Volume 10: Fluids Engineering最新文献

{"title":"Effects of Geometrical Configuration on the Aerodynamic Performance of the Joined Wings","authors":"M. D. Alam, Soheil Soeimanikutanaei","doi":"10.1115/imece2021-72087","DOIUrl":"https://doi.org/10.1115/imece2021-72087","url":null,"abstract":"\u0000 Joined wing holds promises for future generation airplane application. It might provide a superior lift to drag ratio by reducing the effect of the wing vortex as well as the reduced drag. Moreover, it has higher structural rigidity, therefore, provides a lighter aircraft design facility. In this paper, the aerodynamic performance of a joined wing with a different sweep angle of the front and aft wings has been studied numerically. The Reynolds-averaged Navier–Stokes (RANS) equations were solved by the SST model to study the fully developed turbulence flow over the wing. The solution of the flow obtained by commercial software Ansys Fluent. The lift, drag and lift to drag ratio for the various angle of attacks have been calculated and plotted for the different specified geometries. The simulation result shows that the lift, drag coefficient increase with the increase of angle of attack whereas, the lift to drag coefficient increase first then gradually decreases for different joined wing configurations. In some cases, irregular behavior was observed, the vortex shedding behind the front wing could highly affect the aft wing so it might be the reason for this irregularity. The study findings emphasize that the aerodynamic wing performance for joined wing depends on the specification of each wing as well as also the mutual interaction between them.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115375601","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 Model Experiment of Aortic Valve Stenosis to Correlate Narrowness With the Acoustic Spectrum","authors":"Hannah Zukowski, Marco Rupp, Winrose Mollel, T. Ning, C. Byers","doi":"10.1115/imece2021-70771","DOIUrl":"https://doi.org/10.1115/imece2021-70771","url":null,"abstract":"\u0000 A model experiment is used to investigate the relationship between a narrowing in a pulsatile flow and the relative energy contained in the measured acoustic spectrum. Inspired by studies of aortic stenosis, this experiment models increasingly severe narrowings in an internal flow with a semi-triangular opening to mimic the shape of an open tricuspid valve. A baseline case is attained through use of dynamic similarity to the average flow through an unrestricted aortic valve. Normalized spectra for each case provides an indication of relative energy in each frequency band which shows how the distribution of energy changes with each restriction. Increasing narrowness of the model valve opening results in enhanced energy content across all frequency bands up to 400Hz. Frequency bands identified as relevant to more extreme cases of stenosis in actual heart valves, such as the 40Hz–80Hz band, show significantly increased overall energy in these model cases. While all restricted cases demonstrate a nominal amount of increased energy, there appears to be more significant changes when the narrowing exceeds an area reduction of 40%.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124838916","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":"The Influence of Plain-Orifice Geometry on Pintle Injector Flow Discharge Coefficient","authors":"Colton Harms, Hamid Fazeli, Jordan Vanaken","doi":"10.1115/imece2021-73280","DOIUrl":"https://doi.org/10.1115/imece2021-73280","url":null,"abstract":"\u0000 In this study, an experiment was carried out to understand the behavior of incompressible flow passing through the plain-orifices of pintle injector to characterize the discharge coefficient (Cd) for different orifice geometries. Three types of orifices, including primary, secondary, and film-cooling orifices, were utilized to characterize the discharge coefficient and understand each orifice flow pattern with high-speed imaging. Each of these orifices will be separated and tested in their test article. The impacts of parameters, including shape and size, on discharge coefficient were studied. The discharge coefficient was determined for each test article by subjecting the orifices to a range of flow rates and measuring the pressure differential. The results obtained for the test article F show a good agreement with the choked fit curve obtained from the analytical relation. In contrast, the results of other test articles show an inconsistency due to the cavitation phenomenon as an unstable flow in their trends. However, they show that after the cavitation, they precisely follow the expected trends.