Volume 10: Fluids Engineering最新文献_第9页

3D Modeling of Additive Manufacturing Process: The Case of Polymer Laser Sintering 增材制造过程的三维建模:以聚合物激光烧结为例

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-23550

Lan Zhang, M. Boutaous, S. Xin, D. Siginer

{"title":"3D Modeling of Additive Manufacturing Process: The Case of Polymer Laser Sintering","authors":"Lan Zhang, M. Boutaous, S. Xin, D. Siginer","doi":"10.1115/IMECE2020-23550","DOIUrl":"https://doi.org/10.1115/IMECE2020-23550","url":null,"abstract":"\u0000 This work focusses on studying multiphysical transient phenomena in polymer powders occurring during selective laser sintering in polymers powders. Multiple phenomena stemming from the interaction of the laser with the polymer powder bed and the transfer of the laser power to the powder bed including laser scattering and absorption, polymer heating, melting, coalescence, densification, and the variation of the material parameters with the temperature are simulated via the modified Monte Carlo-ray tracing method coupled with the Mie theory. A finite volume method is adopted for the heat transfer. The model couples heat diffusion, melting, coalescence and densification of the polymer grains, and the crystallization kinetics during the cooling steps. Laser intensity is concentrated on the surface of the material contrary to the predictions of the Beer-Lambert law. Laser acting on thermoplastic material cause the polymer powder melt, coalescence between melted grains, air diffusion versus densification, crystallization and volume shrinkage. All these processes are simulated by a series of multiphysical models. The reliability of the modeling is tested by comparison with experiments in the literature, and a parametric analysis is performed, based on the process characteristics such as laser sweep speed, its intensity and shape, polymeric grain size among others. Several recommendations to optimize the process are proposed.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"263 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124034249","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}

引用次数: 0

The Flow Dynamics of Stranded Cables 绞合电缆的流动动力学

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-23141

M. Abdelhady, D. Wood

引用次数: 0

Numerical Modeling of Non-Affine Viscoelastic Fluid Flow Including Viscous Dissipation Through a Square Cross-Section Duct: Heat Transfer Enhancement due to the Inertia and the Elastic Effects 含粘性耗散的非仿射粘弹性流体在方截面管道中的流动数值模拟:惯性和弹性效应对传热的增强

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-23558

Fouad Hagani, M. Boutaous, R. Knikker, S. Xin, D. Siginer

{"title":"Numerical Modeling of Non-Affine Viscoelastic Fluid Flow Including Viscous Dissipation Through a Square Cross-Section Duct: Heat Transfer Enhancement due to the Inertia and the Elastic Effects","authors":"Fouad Hagani, M. Boutaous, R. Knikker, S. Xin, D. Siginer","doi":"10.1115/IMECE2020-23558","DOIUrl":"https://doi.org/10.1115/IMECE2020-23558","url":null,"abstract":"\u0000 Non-isothermal laminar flow of a viscoelastic fluid including viscous dissipation through a square cross–section duct is analyzed. Viscoelastic stresses are described by Giesekus modele orthe Phan-Thien–Tanner model and the solvent shear stress is given by the linear Newtonian constitutive relationship. The flow through the tube is governed by the conservation equations of energy, mass, momentum associated with to one non–affine rheological model mentioned above. The mixed type of the governing system of equations (elliptic–parabolic–hyperbolic) requires coupling between discretisation methods designed for elliptic–type equations and techniques adapted to transport equations. To allow appropriate spatial discretisation of the convection terms, the system is rewritten in a quasi-linear first-order and homogeneous form without the continuity and energy equations. With the rheological models of the Giesekus type, the conformation tensor is by definition symmetrical and positive-definite, with the PTT model the hyperbolicity condition is subject to restrictions related to the rheological parameters. Based on this hyperbolicity condition, the contribution of the hyperbolic part is approximated by applying the characteristic method to extract pure advection terms which are then discretized by high ordre schemes WENO and HOUC. The algorithm thus developed makes it possible, to avoid the problems of instabilities related to the high Weissenberg number without the use of any stabilization method. Finally, a Nusselt number analysis is given as a function of inertia, elasticity, viscous dissipation, for constant solvent viscosity ratio and constant material and rheological parameters.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122307351","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}

引用次数: 2

Large Eddy Simulations of Francis Turbine Operating at Ultra-Low Loads 混流式水轮机超低负荷大涡模拟

