查询词典 vortex

Based on analysis of the current state of the flow pattern modeling abroad and at home, explains the meaning of the mathematical simulation of the flows in the valve.(2) Comparing flow simulation data of jet pump with its experimental one, the feasibility and reliability of FLUENT used for flow simulation are proved.(3) Based on the characteristic of valves, the fluid field analysis of specific ring-spray type flow-adjustable is finished. The valve structure is optimized to meet the need, which makes it have such advantages:(1)smaller vortex area and faintish vortex intensity, so the vibration of vortex is controlled effectively;(2)the pressure is distributed more equality, the transition area is larger.

论文的主要内容包括：(1)简述了阀门研究的现状与发展，在分析与总结国内外流体流动模拟研究的基础上，探讨开展阀门内水流运动数值模拟的意义；(2)对特定型号的射流泵进行了内部流场的数值模拟研究，并与实验数据相比较，验证了应用Fluent进行数值模拟的可行性和可靠性；(3)针对调流阀的特点，对特大口径环喷式流量调节阀进行流场计算，其设计指导思想如下： 1、控制旋涡，减小旋涡区，减小涡的强度； 2、控制压力分布，使阀体受力更均匀，改善局部应力状态，提高阀门使用的安全性； 3、最小绝对压力高于水的汽化压力，不产生汽蚀。

We have got the following conclusions from the simulation in the thesis:(1) In even diameter hole, the tangental velocity has the characteristic of combination vortex; with the boundary of points for maximal speed, the insides is norm forced vortex, the outside is norm free vortex; the axis symmetry of tangental velocity is very well.

等直径工件孔内的螺旋流场，其切向速度分布具有组合涡的特点，以最大切向速度点形成的面为界，内部是强制涡，外部是自由涡，其轴对称性很好。

In this paper, The delta wing of Mach number 0.8 at an attack angle of 21. 8 degree is simulated by our program. Then, using the visualizing program, we map the figures of space streamlines, cross streamlines near the vortex axis, three dimensional vortex lines, cloud atlas for pressure and vortex and targer of particles.

在这一章里，我们先用所建立的计算软件数值模拟了来流马赫数为0.8、攻角为21.8°的三角翼的流场，之后以拓扑分析结果做指导，研制了一套数值显示流场、旋涡结构的软件，用该软件我们绘制了跨音速三角翼背风区涡轴附近截面流线、空间流线、三维涡量线、压力和涡量云图以及粒子屏痕图。

The results show that for a supersonic shear layer without reaction, a disturbance can make the shear layer become unstable, this results in one vortex or more than one vortex. The combination and seperation of vortex can intensify the mixing. But it is not easy for supersonic reacting shear layer with exotherm to become unstable with disturbance, and the effect duration is very long.

结果表明，对完全气体的超声速剪切层流动，一定的激励方式能使原先较为稳定的剪切层流动变得不稳定，产生单涡或多涡结构，发生多涡间的合并，使混合加剧；但对于存在放热现象的反应超声速剪切层流动，外加激励方式不易使流动从稳定变为不稳定，而且外加扰动的作用特征时间也较长，实际应用前景不乐观。

It relies on two vortex plate to work with each other movements which has a very high machining accuracy and mutually gearing, in which one fix on the machine rack, called the static vortex plate; the other is driven by the partiality shaft to move around the static disk base circle center , called the moving vortex plate.

它是依靠加工精度很高且相互啮合的两个涡盘的相互运动而工作的，其中一个固定在机架上，称为静涡盘；另一个由偏心轴驱动绕静盘基圆中心平动，称为动涡盘。

After analyzing the performance anduncertainty of the DDPM vortex flowmeter in gas-liquid bubble flows, the vortexflowmeter-Venturi tube combinative method using the vortex flowmeter and the Venturi tube as measuring cells was put forward, the measurement model based on thevortex frequency and the Venturi differential pressure was established, and it showsthat the relative errors of this method for the mass flow measurement of bubble flowsare within±5%. Furthermore, the flowrate and volume void fraction of bubble flowswere obtained using a single DDPM vortex flowmeter through the relationshipbetween the frequency and amplitude of the circumferential DDPM signal, and resultsdemonstrate that the relative errors of the flowrate and volume void fraction of bubbleflows are within±5% and±10% respectively, which indicates the broad applicabilityof this method to large numbers of engineering fields.

