{"title":"The Computation of Axi-Symmetric Rotor-Stator Flows Related to Cooling Passages of Electrical Generators","authors":"H. Iacovides, M. Leschziner, H. Li","doi":"10.59972/j3ghjjyg","DOIUrl":"https://doi.org/10.59972/j3ghjjyg","url":null,"abstract":"The objectives of this exploratory study have been, first, to investigate the effectiveness of variants of the high-Re k-ε model in the present rotating flow - a practice widely used in industrial computations - and second, to examine the influence of swirl, multiple injection and exit, through a series of steady-state, two-dimensional-flow computations. The rationale of the 2-D simplification is rooted in the assumption that the present type of swirl, provoked by the rotating inner cylinder, will destabilise turbulence and will therefore tend to reduce circumferential variations. Consequently, the assumption of an axi-symmetric, i.e. two-dimensional flow, is not expected to cause serious differences between the computed and the actual flow behaviour...","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121617501","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 Validation of Incompressible Cross-Flow Discharge Coefficients","authors":"Q. Rayer","doi":"10.59972/5xber0cm","DOIUrl":"https://doi.org/10.59972/5xber0cm","url":null,"abstract":"Validation against air systems problems is required to enable Computational Fluid Dynamics (CFD) codes to be confidently used in the design of turbine cooling air systems. CFD calculations of orifice cross-flow discharge coefficients (Cd) have been compared with measurements by Rohde et al [1]. Simulations have been carried out for cases with a low main duct Mach number (Md ~ 0.25) using incompressible flow modelling. Comparisons have been made of cross-flow discharge coefficients for a range of pressure-head ratios and Mach numbers. Results at a main duct Mach number of 0.07 were obtained using the standard k-ε.: turbulence model which gave agreement to better than 5% for absolute values of pressure-head ratios and discharge coefficients. The trends in the data for pressure-head ratios and Mach numbers were also reproduced. At a higher main duct Mach number of 0.25, the Mach number in the vicinity of the orifice reached 0.8. As expected this rendered incompressible flow modelling unsuitable, resulting in inaccurate determinations of orifice pressure-drops. Work is already in progress to simulate high Mach number cases using a more suitable compressible flow model. The results obtained so far give confidence that CFD will become a valuable tool for evaluating air system losses in novel configurations.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116950217","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":"Transient and Steady Flow Computations for an Electro-Mechanical System","authors":"Z. Pan, P. Tucker","doi":"10.59972/lf72jdna","DOIUrl":"https://doi.org/10.59972/lf72jdna","url":null,"abstract":"The computation of transient turbulent flows has considerable engineering significance. During the period from the mid 1980's until now Computational Fluid Dynamics (CFD) has been used in a wide range of industries. The use of CFD in electronic/mechatronic system design is just one of many examples. The flows in these systems effect component operating temperatures and also the deposition of contaminants. Both of these factors are strongly related to product reliability. As with many other engineering systems, most forced convection flows in electronics/mechatronics are transitional or turbulent. A significant amount of numerical work has been motivated by the need to predict fluid flow in electronic systems. Much of this is reviewed by Tucker (1997), being mostly for steady flows. However, Reindl et al. (1991) study transient laminar flow in a square enclosure with a heated wall. Also, Shy and Rao (1993) predict transient laminar free convection around an enclosed vertical channel. The application of CFD to mechatronics is discussed by Tucker and Hewit (1996). The present work attempts to investigate the performance of turbulence models when predicting both transient and steady flows for the geometry presented in Figure 1. The flow inlet area shown has a suddenly opening shutter, giving rise to an in rush of air from an external air source. The geometry is quite specific being part of an electronic/mechatronic Automatic Teller Machine (ATM). However, the results produced here have a wider context. They are suggestive of the choice of turbulence models when predicting flows in systems with similar flow features. These include streamline curvature, large vortical structures and stagnation resulting from an impinging rectangular jet. The turbulence models tested include the standard k-ε model (Launder and Spalding, 1974), low (Wolfshtein, 1969) and high Reynolds number k-l models, and a standard mixing length (ml) model. Also, two zonal models are tried using the k-ε model away from walls with the k-l and ml models applied elsewhere.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129755562","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 Study of a Steam Condenser","authors":"N. Rhodes, M. Swain","doi":"10.59972/364dxa22","DOIUrl":"https://doi.org/10.59972/364dxa22","url":null,"abstract":"The heat and mass transfer processes occurring in a steam condenser are very complex, involving a multi-phase flow comprising steam, water and air. Steam condenses onto the tubes through which cooling water passes. The condensate forms films of water which drain from the tubes forming droplets which migrate under gravity and aerodynamic forces toward the sump of the condenser. These processes cannot be represented exactly in a CFD model. However, by using correlations for heat and mass transfer and friction and some representation of turbulence, predictions of performance can be made. This study illustrates some of the effects of basic parameters by application to a simple experimental case. The program used to simulate the flow within the condenser was CFX release 3.3.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114717542","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}
P. Birky, F. Sinclair, A. Savill, R. Cant, W. Dawes
