气体涡轮流量传感器叶轮压力的数值模拟

在严格按照实际涡轮流量传感器几何结构的基础上,运用Solidworks三维建模,通过运用计算流体动力学的方法对内径为80mm的气体涡轮流量传感器进行了数值模拟,给出了流量计在不同流量下内部的压力场并特别给出叶轮表面的压力分布.从压力分布分析叶轮部分的受力情况,以此来讨论叶轮动受力.     

涡轮流量计内部流场数值模拟研究

利用数值仿真技术对涡轮流量计内部流场进行了研究,目的是为优化涡轮流量计的结构设计提供指导。利用叶轮转速与平均力矩系数存在线性关系,提出两点法确定叶轮在力矩达到平衡状态下的转速。数值分析结果表明,前导流件叶片后形成的尾流影响叶轮人口的流体速度分布,继而影响叶轮的旋转稳定性;叶轮叶片压力面上靠近叶片前缘以及吸力面上靠近尾缘处存在压力突变区,易产生脱流现象;叶轮轮毂前后间隙区内流体受叶轮旋转影响而易产生漩涡流和明显的切向速度分量。     

气体涡轮流量计流场仿真及计量误差分析

利用控制体积法的SIMPLEC算法对气体涡轮流量计的内流场进行了数值模拟,给出了内流场信息,分析了内部几何结构对压力和速度分布的影响,及其与流量系数的关系.结果表明在湍流状态时的仪表系数K为常数,累计流量和瞬时流量的误差较小;而在层流以及转捩状态时,仪表系数总是在变化,累计流量和瞬时流量的误差较大.建议通过结构优化,促使层流向湍流状态的快速转捩,并保证叶轮动平衡,从而加大涡轮流量计的量程范围.该研究结果对涡轮流量计的结构优化设计具有一定的指导意义.     

环槽流量计的数值模拟与优化

研究流量计内部流场和结构优化,对改善流量计的测量性能和提高测量精度,具有重要的现实意义。将计算流体力学(CFD)仿真试验应用于一种新型差压流量计——环槽流量计,考查不同等效直径比β、前端和尾部长度、等直径段长度以及雷诺数对环槽流量计的流出系数和压力损失的影响。结果表明:随着雷诺数的增加,流出系数逐渐增大并达到稳定值;随着β增大,流出系数先增大后减小;前端及尾部长度对流出系数影响不大,但尾部长度越大,永久压损越小;等直径段长度越小,永久压损越小。根据结果拟合出环槽流量计流出系数的公式,CFD数值模拟作为一种辅助设计和标定手段,有助于指导环槽流量计的现场测试。     

纺锤体流量计的流场数值模拟

介绍了一种新型的节流式差压流量计——纺锤体流量计（又名槽道流量计）。数值模拟结果表明,在来流规则或畸变情况下纺锤体等直径段部分均能很好地形成环形槽道流动,使测量重复性和精确度得到大幅提高成为可能;同时,由于完全避免了流动分离,在高雷诺数下的压力损失与所得差压之比可小于孔板流量计的二分之一。实验结果验证了数值模拟的可靠性。     

涡街流量计与孔板流量计压力损失的比较研究

通过试验对涡街流量计的压力损失进行了研究,并与孔板流量计的压力损失进行了比较.涡街流量计与孔板流量计使用广泛,因此有些研究人员对两种流量计的压力损失进行过比较,但比较时没有在保证两种流量计有效流通面积相等的情况下进行,这就使最后的结果没有说服力.在保证两种流量计流通面积相等的条件下,对它们的压力损失进行了比较.结果表明,孔板流量计的压力损失与涡街流量计的压力损失的比值并没有一些文献中给出的那么大.     

机械智能CPU卡一体化气体涡轮流量计的研究

介绍了机械智能CPU卡一体化气体涡轮流量计的构成.研究了气体涡轮流量计基表数学模型,论述了其关键零部件--涡轮和主轴轴承的设计对基表性能的影响,分析不同设计方案的差异,并通过试验进行验证.结果表明:涡轮设计、流通面积与圆管面积之比A/S的选取要兼顾准确度等计量性能和压力损失的要求,应通过试验找到最佳值;低压时涡轮材质选聚甲醛,高压时选硬质铝合金;选用陶瓷向心球轴承作为主轴轴承,应通过耐久性、过载试验验证主轴轴承设计.     

