共查询到20条相似文献,搜索用时 46 毫秒
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减弱或消除环境风对直接空冷凝汽器性能的影响对于保证其安全和经济运行具有十分重要的意义。以某电厂600MW直接空冷机组为例,设计了一种应用于空冷单元的进风扩压装置,建立了空冷单元和加装进风扩压装置空冷单元几何模型,基于CFD软件进行数值模拟。计算结果表明,所设计的进风扩压装置能有效降低各风机入口的平均温度,提升风机性能,增加了风机进风量。在环境平均风速6m/s的情况下,可使风机进风量增加63kg/s。环境风工况下,加装进风扩压装置使得空冷凝汽器的换热性能得到提升,当环境风速9m/s,机组换热效率提高3%。 相似文献
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直接空冷凝汽器加装防风网的数值模拟 总被引:2,自引:0,他引:2
利用Fluent软件,以国内某600 MW直接空冷机组为例,对迎风侧2个相邻空冷凝汽器进行了数值模拟,得到了不同环境横向风速下空冷凝汽器的传热效率随着风速的增大而降低,而且被环境风冲刷越严重的凝汽器受影响程度越大的结论.针对横向风对空冷凝汽器传热效率的影响,在凝汽器挡风墙下延方向加装了防风网.对加装防风网后的空冷凝汽器进行了数值模拟,分析了防风网的不同结构参数(开孔率、高度)对空冷凝汽器传热效率的影响,结果表明:在加装防风网后凝汽器传热效率显著提高,防风网的结构参数对其防风效果有明显影响,为直接空冷机组的防风网改造提供了理论依据. 相似文献
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针对某电厂330 MW直接空冷机组的运行条件,设备状况和凝汽器Λ型结构内部空气流场的特点,在空冷单元中风机上方对称加装导流板、空冷单元四周加装不同角度的挡板,通过空冷凝汽器的性能试验对加装导流装置前后机组的背压情况进行了计算分析。结果表明:加装导流装置后,空冷单元内的空气场及换热器表面温度场分布趋于均匀,运行背压降低约1.1 k Pa,平均供电煤耗下降1.9 g/(k W·h)。 相似文献
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通过对发动机气道内气体流动过程的相似分析,在雷诺Re准则数足够大的前提下,非定性准则欧拉Eu数和相似不变量无因次涡流NR保持不变。这就证实通过稳流试验来测量气道的流通性能是可行的。通过数理推导,评价参数流量系数μσ真实就是欧拉Eu准则数的一种表现形式。 相似文献
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为研究锥阀空化现象,运用ANSYS Fluent流体力学有限元计算软件,分析锥阀在内流和外流两种情形下的流场,得到锥阀在内流和外流两种流动方式下空化区域0~3s内气体的体积分数。计算对比发现,在液体流速和压力的突变区域空化现象明显,外流较内流空化区域大,空化程度比内流严重。为降低空化现象对锥阀型腔造成的损伤,优化锥阀型腔阀芯结构,优化模型1可避免内流时空化的发生,优化模型2在内流和外流情况下均能有效避免空化的发生,优化模型2的结构形式更为合理。研究成果可为锥阀设计提供参考。 相似文献
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Bo LIU Weimin HOU Changyou MA Yangang WANG Qiang ZHOU 《Frontiers of Energy and Power Engineering in China》2008,2(4):448-452
The dynamic pressure measurement device and test technology are described in this study. The tip clearance unsteady flow development
from the inlet to the outlet of an axial-flow rotor was revealed by analyzing pressure frequency spectrum acquired from measuring
the unsteady pressure field of the tip endwall. The experiment provides test basis for thoroughly understanding the tip clearance
unsteady flow and building interaction models of tip clearance flow and main flow.
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Translated from Compressor, Blower & Fan Technology, 2007, (5): 12–15 [译自: 风机技术] 相似文献
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An experimental study on the shape of a single bubble similar to those observed in a horizontal plug/slug flow was performed using visual observation and conductance probes. The results indicated that the shapes of the bubble nose and the bubble body depend on the Froude number defined by gas/liquid mixture velocity, whereas the shape of the back region of the bubble depends on both the Froude number and bubble length. The photographic images showed that the structural feature of the bubble head is related to the motion characteristics of the bubble. The transition from plug flow to slug flow occurs when the tail of the bubble changes from a staircase to hydraulic jump pattern with the increasing of the Froude number and bubble length. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(5): 276– 285, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20161 相似文献
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Experimental Studies on The Mechanism and Control of Secondary Flow Losses in Turbine Cascades 总被引:2,自引:0,他引:2
This paper summarizes the results of the authors' 4 year experimental studies on the secondary flow losses in turbine cascades. Cascade wind tunnel experiments were carried out concerning the influence of aspect ratios, incidence, turning angles and outer endwall divergent angles in order to unveil the evolution mechanism of secondary flow losses in turbine cascades without end clearance. Some methods for controlling the secondary flows are investigated including the blade leaning, blade cambering, endwall convergence and leading edge extension at two ends of the blade. 相似文献
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Yiping Liu Weilin Yang Jing Wang 《Frontiers of Energy and Power Engineering in China》2008,2(2):152-157
Theoretical relations that predict the transition from a stratified pattern to a slug pattern, including a onedimensional
wave model that contains less empiricism than the commonly used Taitel-Dukler model, and the ideal model for stratified flow
for the gas-liquid flow in horizontal pipes are presented. Superficial velocities of each phase, as the onset of slugging
occurs, were predicted, and theoretical analysis was conducted on the stratified to slug flow regime transition. The friction,
existing between the fluid and pipe wall, and on the interface of two phases, was especially taken into account. A theoretical
model was applied to an experiment about air-oil two-phase flow in a 50 mm horizontal pipe. The effect of pipe diameter on
the transition was also studied. The results show that this approach gives a reasonable prediction over the whole range of
flow rates, and better agreement has been achieved between predicted and measured critical parameters.
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Translated from Journal of Shanghai Jiaotong University, 2006, 40(10): 1782–1785, 1789 [译自: 上海交通大学学报] 相似文献