Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl最新文献

{"title":"Fluid Flow and Heat Transfer Behavior for Turbulent Flows in a Tube With Vortex Generator Pairs for an Efficient Heat Exchanger","authors":"Islam, Z. Chong, S. Bojanampati","doi":"10.1115/FEDSM2018-83240","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83240","url":null,"abstract":"Various technologies have been developed to enhance flow mixing and heat transfer in order to develop an efficient compact heat exchanging devices. Vortex generators/turbulent promoters generate the vortices which reduce the boundary layer thickness and introduce the better mixing of the fluid to enhance the heat transfer. In this research experimental investigations have been carried out to study the effect of delta winglet vortex generator pairs on heat transfer and flow behavior.\u0000 To generate longitudinal vortex flow, two pairs of the delta winglet vortex generators (DWVG) with the length of 10mm and winglet-pitch to tube-diameter ratio (PR = 4.8) are mounted on the inner wall of a circular tube. The DWVG pairs with two different winglet-height to tube-diameter ratios (Blockage ratio, BR = 0.1 and 0.2), three attack angles (α = 10°, 20°, 30°) and three spacings between leading edges (S = 10, 15 and 20mm) are studied. The experiments were conducted with DWVGs pairs for the air flow range of Reynolds numbers 5000–25000. The influence of the DWVGs on heat transfer and pressure drop was investigated in terms of the Nusselt number and friction factor. The experimental results indicate that DWVG pair in a tube results in a considerable enhancement in Nusselt number (Nu) with some pressure penalty. It is found that DWVG increases Nu up to 85% over the smooth tube. It is also observed that Nusselt number increases with Re, blockage ratio and attack angle. Friction factor decreases with Re but increases with blockage ratio, spacing and attack angle. And 30° DWVG pair with S = 20mm, BR = 0.2 gets the highest friction factor. The Highest thermal performance enhancement (TPE) was noticed for α = 10°, S = 20mm, BR = 0.2 for turbulent flows. To obtain qualitative information on the flow behavior and vortex structures, flow was visualized by laser sheet using smoke as a tracer supplied at the entrance of the test section. The generation and development of longitudinal vortices influenced by DWVG pairs were clearly observed.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87669181","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":"Experimental Investigation of a Flapping Motion Downstream of a Backward Facing Step","authors":"Zhuoyue Li, N. Gao","doi":"10.1115/FEDSM2018-83327","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83327","url":null,"abstract":"The flow field downstream of a backward facing step with Reynolds numbers of 1050–3890 were studied using stereoscopic particle image velocimetry (PIV) with field-of-views perpendicular to the incoming flow. It was found that the separated shear layer underwent a flapping motion with a frequency fH/Uo ≲ 0.04, much smaller than the shedding frequency (fH/Uo ≈ 0.1) for Reynolds number larger than 2000. Here H is the step height and Uo is the freestream velocity. The low frequency flapping motion appeared to be two dimensional, i.e. the motion was in-phased in the spanwise direction. The cause of the flapping motion is still not clear.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72651348","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":"Oxidation-Assisted Pulsatile Three-Stream Non-Newtonian Slurry Atomization","authors":"W. Strasser","doi":"10.1115/FEDSM2018-83025","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83025","url":null,"abstract":"Past work involving validated “cold-flow” CFD modeling of self-generating and self-sustaining pulsating transonic non-Newtonian slurry atomization elucidated acoustic signatures, atomization mechanisms, and the effects of numerics and geometric permutations. The numerical method has now been incorporated with exothermic oxidation reaction kinetics relations along with radiation, i.e. no longer cold-flow. These models provide substantially increased model rigor and allow for new pulsing thermal measures which help assess injector thermal stresses. Twelve models have been run for extended periods of time in order to assess the effects of dramatic changes in gas feed rate and prefilming (retraction) length. Given the new metrics and models, multiple statistically optimized designs are potentially available depending on the objective function(s) and their relative weightings in the overall value proposition to the project. In the case in which all metrics have equal value to the project and are simultaneously considered in a statistical model, the optimum design involves a mid-level of retraction and a mid-level gas feed rate. If, however, more relative weighting is placed on the importance of droplet size minimization and injector thermal management in lieu of feed passage pressure drop minimization, the optimum design involves a similar retraction but a very high level of gas feed rate.