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-23380

Muhannad Altimemy, Justin Caspar, Saif Watheq, A. Oztekin

{"title":"Large Eddy Simulations of Francis Turbine Operating at Ultra-Low Loads","authors":"Muhannad Altimemy, Justin Caspar, Saif Watheq, A. Oztekin","doi":"10.1115/IMECE2020-23380","DOIUrl":"https://doi.org/10.1115/IMECE2020-23380","url":null,"abstract":"\u0000 High-fidelity large eddy simulations (LES) were conducted to characterize the spatial and temporal structure of turbulent flows in an industrial-sized Francis turbine. The unit operated at 50% and 40% of the best efficiency design flowrate. Contours of vorticity, velocity, pressure, and iso-surfaces of Q-Criterion were presented to characterize the effects on the draft tube. Probes placed alongside the draft tube measure the pressure signal to investigate the flow-induced pressure fluctuations inside the turbine unit. The maximum intensity of pressure fluctuations at 50% partial load was 22.66% of the turbine head, while the strength of the pressure fluctuations was 26.36% at 40% partial load. A large number of unorganized smaller vortices observed in the draft tube contribute to the creation of pressure fluctuations. Two pressure modes can be easily recognized (1) high frequency with low amplitude pressure fluctuations and (2) low frequency with high amplitude fluctuations. These pressure fluctuations could be harmful to the structural integrity of the unit and also have undesirable influences on the operational stability of the hydro-turbines.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132609505","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}

引用次数: 0

Impact of the Gas Phase on the Properties of Foams 气相对泡沫材料性能的影响

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-23900

A. Pruvot, Zhifeng Zhang, C. Conner, J. Mcandrew

引用次数: 0

Multi-Fidelity Aerodynamic Modeling of a Floating Offshore Wind Turbine Rotor 海上浮式风力发电机转子多保真度气动建模

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-24608

Kai Zhang, O. Bilgen

{"title":"Multi-Fidelity Aerodynamic Modeling of a Floating Offshore Wind Turbine Rotor","authors":"Kai Zhang, O. Bilgen","doi":"10.1115/IMECE2020-24608","DOIUrl":"https://doi.org/10.1115/IMECE2020-24608","url":null,"abstract":"\u0000 This paper presents a comparison of low- and mid-fidelity aerodynamic modelling of floating offshore wind turbine rotors. The low-fidelity approach employs the conventional Blade Element Momentum theory implemented in AeroDyn of OpenFAST. This model ignores the aerodynamic interactions between different blade elements, and the forces on the blade are determined from the balance between momentum theory and blade element theory. With this method, it is possible to calculate the aerodynamic performance for different settings with low computational cost. For the mid-fidelity approach, the Actuator Line Modeling method implemented in turbinesFoam (an OpenFOAM library) is used. This method is built upon a combination of the blade element theory for modeling the blades, and a Navier-Stokes description of the wake flow field. Thus, it can capture the wake dynamics without resolving the detailed flows near the blades. The aerodynamic performance of the DTU 10 MW reference wind turbine rotor is studied using the two methods. The effects of wind speed, tip speed ratio, and blade pitch angles are assessed. Good agreement is observed between the two methods at low tip speed ratios, while the Actuator Line Modeling method predicts slightly higher power coefficients at high tip speed ratios. In addition, the ability of the Actuator Line Modeling Method to capture the wake dynamics of the rotor in an unsteady inflow is demonstrated. In the future, the multi-fidelity aerodynamic modules developed in this paper will be integrated with the hydro-kinematics and hydro-dynamics of a floating platform and a mooring system, to achieve a fully coupled framework for the analysis and design optimization of floating offshore wind turbines.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127996367","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}

引用次数: 3

Modeling, Analysis and Design of the Formula SAE Aerodynamics System 方程式SAE空气动力学系统的建模、分析与设计

