共查询到20条相似文献,搜索用时 687 毫秒
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为了分析旋风分离器壁面磨损问题,基于计算流体力学的方法,应用Fluent软件中的雷诺应力模型(气相)和离散相模型(固相),通过对旋风分离器内气固两相流场的耦合计算,对分离器流场中颗粒浓度分布和气固两相流场对壁面的磨损进行了数值模拟,并对计算结果和磨损原因进行了分析。结果表明:数值计算能够定性的预测旋风分离器壁面的磨损情况,能得出壁面磨损的主要部位即入口区域、锥体下部、灰斗以及料腿的上部等,同时也得出了壁面磨损的分布云图,这些对旋风分离器的设计、壁面磨损的分析和防磨措施的提出具有一定的参考价值。 相似文献
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为探寻电动汽车空调涡旋压缩机中油气分离规律,利用FLUENT软件对不同进口方式和不同进口速度下的油气分离器进行了数值模拟,先用RNGκ-ε模型计算连续相的压缩气体,得到分离器内旋转流场的流线、压力及速度分布规律,再用DPM模型加入离散相的液态油滴进行计算,得到了油气分离效率。对比分析两相流场的模拟结果,得到入口方向和进口速度对分离效率的影响规律,为油气分离器的优化设计提供了理论依据。 相似文献
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用数值模拟的方法研究喷油螺杆压缩机油气分离器部件内的流场,对气液两相流场采用离散相模型计算。通过对油气分离器建立多个单一变量模型并设定相应边界条件,对计算结果分析发现,除合理设定内筒内外截面面积比外,油气分离器入口截面形状及出气口相对位置对提高分离效果也具有积极作用,据此提出优化设计方案和为认识油气分离器内部流场提供参考。 相似文献
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An experimental study was performed for measuring velocity and turbulence intensity in a circular tube for Re=10,000, 15,000 and 20,000, with swirl and without swirling flow. The velocity fields were measured using PIV techniques and swirl motion was produced by a tangential inlet condition. Some preliminary measurements indicated that over the first 4 diameter, two regions of flow reversal were set up (the so called 2-cell structure). At the highest Reynolds numbers, the maximum values of the measured axial velocity components had moved toward the test tube wall and produce more flow reversal at the corner of the tube. As the Reynolds number increased, the turbulence intensity of swirling flow at the tube inlet also increased. 相似文献
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An experimental study is performed for turbulent swirling flow behind a circular cylinder using 2-D PIV technique. The Reynolds number investigated are 10,000, 15,000, 20,000 and 25,000. The mean velocity vector, time mean axial velocity, turbulence intensity, kinetic energy and Reynolds shear stress behind the cylinder are measured before and behind the round cylinder along the test tube. A comparison is included with non swirl flow behind a circular and square cylinder. The recirculation zones are showed asymmetric profiles. 相似文献
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Jang-Kweon Kim 《Journal of Mechanical Science and Technology》2008,22(1):180-189
Mean velocities and turbulence characteristics in the swirling flow of a gun-type gas burner (GTGB) were measured with a triaxial
hot-wire probe (T-probe) and compared with previous data measured with an X-type hot-wire probe (Xprobe). Vectors and axial
mean velocity data obtained by the measurement of the two types of probes in the horizontal plane and in the cross section
differ in magnitude, but have very similar shape in overall distribution. Axial mean velocity components show especially wide
differences around the slits and outer part of the swirl vanes within the range of X/R=2. Also, various turbulence intensities
appear in a similar trend to axial mean velocity components within the range of X/R=2. The radial component of turbulence
intensity around the slits and the outer part of swirl vanes above the range of X/R=2 has an opposite phenomenon. On the whole,
the T-probe’s measurements appear smaller than the X-probe’s. This shows that the X-probe is better than the T-probe, especially
on the swirling flow because it is much easier to use. 相似文献
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Flow unsteadiness is a typical feature of both combined and storm sewer flow. The following study therefore deals with both theoretical and experimental investigations of the steady uniform and transient turbulent open-channel flows in a circular conduit with smooth walls as well as over rough sediment deposits. The aim of the study is to define the relationship between flow unsteadiness and selected flow/turbulence characteristics estimated in a circular tube running partially full using the ultrasonic velocity profiler (UVP) method. The temporal/spatial turbulence intensities and the Reynolds stress distribution were identified in the mid-vertical of the pipe. Generally, the absolute values of turbulent characteristics are larger in the rising branch of the hydrograph than in the descending one for the same flow depths. This difference in absolute values is related to the flow equilibrium parameter. Furthermore, the influence of the sediment bed on selected flow/turbulence variables was studied. The results show a strong impact of cross-section geometry on local values of friction velocity, i.e. bottom shear stress, along the wetted perimeter of the channel cross-section. Interestingly, their relative values decreased along with an increase in flow depth. 相似文献
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采用RNG k-ε模型对水平管内以叶轮起旋的螺旋流的流动特性进行了数值模拟研究,通过试验验证了数学模型的准确性和可靠性。研究结果表明:叶片旋流器产生的旋流场,切向速度分布具有近似Rankine组合涡结构的特点,径向速度最大值达轴向速度的0.5倍。雷诺数对旋流强度影响较大,Re数越大,旋流强度越大,且旋流强度的衰减速率越小。强旋流使轴向逆压力梯度足够大而引发轴向回流,从而产生了中心回流区域;能够增加反应介质的滞留时间,提高气液两相的传质和传热效率,促进水合物浆体快速生成,保障管道安全输送。 相似文献
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Klaus Bremhorst Matthew Brennan Kyung-Soo Yang 《Journal of Mechanical Science and Technology》2014,28(3):945-951