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80686669","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 Transient Two-Phase Flow in Pressure Safety Valve Outlet Headers","authors":"Maral Taghva, L. Damkilde","doi":"10.1115/FEDSM2018-83142","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83142","url":null,"abstract":"To protect a pressurized system from overpressure, one of the most established strategies is to install a Pressure Safety Valve (PSV). Therefore, the excess pressure of the system is relieved through a vent pipe when PSV opens. The vent pipe is also called “PSV Outlet Header”. After the process starts, a transient two-phase flow is formed inside the outlet header consisting of high speed pressurized gas interacting with existing static air. The high-speed jet compresses the static air towards the end tail of the pipe until it is discharged to the ambiance and eventually, the steady state is achieved. Here, this transient process is investigated both analytically and numerically using the method of characteristics. Riemann’s solvers and Godunov’s method are utilized to establish the solution. Propagation of shock waves and flow property alterations are clearly demonstrated throughout the simulations. The results show strong shock waves as well as high transient pressure take place inside the outlet header. This is particularly important since it indicates the significance of accounting for shock waves and transient pressure, in contrast to commonly accepted steady state calculations. More precisely, shock waves and transient pressure could lead to failure, if the pipe thickness is chosen only based on conventional steady state calculations.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"14 2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90396347","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":"Mechanistic Modeling of Liquid Carry-Over for 3-Phase Flow in GLCC© Compact Separators","authors":"S. Kolla, R. Mohan, O. Shoham","doi":"10.1115/FEDSM2018-83407","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83407","url":null,"abstract":"Gas-Liquid Cylindrical Cyclone (GLCC©) Separators have been in use in petroleum and other related industries for over two decades. Prediction of Liquid Carry-Over Operational Envelope (LCO-OE) is essential for designing and proper operation of GLCC©. Earlier mechanistic models for predicting LCO-OE were based on gas-liquid phase flow. A new mechanistic model has been developed for the prediction of the LCO-OE incorporating the effect of watercut and fluid properties for a GLCC© under liquid level and pressure control configuration. The new model captures the effect of viscosity and surface tension on the LCO-OE and the effect of water cut on the onset of annular mist velocity. Comparison between the developed mechanistic model predictions for LCO-OE with the experimental data show a good agreement.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91331040","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":"Wing Tip Vortex Development Under a Grid Generated Turbulent Flow","authors":"Kamal Ben Miloud, Marouen Dghim, H. Fellouah, M. Ferchichi","doi":"10.1115/FEDSM2018-83478","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83478","url":null,"abstract":"The interaction of a NACA 0012 wingtip vortex with a grid-generated flow was investigated in this paper. The experiments were conducted in the near and mid-wakes regions at three free stream turbulence (FST) levels of 0.5% (empty wind tunnel), 3% and 6%, and at two Reynolds numbers, based on the wing chord length, of 2 × 105 and 3 × 105. Stereoscopic Particle Image Velocimetry (SPIV) and hot wire measurements were carried out at four downstream positions, namely x/c = 0.5, 2.5, 5 and 7. Streamwise velocity contours showed that the wingtip vortex decayed with increased FST and downstream distance. In the vortex core region, the streamwise velocity decelerated while the vortex adopted a wake-like profile. FST was found to decrease the vortex circulation, to increase the vortex radius, and to increase the vortex meandering amplitude. By increasing the Reynolds number, the grid cases showed a small variation of the vortex radius and vorticity peak, particularly at downstream positions of 5 and 7. With meandering correction, the turbulence level within the vortex core were found to be reduced as the artificial turbulence induced by the vortex meandering was removed.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91332746","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":"Optimization of Piece-Wise Conical Nozzles: Theory and Application","authors":"K. Hasselmann, Muhammad Aiman Bin Khamalrudin, S. Wiesche, E. Kenig","doi":"10.1115/FEDSM2018-83055","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83055","url":null,"abstract":"In this contribution, an optimization study based on computational fluid dynamics (CFD) in combination with Stratford’s analytical separation criterion was developed for the design of piece-wise conical contraction zones. The occurrence of flow separation can be formally described by a newly introduced dimensionless separation number. In the optimization process, the risk of flow separation is reduced by minimizing this separation number. It was found that the optimized piece-wise conical nozzle shape did not correspond to a simple geometric approximation of the ideal polynomial shape. In fact, it was beneficial to reduce the deflection in the outlet region for a piece-wise conical nozzle stronger than for a conventional one. In order to validate the new design method, large-scale tests for different nozzle designs were conducted. The measured velocity profiles and wall pressure distributions agreed well with the CFD predictions. The new method was applied for designing the contraction zone of a new closed-loop organic vapor wind tunnel (CLOWT) working at elevated pressure levels.