NAFEMS International Journal of CFD Case Studies最新文献

{"title":"Design and Verification of Tuned Liquid Column Dampers for High-rise Buildings Using CFD","authors":"F. Campos, E. De Villiers, S. Cammelli","doi":"10.59972/c20013cz","DOIUrl":"https://doi.org/10.59972/c20013cz","url":null,"abstract":"BMT Fluid Mechanics conducted a comprehensive flow study on the effectiveness of a pair of Tuned Liquid Column Dampers (TLCDs) aimed at mitigating wind-induced accelerations in a high-rise building. The study successfully combined Computational Fluid Dynamics (CFD) with physical model tests performed at the 6 degree-of-freedom shake table facility located at the Department of Civil Engineering of the University of Bristol. The original TLCD concept discussed in this work was proposed at the early design stages of a slender 42-storey high-end residential building located in the Middle East. On-site full-scale measurements and High Frequency Force Balance (HFFB) wind tunnel tests performed by BMT Fluid Mechanics showed that the highest occupied floors could experience excessive wind-induced motion. Depending on the inherent damping of the finished structure, this motion had the potential to exceed standard occupant comfort criteria. A new CFD methodology was developed to assess the performance of the TLCD design using the multi-phase Volume-of-Fluid (VOF) solver and dynamic mesh motion libraries available in the CFD software tool HELYX®. The damping effects introduced by the array of internal porous baffles in the TLCD were approximated using a Darcy-Forchheimer porosity model. Comparisons of free-decay damping performance between CFD results and shake table experiments for a 1:20 scale model of a 3 baffles’ TLCD configuration were found to be satisfactory for design purposes. The results for the amplitude of the net forces acting on the TLCD, as well as the frequency response measured using the free-decay logarithmic decrement approach, confirmed that the proposed CFD methodology provides an accurate representation of real operating conditions. The same CFD approach was successfully applied to model the full-scale TLCD device. With the introduction of a pair of identical purposely designed TLCDs, a 30% increase performance of the structural response of the 42-storey building to wind loading excitation was achieved.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128506575","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}

{"title":"A Study of Aerothermal Loads in the Presence of Edney Type IV Interaction","authors":"L. Gurov, A. Ivanov","doi":"10.59972/le120uhw","DOIUrl":"https://doi.org/10.59972/le120uhw","url":null,"abstract":"Numerical simulation results of specific supersonic and hypersonic flows interactions leading to complex shocks structures are presented in the paper. These interactions can produce abnormal thermal loads that should be taken into account for Thermal Protection System design for hypersonic vehicles. Calculations were made with the aid of CAD-Embedded CFD software FloEFD. To validate the CFD code in this field a study of shock/shock interaction near 2D cylinder has been carried out. Good agreement with experimental data in terms of shock structure, surface pressure and surface heat flux distributions was obtained. To demonstrate how these shocks interactions effects can affect in case of a real 3D complex hypersonic vehicle a 3D study of interaction between the Space Shuttle Orbiter bow shock and External Tank bow shock under certain flow regime has been carried out. Comparison with the data obtained in the simulation of the ‘single Orbiter’ flow showed a small-scale zone on Orbiter nose with considerably increased peak pressure and heat flux values due shock/shock interaction.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128389903","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}