The low Reynolds number stress-omega model is applied to flow associated with a rotating cylinder operating in a larger, stationary cylinder. The working fluid fills the gap between the cylinders. Direct numerical simulation data are used to test the predictions by this turbulence model. Previous work has shown that simpler models are unable to predict with reasonable accuracy the wall shear stress experienced by the rotating cylinder. The present study with a more complex turbulence model shows that the wall shear stress on the rotating cylinder is underestimated significantly. Examination of turbulence velocity fluctuation intensity distributions points to underprediction of the streamwise turbulence level and excessive values of the wall normal turbulence level. Results are given for no shear and a wall shear at the outer cylinder surface but no effect on the inner cylinder statistics was found. An examination of the Reynolds stress anisotropy tensor components highlights a significant deficiency in this parameter which is an essential component of the pressure-strain modelling of Reynolds stress models. The most significant aspect is a rapid decrease of the streamwise component of the Reynolds stress anisotropy tensor relative to the direct numerical simulation results and values which are too low for the other two components. 相似文献
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The purpose of this work is to study the influence of the axial flow fan sweep on the downstream turbulent flow. The fans studied are three low-pressure and low-Mach-number axial flow fans, with respectively a radial, a forward and a backward sweep. Experimental and computational fluid dynamics (CFD) investigations are carried out on three fans, and the results are compared. The CFD method is a three-dimensional (3D) Reynolds average Navier–Stokes (RANS) numerical simulation with the Reynolds stress model (RSM) as the turbulence model. It allows us to compute the Reynolds stress tensor components. Unsteady velocity measurements are carried out downstream of the fans with hot-wire anemometry. The values of the three velocity components of the flow and the six components of the Reynolds stress tensor obtained from experiments and simulations are compared. Overall performances are also measured to validate the design and fan simulation. It appears that a forward sweep decreases the radial component of the velocity whereas a backward sweep increases this component. Moreover, the sweep has a significant influence on the turbulent kinetic energy downstream of the fan. 相似文献
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A.F. Najafi S.M. Mousavian K. Amini 《International Journal of Mechanical Sciences》2011,53(10):801-811
Due to the importance of predicting the SIDR1 associated with engineering problems such as combustion chambers, draft tube of the Francis and Kaplan turbines, heat exchanger tubes, separators and so forth, in this research the trend of SIDR and its affecting factors, through a turbulent swirl decay pipe flow have been investigated. The swirling flow is created by means of a rotating honeycomb which produces solid body rotation at the inlet of a fixed pipe. First of all, turbulent swirling decay flow has been numerically surveyed using different flow conditions at the pipe inlet. The numerical results have been validated and compared with the existing experimental data and mathematical relations, showing satisfactory coincide. The obtained results show that, the SIDR depends mainly on the Reynolds number of the passing flow. On this basis, correlations have been proposed in order to improve the predictions of swirl intensity decay rate at upstream regions as well as those with high swirl intensity. In addition, conducted analyses demonstrates (analyses have been made to demonstrate) that the previous developed correlations for predicting swirl intensity decay rate, agree with those provided in this study only for regions far enough from downstream having the low swirl intensity. This implies that the swirl intensity decay rate should be a function of the type of swirl generator at the pipe inlet. 相似文献
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Shin Hyuk Joo Kwang Min Chun Younggy Shin 《Journal of Mechanical Science and Technology》2000,14(12):1412-1420
The objectives of the study are to investigate the effect of swirl on the flame propagation and to propose a flame propagation model that predicts the behavior of the flame front in the presence of significant swirl flow field by analyzing flame images pictured with a high speed digital video at idle. The velocity distribution of the charge in the cylinder was measured using an LDV measurement system. From the experimental results and analyses, a new flame propagation model is proposed in which flame frontal locations can be traced by superposing the convective flow field and the uniform expansion speed of the burned gas, and the proposed model reveals that the increase of the flame propagation speed in the presence of swirl motion within 1 ms after ignition is mainly due to the flame stretch, and mainly due to increased turbulence intensity later than 1 ms after ignition. 相似文献