积垢对离心压气机叶轮气动性能的影响

建立表征离心压气机叶轮积垢分布的粗糙度模型,在叶片表面生成三维、非均匀分布的粗糙带,数值研究干净和积垢状态下叶轮的气动性能和内部流场,并通过敏感性分析,找到对叶轮气动性能影响最大的积垢区域。结果表明:积垢叶轮的多变效率和总压比较干净叶轮均有显著下降;随着流量增大,性能衰减愈发明显;离心压气机叶片前缘靠近叶顶部位为气动性能对积垢的最敏感区域.研究工作为离心压气机的鲁棒设计优化奠定了理论基础。     

基于伴随方法的多级叶轮机三维叶片优化设计

伴随方法单次优化循环计算量与设计变量数目基本无关,多设计变量时计算成本低。本文采用伴随方法发展了多级叶轮机三维黏性气动形状优化方法,包括伴随方程及其边界条件、目标函数与设计变量的敏感性关系。结合基于Hicks-Henne函数的三维叶片参数化方法和最速下降法建立了气动形状优化设计系统。针对1.5级压气机第二排叶片的反设计验证了该优化系统的有效性;以进、出口熵增为目标函数改型设计某1.5级超音压气机,改型后气动性能明显提升。     

高比转速离心压气机模型级叶轮内部三维流场分析与改进

利用三维数值模拟计算(CFD)技术和模型级与国外某 75 kW 燃气轮机压气机叶轮的内部流场进行了数值模拟,得到了相应的特性曲线与主要气动参数分布。完成的初步流场分析表明,尽管模型级有较高的效率和较宽广且平坦的工作特性,但叶轮设计仍有较多可改进之处。通过对计算结果进行的分析比较,得到了在离心压气机叶轮设计中有价值的初步性结果,为进一步的设计提供了改进途径和相应的基础数据。75 kW 燃气轮机的进气道型线经过优化改进后,总压恢复系数提高了 7.5％,并有进一步改进的余地。     

关于叶轮机时均(准四维)和非定常(四维)气动设计体系的初步诠释

本文以考虑非定常流动的完整性为线索,总结概述了先前气动设计体系的困难与限制,在此基础上,以描述叶轮机流动的时均和时间精确模型为核心分别从其构成和标志性技术对叶轮机时均和非定常气动设计体系进行了初步诠释。文章认为促成时均(准四维)和非定常(四维)气动设计体系现实应用是叶轮机发展的最后契机。     

径、混流式三元叶轮“全可控涡”设计的理论和方法

一、引言 本文是一种尝试,企图运用已有的试验资料及理想流体准三元流动理论设计出具有较高气动性能,便于制造的径、混流式三元叶轮.W.Jansen提出了一种很好的离心式压缩机叶轮叶片的设计方法.他把叶轮叶片的设计分成二大步.第一步,根据设计要求     

高比转速离心压气机叶轮的设计及其三维流场分析

利用三维数值模拟计算(CFD)技术进行了100 kW微型燃气轮机的高比转速离心压气机叶轮的设计与内部流动的数值模拟与分析,得到了相应的特性曲线与主要气动参数分布。根据数值模拟分析,设计的100 kW微型燃气轮机高比转速离心压气机叶轮具有较高的效率和较宽广且平坦的工作特性,可以满足微燃机总体设计对压气机的要求。流道内存在复杂的跨音速流动现象。在下一步工作中,有必要优化设计叶轮几何型线,提高压气机效率。     

MW级超临界二氧化碳向心涡轮设计及分析

本文以某MW级超临界二氧化碳(S-CO2)向心涡轮为研究对象,对S-CO2向心涡轮的设计体系展开进一步探索,并利用一维分析方法和三维数值模拟方法对其进行气动分析.文中先介绍了本课题组已经开发完成的针对向心涡轮喷嘴和转子叶轮的一维气动优化设计方法,然后补充向心涡轮进气蜗壳的设计方法,最后利用三维CFD方法对设计方案的进气...     

