Measurement of heat flux distribution of supercritical kerosene fueled supersonic combustor

Heat flux distribution of supercritical kerosene fueled, single-side expanded supersonic combustor with two dislocated cavities was experimentally studied. The effects of inlet Mach number, total temperature, mass flow rate and fuel equivalence ratio on the combustion and heat transfer characteristics in the supersonic combustor were analyzed. The isolator inlet Mach number is 2.0 and 2.5, the total temperature is 1305 K to 1701 K and the mass flow rate is 2.0 kg/s to 3.0 kg/s. Pilot hydrogen and liquid or supercritical (773±20 K) China No.3 kerosene were injected in front of the cavities with the equivalence ratio ranges from 0.52 to 0.88. Results show that heat flux increases with the inlet temperature and mass flow rate, however, the influence of equivalence ratio is non-monotonic in the range of this study. The two inlet Mach numbers also trigger different combustion modes, which further complicates the heat flux distribution. In the end, a three parameter correlation is proposed and fitted to normalize the experiment results for comparison and discussion. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved

Surface and Sructure Investigations of Membrane Electrode Assembly in DMFC Lifetime Testing~*

设计并组装单电池寿命测试系统,测试直接甲醇燃料电池(DMFC)的运行寿命,获得不同运行时间下单电池的极化和功率曲线.测试结束后,分别对运行过的膜电极(MEA)催化剂(铂黑和铂钌黑)和Nafion117(膜作XRD,HRTEM,FTIR及Raman等表征.考察在长期运行条件下电池寿命性能与膜电极中催化剂的颗粒大小、分布、形态、表面物种以及膜的结构之间的关系.寿命测试结果表明,单电池在不同运行阶段其性能变化也不同.运行前200 h,电池性能衰减较显著;运行200~704 h性能较稳定,运行1 002 h后电池性能恶化.波谱实验发现,单电池长期运行后,其膜电极的阴、阳极催化剂颗粒变大.电池寿命性能的衰退伴随膜电极微结构、表面组成、催化剂/膜界面结构的变化以及Nafion 117(膜的老化.The lifetime and performance of a direct methanol fuel cell (DMFC) were investigatedto understand the correlation between thestructure of catalysts /membrane and cell performanceversus time.The cell polarization and performance curves were obtained during the DMFC operation with the time.The catalysts and Nafion~ membrane of the membrane electrode assembly (MEA) from the lifetime test were comprehensively examined by XRD, HRTEM, FTIRand Raman spectroscope techniques.The results revealed that there was significant performance degradation during the first 200 hours operation; while the degradation was slowing down between 200 and 704hours operation.The degradation became worse after 1 002 h operation.The increases of the catalyst particle size from both anode and cathode catalysts wereobserved after the DMFC lifetime test.The changes of microstructure, surface composition, the interfacial structure of the MEA, and the aging of Nafion~ under the DMFC lifetime tests were also observed.作者联系地址：厦门大学化学系,厦门大学化学系,厦门大学化学系,厦门大学化学系,厦门大学化学系 固体表面物理化学国家重点实验室厦门大学材料科学与工程系厦门361005 ,固体表面物理化学国家重点实验室厦门大学材料科学与工程系厦门361005 ,固体表面物理化学国家重点实验室厦门大学材料科学与工程系厦门361005 ,固体表面物理化学国家重点实验室厦门大学材料科学与工程系厦门361005 ,固体表面物理化学国家重点实验室厦门大学材料科学与工程系厦门361005Author's Address: Department of Chemistry*, Department of Materials Science and Engineering, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005,Chin

Electrochemical Behavior of Redox Proteins on ZnO Nanorod-Modified Electrodes Prepared by Electrodeposition

Corresponding authors. ZHOU Jian-Zhang, Email: [email protected]; Tel: +86-592-2189663.[中文文摘]采用恒电位阴极还原法在金电极表面一步修饰ZnO纳米棒,制备成ZnO纳米棒修饰电极.扫描电子显微镜(SEM)和X射线衍射(XRD)结果显示制得的ZnO为直径约100nm的六棱柱状纤锌矿晶体纳米棒.使用ZnO纳米棒修饰的金电极研究细胞色素c的直接电化学行为,结果表明:ZnO纳米棒修饰的金电极能有效探测到细胞色素c的铁卟啉辅基在不同价态下的电化学行为;细胞色素c吸附后,ZnO纳米棒修饰的金电极对过氧化氢的电流响应呈现良好的线性关系.[英文文摘]We successfully prepared ZnO nanorod-modified Au (ZnO nanorod/Au) electrodes using one-step cathodic electrodeposition. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the morphology and crystal phase of the ZnO nanorods. The data showed that the ZnO nanorods were wurtzite type crystals with a hexagonal rod shape and a diameter of about 100 nm and that the ZnO nanorods were arranged well on the surface of electrodes. These ZnO nanorod-modified electrodes were able to detect direct electron transfer from cytochrome c (cyt c). Cyclic voltammograms showed that the direct electron transfer of cyt c with heme iron in different valence states was easily achieved by the ZnO nanorod/Au electrode. Data of amperometric responses demonstrated that a linear amperometric response to hydrogen peroxide was observed on the ZnO nanorod/Au electrodes after adsorbing cyt c.国家自然科学基金(20603027,21021002,20973134); 国家高技术研究发展专项经费项目(2009AA03Z327)资

