机坪输油管道冲刷腐蚀研究

研究了冲刷腐蚀过程的发生机理,分析了流体的流速、管道的结构、流体中的第二相、流体的流动状态等因素对冲刷腐蚀过程的影响。就机坪输油管道系统中常见的易腐蚀管件90°弯管和T形管的冲刷腐蚀问题展开讨论,采用ANSYS 3.0软件中Fluent模块进行数值模拟,计算在不同工况下管道冲蚀减薄规律和特点,从而解释腐蚀的破坏程度。最后考虑到管材冲刷腐蚀的减薄程度和机坪输油系统的设计使用年限,得出冲刷腐蚀对于机坪输油管道使用寿命的影响。     

全液压制动系统控制阀变参数仿真分析

控制阀决定了全液压制动系统的充液压力。从物理运动及结构两方面介绍全液压制动控制阀的工作原理,分析影响充液压力上限的因素。建立控制阀三维数学模型,应用Fluent软件对不同进口速度u、阀芯套筒锥角β以及钢球直径D的控制阀进行模拟研究,对比分析其内部流场的变化。搭建全液压制动系统试验台进行充液压力上限测试试验,验证理论分析及仿真结果的有效性,得出各参数对充液压力上限的影响规律。结果表明,控制阀的进口速度、阀芯套筒锥角与充液压力上限呈正相关,钢球直径与充液压力上限呈负相关。     

Research on flow field in a modified ring spinning system with the air nozzle

Twisting is one of the most important steps in the yarn spinning, which influences the geometry of spinning triangle and determines the properties of spun yarns. Airflow is one of the most important measures on improving yarn spinning. In this paper, a kind of air nozzle with vortex guiding channel was designed and used on the modification of ring spinning system, and the spun yarn qualities was studied by analyzing the airflow field in the nozzle. Firstly, the three-dimensional physical model of nozzle was given using CAD software according to the geometrical size of the practical nozzle model. Then, the numerical simulations of the three-dimensional flow field in the nozzle were given using Fluent software. Finally, two different kinds of yarns 10Ne and 20Ne were spun in the modified ring spinning system with the nozzle installed. The airflow pressure 0.01 Mpa and two different swirling directions, anticlockwise and clockwise, were chosen. The qualities of spun yarns, hairiness, strength, evenness, and number of snarling were measured and analyzed. It is shown that the high vortex airflow can be produced in the nozzle, and then corresponding twist can be produced. For the Z(S) twisting spun yarn, under the effects of the clockwise (anticlockwise) vortex airflow, the pre-twisting would be produced and the yarn twist can be strengthened, while under the effects of the anticlockwise (clockwise) vortex airflow, the untwisting effect would be produced, and the yarn twist can be decreased.     

某型发动机高温转速不足分析

文章分析了某型发动机在外场点火试车试验中,发动机到达一定的转速后,发动机转速增加缓慢,伺服阀可能产生的原因.重点从系统油压波动、油液温度、液流流态等方面对伺服阀进行了分析.     

Combustion characteristics of solid waste biomass,oil shale,and coal

In this study, a developed two-dimensional mathematical model was used to represent the physical model of the combustion process of olive cake and date seed, and solve the governing equations using finite-volume method. The simulation was performed using ANSYS/Fluent software in order to estimate maximum temperature, heating values and pollutants concentrations. The obtained results were compared with experimental results, and corresponding values of oil shale and coal. The experimental work of direct burning of olive cake and date seeds was performed using an existing circulated fluidized bed (CFB) unit.

It was found that the adiabatic flame temperatures were 1380 K and 839 K for olive cake and date seed, and 2260 K and 1080 K for coal and oil shale, respectively. The experimental results showed that the maximum temperatures were 1126 K and 723 K for olive cake and date seed, respectively. The lower heating values were 19,500 kJ/kg and 16,400 kJ/kg for olive cake and date seed, and 29,000 kJ/kg and 7000 kJ/kg for coal and oil shale, respectively.

Thus, biomass such as date seed and olive cake may be used as an alternative fuel in electrical power plants in olive- or date-producing countries, which may save 40% of fuel cost.     

基于Fluent的气固喷射器三维数值模拟研究

根据CFD和仿真思想,采用标准k-ε湍流模型,并利用拉格朗日法和欧拉法相结合的三维数值模拟技术,对气固喷射器内的流场和颗粒行为进行了数值模拟研究。对固体颗粒采用了离散相模型,考察了气固两相间的相互耦合[1]作用,结果表明:在该喷射器的接收室中,喷嘴管道周围的一些无效区域内有颗粒的聚集和停留,流场的湍动能在喷嘴出口区域周围达到最大值。其主要原因在于,喷射器中心高速射流区域周围产生了明显的回流现象,固体颗粒的加入对气体流动情况产生了一定影响,气体流场随后逐步稳定。     

袋式除尘器内部湍流流场数值模拟研究

袋式除尘器内部有着复杂的湍流流场,形成的漩涡回流易造成尾部滤袋磨损和破坏。针对这一问题,利用CFD软件对袋式除尘器内部湍流流场分布进行了数值模拟。通过设置入口速度等边界条件,采用k-ε湍流模型模拟气相流动,分析了袋式除尘器内部各处速度流场、气体流场轨迹的情况,为袋式除尘器的改进和设计提供了理论依据。     

基于Fluent的阀门开启过程阀芯气动力仿真研究

利用Fluent动网格和UDF技术对适当简化的阀门2D模型进行数值模拟,得到开启过程中作用在阀芯上的轴向气动力变化规律。     

低功耗超声流量计的研究

针对超声波流量测量中管道结构对测量精度的影响,采用Fluent仿真软件模拟了不同管道中流体的流动状况,对管道内的超声波信号进行了分析和比较,设计了超声波流量传感器,并应用设计的流量传感器,研制了超声波流量积算仪的硬件电路和软件,最终的样机实验结表明,该超声流量计流量误差小于±2%,系统的平均工作电流为35μA。     

Flow simulation in Electro-Static-Precipitator (ESP) ducts with turning vanes

Flow simulation in inlet ducts along with several turning vanes used in electrostatic precipitator (ESP) are analysed to understand the flow pattern at its exit locations. The geometry of inlet duct has been extracted from the Plant Design Manufacturing System (PDMS) and refined with turning vanes placed at several locations. The domain of duct geometry around turning vanes are decomposed with several volumes and filled with hexahedral elements with the help of stat-of-art mesh generator - Hypermesh. The resulting computational grid has been used in TASCflow solver to predict its flow pattern in the duct. Simulation for the specified conditions predicts uneven flow distribution in the ESP inlet duct. Due to large flow recirculation and turbulent losses in the duct, non-uniform averaged mass flow rates are noticed at duct exit locations. Simulation results suggest that the improvement of flow distribution in the duct through optimization can be tried by placing more turning/splitter vanes in the inlet duct. In order to ensure that the results obtained from TASCflow are meaningful and in right direction, in the absence of measurement data, simulation was benchmarked with other industry standard commercial flow solvers. The observations made from these popular solvers confirm the findings obtained using the TASCflow solver. The analysis with multiple solvers indicates that Fluent provides quick results, while better visualization can be made using CFX solver. The Star-CD solver, which captures the turbulent losses accurately takes more time for convergence provides alternatives.