The flow of a variable viscosity fluid between parallel plates with shear heating

A model for the flow of a fluid through a channel with parallel plates is investigated. The channel is narrow, so that the lubrication approximation may be applied. The channel walls are maintained at a constant temperature. Shear heating effects are included and the fluid viscosity decreases exponentially with temperature. When the flow is driven solely by shear stress or imposed velocity at the top, analytical progress is possible. When pressure gradient also drives the flow the problem is solved numerically.     

倾斜下降管气液两相分层流截面含气率的计算与液层高度的预测

分层流是气液两相流中常见的流动型式，分层流中液层高度是计算的基本数据，由于界面波的存在，对液层的测量和预测都很困难．Ｖｌａｃｈｏｓ提出了预测气液两相分层流液层厚度的关系式，但这一关系式并不适用于倾斜下降管气液两相流．本文提出了计算倾斜下降管气液两相分层流截面含气率的理论模型，在这种模型下得到的截面含气率和实验结果符合良好．在大量实验的基础上，考虑了倾角、管径、气液各相折算速度的影响，根据实验数据提出了预测液层厚度的关系式。     

进口畸变条件下改善压气机性能的数值研究

依据"非定常两代流型"理论,验证了二维叶栅在均匀进气条件下,施加激励对其性能所起的改善作用,尔后重点研究了进口具有总压的周向畸变时,施加激励对其气动性能的影响。计算结果表明,在有无进口畸变时,施加一定的激励都会改善流场结构,气动参数有积极变化,压升和效率增加,特别是在流量比较小时,变化尤为明显.对于进口畸变和施加激励影响压气机性能的内在原因,从流场结构的变化方面进行了初步分析。     

Residual currents and corridor of flow in the Rio de la Plata

The Rio de la Plata is a large and shallow water body that discharges onto the Atlantic Ocean. The main driving forces for the river flow are the bathymetry, tides, the outflow from the Paraná and Uruguay rivers and the winds. A numerical model covering the entire river was set up with the objective of increasing our understanding of the hydrographical features and morphological dynamics in the Estuary. The simulations revealed a counter-clockwise residual circulation in the Samborombón Bay and an eastward net flow near the Uruguayan coast. The residual flow is forced by both the tides and the bathymetry. The residence time for the entire river ranges from 40 to 80 days. However, residence times above 120 days was found in the Samborombón Bay. Three corridors of flow have been identified.     

基于二次插值的非饱和土壤水流问题的特征差分方法及数值模拟

本文针对一类非饱和土壤水流问题,提出了基于二次插值的特征差分格式,得到了严谨的L2模误差估计.并作了数值试验,指明方法的有效性.     

An improved algorithm for decomposing arc flows into multipath flows

We consider a multipath maximum flow problem introduced by Kishimoto (Networks 27(4)(1996)279-291). The focus is on efficient transformation from arc flows into multipath flows, where a multipath flow is a nonnegative combination of multipaths. A new algorithm that is more efficient than existing ones is proposed for the transformation.     

稀薄气体二维外部柱体绕流特性研究

本文采用直接模拟蒙特卡罗方法对稀薄气体二维外部柱体绕流问题进行了数值模拟。结果表明:外部绕流问题,在特定情况下会产生激波,激波的产生,不仅与气体的稀薄程度有关,还与来流马赫数有关。而气流与壁面之间的换热,随来流马赫数增加而增加,随气体稀薄程度增加而减小。     

环形燃烧室火焰简及旋流器流场计算

本文采用偏微分方程法生成贴体网格,在任意曲线坐标系下数值研究两种先进燃烧室火焰筒及其旋流器三维紊流流场。由于旋流器的形状复杂,本文采用型线定点法确定网格的边界。在非交错网格系下采用SIMPLE算法和混合差分格式对离散方程进行求解。计算结果表明计算方法合理,这计算程序进一步扩展,可用来预估环形燃烧室反应流流场。     

Interior point cutting plane method for optimal power flow

In this paper, an interior point cutting plane method (IPCPM)is applied to solve optimal power flow (OPF) problems. Comparedwith the simplex cutting plane method (SCPM), the IPCPM is simpler,and efficient because of its polynomial-time characteristic.Issues in implementing IPCPM for OPF problems are addressed,including (1) how to generate cutting planes without using thesimplex tableau, (2) how to identify the basis variables inIPCPM, and (3) how to generate mixed integer cutting planes.The calculation speed of the proposed algorithm is further enhancedby utilizing the sparsity features of the OPF formulation. Numericalsimulations on IEEE 14-300-bus test systems have shown thatthe proposed method is effective.     

低进汽压力下超音速两相流升压特性实验研究

本文采用实验方法研究了进汽压力为0.2 MPa以下时,由蒸汽喷嘴、混合腔及相应的阀门和管道组成超音速汽液两相流升压加热装置的运行特性。实验表明在进汽压力为0.1 MPa-0.2 MPa时,超音速汽液两相流升压加热装置都可稳定可靠地运行,且升压效果明显,可满足电力、供暖、轻工等许多行业蒸汽加热的要求。