共查询到19条相似文献，搜索用时 125 毫秒
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基于热探针法原理,测试了在杭州湾以东陆架区取得的28个海底表层柱状样0.2、1.0和1.8 m处的导热系数,结合激光粒度分析结果,比较了研究区6种土导热系数的大小,发现含砂量大于10%的粗粒土拥有较大的导热系数。土质类型相同时,含水量和干密度对其导热系数影响显著。杭州湾沉积区、混合沉积区,陆架砂质沉积区表层土导热系数的平均值分别是:1.25、1.45 和1.46 W·m-1·K-1,呈现出由近岸向外海增大的趋势。而土样导热系数在垂向的变化表明:水深、埋深等空间分布因素对海洋土的热物性没有直接影响。 相似文献
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对近破波作用下沉箱式防波堤的运动特性进行了模型实验研究。实验中测量了沉箱模型与基床的摩擦系数、基床刚度和阻尼系数;不同水位情况下作用于沉箱模型上的近破波波压力时程;近破波作用下沉箱模型的位移和转角响应时程等,并与数学模型计算结果进行了比较分析。实验结果表明,若沉箱的滑移力大于沉箱与基床间的摩擦力,在连续波浪作用下,沉箱将连续出现间歇式滑移运动,数学模型可较好地模拟这一运动过程。 相似文献
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将海藻石莼通过预炭化得到半焦,再用KOH活化制备高附加值产品活性炭。以亚甲基蓝吸附值、碘吸附值为吸附性能指标,探究碱炭比、活化时间、活化温度等单因素对活性炭吸附性能的影响。Box-Behnken设计-响应面法优化活化工艺,亚甲基蓝吸附模型和碘吸附模型的P值均小于0.0001表现出具有极高的显著性,两个模型方程的确定性系数均大于0.99。亚甲基蓝模型的各因素交互影响P值也都小于0.0001,影响极显著;碘模型中各因素对吸附值的影响,活化温度大于碱炭比大于活化时间。通过对模型优化确定最佳工艺参数:碱炭比为2.99、活化时间为44.47 min、活化温度为809.91℃;该条件下的理论亚甲基蓝吸附值为809.91 mg/g、碘吸附值为1 843.11 mg/g。活性炭吸附废水亚甲基蓝的吸附过程符合准二级动力学模型方程。吸附等温线更符合Langmuir模型方程,略优于Freundlich模型方程,随着温度升高活性炭的吸附能力和饱和吸附量下降。 相似文献
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模型变率对斜坡上泥沙起动相似影响研究 总被引：1，自引：0，他引：1
本文在前人的理论分析及水槽试验工作的基础上，分析了上举力系数对边坡泥沙起动影响，研究了常用模型沙（木屑、煤屑、电木粉），以平床泥沙起动相似设计，变态模型变率对边坡及水流纵向坡面上泥沙起动相似偏离影响 相似文献
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实验研究了过滤池和吸附床水头损失实验测量的原理、方法及其装置,并比较了根据Ｃａｒｍ ａｎＫｏｚｅｎｙ 方程式计算的理论值与实测值的差异,结果表明理论值普遍小于实测值,但误差范围在２５％ 之内;随着填料颗粒的非均匀系数的增大,理论值与实测值的差异有增大的趋势。实验证明,该方法可为实际工程设计提供较为准确的水头损失数据。 相似文献
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一、前言根据一些无机离子交换剂的离子交换性质,利用它们直接从大体积海水中有选择地吸附某种或某几种放射性核素,然后进行非破坏性的r能谱分析被认为是一种有效的快速分析方法.我们曾用K_4[Fe(CN)_6]与Cu(No_3)_2合成了亚铁氰化铜(CuFC),并初步研究了CuFC定量吸附铯的最佳分析条件,证实合成的CuFC在海水中有极好的机械稳定性及在酸性、碱性和中性条件下对Cs均有很高的选择交换吸附能力.在此基础上本文就CuFC对Cs的最大吸附容量,和铯载体量,吸附时的温度,不同流速等对铯吸附效率的影响及对几种核素的分配系数等作了进一步探讨. 相似文献
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海草所形成的植物消波体系能有效防止岸线的侵蚀。利用Sánchez-González等的实验数据分析了波浪非线性对海草消波特性的影响。研究结果表明，相对水深和波陡对海草床的波能衰减系数影响依赖于海草淹没度。相对波高一定时，拖曳力系数随相对水深的增大而增大。对给定的相对水深，拖曳力系数随波陡的增大而减小。波浪非线性对于规则波和非规则波海草消波特性的影响并不一致。用无量纲参数（邱卡数、雷诺数、厄塞尔数）表达拖曳力系数的效果取决于拖曳力系数与无量纲参数的关系中是否充分考虑波浪非线性对拖曳力系数的影响。 相似文献
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发动机排气余热吸附式制冷机性能及其热力学机理的研究(英文) 总被引：2，自引：0，他引：2
分析一台以6缸柴油机排气余热为热源的吸附式制冷机的性能和热力机理。研制了一台以CaCl2为吸附剂，NH3为工质的8KW冷量吸附式制冷机。该制冷机的工作特性表明在不变蒸发温度时，制冷机冷量随发动机排气功率变化。对吸附制冷单管的热力试验研究表明；CaCl2介质中的热／质迁移是相互作用的。建立了以非平衡态热力学为基础的数值模型来描述这些热力过程。 相似文献
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The calculative method of heat transfer coefficient between ice cover and water is analyzed considering the heat balance at ice cover bottom firstly. The heat transfer coefficient is calculated with the meteorological, oceanographic data and sea ice conditions measured on the JZ20-2 Oil/Gas Platform in the Bohai Sea during the winter of 1997/1998. From the results, it is shown that the heat transfer coefficient is smaller in the freezing and melting periods, which is about 0.16× 10-3 and 0.04× 10-3 respectively. In the middle of ice season, the heat transfer coefficient has a larger value, which is about 0.5 × 10-3. Lastly, the influences of ice thickness and ice type on the heat transfer coefficient are discussed. With the heat transfer coefficient determined above, the oceanic heat flux in the winter of 1997～1998 is calculated, and its trend in the winter is analyzed. This study can be referenced in the sea ice numerical simulation and prediction in the Bohai Sea. 相似文献