孔板流量计内空化现象的数值模拟

以计算流体动力学CFD软件为工具,通过引入Schnerr-Sauer空化模型,并结合多相流Mixture模型与RNG k-ε湍流模型,对两通道非标准孔板流量计在空化发生条件下的内部流场进行数值模拟。考查等效直径比β=0.7时,流场中蒸汽体积分数和压力分布的变化规律,入口压力对空化数的影响以及雷诺数对流出系数和压力损失的影响。结果表明:入口压力增加到一定值时,在环隙边缘处首先发生空化现象,并且随着压力的增大,空化发生的区域增大,空化程度加剧;空化数随入口压力的增大而减小;空化效应对流量计的流出系数的影响较大,而对压力损失的影响较小。研究结果对孔板流量计的测量误差原因分析和提高测量精度有参考价值。     

气体涡轮流量计应用探讨

文章从气体涡轮流量计的原理和工作特性出发,解析了在选型、安装、使用中应该注意的问题。并从实际应用中与旋进旋涡流量计的对比计量,分析了气体涡轮流量计用于流量波动较大的场合的适应性,以及应注意的问题。     

涡轮流量计的应用

涡轮流量计的应用新疆独山子乙烯厂赵立对于大型化工企业，新水、循环水的用量很大，这些量的总管口径多大于５００ｍｍ，对于这样的大口径管道的计量与中小管径流量的计量相比有许多特殊性，因此流量计如果选型不当，就可能造成流量计不能正常使用或测量数据不准，从而给...     

Numerical simulation of the gas flow in a circuit-breaker

A computational methodology for the solution of unsteady two-dimensional/axisymmetric Euler equations within geometries with moving boundaries is presented. The flow simulation is carried out by applying a finite-volume method which makes use of a Lagrangian-Eulerian version of Roe's approximate Riemann solver. The domain discretization is handled via unstructured triangular grids. Grid adaptation is applied on the basis of geometric and physical requirements. The importance of the implicit treatment of the space conservation laws, based on geometric analysis, is evoked. The procedure for reconstructing Roe's method for moving meshes is described and validated. Finally, the ability of the method for the prediction of the transient flow in a circuit-breaker during its opening phase is illustrated.     

膜式燃气表内部流动数值模拟研究

采用CFD数值模拟方法对有柔性膜片的膜式燃气表内部流动进行数值模拟研究,解决了皮膜和旋转阀之间的联动关系以及旋转阀转动与皮膜运动的仿真实现等技术问题;运用滑移网格、动网格及用户自定义函数(UDF)技术实现了膜式燃气表内部流动的动态数值模拟,获得了旋转阀与阀座存在1mm间隙的情况下膜式燃气表内部流场和仪表压损数据.结果表明,数值模拟技术用于膜式燃气表这种复杂结构的内部流动研究是可行的.     

Numerical simulation of gas flow in pneumatic components

The flow through pneumatic components is characterized by very complex flow phenomina. In general the flow is viscous, transonic (0≦M≦4) and turbulent. Small geometrical dimensions of pneumatic components make flow measurement difficult or sometimes impossible. Hence the accurate numerical prediction of the flow field becomes of great importance. In this paper we present the theoretical framework and the numerical capabicities of the commercial Navier-Stokes CFD code TASC flow. We solve some test problems which reflect many features of the numerical flow simulation in pneumatic components. For the test cases considered here, TASC flow was found to be an excellent tool for fast and accurate flow simulation.     

Numerical simulation of high-pressure gas atomization of two-phase flow: Effect of gas pressure on droplet size distribution

This paper deals with the physics of high-pressure gas atomization in metal powder production. To gain understanding of the effect of gas pressure on droplet size distribution, a numerical two-phase flow study is performed using Eulerian-Eulerian Volume of Fluid (VOF) interface tracking method. Annular-slit, close-coupled gas atomizer is considered to atomize molten aluminum using nitrogen as the atomizing gas. Four cases with different gas pressures are considered, while geometry and other operational parameters are fixed. Characteristics of several interfacial instabilities have been identified at different stages of the atomization process. Despite the increment in the rate of the atomization with the increasing gas pressure, deformation characteristics and the breakup mechanisms remain unchanged. Droplet size and the cumulative volume distributions indicate that the effectiveness of the atomization process increases with the elevating gas pressure. Cumulative volume obtained from the numerical simulations at low gas pressures display similar trends to the experimental results.     

Numerical simulation of a wave channel

The application of the Mixed Eulerian-Lagrangrian method to the simulation of transient free surface flows in the vicinity of a free surface piercing structure is considered. Particular attention is given to the validation of the numerical procedure.

Several applications are studied. Comparisons between the results of the numerical scheme and those of approximate theories or experiments are shown. They demonstrate the accuracy and versatility of the simulation that can be used as a “standard” to check the applicability of approximate theories.

The main limitation of the method is that it cannot account for viscous effects, in particular in the vicinity of the free surface. Approximate ways to simulate dissipative phenomena associated to breaking would be most useful.     

Two-phase gas/liquid flow pressure loss in bends

The state of the art with respect to the prediction of the pressure loss in bends in the case of fluiddynamic subcritical two-phase flow with Newtonian liquid phase behaviour is presented. In analysing the structure and model parameters included in the bend pressure loss correlations doubts arise on the predictive quality and general validity. Some predictions of the correlations by Chisholm, Sookprasong and Paliwoda as relative most complete from a theoretical standpoint, are discussed. The use of Chisholm's model is provisionally recommended.