{"title":"CFD analysis of a check valve from SAFRAN Helicopter Engines using a Lattice-Boltzmann solution","authors":"Zaki Abiza, D. Holman, David Taieb, Marine Robin","doi":"10.59972/b7bd6y72","DOIUrl":"https://doi.org/10.59972/b7bd6y72","url":null,"abstract":"Unsteady Computational Fluid Dynamics (CFD) solvers with accurate turbulence modelling are increasingly required to solve real industrial problematics where most applications include complex moving parts, highly turbulent flows and transient phenomena. Most of these industrial requirements are out of reach for the traditional CFD solutions based on steady state or unsteady Reynolds-Averaged Navier-Stokes (RANS) turbulence approaches and with limited capabilities to deal with moving parts and Fluid-Structure Interaction (FSI). XFlow is the innovative CFD software developed by Next Limit Dynamics to deal with this increasing demand on new industrial applications. XFlow features a particle-based discretization approach that uses a state-of-the-art Lattice-Boltzmann Method (LBM) to discretize the continuous Boltzmann equation, a time evolution equation for statistical probability distribution functions that describe accurately the behavior of a fluid. This proprietary particle-based kinetic solver implements at collision operator a Large Eddy Simulation (LES) turbulence model fully coupled with a generalized law of the wall (WMLES) in order to solve the transient turbulent effects usually observed on industrial applications. The aim of the work presented in this paper is to demonstrate the capability of the XFlow approach to predict costly instability issues of the Check Valves (CV) integrated inside the fuel circuit in helicopter engines. The results of XFlow will be compared to the experimental measurements provided by SAFRAN Helicopter Engines on one of their CV designs during real working conditions. The CV dynamics will be modelled in XFlow as a rigid body with one degree of freedom along the axis aligned with the flow direction. A spring effort is modelled with a pre-load force and a stiffness. With these two parameters, XFlow computes dynamically the valve position according to the dynamic movement equation based on the hydraulic and spring forces applied on. As preliminary step, different fixed flow-rate boundary conditions will be applied at the inlet of the CV in order to validate the global valve characteristics with the incompressible solver. The CV oscillations are studied considering acoustics with an additional bulk viscosity term inside the flow equations. An increasing inlet volumetric flow law is applied to compute the dynamic response of the valve and to predict the frequency and the flow-rate range at which instabilities appear. This simulation shows a good agreement; the experimental instability range is well predicted as the eigen frequency.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116858270","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}

{"title":"Fluid-Structure Interation of a Rigid Wing for Minesto Deep Green, a Tidal Energy Device","authors":"Daniel Hung, A. Mosquera, D. Mcglinchey","doi":"10.59972/ef8rt5x2","DOIUrl":"https://doi.org/10.59972/ef8rt5x2","url":null,"abstract":"Fluid structure interaction (FSI) analysis has been performed on the main wing structure of an underwater renewable energy tidal flow device using methods of different fidelity. A lower fidelity method represented the wing as a series of beams (1D line elements) which deflect and rotate under hydrodynamic load. These deflections and rotations were used to update the geometry for the hydrodynamic model where updated forces and moments were calculated using potential flow theory with integral boundary layer (2D panel methods). The higher fidelity method represented the wing using a combination of 3D solid elements for the foam structure inside the wing and 2D shell elements for the carbon fibre wing stiffening beams and fibre glass wing skin. The results of a modal analysis of the wing structure were used in a 3D CFD simulation that coupled the modal equations with the Navier-Stokes equations to compute the deformed shape of the wing under hydrodynamic load. In both cases, the maximum deformations of the wing were quite small (<25mm) compared to the wing size (12m span, 3.3m maximum chord) but the effect on hydrodynamic characteristics was quite different. The low fidelity analysis made the assumption that the wing cross-sectional shape profile did not change, although it could move and rotate. There was no significant change in the predicted hydrodynamic characteristics between the deformed and undeformed wing shapes. The contribution of the foam to the stiffness of the wing was not included in the low fidelity analysis as it was thought to be minor contributor due the much lower Young’s Modulus compared to the carbon fibre and fibre glass of the main wing structure. In contrast, the high fidelity method resulted in about a 15% reduction in lift and 6% in drag forces due to deformation of the wing cross-section profiles rather than bending and twisting of the wing which the low fidelity analysis showed not to be significant. The effect on energy yield of these changes is estimated to be very small.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121531682","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}

{"title":"Pressure Fluctuations in Railway Tunnels","authors":"Javier Rodríguez, L. Lacoma, J. Martí","doi":"10.59972/vjy6fz48","DOIUrl":"https://doi.org/10.59972/vjy6fz48","url":null,"abstract":"When high-speed trains enter and exit tunnels, major pressure transients are produced, which travel in the form of waves along the tunnel and are reflected at the portals. Guidelines and regulations limit the pressure changes felt inside the cars to ensure the health and aural comfort of the passengers. The authors developed a one-dimensional program, based on the method of characteristics, to carry out the necessary calculations. After validating the program against results from other codes, including full 3-D CFD calculations, they used it to confirm the design of a tunnel for high-speed rail traffic.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128782123","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}