透平准三元设计中S_2流面计算探讨

一、引言 自从吴仲华教授创立的叶轮机械三元流动理论广泛应用于叶轮机械的气动设计以来,S_1、S_2两类流面的三元迭代求解方法有了迅速发展。在准三元迭代计算中,由于流线在子午面投影是连续的,若给定远方进、出口参数及间隙站环量,就可一次解出多级叶片中心S_1流场,而S_2流面由于动静叶间有相对运动,在稳定流动下只能计算一有前后延伸空段的单排叶片段,且此延伸空段的参数是多级中心S_2流面计算所没有的。因此为S_1流     

叶轮机械数值计算与设计方法进展及其在汽轮机中的应用──第一部分:数值计算及设计方法进展

本文对多级汽轮机通流部分气动热力学数值计算方法与设计体系研究所取得的进展进行了回顾，主要内容包括通流部分气动热力准三维、全三维计算方法进展、程序的校准方法、多级轴流透平气动热力设计体系研制等，并提出了今后进一步开发的设想．     

基于三维粘性流动分析的离心压缩机叶轮设计方法

本文尝试了一种以三维粘性分析为参考准则设计离心压缩机三元叶轮的实用方法.以角动量为控制手段对Krain实验叶轮进行了变型设计,并对Krain原始叶轮与新设计叶轮进行了三维粘性流场计算,对典型通流截面的子午速度与转子焓分布做了分析,并对三种叶轮的总体性能进行了比较。结果表明,角动量的不同分布对所设计叶轮的压比和效率有明显的影响。     

Design of cylindrical air inlets for high flight speeds from a combination of plane flows

In the present paper, we discuss a procedure for designing of cylindrical air inlets for high flight speeds with the use of V-shaped bodies for forming a plane flow with an initial oblique compression shock. In design regime, characteristics of such air inlets can be obtained by means of simple calculations performed in a broad range of governing parameters. The difference between the performance characteristics of a typical cylindrical inlet in design and off-design flow conditions was elucidated with the help of 3D numerical calculations.     

实验轴流透平级设计及流场分析

本文介绍了在S_2通流设计基础上,采用商用软件BladeGen作几何初步造型,利用基本截面变截面宽度扭曲、动叶多截面三维整体造型等多种手段来设计单级实验透平的过程,并进行了透平级三维流场数值模拟与分析,取得了基本性能参数与S_2通流设计相一致的结果,为后续实验研究和数值模拟工作提供了可用的实验条件和可靠的设计数据.     

Theoretical models for designing a 220-GHz folded waveguide backward wave oscillator

In this paper,the basic equations of beam-wave interaction for designing the 220 GHz folded waveguide(FW)backward wave oscillator(BWO) are described.On the whole,these equations are mainly classified into small signal model(SSM),large signal model(LSM),and simplified small signal model(SSSM).Using these linear and nonlinear one-dimensional(1D) models,the oscillation characteristics of the FW BWO of a given configuration of slow wave structure(SWS) can be calculated by numerical iteration algorithm,which is more time efficient than three-dimensional(3D)particle-in-cell(PIC) simulation.The SSSM expressed by analytical formulas is innovatively derived for determining the initial values of the FW SWS conveniently.The dispersion characteristics of the FW are obtained by equivalent circuit analysis.The space charge effect,the end reflection effect,the lossy wall effect,and the relativistic effect are all considered in our models to offer more accurate results.The design process of the FW BWO tube with output power of watt scale in a frequency range between 215 GHz and 225 GHz based on these 1D models is demonstrated.The 3D PIC method is adopted to verify the theoretical design results,which shows that they are in good agreement with each other.     

