Detailed numerical investigations on the unsteady flow excitation characteristics and mechanical performance under unsteady surface pressure of last turbine stage long blade are conducted by applying sliding interface method and fluid-structure interaction approach. Unsteady aerodynamic performance of turbine stage is analyzed through solving the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solution and k-ε turbulent model using commercial CFD software ANSYS-CFX. The computational domains include last stage stator domain, rotor domain, shroud domain and curved diffusor. Unsteady pressure on long blade surfaces in every time step is transferred to the mechanical grids of long blade after interpolated in the fluid-solid interface. The mechanical performance of long blade with damper shroud and part-span connector (PSC) is obtained using finite element method (FEM) while considering the unsteady aerodynamic load and nonlinear contact between adjacent damping tip-shroud and PSC. The numerical results show that static pressure on long blade surface presents obvious periodic fluctuation; with the decrease of mass flow, blade loading reduces obviously and separation vortex appears in the diffusor and extends to the rotor passages; the frequency of separation vortex is about 126 Hz; the maximum displacement and maximum Von-Mises stress of long blade both show periodic features.
采用滑动界面法和流固耦合法对末级长叶片在非定常面压作用下的非定常流场激励特性和力学性能进行了详细的数值研究。利用商业CFD软件ANSYS-CFX，通过求解三维reynolds - average Navier-Stokes (RANS)解和k-ε湍流模型，分析了涡轮级的非定常气动性能。计算域包括末级定子域、转子域、叶冠域和弯曲扩散域。每个时间步长叶片表面的非定常压力在流固界面内插值后传递到长叶片的机械网格上。考虑非定常气动载荷和相邻阻尼叶冠与部分跨连接件之间的非线性接触，采用有限元法对带阻尼叶冠和部分跨连接件的长叶片进行了力学性能分析。数值计算结果表明，长叶片表面静压存在明显的周期性波动;随着质量流量的减小，叶片负荷明显减小，分离涡在扩压器内出现并向转子通道延伸;分离涡的频率约为126 Hz;长叶片的最大位移和最大Von-Mises应力均呈现周期性特征。
{"title":"Investigations on Unsteady Flow Excitation and Mechanical Performance of Last Turbine Stage Long Blade Using Fluid-Structure Interaction Method","authors":"Jun Li, Zhigang Li, Liming Song, Qinghua Deng","doi":"10.1115/IMECE2018-86950","DOIUrl":"https://doi.org/10.1115/IMECE2018-86950","url":null,"abstract":"Detailed numerical investigations on the unsteady flow excitation characteristics and mechanical performance under unsteady surface pressure of last turbine stage long blade are conducted by applying sliding interface method and fluid-structure interaction approach. Unsteady aerodynamic performance of turbine stage is analyzed through solving the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solution and k-ε turbulent model using commercial CFD software ANSYS-CFX. The computational domains include last stage stator domain, rotor domain, shroud domain and curved diffusor. Unsteady pressure on long blade surfaces in every time step is transferred to the mechanical grids of long blade after interpolated in the fluid-solid interface. The mechanical performance of long blade with damper shroud and part-span connector (PSC) is obtained using finite element method (FEM) while considering the unsteady aerodynamic load and nonlinear contact between adjacent damping tip-shroud and PSC. The numerical results show that static pressure on long blade surface presents obvious periodic fluctuation; with the decrease of mass flow, blade loading reduces obviously and separation vortex appears in the diffusor and extends to the rotor passages; the frequency of separation vortex is about 126 Hz; the maximum displacement and maximum Von-Mises stress of long blade both show periodic features.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115451406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Several critical aspects control the successful reentry of vehicles on the earth’s atmosphere: continuous communication, GPS signal reception and real-time telemetry. However, there are some common issues that can interfere with the instruments operation, the most typical being the radio blackout, in which the plasma layer frequency modifies the electromagnetic waves in a way that makes communications to and from the spacecraft impossible. So far, there have been several proposed techniques to mitigate radio blackout, one of which is the usage of electromagnetic fields. Previous studies have proven the effectiveness of the usage of an electric and/or magnetic fields to manipulate plasma layers. Experiments on plasma layer manipulation during hypersonic flight regime are extremely costly. Therefore, there has been a continuous interest in the development of cheaper solutions, that can guarantee a reliable degree of accuracy, such as the development of complex multiphysics computational models. These models are becoming increasingly realistic and accurate, as more and more physical aspects can be considered, greatly increasing the accuracy and range of models. However, those models need to be validated with recourse to experimental data. In this paper we propose a model that uses a Low Magnetic Reynolds number, and accounts for five common neutral species: N2, O2, NO, N and O, along with several of their respective reactions: dissociation of molecular nitrogen and oxygen, and exchange. The model chemistry is then validated based on experimental data gathered by several authors.