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斜抽运无机液体激光器的流场热分布 总被引：1，自引：0，他引：1
激光二极管斜抽运的多增益段串接的液体激光器能够明显地提高激光光束质量、获得较高的输出功率.针对斜抽运子增益段工作时所涉及的流动、传热和壁面耦合,建立了计算子增益段流场热分布的流-热-固耦合模型,应用有限单元法完成了其瞬态流场热分布的数值模拟.该方法排除了不精确的换热系数对计算结果的影响,使得换热系数不再是计算的先决条件,而只是计算结果之一;并且为评价流道形状、流速、吸收系数等因素对流场热的影响,以及进一步改进和控制液体激光介质的流场热分布,提供了可靠的分析方法.数值模拟研究表明:换热系数是空间位置的函数; 相似文献
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对传统可拆式板式换热器进行了改良,以适用于海洋温差能发电系统工况,并对改良后的板式换热器进行了理论数值分析。研建了海洋温差发电系统测试平台,对系统内的换热器换热特性进行测试,在不同工况下对换热器换热特性进行了实验研究,得到了板式换热器瞬态运行特性,同时还得到了换热器换热特性随热流密度的变化曲线及压降随工质流量的变化关系。结合实验数据拟合了换热器换热特性经验关联式和压降随工质流量关联式,预测值和实验值偏差均在20%以内。结果表明:在实验系统运行工况范围内,换热器的换热系数随着热流密度的增加而增大,当热流密度大于3 kW/m2时,换热系数随热流密度变化的曲线斜率变小;换热器压降随着工质流量增大而增加,压降随工质流量变化的曲线斜率变大。 相似文献
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Abstract Two mathematical models of different complexity were used to study transverse dispersion and surface heat transfer in the lower Waikato River. A simple analytical streamtube model (HPLUME) gave adequate temperature predictions in a reach where the channel was fairly regular but performed poorly where there were extensive shallows. In the latter reach, a two‐dimensional numerical model (SYSTEM21) gave good temperature and flow predictions once properly calibrated. Model calibration proved to be difficult in the Waikato River because the natural river temperature varied significantly along the channel. A search method was developed to estimate both the transverse dispersion and surface heat exchange coefficients from measured plume temperature profiles based on the observation that transverse variations in natural temperature were small. This method was used to calibrate SYSTEM21 in two separate reaches. Coefficient estimates were sensitive to measurement errors and slight departures in homogeneity of natural temperature and it would be desirable to corroborate the estimates of Ez using dye tests. In the upper reach, the average transverse dispersion coefficient was Ez/hu? = 1 which is high but within the range of published values. A sharp bend and buoyant spreading contributed to the high Ez value. Ez increased with river flow because both h and u? increase with flow. In the lower reach, Ez/hu? = 0.1 which is lower than expected but islands may have affected the model calibration. The surface heat exchange coefficient averaged K = 84–167 W m?2 s?1 °C?1 which falls within the range of published values. No significant relationship could be found between surface heat exchange coefficient and meteorological variables. 相似文献
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Bong Ju Kim 《Ocean Engineering》2010,37(13):1159-1168
The aim of this study was to evaluate the load characteristics of steel and concrete tubular members under jet fire, with the motivation to investigate the jet fire load characteristics in FPSO topsides. This paper is part of Phase II of the joint industry project on explosion and fire engineering of FPSOs (EFEF JIP) (
