熵产控制体方法对压气机近零间隙流动损失的演变规律

以澄清近零间隙流动结构及流动损失随间隙的变化规律为目标,提出熵产控制体分析方法,可精确量化流场任意位置的局部不可逆损失.数值模拟发现,间隙在0.4%叶高范围内（称近零间隙）效率水平最高且出现一对应峰值效率最高的最佳非零间隙.熵产控制体分析表明：通道内总熵产随间隙变化规律与效率一致;间隙变化对动叶端区20%~80%弦长范围内的熵产改变最为明显,主导了总熵产的变化;间隙变化时熵产改变的流动区域不同,这是由于动叶端区主导损失的流动结构发生改变造成的.进一步结合流场结构,探讨近零间隙流动损失演变的可能原因：间隙为零时壁面剪切力是造成损失的主导因素;最佳间隙时流动均匀,损失最小.

控制体有限元方法中质量加权迎风格式的迁延修正

控制体有限元方法对于处理流动问题提供了一种较好的数值模拟方法，但对于大Ｒｅｙｎｏｌｄｓ数的回流流动问题，该方法在采用各种迎风格式时仍存在着严重的假扩散．为此，对二维质量加权迎风格式，给出了一种由插值单元及其一个与插值点最靠近的相邻单元所确定的多项式插值格式迁延修正的形式．通过对Ｒｅ＝４００、１０００、５０００三种情形的二维空穴流问题的计算，表明该格式可有效地减少控制体有限元方法对回流问题数值模拟的假扩散．

透平机械动密封动力特性数值方法研究

密封动力特性系数是评价透平机械转子稳定性的重要参数。对现有密封动力特性数值方法进行了综述,为了比较分析不同的密封动力特性数值方法,分别建立了基于控制体方法的双控体求解模型和基于CFD方法的稳态旋转坐标系与瞬态转子平动、转子单/多频椭圆涡动求解模型,综合比较分析了控制体法、CFD稳态旋转坐标系法和CFD瞬态平动法、单/多频法之间的差异以及适用范围,研究了转子涡动频率对密封气流力和动力特性系数的影响。研究结果表明:控制体法求解速度较快,但求解精度较低,稳态旋转坐标系法只适用于转子做小轨迹同心涡动的求解模型,瞬态平动法求解速度较慢;瞬态单/多频法考虑了转子的涡动频率,更符合密封的实际工作情况;应用瞬态单/多频法得到的密封气流力变化频率与转子涡动频率相同,但气流力的相位滞后于转子涡动位移的相位;密封的直接刚度系数随着转子涡动频率的增加而增大,交叉刚度系数和阻尼系数的绝对值随着转子涡动频率的增加而减小。

半圆域上自然对流的数值模拟

对半圆域上的自然对流采用控制体有限元方法进行数值模拟 .采用非结构三角形网格与质量加权迎风格式对计算域及控制方程进行离散 ,对压力离散方程采用波前法求解 ,保证了对所有Ra≤ 10

Computational modeling of free-surface slurry flow problems using particle simulation method

The particle simulation method is used to solve free-surface slurry flow problems that may be encountered in several scientific and engineering fields.The main idea behind the use of the particle simulation method is to treat granular or other materials as an assembly of many particles.Compared with the continuum-mechanics-based numerical methods such as the finite element and finite volume methods,the movement of each particle is accurately described in the particle simulation method so that the free surface of a slurry flow problem can be automatically obtained.The major advantage of using the particle simulation method is that only a simple numerical algorithm is needed to solve the governing equation of a particle simulation system.For the purpose of illustrating how to use the particle simulation method to solve free-surface flow problems,three examples involving slurry flow on three different types of river beds have been considered.The related particle simulation results obtained from these three examples have demonstrated that:1) The particle simulation method is a promising and useful method for solving free-surface flow problems encountered in both the scientific and engineering fields;2) The shape and irregular roughness of a river bed can have a significant effect on the free surface morphologies of slurry flow when it passes through the river bed.

