法的工作曲线,指出这种方法的非线性会导致目标距离估值不唯一的风险。本文应用非线性校正技术,构造了新的距离估计算法。得到了一个利用3~5和8~12 μm双波段红外传感信息,目标背景温度和气象条件的测距公式。研究表明,当目标与背景表观温差等于5 K、而背景温度估计偏差不超过±5 K时,目标距离估计误差可控制在10%左右。 相似文献
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为了拓宽等离子体参数测量范围,对EAST极向弯晶谱仪(PXCS)进行了升级改造。配合高通量大面积水冷固体探测器,提高了极向弯晶谱仪系统的光子计数率、时间分辨率、空间探测范围以及长时间运行稳定性,并在EAST装置上成功运行。实验结果表明,升级后的谱仪获得了高信噪比的类氦氩离子的母线及其一系列伴线谱,通过光谱拟合分析给出了等离子体温度时间演化及其剖面信息,测量结果与切向弯晶谱仪的数据一致,验证了极向弯晶谱仪的升级结果和数据测量的可靠性,并且在EAST长脉冲实验运行也能够稳定地提供全时间的参数分布。 相似文献
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《Heat Recovery Systems and CHP》1993,13(5):409-418
The thermodynamic performance of a variety fluids circulated in an ideal organic Rankine cycle (ORC) engine has been evaluated with the aid of the Iwai-Margerum-Lu equation of state. Two merit number indices were also calculated to represent the inherent heat-transfer capability of the working media at evaporation and condensation, respectively. The result indicated that the thermophysical capability of compounds correlates with the fluid's normal boiling point, critical pressure and molecular weight. It also showed that HCFC-123 could be one of the most favourable ozone-safe working fluids for the ORC energy-recovery system. 相似文献
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The analysis and experimental procedure of a controlled temperature laser heat treating process are reported.Key features are the ease of predicting working results and the capability of getting on-line process diagnostics for use in a highly automated industrial environment. 相似文献
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The research on the setup and application of scanning near-field optical microscopy (SNOM) performed in our laboratory is reviewed in this report. We have constructed a versatile low temperature scanning near-field optical microscope with the capability of near-field imaging and spectroscopy, operating at liquid nitrogen temperature. A special designed coaxial double lens was used to introduce the illumination beam through a 200μm fiber; the detected optical signal was transmitted via a fiber tip to an avalanche photon detector. The performance test shows the stability of the new design. The shear force image and optical image of a standard sample are shown. A system of SNOM working at room temperature and atmosphere was used to characterize semiconductors and bio-molecular samples. It revealed the unique features of semiconductor microdisks in the near-field that is significantly different from that of far-field. The effects of different geographic microstructures on the near-field light distribution of InGaP, GaN, and InGaN multi-quantum-well microdisk were observed. 相似文献
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Jianxun Jin Luhai Zheng Youguang Guo Wei Xu Jianguo Zhu 《Physica C: Superconductivity and its Applications》2011,471(17-18):520-527
A high temperature superconducting (HTS) linear propulsion system composed of a single-sided HTS linear synchronous motor (HTSLSM) in its middle and HTS magnetic suspension sub-systems on both sides has been developed. The HTSLSM uses an HTS bulk magnet array on the moving secondary, and the field-trapped characteristics of the HTS bulk using different magnetized methods have been measured and compared to identify their magnetization capability. In order to generate a large levitation force for the system, three different types of permanent magnet guideways (PMGs) have been numerically analyzed and experimentally verified to obtain an optimal PMG. Based on comprehensive experimental prototype tests, the results show that the HTS linear propulsion system can run with stable magnetic suspension having a constant air-gap length, and the thrust characteristics versus the exciting current, working frequency and the air-gap length have also been obtained. This work forms the basis for developing a practical HTS linear propulsion system by using HTS bulks both for propulsion and suspension. 相似文献
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介绍了采用PIN硅光电二极管作光接收器件实现的一种被动式实时测温系统。该系统主要由光学接收系统、信号放大与处理系统及显示系统三部分组成。从系统的相对测温灵敏度及探测器的温度分辨力与波长间的关系出发,结合大气对红外辐射的透射特性,确定了系统的工作波长;从系统的抗反射辐射能力出发,并结合探测器的最小可探测光功率要求,确定了系统的波长带宽。从P1、P2的测量不确定度出发,讨论了待测目标的发射率及温度的测量精度。结果表明,当λ=0.80μm、Δλ=20nm时,在测温范围600~2500℃内,系统的测温不确定度优于0.3%,满足设计要求。 相似文献