{"title":"The Use of an Unstructured Adaptive Mesh Code to Perform Resolved Obstacle Computations for Confined Explosion Hazards","authors":"P. Birky, F. Sinclair, A. Savill, R. Cant, W. Dawes","doi":"10.59972/yzxn5vgx","DOIUrl":"https://doi.org/10.59972/yzxn5vgx","url":null,"abstract":"The establishment of safety cases for oil and gas installations requires accurate estimations of the effects of confined explosions and in particular the over-pressures generated. The shortcomings of the current understanding, traditional semi-empirical methods, and Computational Fluid Dynamic (CFD) techniques have been clearly highlighted in many cases, including the recent SCI full-scale evaluation exercise, where over-pressures were severally underpredicted. Despite this, there is a growing recognition that CFD has an important role to play and a number of different techniques are currently being developed for confined explosions, e.g. see [1-4]. Structured mesh codes can typically handle only about 10 obstacles. Extension of such codes to larger numbers of obstacles is limited by computer resources required to ensure at least 10 cell resolution of the obstacles and more importantly their shear layers [1]. For real installation modules, containing several hundred or even thousands of obstacles, unresolved calculations using Porosity, Distributed Resistance (PDR) models are currently the only CFD option. In this approach obstacles are not resolved, but are represented by resistance terms appended to the mean and turbulent sources, and these methods are limited by the accuracy of these terms, which can only be improved by access to detailed parametric data or high quality resolved computational results. Formulating resistance terms is thus very difficult for complex geometries...","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"05 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127228489","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":"Installation and Viscosity Effects in Turbine Meters","authors":"A. Neal, D. McEwen","doi":"10.59972/0ug5gknc","DOIUrl":"https://doi.org/10.59972/0ug5gknc","url":null,"abstract":"Turbine flow meters are commonly used in the oil industry. The rotor rotates freely and takes from the flowing fluid only the torque required to overcome its losses. The speed of rotation of the rotor is monitored with a pick-up which generates a pulse at the passing of each rotor blade. The calibration of the meter is presented as a curve of the meter's 'K-factor' (the number of pulses generated per unit volume of fluid passing through the meter) as a function of flow rate. For a given installation and fluid a meter's K-factor will typically be constant to within ±0.2% over 15% to 100% of the meter's design flow range. For the user, the difficulty in employing turbine meters is their sensitivity to installation effects and fluid properties; the upstream pipework and the viscosity of the fluid being metered can both affect the meter characteristics. The aim of this project was to use the FLUENT modelling package to try and identify aspects of meter design which affect the sensitivity to inlet flow and to fluid viscosity, and to check the predictions against meter calibrations carried out at NEL. In co-operation with Halliburton Manufacturing and Services Ltd, a modular, 102 mm diameter meter was designed and a range of components were manufactured. Several combinations were analysed using the CFD software, and calibrated with different upstream flow conditions and oils.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134102278","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":"Modelling of Atmosphere Dispersion Near Buildings","authors":"R. Hall, I. Cowan","doi":"10.59972/43kzgmdk","DOIUrl":"https://doi.org/10.59972/43kzgmdk","url":null,"abstract":"The problem of atmospheric dispersion of toxic and hazardous gas in the immediate vicinity of buildings is an important topic in the preparation of safety reports for chemical sites. The test case presented in this paper represents a 'simple' example of the type of scenarios of interest. It involves a single L-shaped building on flat terrain with a continuous release of neutrally-buoyant gas from an area source in the side of the building. The area source is intended to represent the doorway of a loading bay into which a road tanker might enter to offload its contents of chemicals...","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115507086","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":"Heat Transfer in Offshore Pipeline Bundles","authors":"A. Mosquera, G. Paczkowski, J. Brydon","doi":"10.59972/ccst3wm0","DOIUrl":"https://doi.org/10.59972/ccst3wm0","url":null,"abstract":"A key design parameter for the operation of subsea pipeline systems is the Overall Heat Transfer Coefficient or \"U Value\". In some cases for bundles with flow lines insulated in a common sleeve, the steady state flow condition \"U Value\" is not a characteristic parameter since it varies depending on the individual flowline temperatures and corresponding heat fluxes along the length. It is therefore difficult to specify an overall \"U Value\" coefficient either for the bundle or for each flowline in the bundle. It is, however, possible to use computational fluid dynamics models to evaluate these heat fluxes and effective \"U Values\" for each pipeline over a short bundle segment given specified flowline temperatures. Prediction of the flowline temperatures is difficult particularly in cases when fluids are flowing in the opposite directions i.e. production lines and gas injection line, but by using a simplified Rockwater in-house thermal analysis model, the temperature inputs to the CFD model of the bundle section can be estimated. FIDAP, a general purpose CFD code based on the finite element method has been used in the present studies. FIDAP works with the 2-D bundle model to predict heat flux under steady state conditions thus verifying the Rockwater mathematical model by calculating convection velocity and temperature contours.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127020359","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":"Mixing in a Ventilation System Tee Junction","authors":"S. Graham","doi":"10.59972/pghrcll7","DOIUrl":"https://doi.org/10.59972/pghrcll7","url":null,"abstract":"In part of BNFL plant, sampling has indicated that two streams in a tee junction duct configuration were insufficiently mixed. Following this observation a study was initiated to investigate ways in which the problem could be overcome, involving both an experimental programme and a theoretical analysis using CFD.","PeriodicalId":183819,"journal":{"name":"NAFEMS International Journal of CFD Case Studies","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124416761","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}
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号