{"title":"Numerical and Experimental Stability Analysis Predicting Natural Laminar Flow Extension on a Realistic Swept Wing","authors":"D. de Rosa, S. Donelli, G. Romano","doi":"10.59972/0ju4twsp","DOIUrl":"https://doi.org/10.59972/0ju4twsp","url":null,"abstract":"It is well known that the stability theory, coupled with eN method, offers a rational approach to predict transition from laminar to turbulent flow condition in several aerodynamic applications. It is also known that stability analyses are affected by the accuracy of the mean flow that strongly depends from an adequate resolution in the boundary layer region. Unfortunately, Navier-Stokes analyses for stability investigations are often not affordable since the large number of points normal to the wall, necessary in the viscous layer to have desiderata boundary layer accuracy, makes RANS computations extremely time consuming. Furthermore, the classical definition of the boundary layer edge (the height where the boundary layer velocity reaches 99% of the no-viscous velocity) is not a straightforward task. For these reasons, in the framework of EU-funded Research Project RECEPT, a three-step approach has been applied to perform stability analyses. The first step consists of Euler computations to evaluate the mean flow. In the second step, a 3-D boundary-layer code, starting from the no-viscous flow field, allows to compute the boundary layer data necessary to perform the linear stability analysis and, finally, a 2.5D linear stability code is used to predict transition location. The reference geometry used to test this approach is the laminar wing developed by CIRA and Piaggio Aero Industries S.p.A. (PAI) in the framework of an Italian national program called VITAS (Vettore Innovativo per il Trasporto AeroSostenibile). This wing has been selected because an extended set of experimental data is available. Among the available experimental results, four different conditions have been selected and numerical analyses were performed. The selection has been driven preferring the data that presented both the best IR (Infra-Red) camera results and the pressure distributions. Euler computations have been performed using the commercial CFD (Computational Fluid Dynamic) code CFD++ and the boundary layer computations have been performed using the ONERA (Office National d'Études et de Recherches Aérospatiales) 3C3D laminar/turbulent boundary layer code. Stability computations have been performed using the compressible code NOLLI (NOn Local Linear Instability code) developed in house by CIRA and based on the application of the multiple scale technique and ray tracing theory. For stability analyses the fixed span- wise wavenumber strategy has been used.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131950670","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}

{"title":"Computational Fluid Dynamics Validation Utilizing a Tracer Gas Study Related to a Mine Mill Area Toxic Gas Release for Emergency Response Planning","authors":"D. Hall, C. Strode, J. Rasmuson, A. Korchevskiy, R. Strode","doi":"10.59972/hrt8rrs2","DOIUrl":"https://doi.org/10.59972/hrt8rrs2","url":null,"abstract":"Many dispersion models (e.g. DEGADIS, SLAB, INPUFF, and ALOHA) have been developed by regulatory agencies for emergency response related to dense toxic gas releases. The National Oceanic and Atmospheric Administration’s (NOAA) Area Locations of Hazardous Atmospheres (ALOHA) software is an example one such model. However, such models typically over-predict dense toxic gas plume dispersion concentrations and do not take into account complex terrain or complex building canyon geometries. This creates imprecise and inaccurate emergency response plans for industries that utilize such gases for production processes. The application of Computational Fluid Dynamics (CFD) mostly overcomes these challenges and provides a refined understanding of dense gas plume dispersion. Evaluating micro-scale atmospheric models is typically conducted in a wind tunnel tracer gas experiment; however, the one-hour tracer gas experiments utilized in this study evaluation were conducted in a real-world, full-scale, industrial setting. These same industries are often faced with worker health risks related to airborne respirable particulates and fibers with low settling velocities and where transport is dominated by air movement. Thus, it is anticipated that this evaluation may be applied to exposure characterization and risk assessment.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115561288","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}