<Emphasis Type="BoldItalic">λ</Emphasis> /4 rule used for designing large high-reflectance region in 2D and 3D photonic crystals

Based on a series of numerical results calculated by the transfer-matrix method, we find that the /4 rule for one-dimensional (1D) optical films is also valid for 2D and 3D photonic crystals (PCs) in designing a large high-reflectance region (HRR), if the 1D counterpart approximation is used for them. A detailed process of the 1D counterpart approximation is described. The results of the 1D counterparts of real 2D and 3D PCs are in good agreement with the /4 rule. Therefore, the /4 rule can be extended to 2D and 3D structures for designing large HRRs. PACS 42.70.Qs; 42.25.Bs     

面阵CCD交汇测量系统布站方式的优化设计

为了得到最佳的坐标测量精度,针对面阵CCD交汇测量系统的布站方式进行了优化设计。以四台测量站为例建立了优化设计的数学模型,用计算机进行仿真,得出了最佳布站方式。给出了不同布站方式下在测试范围内各点坐标的误差分布的三维图。     

High Level Languages Implementation and Analysis of 3D Navier-Stokes Solvers

In this work we introduce PRIN-3D (PRoto-code for Internal flows modeled by Navier-Stokes equations in 3-Dimensions), a new high level algebraic language (Matlab$^®$) based code, by discussing some fundamental aspects regarding its basic solving kernel and by describing the design of an innovative advection scheme. The main focus was on designing a memory and computationally efficient code that, due to the typical conciseness of the Matlab coding language, could allow for fast and effective implementation of new models or algorithms. Innovative numerical methods are discussed in the paper. The pressure equation is derived with a quasi-segregation technique leading to an iterative scheme obtained within the framework of a global preconditioning procedure. Different levels of parallelization are obtainable by exploiting special pressure variable ordering patterns that lead to a block-structured Poisson-like matrix. Moreover, the new advection scheme has the potential of a controllable artificial diffusivity. Preliminary results are shown including a fully three-dimensional internal laminar flow evolving in a relatively complex geometry and a 3D methane-air flame simulated with the aid of libraries based on the Flamelet model.     

点火黑腔二维模拟设计

基于二维激光靶耦合流体力学程序,研究设计惯性约束聚变间接驱动点火黑腔的方法.提出先调控X射线驱动温度再调控辐照均匀性的设计顺序.给出总激光功率(特别是主脉冲激光功率)的设计方法.模拟表明,填充气体密度的上限受到槽脉冲P²辐照不均匀性的限制.另外,增加腔长可以抑制靶丸烧蚀层物质的膨胀.最后给出点火黑腔二维设计结果.     

三维面形测量数据的计算全息可视化

提出利用计算机制全息进行三维面形测量数据立体重现的技术。首先利用三维面形测量技术同时获取三维物体的强度和距离像；然后根据三维面形测量数据，设计和制作菲涅耳计算全息图；最后将计算全息和光学全息相结合，以菲涅耳计算全息图的光学再现像为对象，记录光学像全息。这样既解决了计算机制全息术中真实三维物体立体信息数据捕捉的问题，又为三维面形检测提供了一个行之有效的立体重构技术。给出了这种方法的原理、计算全息的设计、制作方案和实验验证结果。     

Optimized free-form optical trapping systems

We report a comprehensive process for designing and prototyping new and optimized optical trapping systems. A combination of traditional lens design strategies, simulation of optical forces, and high-end ultraprecision machining of optical free-form surfaces is applied to the realization of a highly specialized optical trapping system. The resulting compact and lightweight optical modules potentially open new classes of applications for optical manipulation. As an example we present a customized 3D trapping module made of a single piece of polymethylmethacrylate, with a large working distance of 650?μm.     

Two-dimensional dissimilar electromagnetic cloak for irregular regions

A general method to design a 2D dissimilar cloak for irregular regions is presented by operating a nonlinear transformation in polar coordinates. The material parameters avoid discontinuities while the thickness of the cloak shell is effectively limited in elongated directions. Full-wave simulations of an elliptic cloak, a rectangular cloak, and an arbitrary-shape cloak are performed to verify the validity of the design. Both the material parameters and the scattering widths of different models are calculated and illustrated for comparison. This method provides a possible approach for designing complex shaped cloaks.