4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I最新文献

{"title":"Experimental Study of Vibration and Acoustic Radiation of a Pipe Induced by Fully-Developed Turbulent Air Flow","authors":"C. Durant, G. Robert","doi":"10.1115/imece1997-0082","DOIUrl":"https://doi.org/10.1115/imece1997-0082","url":null,"abstract":"\u0000 Experimental results are presented concerning the vibro-acoustic response of a pipe excited by an internal fully-developed turbulent air flow. The internal wall pressure field generated by the flow, the vibration response and the external acoustic field were measured for Reynolds numbers Re = UoD/v ranging from 5.3 × 105 to 12.5 × 105.\u0000 The measured statistical properties of the wall pressure field include power spectral densities and cross-spectra. Power spectral density is analyzed after cancellation of a contaminating acoustic component of the wall pressure fluctuations. Convection velocity and correlation lengths are calculated from measured cross-spectra to complete a Corcos model for the cross-spectrum of the turbulent wall pressure fluctuations. The ratio of convection velocity to centerline velocity ranges from 0.7 to 0.8. The coefficient α1 of the standard Corcos model is calculated from the longitudinal correlation length and is found to be around 0.18. To have further information about the convection velocity and correlation lengths in a lower frequency range than presented here, the measured cross-spectral data need to be decontaminated from the acoustic component of the wall pressure.\u0000 The acceleration response of the pipe wall shows the influence of the structural modes of the test section. Only some of them have a significant influence on the external acoustic field.","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123240430","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":"Identification of Linearised Parameters for Fluidelastic Instability","authors":"C. Meskell, J. Fitzpatrick","doi":"10.1115/imece1997-0073","DOIUrl":"https://doi.org/10.1115/imece1997-0073","url":null,"abstract":"\u0000 A method for estimating the parameters of a linearized model of the fluidelastic forces in an array of cylinders is described. The behaviour of a tube on a flexible mount in the third row of an otherwise rigid 5 row normal triangular array, with pitch-to-diamter ratio of 1.58, has been investigated. The fluid stiffness and damping over a range of flow velocities has been estimated from experimental data. The results are then used to predict a stability threshold which is in agreement with previously published data for critical velocities. The damping in the flexible mount has been varied and shown not to effect the estimated fluid parameters.","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129822264","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":"Failure Mechanism of a Thermocouple Well Caused by Flow-Induced Vibration: (2) — Interaction Between Flow-Induced Vibration and Fatigue Crack Growth in a Thermocouple Well","authors":"Y. Wada, M. Morishita, Akira Yamaguchi, K. Iwata, M. Ichimiya","doi":"10.1115/imece1997-0054","DOIUrl":"https://doi.org/10.1115/imece1997-0054","url":null,"abstract":"\u0000 In the preceding paper a simplified master diagram on the relationship between a reduced velocity Vr (= V/fD) and a reduced displacement amplitude y/D is investigated for the in-line oscillation mode of thermocouple well. Based on this diagram, high cycle fatigue failure process of a thermo-couple well; crack initiation, crack growth/arrest, and final stage of fracture, is evaluated in this paper.\u0000 The strain amplitude at the root between thin and thick well tubes can be analytically estimated considering the sharp notch effect, and the crack initiation life can be evaluated using a fatigue curve. After short crack growth the crack front line can move as a long crack. Both of natural frequency and damping constant are changed, and crack growth reduces the displacement amplitude. As the results crack arrest and delayed failure, which are peculiar in flow-induced vibration, can occur in a thermometer.","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128039653","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":"Computation of Jet Noise Using Large-Eddy Simulation and Lighthill’s Analogy","authors":"D. Schein, W. Meecham","doi":"10.1115/imece1997-0087","DOIUrl":"https://doi.org/10.1115/imece1997-0087","url":null,"abstract":"\u0000 Computational aeroacoustics involves numerical study of the acoustic field generated by unsteady fluid motion. An area of significant interest is unsteady turbulent flow in free jets and resultant far field acoustic pressure fluctuations. Since Lighthill’s mathematical formulation for jet noise generation in the early 1960’s, a search has continued for a physical interpretation of his formal results and, in particular, the noise source term. Far field measurements have not provided a clear picture concerning the nature of the acoustic source. Therefore, industry standard procedures for prediction of far field noise from exhaust jets rely on semi-empirical methods to calculate mean sound pressure levels and directivity. Our objective is to contribute to a more thorough understanding of the acoustic source from a shear flow using Large-Eddy Simulation (LES) turbulence modeling.\u0000 Published work for direct numerical simulation of these flows has been confined to low Reynolds number (< 3000) with Mach numbers up to 2.0, to study the physics of sound generation and test aeroacoustic prediction methods (Mitchell, et al, 1995). While furthering understanding of jet noise generation, these cases limit exhaust dimensions to millimeters and make it difficult to compare results to measured data. Here we address large Reynolds numbers and high subsonic Mach number (compressible) flow combined with realistic geometries more representative of aircraft engine exhausts.