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-24374

Isaac Van Baren, A. Milligan, S. Ashcraft, S. Rosser, Xiuling Wang

{"title":"Modeling, Analysis and Design of the Formula SAE Aerodynamics System","authors":"Isaac Van Baren, A. Milligan, S. Ashcraft, S. Rosser, Xiuling Wang","doi":"10.1115/IMECE2020-24374","DOIUrl":"https://doi.org/10.1115/IMECE2020-24374","url":null,"abstract":"\u0000 This project developed a study on methods to increase downforce on the university’s Formula SAE vehicle by implementing a lightweight, efficient aerodynamic design. The team planned to improve the performance and reduce lap times of the vehicle with an undertray, which grants better wheel traction and stability while handling corners. Upon completion, the aerodynamic component would have allowed the PNW Motorsports team to more effectively compete at the FSAE design competition in the spring of 2020.\u0000 While reducing drag, an undertray provides the capability to direct the air beneath the vehicle chassis in a way which adds “artificial weight” to the system. A pressure gradient of high magnitude is established between the two sides of the undertray, with a low negative pressure region found beneath the body. This design is based upon the principles of fluid dynamics, in particular the venturi effect through the use of nozzles and diffusers. In this fashion, the vehicle can receive the benefits of a heavier car around corners while maintaining the higher straight-line acceleration of a lighter car.\u0000 This report describes the use of simulation software in the design of an undertray, as well as the approach to manufacture it. Two-dimensional benchmark cases were performed in the replication of results obtained in a literature search. Subsequently, the undertray model was optimized with CFD and FEA/FEM techniques to obtain a component that was prepared for manufacturing. An operating procedure was established to outline the complicated steps of its assembly. Finally, it provides future aerodynamics teams with a solid foundation upon which improvements can be made.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"125 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124528311","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}

引用次数: 0

Pressure Loss Coefficients for VAV Terminal Units 变风量终端的压力损失系数

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-23047

K. Lankalapalli, S. Idem

引用次数: 0

Numerical Analysis of Fluid Flow in 2D Domains Containing Moving Objects 含运动物体二维区域内流体流动的数值分析

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-23223

A. Mazumder

{"title":"Numerical Analysis of Fluid Flow in 2D Domains Containing Moving Objects","authors":"A. Mazumder","doi":"10.1115/IMECE2020-23223","DOIUrl":"https://doi.org/10.1115/IMECE2020-23223","url":null,"abstract":"\u0000 This study presented a two-dimensional (2D) numerical analysis of fluid flow in domains containing moving objects. The method falls into the general category of Arbitrary-Lagrangian-Eulerian (ALE) methods, which is based on a fixed mesh that is locally fitted at the moving objects. The moving objects are described using sets of marker points which can slide over the basic mesh. Once the moving object has gone through the stationary element, the element is restored to its original form. Therefore, the mesh adaptation is performed only in those elements intersected by an object and is local both in space and time. As a result, the method does not require interpolation and there are a fixed number of possible modifications to the intersected elements. As the global mesh is independent of object movement, therefore it eliminates the possibility of mesh entanglement. The mesh never becomes unsuitable due to its continuous deformation, thus eliminating the need for repeated re-meshing and interpolation. A validation is presented via a problem with an exact analytical solution to the case of 2D flow between two parallel plates separating with a prescribed velocity. The method’s capabilities and accuracy are illustrated through application in realistic geometrical settings which show the robustness and flexibility of the technique.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116667597","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}

引用次数: 0

A CFD Approach for the Simulation of an Entire Swash-Plate Axial Piston Pump Under Dynamic Operating Conditions 斜盘式轴向柱塞泵动态工况模拟的CFD方法

Volume 10: Fluids Engineering Pub Date : 2020-11-16 DOI: 10.1115/IMECE2020-23720

M. Milani, L. Montorsi, G. Muzzioli, A. Lucchi

{"title":"A CFD Approach for the Simulation of an Entire Swash-Plate Axial Piston Pump Under Dynamic Operating Conditions","authors":"M. Milani, L. Montorsi, G. Muzzioli, A. Lucchi","doi":"10.1115/IMECE2020-23720","DOIUrl":"https://doi.org/10.1115/IMECE2020-23720","url":null,"abstract":"\u0000 The paper proposes a CFD approach for the simulation of a swash-plate axial piston pump including the full 3D geometry of the real component.\u0000 Different meshing techniques are integrated in order to reproduce all the internal motions of the pump. The overset mesh procedure is used to simulate the dynamic evolution in regions’ shape and the variable orientation between parts in the piston-slipper ball joints while the alternating motion of the piston is accounted for by sliding interfaces with the neighboring regions.\u0000 The multiple dynamics of the different moving elements are implemented in terms of superposing motions in order to reproduce the real position time histories as a function of the rotational speed and the swash plate inclination angle.\u0000 The proposed numerical model includes all the leakages that characterize the coupling of the many components of the pump and nominal values are assumed (i.e. 10μm) throughout the entire simulation.\u0000 A pressure-dependent fluid density approach is adopted to improve the performance prediction of the pump under real operating conditions. Moreover, the turbulent behavior of the flow is addressed by means of the two equation k-omega SST model.\u0000 Therefore the proposed modeling approach highlights the capabilities to address any type of swash-plate axial piston pump in order to simulate the entire machine under dynamic operations; the numerical results are discussed in terms of flow ripple, pressure distribution and fluid-dynamic forces.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131412632","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}

引用次数: 1