几个关键方面控制着飞行器成功重返地球大气层:连续通信、GPS信号接收和实时遥测。然而，有一些常见的问题会干扰仪器的操作，最典型的是无线电中断，在这种情况下，等离子体层的频率改变了电磁波，使与航天器的通信变得不可能。到目前为止，已经提出了几种缓解无线电停电的技术，其中之一是使用电磁场。以前的研究已经证明了使用电场和/或磁场来操纵等离子体层的有效性。高超声速飞行过程中等离子体层操纵的实验非常昂贵。因此，人们一直对开发更便宜的解决方案感兴趣，这些解决方案可以保证可靠的准确性，例如开发复杂的多物理场计算模型。这些模型变得越来越逼真和准确，因为越来越多的物理方面可以考虑，大大提高了模型的准确性和范围。然而，这些模型需要借助实验数据进行验证。在本文中，我们提出了一个使用低磁雷诺数的模型，并考虑了五种常见的中性物质:N2, O2, NO, N和O，以及它们各自的几种反应:分子氮和氧的解离和交换。然后根据几位作者收集的实验数据对模型化学进行验证。
{"title":"Numerical Analysis of a Multi-Species MHD Model for Plasma Layer Control of Re-Entry Vehicles","authors":"F. Dias, José C. Páscoa, C. Xisto","doi":"10.1115/IMECE2018-87467","DOIUrl":"https://doi.org/10.1115/IMECE2018-87467","url":null,"abstract":"Several critical aspects control the successful reentry of vehicles on the earth’s atmosphere: continuous communication, GPS signal reception and real-time telemetry. However, there are some common issues that can interfere with the instruments operation, the most typical being the radio blackout, in which the plasma layer frequency modifies the electromagnetic waves in a way that makes communications to and from the spacecraft impossible. So far, there have been several proposed techniques to mitigate radio blackout, one of which is the usage of electromagnetic fields. Previous studies have proven the effectiveness of the usage of an electric and/or magnetic fields to manipulate plasma layers. Experiments on plasma layer manipulation during hypersonic flight regime are extremely costly. Therefore, there has been a continuous interest in the development of cheaper solutions, that can guarantee a reliable degree of accuracy, such as the development of complex multiphysics computational models. These models are becoming increasingly realistic and accurate, as more and more physical aspects can be considered, greatly increasing the accuracy and range of models. However, those models need to be validated with recourse to experimental data. In this paper we propose a model that uses a Low Magnetic Reynolds number, and accounts for five common neutral species: N2, O2, NO, N and O, along with several of their respective reactions: dissociation of molecular nitrogen and oxygen, and exchange. The model chemistry is then validated based on experimental data gathered by several authors.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"156 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133809120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The metamaterial concept was first oriented to electromagnetic field applications and the main objectives were to develop materials with peculiar properties such as negative dielectric constant, negative magnetic permeability and negative refraction index. Gradually, other areas started using parameters that do not exist in the materials found in nature and, classifying them as metamaterials. So, areas such as acoustics, optics and mechanics opened up space for applications of this innovative “material”. Many efforts for an adequate modeling were made searching also for all kinds of possible applications. One example of application in optics is the use of conformal transformation to design devices with new functionalities from non-homogeneous isotropic dielectric media. The mirages created in the desert are the result of these non-homogeneities. These studies are supposed being helpful to develop invisible cloaks using metamaterials. The present work deals with elastic metamaterial application in mechanical engineering. It is well knowing that metamaterials are able to filter harmonic wave propagation and many works present this capability caused by a bandgap that appears in some range of frequency due to the system’s features. However, it is not very clear how the parameters used for the metamaterials design should be defined. The purpose of this work is to propose a methodology to design an optimized metamaterial component to filter the mechanical wave propagation in a finite chain of masses. It is also in the scope of this work to analyze the borders of the bandgap of the studied chain of masses and how the propagated wave is attenuated along this region.