\u0000 Standard turbulence models compute the average flow field, which cannot be used to calculate the aeroacoustic field. Temporal fluctuations are required and can be obtained using LES, with a spatial filtering operation applied to the equations of motion. The technique is based on computing only large scale motions directly subject to the problem’s boundary conditions, while small scale motions are assumed to be more universal and their statistics and effect upon large scales are predicted using a “subgrid-scale” model. The motivation for this approach is that experimental observations of turbulent flows show that large scale turbulent structures vary markedly from one flow situation to another, while small scales show less variation from case to case.\u0000 The acoustic radiation calculation consists of three steps; 1) an approximate result for the mean flow field using a compressible flow code employing a k-ϵ turbulence model, 2) unsteady turbulent fluid field simulation using the CFD code appended with a LES turbulence model (the k-ϵ prediction serving as an initial guess) and 3) far field acoustics obtained using Lighthill’s analogy. Extensive far field noise data from ground static measurements of a WR19-4 mini-turbofan engine are being drawn from for comparisons between computed results and measurements.","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128431922","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":"Vortex Structures in Flow Over a Rectangular Plate","authors":"J. Sheridan, K. Hourigan, R. Mills","doi":"10.1115/imece1997-0046","DOIUrl":"https://doi.org/10.1115/imece1997-0046","url":null,"abstract":"\u0000 Vortex shedding behind plates with rectangular trailing edges and both aerofoil and rectangular leading edges was investigated in a water tunnel. Previous studies, such as that presented by Mills et al. (1995), have shown that the base pressure, and hence drag, of such plates can be significantly altered by applying transverse perturbations at certain frequencies. Evidence has been presented to show that this is dependent on the interaction of shed vortices; this study is a first attempt to study the nature of the vortices and how they are influenced by the applied perturbation. This is done by using particle image velocimetry to measure the velocity field close to the plates. From these the vorticity field is derived and its response to perturbation examined. It is shown that the perturbation orders the vorticity field, resulting in increased peak vorticity and circulation in the shed vortices. Thus, their potential for inducing greater suction in the wake has been increased.","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134540432","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":"Identification of Fluid Dynamic Coefficients for Multiple Mode Vibrations of a Lightly Damped Rectangular Prism in Cross Flow","authors":"K. Kerenyi, T. Staubli, H. Drobir, N. Massinger","doi":"10.1115/imece1997-0076","DOIUrl":"https://doi.org/10.1115/imece1997-0076","url":null,"abstract":"\u0000 An experimental investigation of lightly damped multiple-mode vibrations of a rectangular prism in cross flow will be described. The identification of the fluid dynamic force coefficients is performed by means of a regression analysis (Least-Squares-Procedure) accompanied by online numerical simulation, which allows minimization of errors. Non-linear modelization of the equation of motion is shown, which is needed for stability discussion and to describe the response beyond the stability limit. The fluid dynamic damping will be chosen as the responsible control parameter in the model test for a supercritical Hopf bifurcation.","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125622594","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 Fluid-Structure Interaction by Means of Dynamic Unstructured Meshes","authors":"F. Blom, P. Leyland","doi":"10.1115/1.2820740","DOIUrl":"https://doi.org/10.1115/1.2820740","url":null,"abstract":"\u0000 This paper presents a computational analysis on forced vibration and fluid-structure interaction in compressible flow regimes. A so-called staggered approach is pursued where the fluid and structure are integrated in time by distinct solvers. Their interaction is then taken into account by a coupling algorithm. The unsteady fluid motion is simulated by means of an explicit time-accurate solver. For the fluid-structure interaction problems which are considered here the effects due to the viscosity can be neglected. The fluid is hence modeled by the Euler equations for compressible inviscid flow. Unstructured grids are used to discretise the fluid domain. These grids are particularly suited to simulate unsteady flows over complex geometries by their capacity of being dynamically refined and derefined. Dynamic mesh adaptation is used to enhance the computational precision with minimal CPU and memory constraints. Fluid-structure interaction involves moving boundaries. Therefore the Arbitrary Lagrange Euler method (ALE-method) is adopted to solve the Euler equations on a moving domain. The deformation of the mesh is controlled by means of a spring analogy in conjunction with a boundary correction to circumvent the principle of Saint Venant. To take advantage of the differences between fluid and structure time scales, the fluid calculation is subcycled within the structural time step. Numerical results are presented for large rotation, pitching oscillation and aeroelastic motion of the NACA0012 airfoil. The boundary deformation is validated by comparing the numerical solution for a flat plate under supersonic flow with the analytical solution.","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"19 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129258221","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":"Wall-Pressure