[Paik and Czujko, 2009] and [Paik, 2010]). To obtain reliable load values, jet fire tests were carried out in parallel with a numerical study. Computational fluid dynamics (CFD) simulation was used to set up an adiabatic wall boundary condition for the jet fire to model the heat transfer mechanism. A concrete tubular member was tested under the assumption that there is no conduction effect from jet fire. A steel tubular member was tested and considered to transfer heat through conduction, convection, and radiation. The temperature distribution, or heat load, was analyzed at specific locations on each type of member. ANSYS CFX, (2008) and KFX, 2007 codes were used to obtain similar fire action in the numerical and experimental methods. The results of this study will provide a useful database to determine design values related to jet fire. 相似文献
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Ahmad Safuan A. Rashid Jonathan A. Black Hisham Mohamad Norhazilan Mohd Noor 《Marine Georesources & Geotechnology》2013,31(6):473-486
This article reports on a series of small-scale, plane strain, 1 g physical model tests designed to investigate the bearing capacity and failure mechanics of end-bearing soil-cement columns formed via Deep Mixing (DM). Pre-formed soil-cement columns, 24 mm in diameter and 200 mm in length, were installed in a soft clay bed using a replacement method; the columns represented improvement area ratios, ap, of 17%, 26%, and 35% beneath a rigid foundation of width 100 mm. Particle Image Velocimetry (PIV) was implemented in conjunction with close-range photogrammetry in order to track soil displacement during loading, from which the failure mechanisms were derived. Bearing capacity performance was verified using Ultimate Limit State numerical analysis, with the results comparing favorably to the analytical static and kinematic solutions proposed by previous researchers. A new equation for bearing capacity was derived from this numerical analysis based on the improvement area ratio and cohesion ratio of the soil column and ground model. 相似文献
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Ping Zeng Huiquan Chen Baichuan Ao Ping Ji Xiaojian Wang Zhiliang Ou 《Coastal Engineering》2002,44(4)
A numerical and experimental modeling is presented for studying the transport of waste heat from a nuclear power plant into coastal water by using a full-field physical model with scale distortion, a local physical model with normal scale and a depth-averaged k− turbulence model with a modified second-order upwind scheme. Field investigations are also used to provide the calibration and validation of the modeling. A case study simulating the turbulent tidal flow and waste heat transport in the coastal water near Daya Bay Nuclear Power Plant in Southern China was conducted. The experimental result of the case study shows that the water temperature in coastal water was a little oversimulated near the surface and was a little undersimulated near the bottom of heated-water layer by the full-field physical model. The numerical study shows that the depth-averaged k− turbulence model presented a satisfied prediction of turbulent tidal flow and far-field temperature distribution in coastal water, although the near-field stratification due to the heated water effluent was not accounted for. The result of the effect of scale distortion on physical model shows that a full-field physical model with a scale distortion of 10 produced a satisfied result of temperature distribution in the present case study. 相似文献