Numerical simulation of steady flow past a liquid sphere immersed in simple shear flow at low and moderate Re

This work presents a numerical investigation on steady internal, external and surface flows of a liquid sphere immersed in a simple shear flow at low and intermediate Reynolds numbers. The control volume formulation is adopted to solve the governing equations of two-phase flow in a 3-D spherical coordinate system. Numerical results show that the streamlines for Re = 0 are closed Jeffery orbits on the surface of the liquid sphere, and also closed curves outside and inside the liquid sphere. However, the streamlines have intricate and non-closed structures for Re ≠ 0. The flow structure is dependent on the values of Reynolds number and interior-to-exterior viscosity ratio.

Illusory Control： Female’s Sexuality and Male’s Fantasy in The Changeling

Thomas Middleton and William Rowley’s The Changeling enacts an astonishment on the stage to the audience about the protagonist Beatrice-Joanna’s down fall-the noble lady being straightly encroached by her desire and being manipulated by the obscene servant De Flores, who, by means of rape, controls her body and finally destroys her. My article attempts to explore male’s expectations and their power over female’s sexuality with Jacques Lacan’s psychoanalytical approach. Moreover, it will elaborate that Beatrice-Joanna’s tragic outcome is not only contributed by her murder and moral degradations, but also, before her transgression being committed, her body has already been regulated by the patriarchal power in the Renaissance society-either she is valuable in the marriage market with her chastity or she is condemned by losing it. Also, the science of medicine employed to test virginity represents the male’s methodological hegemony and anxiety in facing the unknown of a female’s chastity. For the fantasy always regulating the male’s power structure over female’s body, the real manipulation over female sexuality is doomed to be an illusion.

A Transient Multidimensional CFD Approach to the Analysis of a Control Valve Using Non-Newtonian Fluids

In this paper the flow through a control directional valve is studied by means of a CFD （computational fluid-dynamics） analysis under transient operating conditions. The mesh motion is resolved on a time basis as a function of the external actuation system In the analysis, an open source fluid-dynamics code is used and both cavitation and turbulence are accounted for in the modeling. Moreover, the numerical model of the working fluid is modified in order to account also for the non-Newtonian fluids. The effects of the shear rate on the shear stress are accounted for both by using experimental measurements and correlations available in literature, such as the Herschel-Bulkley model. The analysis determines the performance of the control directional valve under different operating conditions when using either Newtonian or non-Newtonian fluids. In particular, the discharge coefficient, the recirculating regions, the flow acceleration angle and the pressure and velocity fields are investigated.

湖北东圣120M造粒塔滑模施工实践

湖北东圣化工集团三期工程20万t/a复合肥高塔造粒工程,由筒体和梯井组成,筒体直径18m,梯井平面尺寸10m×8m,塔体高度120m,其中地下部分5m,地上部分115m。施工采用液压滑模方案,目前筒壁滑模施工已全部结束,工程质量和施工进度赢得了较好的社会信誉。

Design and optimization of low-energy transfer orbit to Mars with multi-body environment

This paper discusses the problem of design and optimization of low-energy transfer orbit with multi-body environment. A new integrative method is proposed to effectively solve the problem, in which the parameterized patched manifolds in CR3BP(circular restricted three-body problems), the shape-based method with multi-body environment, the homotopic method with multi-body environment, and the low-thrust capturing and descending algorithm with multi-body environment are all included. Firstly, the parameters describing the patched manifolds in CR3 BP are optimized until the least total absolute velocity increment has been got, including the employment of the shape-based method with multi-body environment. Secondly, the low-thrust control laws of the transfer orbit are optimized employing the homotopic method with multi-body environment that transfers the fuel optimization problem to an easier energy optimization problem. Thirdly, the low-thrust descending orbit around Mars is computed using the laws proposed in this paper. As a typical example, the Earth-Mars transfer orbit design is discussed. The results showed that the parameters describing the patched manifolds could be optimized by the DE(differential evolution) algorithm effectively; the homotopic method with multi-body environment could get the optimal value that meets the first order optimality conditions; and the low-thrust descending orbit could effectively be captured by Mars and finally become a circular parking orbit around it by the hypothesis control laws proposed in this paper. It shows that the final fuel cost is much less than the optimal transfer in the patched two-body problems. In conclusion, the method proposed in this paper could effectively solve the low-energy low-thrust optimal control problem in multi-body environment for the future deep space explorations.