共查询到17条相似文献,搜索用时 80 毫秒
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我国陆上油田多处于中高含水期,采出原油含水量逐年提高;加之海洋石油工业的不断发展,多相混输已成为今后的主要输送方式。在多相流动中,总流量和各分相流量是多相流的重要参数,流量的准确测定对工程设备运行的经济性和可靠性十分重要。基于多相流混合模型,建立了油水两相流控制方程,针对V锥流量计内油水两相流场进行数值模拟,分析了流速、初始含水量、等效直径比、前锥角等对水平管内轴向压降及油水相态分布的影响。研究表明:入口流速、初始含水量、等效直径比及前锥角对油水两相流轴向压降及相态分布影响较大;降低流速、增加等效直径比、减小前锥角可有效降低轴向压力,使油水相态分布均匀,实现节能降耗。 相似文献
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喷孔结构直接决定多孔非对称缸内直喷汽油(GDI)喷油器的孔内流动状态,进而影响GDI喷油器的雾化特性.建立了不同喷孔内圆倒角、喷孔长径比和喷孔锥角等几何参数模型,并结合CFD仿真、高速摄影和激光测量技术对不同喷孔参数的空穴现象、喷雾形态、贯穿距离和索特平均直径的概率密度等进行了研究.结果表明:喷孔内圆倒角有利于减弱空穴现象,增加贯穿距离,但油雾的索特平均直径增大;喷孔长径比对于空穴现象的影响不明显,对贯穿距离和平均索特粒径的影响并不遵循线性规律;喷孔锥角对空穴现象的影响较小,喷雾贯穿距离随着喷孔锥角的增加而减小,但每一束油束锥角变大,喷雾范围扩大,雾化质量提高. 相似文献
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设计开发一种具有高通量、低流阻特征的空心锥喷嘴,并通过理论与实验方法研究空心锥喷嘴的喷淋性能,基于准自由涡理论建立空心锥喷嘴内部流体流动的数学模型,阐明流量系数、喷淋锥角、喷嘴流量与喷嘴结构参数之间的定量关系,并利用多效蒸馏海水淡化喷淋实验台对理论计算结果进行实验测试和验证。研究结果表明:正常工作状态下喷嘴流量系数、喷淋锥角、喷淋流量等参数理论值与测量值之间的误差小于5%,验证了设计模型的准确性。同时根据实验测试数据,拟合得到该类型空心锥喷嘴喷淋锥角与雷诺数之间的经验公式,可为蒸馏海水淡化用大流量空心锥喷嘴的结构设计、工艺选型提供理论指导和数据支持。 相似文献
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利用高速摄影纹影法研究天然气高压喷射射流特性 总被引:8,自引:0,他引:8
在定容弹上利用高速摄影纹影法开展了不同喷射压力和背压下的天然气高压喷射射流特性试验研究。通过纹影照片得到了不同喷射压力和背压下的射流贯穿距离、射流锥角和射流体积随时间变化的规律,计算得到了射流内整体过量空气系数随时间变化的规律。结果表明:射流发展分两个阶段,射流初期阶段和射流主体阶段。在射流初期阶段,射流贯穿距离快速增加;在射流主体阶段,射流贯穿距离随时间呈线性增加趋势。射流贯穿距离、射流体积和射流内整体过量空气系数随时间而增加,射流发展过程中射流锥角基本保持不变。随着喷射压力的提高,射流贯穿距离和体积增加,射流锥角减小,射流内整体过量空气系数增大。随着容弹背压的增加,射流贯穿距离和射流体积减小,射流锥角增加,射流内整体过量空气系数增大。 相似文献
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In the present study, computational work using the axisymmetric, compressible, Navier-Stokes equations is carried out to predict the discharge coefficient and critical pressure ratio of gas flow through a critical nozzle. The Reynolds number effects are investigated with several nozzles with different throat diameter. Diffuser angle is varied to investigate the effects on the discharge coefficient and critical pressure ratio. The computational results are compared with the previous experimental ones. It is known that the discharge coefficient and critical pressure ratio are given by functions of the Reynolds number and boundary layer integral properties. It is also found that diffuser angle affects the critical pressure ratio. 相似文献
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为明确突缩突扩式消能工能量损失系数与相关影响因素之间的关系,通过数值模拟试验,分析了孔径比、厚径比、雷诺数等因素对能量损失系数的影响。结果表明,孔径比越小,能量损失系数越大;当孔径比超过0.7时,孔径比对能量损失系数的影响不再明显;能量损失系数随厚径比的增大而减小,但当厚径比超过0.5时,能量损失系数随厚径比的增大而减小的趋势变得不明显;当雷诺数大于10~5时,雷诺数对能量损失系数的影响可忽略。 相似文献
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通过计算流体动力学(CFD)研究了燃气轮机二次空气系统中轴向旋转孔的进口圆角比、长径比、压比和进口气流冲角对轴向旋转孔流量系数C_d的影响。计算结果表明,当孔的进口圆角比r/d0.2时,孔圆角的变化对流量系数影响显著;长径比、压比对进口有/无圆角的孔的流量系数影响规律不同,长径比越大时进口气流冲角对流量系数的影响越小;进口圆角比也会影响进口气流冲角对流量系数的影响规律。依据数值计算结果,对典型的旋转孔流量系数估算公式进行了修正,提高了经验公式的计算精度。 相似文献