Fluctuations Under a Three-Dimensional Boundary Layer","authors":"R. Panton","doi":"10.1115/imece1997-0085","DOIUrl":"https://doi.org/10.1115/imece1997-0085","url":null,"abstract":"\u0000 This paper gives a simple model of the pressure spectrum in wavenumber-phase velocity space for three-dimensional boundary layers. Equally as important is the definition proposed for a vector convection velocity and the method proposed for conversion of wavenumber-frequency variables into wavenumber-phase velocity variables. In three-dimensional flows one must define a phase speed that is a vector c = (c1, C3). A complete vector wave speed cannot be determined from pressure data, however, the component ck in the direction of k, ck ≡ Ω/k, can be defined and is found to be sufficient. Here k is the wave vector magnitude and α its direction. This allows the spectrum function to be well represented in the polar form Φ(k, α, ck). Moreover, for given k, a convection velocity may be defined as the point of maximum Φ(k, α, ck). Convection velocity is expressed in the form of a magnitude ck_max(k) and direction αmax(k). The three-dimensional spectrum model was produced as a generalization of Witting’s two-dimensional model. By splitting the boundary layer into two parts, the simplest generalization is formulated. Each part has its own transport velocity vector. Sample calculations are displayed as contour plots of Φ (ck, α) for fixed wavenumber k. On such plots the maximum is the convection velocity. The plots reveal an abrupt transition in the spectrum as the wavenumber increases; a result of the two layer assumption.","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116931234","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":"Symmetric Formulations for Modal Analysis of Internal Fluid Structure Systems","authors":"R. Ohayon","doi":"10.1115/imece1997-0044","DOIUrl":"https://doi.org/10.1115/imece1997-0044","url":null,"abstract":"\u0000 This paper deals with appropriate computational methods for modal analysis of elastic structures containing an inviscid fluid (gas or liquid). These methods, based on Ritz-Galerkin projection using appropriate functional basis, allow us to construct reduced models expressed in terms of physical displacement vector field u in the structure, and generalized coordinates vector r describing the behavior of the fluid. Those reduced models lead to symmetric generalized eigenvalue matrix system involving a reduced number of degrees of freedom for the fluid. More precisely, we construct symmetric matrix models of the fluid considered as a subsystem, by considering the response of the fluid to a prescribed normal displacement of the fluid-structure interface. Two distinct situations are analyzed, namely linear vibrations of an elastic structure completely filled with a compressible gas or liquid and linear vibrations of an elastic structure containing an incompressible liquid with free surface effects due to gravity. The first case is a structural acoustic problem with modal interaction between structural modes with acoustic modes in rigid motionless cavity. Wall impedance can also be easily introduced in order to take into account fluid-structure interface dissipation, for further forced response studies. The second case is a hydroelastic-sloshing problem with modal interaction between incompressible hydroelastic structural modes with incompressible liquid sloshing modes in rigid motionless cavity, involving an elastogravity operator related to the wall normal displacement of the fluid-structure interface. For the construction of reduced models, the static behavior at zero frequency play an important role. This is why we start from “well-posed” variational formulations of the problem, in the sense that zero-frequency behavior must be well retrieved in the equations. It should be noted that the so-called “quasi-static correction” term plays a fundamental role in the Ritz-Galerkin procedure (error truncation). The general methodology corresponds to dynamic substructuring procedures adapted to fluid-structure modal analysis. For general presentations of computational methods using appropriate finite element and dynamic substructuring procedures applied to modal analysis of elastic structures containing inviscid fluids (sloshing, hydroelasticity and structural-acoustics), we refer the reader to Morand and Ohayon (1995).","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114581526","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 Finite Volume Method for the Computation of Fluid Flow With Moving Grid for Fluid-Structure Interactions","authors":"S. Mounsif, A. Mesquita","doi":"10.1115/imece1997-0043","DOIUrl":"https://doi.org/10.1115/imece1997-0043","url":null,"abstract":"\u0000 A finite-volume numerical method is presented for the solution of the two-dimensional incompressible, unsteady Navier-Stokes equations in general moving curvilinear co-ordinates. The method employs the semi-strong conservation form of the governing equations with pressure and physical contravariant velocity components as dependent variables. The k-ε model is utilised to describe the turbulent flow process. The SIMPLE algorithm is used to handle the pressure-velocity coupling. Results for the calculation of the fluctuating flow past an airfoil are compared with the available experimental data. As a simulation of fluid-structure interaction, the calculation of the unsteady flow-field around a stay-vane hydrofoil in forced and free vibration is presented. The numerical results obtained in this work show very good agreement with experimental observations.","PeriodicalId":146109,"journal":{"name":"4th International Symposium on Fluid-Structure Interactions, Aeroelasticity, Flow-Induced Vibration and Noise: Volume I","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123775532","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}