{"title":"Dynamic Simulation of Flight Test Manoeuvres on the Diamond D-Jet","authors":"D. Holman","doi":"10.59972/x8u9weq2","DOIUrl":"https://doi.org/10.59972/x8u9weq2","url":null,"abstract":"The numerical simulation of the complex fluid-structure interaction taking place when manoeuvring an aircraft remains a challenge. A realistic analysis of the airplane manoeuvrability often involves the presence of moving parts, such as the deflection of the elevators, the ailerons, or the elevons. For conventional Computational Fluid Dynamics (CFD) codes, dealing with such moving geometries is a challenging task. The following work uses software based on the lattice-Boltzmann method (LBM) to overcome these issues. This paper presents a numerical study on the dynamic simulation of flight test manoeuvres on the Diamond D-JET, using the XFlow virtual wind tunnel. The pitch capture manoeuvre is first simulated, studying the pitch oscillation response of the aircraft. Dutch roll flight mode is then numerically reproduced. Finally, the D-JET angle of attack is evaluated in the poststall regime under controlled movements of the elevator. Numerical results are eventually compared with the corresponding flight test data recorded by Diamond Aircraft Industries. Numerical and experimental results show reasonable agreement. It may thus be concluded that: (i) the LBM can offer the opportunity to bypass some wind tunnel testing; and (ii) the LBM can complement flight tests by helping in mitigating risks associated with flight test manoeuvres, including fully developed stalls and spin testing.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127009225","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}

{"title":"Analysis of High Velocity Free Surface Flow Interaction with a Bridge Pier in a Trapezoidal Channel using CFD","authors":"A. Abo, Rj Muhammad, A. Raby, A. Kyte, D. Greaves","doi":"10.59972/8xzkaqhw","DOIUrl":"https://doi.org/10.59972/8xzkaqhw","url":null,"abstract":"This study uses the computational fluid dynamics (CFD) code ANSYS-CFX-12, to simulate 3D flow through a straight trapezoidal cross section channel containing a single bridge pier. The fluid flow condition is assumed to be steady state, isothermal and incompressible, with symmetry along the centerline of the channel, and the simulation uses the k - ε turbulence model. The study investigates the impact of variations of aspect ratio (channel bed width/flow depth), bed and side slopes of the channel, discharge (represented by a Froude number), and the length and thickness of the bridge pier on the free surface flow profile, both along the centerline and the on the wall of the channel. The code is based on the finite volume method, and uses the volume of fluid (VOF) approach to predict the free surface flow profile. Prediction of the free surface flow profile is essential for the design of high velocity channels. Prior prediction of flow profiles can inform and improve the design of expensive structures, such as high velocity channels and bridges, in particular the height of channel walls and bridge decks. Firstly, the code was validated against the numerical and experimental work of Stockstill (1996) for a channel containing three piers, and found to agree well. Then, the method was applied to the design test case, and mesh convergence tests to establish the required mesh size were carried out. The simulations were conducted in parallel over 32 cores on the Plymouth University High Performance Computer Cluster (HPCC). Finally, a parametric study was carried out and analytical expressions derived for maximum flow depth at the centre-line and at the side wall of the channel. Useful non-dimensional curves and equations derived from regressions of the study data are provided, which can be used as a guideline for the design of high velocity channels containing a bridge pier. For data regressions the statistical package software Statistical Product and Service Solutions (SPSS) was used.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121296303","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}

{"title":"Validation of Experimental Results of a Realistic Natural Laminar Swept Wing through Advanced Stability Methods","authors":"D. de Rosa, R. Donelli, D. Romano","doi":"10.59972/0ztkg0mu","DOIUrl":"https://doi.org/10.59972/0ztkg0mu","url":null,"abstract":"In a study by Ma et al. (2010), an innovative honeycomb heatsink design for an LED lighting system was analysed using computational fluid dynamics (CFD) and experimentation. The previous simulation results were replicated using an immersed boundary approach, validating the code against that used in the earlier study. When we looked critically at the images of the experiment in Ma et al. (2010), we noted some discrepancies between the simulation model and the experimental setup. Although the experimental setup was not fully described, we were able to identify a number of issues and make near-exact estimates of the dimensions and other values needed to include their effects in the simulation. The resulting simulation matched the test data very well. In this paper, we present the rationale for applying a different approach that is commonly used in electronics thermal design. We also describe the different aspects of the alternative CFD technology used, as these will not be familiar to most readers, to describe how it can handle fluid flow and heat transfer within complex geometries without simplification. These benefits are illustrated using the honeycomb heatsink example.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130236051","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}