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"331 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76577790","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":"Wake Flow Patterns Behind Rotating Smooth Spheres and Baseballs","authors":"P. Mortimer, J. Vaccaro, D. M. Rooney","doi":"10.1115/FEDSM2018-83357","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83357","url":null,"abstract":"An experimental investigation into the flow field behind baseballs at two different seam orientations as well as a smooth sphere of the same diameter was undertaken at Reynolds numbers of 5 × 104 and 1 × 105. The rotational speed of the three spheres varied from 0 to 2400 rpm, with data collected in increments of 400 rpm which correspond to relative spin rates between 0 and 0.94. Mean velocity profiles, turbulence in intensity profiles, and power spectral density of the signals were taken using hot-wire anemometry. The smooth sphere wake was seen to change in orientation over a range of relative rotational speeds. The Strouhal number remained constant around 0.24 for relatively low spin rates. The seams on the baseball suppressed any measurable vortex shedding once rotation began, also eliminating any significant change in wake orientation as evidenced by the mean velocity deficit and turbulence intensity profiles. It was concluded that the so-called inverse Magnus effect recorded by previous investigators at a specific Reynolds number / relative rotational speed of a sphere exists only for a smooth sphere and not for a sphere where the boundary layer separation is governed by raised seams.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79590079","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":"Effects of Offset Height on the Turbulent Characteristics of Rectangular Twin Jets","authors":"C. F. Nwaiwu, M. Tachie, M. Agelin-Chaab","doi":"10.1115/FEDSM2018-83264","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83264","url":null,"abstract":"Turbulent characteristics of a twin jet were experimentally investigated for offset heights, h = 1d and 3d where d is the nozzle diameter. The experiments were conducted using a pair of rectangular nozzles of an aspect ratio of 3, that is oriented in the minor plane and with a nozzle separation ratio of 2.3. The Reynolds number, based on jet exit velocity and nozzle diameter was maintained at 4622. The results show that confinement effect decreased the merging point of the jets by 30% but there is no significant effect on the combined points. Reduced confinement showed an 89% reduction in the acceleration of the mean streamwise surface velocity. Two-point streamwise velocity correlations were used to investigate the large-scale coherent structures. The results revealed enhanced streamwise stretching of the structures as the offset height ratio decreased. In the combined region, the structures are more inclined towards the free surface as the offset height ratio decreased.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79663724","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":"Coherent Structures of Tornado-Like Vortices","authors":"M. Karami, L. Carassale, H. Hangan, M. Refan","doi":"10.1115/FEDSM2018-83152","DOIUrl":"https://doi.org/10.1115/FEDSM2018-83152","url":null,"abstract":"Tornado-like vortices have distinctive characteristics that make them significantly different from atmospheric boundary flows. These dynamic characteristics are highly turbulent and unsteady which make them very complex. In this paper, it is tried to identify these dominant patterns, known as coherent structures, out of tornado-like vortex. These vortices are experimentally simulated in a 1/11 scaled model of WindEEE Dome at Western University.\u0000 Coherent structures provide simplified but physical understanding of the flow. The classical method for extraction of coherent structures is proper orthogonal decomposition (POD) method. However, there are serious concerns about POD as it has orthogonality constraint. Thus, we applied another method called independent component analysis (ICA) which does not have orthogonality restrictions. This method helped us to identify non-physical POD modes and to provide a better physical description of the flow.","PeriodicalId":23480,"journal":{"name":"Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fl","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78959258","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}