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A new spray atomizer, that is, swirling gas–liquid spray atomizer, is presented in this paper based on the analysis of various air-assist atomizers and their atomization mechanism. The air-to-liquid mass flow rate ratio (ALR) of the atomizer during the hot-state tests is 4–6% (by compressed air for emulsified heavy oil). And it is of excellent atomization. The discharge coefficient and the spray cone angle of the atomizer are studied systematically. The influence factors considered are as follows: the structure parameters, ALR and the viscosity of the liquid. Through the experiments, the formula of discharge coefficient and the spray cone angle of the atomizer are given in the paper. And it can give good direction on the atomizer design. The atomizer can be employed in the industrial furnaces and other equipments where the liquid must be atomized. 相似文献
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The internal flow of diesel nozzles has a strong influence on the subsequent spray and atomization characteristics. A flow visualization experiment system equipped with enlarged transparent nozzles was set up to investigate the effect of different nozzle structures and different nozzle enlarged scales on cavitating flow and subsequent spray characteristics. Significant parameters of internal flow including critical pressure of cavitation inception, critical pressure of hydraulic flip, discharge coefficient, Reynolds number, flow rate and cavitation distribution were fully investigated during the experiments. Experimental results show that the nozzles with small length/diameter ratios at the same orifice diameter were more inclined to cavitate and had higher discharge coefficient than that of nozzles with large length/diameter ratios. Cavitating flow in nozzles with different sac volume structures may incur different spray characteristics in the near-nozzle field and it is the internal cavitating flow that induces the asymmetry of subsequent spray. The investigations indicate that the critical pressure of hydraulic flip and discharge coefficient of nozzles under different needle lifts were quite different even under the same boundary conditions and the nozzle flow characteristics have been greatly influenced by the hydraulic flip phenomenon. Two types of cavitation were observed in nozzles with different scaled-up times and the string cavitation was found in three times scaled-up nozzle, while the cloud cavitation bubbles were appeared in five and eight times scaled-up nozzles. A kind of hysteretic cavitation phenomenon was also observed in the experiment and then was analyzed in this paper. 相似文献
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A two-dimensional cone concentrator for sunlight was theoretically and experimentally studied. The calculation revealed the maximum number of reflections that sunlight could make before exiting the cone. A higher number of reflections caused the sunlight to bounce backward to the entrance of the cone. The characteristics and geometric parameters of the cone were assessed. As the cone angle increased from 45° to 90°, the calculated concentration ratio, taking the reflection coefficient into account, increased nonlinearly from one to infinity, while the height of the cone also increased from zero to infinity. The experimental concentration ratio was found to be less than the theoretical one in all cases. 相似文献