微反应器内入口结构对Taylor气泡形成过程的影响

采用计算流体力学方法,考察了微通道入口结构、气液比及两相混合速度对Taylor气泡形成过程的影响,模拟结果与可视化实验符合良好。与单纯流体体积法相比,水平集法（level set）和流体体积法（volume of fluid）相耦合的方法（coupled level set and volume of fluid method,CLSVOF）可获得更精确的气液界面,且CLSVOF法结果与实验结果更符合。数值模拟结果发现,通道入口结构及气液比对气泡长度、气泡生成频率及气泡体积有很大影响。气液比恒定,不同通道入口结构,两相混合速度对气泡长度有不同影响。     

Numerical simulations of morphological changes in barrier islands induced by storm surges and waves using a supercritical flow model

In this paper, an advanced explicit finite volume flow model in two-dimensions is presented for simulating supercritical coastal flows and morphological changes in a tidal/coastal inlet and barrier islands due to storm surges and waves. This flow model is coupled with existing wave-action model and sediment transport model. The resulting integrated coastal process model is capable of simulating flows induced by extreme conditions such as waves, surge tides, river flood flows, etc., and morphological changes induced by rapid coastal currents and waves. This developed supercritical flow model is based on the solution of the conservative form of the nonlinear shallow water equations with the effects of the Coriolis force, uneven bathymetry, wind stress, and wave radiation stresses. The forward Euler scheme is used for the unsteady term; and the convective term is discretized using the Godunov-type shockcapturing scheme along with the HLL Riemann solver on non-uniform rectilinear grids. The accuracy of the developed model is investigated by solving an experimental dam-break test case. Barrier island breaching, overflow and overwash due to severe storm attack are simulated and the predicted morphological changes associated to the events are analyzed to investigate the applicability of the model in a coast where all the physical forces are present.     

来流附面层对吸附式压气机叶栅影响的数值研究

数值研究低速条件下来流附面层特性对吸附式压气机叶栅气动性能的影响,在不同正冲角时,设计不同方案的附面层厚度分布,对比分析叶栅出口气动参数的分布以及叶栅内的三维流场结构,讨论不同来流附面层情况下在压气机叶栅中采用附面层吸除的效果。结果表明,数值模拟结果与试验数据有较好的一致性;附面层厚度的增加导致角区流动三维性增强,且变冲角性能下降,二次流横向作用和角区范围的增加使得附面层抽吸效果减弱;当来流附面层厚度增加时,通过增加抽吸量可以有效降低强吸附式压气机叶栅的损失,变冲角性能得到改善。     

面内弯矩作用下弯管应力高次解

该文采用应变分析和能量法得出了面内弯矩作用下弯管环向和轴向应力的解析解,并提出了高次解的求解方法。该方法的计算结果与其他各种解析解的结果进行比较表明:该文提出的方法能得到更精确的结果,并适用于所有弯曲系数的弯管。该方法可用于计算弯管在面内闭合弯矩和面内张开弯矩下的应力。     

雨水口箅子的孔口流量系数试验研究

孔口流量系数大小对雨水口箅子的泄流能力具有重要影响。对等格条间距和等格条厚度的矩形断面横条箅子和圆形断面横格条箅子的孔口流量系数进行了试验研究,结果表明雨水口箅宽方向截留纵坡向来水时,随来水量增大,矩形断面格条箅子的流量系数呈略减小趋势,其流量系数比圆形断面格条箅子稳定;雨水口泄流箅上深度积水时,矩形断面格条箅子的流量系数明显小于圆形断面格条箅子。该结果可对雨水口箅子的选用和雨水口的设计计算具有重要参考意义。更多还原     

莲花水电站尾水肘管模板设计与施工

莲花水电站根据水力模拟试验结果设计了不规则形状的肘管,模板支设较为复杂。文章从尾水肘管模板设计、结构布置、强度验算、支模施工等方面全面阐述了尾水肘管的设计和施工问题。     

Methodology to determine the appropriate amount of excess air for the operation of a gas turbine in a wet environment

This paper addresses the impact of excess air on turbine inlet temperature, power, and thermal efficiency at different pressure ratios. An explicit relationship is developed to determine the turbine inlet temperature as a function of excess air, pressure ratio and relative humidity. The effect of humidity on the calculation of excess air to achieve a pre-established power output is analyzed and presented. Likewise it is demonstrated that dry air calculations provide a valid upper bound for the performance of a gas turbine under a wet environment.     

微型燃气轮机燃油燃烧室燃烧特性的模化试验研究

基于模化试验方法,对设计的100kW级微型燃气轮机燃油燃烧室在额定工况下的性能以及在保持微型燃气轮机燃烧室出口排气温度不变的情况下,改变进口空气温度对燃烧室燃烧特性的影响进行了研究。结果表明,燃烧室燃烧效率达到99%以上,总压恢复系数达到94.5%,出口温度最大不均匀度低于20%,NOx排放指标低于9g/kg,火焰筒壁面温度分布均匀。此外,随着燃烧室进口温度的升高,燃烧效率增大,出口温度最大不均匀度减少,CO和UHC的排放指标明显降低,但总压恢复系数有所降低,NOx排放指标有所升高。     

防爆柴油机进气栅栏计算流体动力学分析

为了改善某防爆柴油机的进气栅栏的流通特性,应用CFD分析软件对5种不同扩张角度α的栅栏进行对比分析,找到了栅栏设计的合理扩张角度α。由流场分析结果可知,当栅栏扩张角度α=40°时,栅栏的流通特性得到了明显改善。     

川气东送管道工程用Φ1016mm×26.2mm感应加热弯管的性能分析

从对国内某弯管厂生产的川气东送管道工程用Φ1016mm×26.2mm感应加热弯管及其母管的主要理化性能进行的分析比较中发现,感应加热弯管及其母管的主要性能均值明显高于该管道工程技术标准的要求;所制得的弯管较母管强度下降,韧性上升,塑性略有增加;弯管不同部位的性能变化也有一定的差异。