Experimental study on thermal environment of scramjet combustor

超声速燃烧冲压发动机是实现高超声速巡航飞行的关键技术，作为超燃冲压发动机的核心部件，超声速燃烧室是其中热环境最恶劣的部分。超声速燃烧室的热流测量和分析对超燃冲压发动机热防护系统的研制具有重要意义。 本文针对超声速燃烧室的热环境测量和分析做了四方面工作：改进了原有的热流计加工工艺，设计了新的快速标定装置，使热流计能稳定可靠地应用于大规模试验中；对超声速燃烧室热环境进行了详细的参数化的试验研究，得到了一批实验数据并进行了分析；将试验结果与CFD及准一维性能分析方法得到的结果进行了相互比较和分析；提出一套利用一维化CFD结果用于验证准一维性能分析程序的方法。 首先，为了保障较大规模的试验的中热流测量系统的顺利运行，本文针对原有热流计的稳定性和可靠性问题进行了研究，发现导热胶层的质量和高温可靠性是热流计可靠性的瓶颈，从而提出了采用梯级钎焊工艺代替原有的粘压工艺制作热流计的新方法。使用改进后的方法生产的热流计成品率提高1.5倍，技术指标离散程度显著降低，热流灵敏度为12.45±2.84W/cm2/mV，温差灵敏度为35.3±12.5K/mV，响应时间为8.23±1.20s。本文还设计和制作了可以同时标定热流灵敏度和温差灵敏度的稳态电加热热流标定装置，简化了标定流程并提高了标定效率，将标定时间从2小时/个降低至15分钟/个。 其次，针对超声速燃烧的复杂流场中可能影响热流分布的关键参数，本文设计了五组共14次试验，在力学所长时间直连式超声速燃烧试验台上，利用自制的热流传感器，对采用对置错位凹腔的超声速燃烧室上、下和侧板的热流密度分布进行了参数化研究。试验中燃料主要采用超临界的RP-3煤油(温度773±20 K），入口Mach数范围为2.0到2.5，来流总温1305K到1701K，质量流量2.0kg/s至3.0kg/s，煤油当量比0.52到0.88。试验结果确认了热流密度不对称性和地面试验背压导致的分离对热流密度的影响，并分析了其随各主要参数的变化规律，发现热流密度分布随总温线性变化、随流量的0.8次方增加，但是存在热流密度随当量比变化不大，并受来流Mach数影响较大等现象。根据试验数据，在现有理论的基础上，本文针对冷态隔离段的平均热流密度提出了一个三参数的关联式，热流密度根据该关联式归一化后显示出一定的相似性。 然后，本文将试验结果与准一维计算值和采用分离涡模拟（DES）的CFD结果进行了比较，发现计算结果在趋势和量级上能与试验数据相符，但是局部细节有诸多差异。由于流动分离导致芯流面积减小，准一维性能分析方法计算得到的热流值在有较强激波串的隔离段内存在一非物理的热流峰值，而对于隔离段内激波串较弱的情况，则与试验值符合得比较好。通过对采用分离涡模拟的第8次试验的DES计算结果流场与试验值的对比，发现二者基本趋势一致，但是DES结果在上板燃烧区计算得到的热流比试验值偏大约1/3，而在下板边界层受波系扰动区域，DES结果出现热流增大现象，与试验值不一致。同时，DES结算结果显示分层流动和横向效应对热流的空间分布有一定影响。 最后，本文提出了一套将CFD结果进行一维化的方法，并以此对准一维性能分析方法的准确性和误差进行了验证，发现即使在分层流动中准一维性能分析方法计算平均速度依然非常准确，但在计算其他截面平均量有一定误差。误差主要来源于采用流量公式计算密度和采用平均温度计算比显焓的过程，但是误差在除凹腔之外相对大小有限，基本可以满足工程需要。不过在计算壁面损失量时，准一维性能预测方法计算得到的总传热量在燃烧区低于对应的CFD计算值

一种超出参考流量计许用温度的质量流量标定装置及方法

本发明公开了一种超出参考流量计许用温度的质量流量标定装置，该装置包括高温工质供应单元、冷却工质供应测量单元、混合器、中温工质测量单元，由高温工质供应单元提供的高温工质与由冷却工质供应测量单元提供的冷却工质在混合器中互溶后达到中温工质测量单元，高温工质供应单元包括第一压力表、第一温度表、待标定质量流量计，冷却工质供应测量单元包括第二压力表、第二温度表、第一标准质量流量计，中温工质测量单元包括第三压力表、第三温度表、第二标准质量流量计。还提供了采用该装置的方法

Quasi-1D compressible flow of hydrocarbon fuel

Based upon equilibrium thermodynamics, the differential equations of quasi-1D steady flow were formulated for arbitrary equation of state to study dense gas behavior of hydrocarbon fuels. A complete set of dimensionless numbers to characterize the quasi-1D dense gas dynamics is identified, classified and discussed. A new numerical method based on conservation laws is proposed to study isentropic flow and shock wave of dense gas and applied to flows of n-dodecane. Furthermore, temperature dependence of supercritical kerosene jet structure is partially interpreted by Prandtl-Meyer expansion of dense gas. It is also proved that the maximum momentum flux at the outlet of a nozzle can be achieved at Mach number √2 for isentropic flow of arbitrary fluid

一般流体的准一维定常流方程组及其在超临界碳氢燃料可压缩流动中的应用

本文基于平衡态热力学理论推导了一般流体的单相准一维定常流动微分方程组,讨论了一般流体的可压缩流动特性,并证明了在给定滞止参数的情况下,任何流体出口动量最大时的马赫数为,给出了激波后总温升降与滞止状态焦汤系数的关系。最后本文构造了准一维定常流动和激波的计算方法,并结合Supertrapp碳氢燃料热物性计算软件,以正十二烷为例计算了超临界碳氢燃