{"title":"Elastic Metamaterial Design to Filter Harmonic Mechanical Wave Propagation","authors":"Gustavo Rodrigues, H. Weber, L. Driemeier","doi":"10.1115/IMECE2018-87753","DOIUrl":"https://doi.org/10.1115/IMECE2018-87753","url":null,"abstract":"The metamaterial concept was first oriented to electromagnetic field applications and the main objectives were to develop materials with peculiar properties such as negative dielectric constant, negative magnetic permeability and negative refraction index. Gradually, other areas started using parameters that do not exist in the materials found in nature and, classifying them as metamaterials. So, areas such as acoustics, optics and mechanics opened up space for applications of this innovative “material”. Many efforts for an adequate modeling were made searching also for all kinds of possible applications. One example of application in optics is the use of conformal transformation to design devices with new functionalities from non-homogeneous isotropic dielectric media. The mirages created in the desert are the result of these non-homogeneities. These studies are supposed being helpful to develop invisible cloaks using metamaterials. The present work deals with elastic metamaterial application in mechanical engineering. It is well knowing that metamaterials are able to filter harmonic wave propagation and many works present this capability caused by a bandgap that appears in some range of frequency due to the system’s features. However, it is not very clear how the parameters used for the metamaterials design should be defined. The purpose of this work is to propose a methodology to design an optimized metamaterial component to filter the mechanical wave propagation in a finite chain of masses. It is also in the scope of this work to analyze the borders of the bandgap of the studied chain of masses and how the propagated wave is attenuated along this region.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132145377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A basic problem of of micromechanics is analysis of one inclusion in the infinite matrix subjected to a homogeneous remote loading. A heterogeneous medium with the bond-based peri-dynamic properties (see Silling, J. Mech. Phys. Solids 2000; 48:175–209) of constituents is considered. At first a volumetric boundary conditions are set up at the external boundary of a final domain obtained from the original infinite domain by truncation. An alternative sort of truncation method is periodisation method when a unite cell (UC) size is increased while the inclusion size is fixed. In the second approach, the displacement field is decomposed as linear displacement corresponding to the homogeneous loading of the infinite homogeneous medium and a perturbation field introduced by one inclusion. This perturbation field is found by the Green function technique as well as by the iteration method for entirely infinite sample with an initial approximation given by a driving term which has a compact support. The methods are demonstrated by numerical examples for 1D case. A convergence of numerical results for the peristatic composite bar to the corresponding exact evaluation for the local elastic theory are shown.
细观力学的一个基本问题是分析无限矩阵中一个包体在均匀远程载荷作用下的问题。具有基于键的非均质介质的动态特性(参见Silling, J. Mech。理论物理。固体2000;48:175-209)的成分被考虑。首先在截断得到的最终域的外边界处设置体积边界条件;另一种截断方法是周期化法，当包涵体大小固定时，单位细胞(UC)的大小增加。在第二种方法中，将位移场分解为无限均匀介质的均匀载荷对应的线性位移和一个包含引入的微扰场。该扰动场是用格林函数技术和完全无限样本的迭代方法求得的，初始近似由具有紧支撑的驱动项给出。通过一维情况下的数值算例对该方法进行了验证。给出了弹性复合杆的数值结果收敛于相应的局部弹性理论的精确计算。
{"title":"One Inclusion in the Infinite Peristatic Matrix","authors":"V. Buryachenko","doi":"10.1115/IMECE2018-86519","DOIUrl":"https://doi.org/10.1115/IMECE2018-86519","url":null,"abstract":"A basic problem of of micromechanics is analysis of one inclusion in the infinite matrix subjected to a homogeneous remote loading. A heterogeneous medium with the bond-based peri-dynamic properties (see Silling, J. Mech. Phys. Solids 2000; 48:175–209) of constituents is considered. At first a volumetric boundary conditions are set up at the external boundary of a final domain obtained from the original infinite domain by truncation. An alternative sort of truncation method is periodisation method when a unite cell (UC) size is increased while the inclusion size is fixed. In the second approach, the displacement field is decomposed as linear displacement corresponding to the homogeneous loading of the infinite homogeneous medium and a perturbation field introduced by one inclusion. This perturbation field is found by the Green function technique as well as by the iteration method for entirely infinite sample with an initial approximation given by a driving term which has a compact support. The methods are demonstrated by numerical examples for 1D case. A convergence of numerical results for the peristatic composite bar to the corresponding exact evaluation for the local elastic theory are shown.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125350547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This online compilation of papers from the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels (ICNMM2016) represents the archival version of the Conference Proceedings. According to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference by an author of the paper, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.
这篇来自ASME 2016第14届纳米通道、微通道和迷你通道国际会议(ICNMM2016)的在线论文汇编代表了会议论文集的存档版本。根据ASME的会议主讲人出席政策，如果一篇论文没有由论文的作者在会议上发表，该论文将不会发表在美国国会图书馆注册的官方档案论文集上，并提交摘要和索引。该论文也不会在ASME Digital Collection上发表，也不能作为已发表论文被引用。
{"title":"ASME Conference Presenter Attendance Policy and Archival Proceedings","authors":"","doi":"10.1115/detc2018-ns5b","DOIUrl":"https://doi.org/10.1115/detc2018-ns5b","url":null,"abstract":"This online compilation of papers from the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels (ICNMM2016) represents the archival version of the Conference Proceedings. According to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference by an author of the paper, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.","PeriodicalId":119220,"journal":{"name":"Volume 1: Advances in Aerospace Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134410172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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