通过分析管壁差压式涡街流量计在气液泡状流中的性能和不确定度，提出了以涡街流量计和文丘里管作为测量元件的&涡街—文丘里联合法&，建立了以涡街频率和文丘里差压为被测量的测量模型，该方法对气液泡状流质量流量的测量相对误差可达±5％；通过建立涡街周向管壁差压信号频率和幅度与被测流体的关系，使用单个涡街流量计实现了对气液泡状流流量和体积含气率的双参数测量，该方法对气液泡状流流量和体积含气率的测量相对误差分别为±5％和±10％，可以满足大量工业实际应用的要求。

The southwest vortex restricted the development of the plateau vortex in some way at the early stage when it appeared in the lower atmosphere. When they were coupled longitudinally, the vertical difference caused by the different vorticity advections between the upper and lower levels excitated the updrafts under 500 hPa and strengthened cyclone vorticity, and then the positive vorticity at 500 hPa and 700 hPa increased by two times The change rate of positive vorticity facilitated the plateau vortex to move eastward.

分析表明：高原涡与西南涡涡心之间的纬向距离在5个纬度的时候，两者上升气流都在500 hPa以下，当两者继续东移，在经向上耦合的时候，二者同时得到发展，西南涡中心的上升气流达到300 hPa，而高原涡中心的上升气流突破200 hPa；西南涡在低层出现初期，在一定程度上制约了高原涡的发展，随着两者在经向方向发生耦合，上下涡度平流不同造成垂直差动，将激发500 hPa以下的上升运动与气旋性涡度加强，使得500 hPa与700 hPa涡心正涡度值的增大近 1倍。

The above problems are studied in this thesis. First, the implicit NND scheme with mix flux splitting method proposed by Zhang Hanxin that is first order accurate in time and second order in space is modified. The modified scheme keeps the characteristics of fast convergence and is second order accurate both in time and space. It can be capable of simulating the unsteacly flow. Second, the topological method founded by Zhang Hanxin is improved to study the characteristics of vortex near the singular point on its axis and the cross streamlines on the longitudinal section passing the vortex axis. On the basis of topological results, a program which visualises numerical results is made out. It can help us analyse the characteristics of vortex motion.

本文对上述问题做了研究：第一，在数值模拟方面，借助于张涵信提出的NND算法和混合通量法，我们将他建立的时间为一阶、空间为二阶精度的快速隐式算法推广为时间和空间均为二阶精度的算法，这样做保留了原格式收敛快的特点，而且能适用于真实的非定常流态的计算；第二，将张涵信的拓扑分析方法加以推广，研究了涡轴附近及破裂点邻域内流场的空间特征，并以这些拓扑分析结果为指导，研制了一套显示计算结果的软件，这一软件能很好地帮助我们分析流场的计算结果和旋涡演变的特征。

To calculate the pressure drop of cyclone must consider the tangential velocity. Researchers regarded inner vortex as quasi-forced vortex and outer vortex as quasi-free one before.

旋风分离器阻力损失的理论计算离不开切向速度分布，以往在切向速度的研究中，认为内涡旋是准强制涡、外涡旋是准自由涡。

The swirling flow inside the cyclone showed the Rankine vortex characteristics, i e, strong swirling vortex at the central region of the cross-section and weak swirling quasi-free vortex near the wall.

方形旋风分离器内的流动具有Rankine涡的特点，即中心部分为强制涡区，边壁附近是准自由涡区。

In the United States, chronic alcoholism and hepatitis C are the most common ones.

在美国，慢性酒精中毒，肝炎是最常见的。

If you have any questions, you can contact me anytime.

如果有任何问题，你可以随时联系我。