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122008303","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 and Computational Studies on Saltation of Metal Powders Used in Laser Powder Bed Fusion Systems for Metal Additive Manufacturing","authors":"T. Tran-Le, Jia-xuan Wang, Margaret Byron, S. Lynch, R. Kunz","doi":"10.1115/imece2021-69550","DOIUrl":"https://doi.org/10.1115/imece2021-69550","url":null,"abstract":"\u0000 The ability of Powder Bed Fusion (PBF) to create complex geometries across a wide range of materials makes PBF a widely used powder-based metal additive manufacturing (AM) process in various industries for advanced applications. However, compared to conventional manufacturing processes, the metal parts printed by PBF exhibit lower surface quality due to soot and spatter particles arising from laser-powder interaction. To minimize spatter and soot generation during the build, PBF systems are equipped with cross-flow nozzles that are designed to flow inert gas across the build platform. It is desired that these gas flow systems have the ability to remove most of the spattered powder from the build chamber, but do not erode the freshly spread layer of powder on the to-be-printed surface to ensure high-quality manufactured parts. The onset of particle bed erosion can be characterized by the critical Shields number. Once the critical Shields number is known for the metal powders and system of interest, the flow of inert gas in the build chamber can be optimized to ensure the build process is efficient and clean.\u0000 This work proposes a Shields number-based method for obtaining engineering design guidance for PBF gas flow systems to optimize the spatter removal process. A combined experimental and Computational Fluid Dynamics (CFD) study was performed to provide design guidance for these cross-flow systems. All experiments were conducted using a small, closed-loop wind tunnel, with built-in flexibility, capable of testing a number of cross-flow configurations. A high-speed camera captured the threshold of particle movement at a variety of operating conditions for various metal powders used in metal AM including aluminum alloy AlSi10Mg, nickel-based superalloy Inconel 718, titanium alloy Ti-6Al-4V, steel alloy 4340, and 316L stainless steel. Time-averaged flowfield measurements of the gas flow inside the test section were made using particle tracking velocimetry (PTV) and a hot-wire air flow meter at the same conditions. Using these experimental measurements and attendant CFD simulations, CFD predictions of wall shear stress can be used to calculate the Shields number at the condition of incipient movement as identified experimentally.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132397668","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":"Electrohydrodynamic Settling Droplet With Weak Inertia Subjected to a Uniform Electric Field Based on the Lattice Boltzmann Method","authors":"Yi-Mo Zhang, Yu Zhang, K. Luo, H. Yi","doi":"10.1115/imece2021-70308","DOIUrl":"https://doi.org/10.1115/imece2021-70308","url":null,"abstract":"\u0000 Electrohydrodynamic settling of droplets is governed by the combined influence of electric field and gravitational field in many practical applications and innovative researches. To simulate the deformation and motion of the droplet under the interaction of gravity and electric stress, a numerically multiphase model based on the lattice Boltzmann method (LBM) is established. A perfectly dielectric (PD) drop suspended in another immiscible medium with perfectly dielectric fluids and a leaky dielectric (LD) drop immersed in a leaky dielectric medium are considered to study the dynamic behavior of an electrified droplet driven by gravity. The predictions of the LBM model demonstrated in this paper are in good agreement with classic analytical solutions and conventional numerical results reported in previous literature, particularly for drops with small deformation. Moreover, the electrohydrodynamics of settling droplets subjected to a uniform electric field which is perpendicular to a weak gravitational field is studied computationally for fluids with various electrical parameters. Numerical simulations for droplets with different permittivity ratios and conductivity ratios are conducted over a range of electric capillary numbers. It is found that, unlike PD settling droplets which always transform into a prolate shape due to the presence of the electric field, whether the LD droplets under weak inertia deform into a prolate or an oblate shape depends on the electrical properties of the dispersed medium and surroundings. This phenomenon is in a similar manner as in the previous work for EHD droplets owing to the imposition of weak inertia. However, with the shape feature unaltered, the electric stress acted at the fluid-fluid surface has a significant influence on the drop deformation and the distribution of charges and consequently results in noticeable changes in transient settling speed.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127567759","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 One-Dimensional Mechanistic Model for Tracking Unsteady Slug Flow","authors":"J. Padrino, N. Srinil, V. Kurushina, D. Swailes, C. Pain, O. Matar","doi":"10.1115/imece2021-70735","DOIUrl":"https://doi.org/10.1115/imece2021-70735","url":null,"abstract":"\u0000 A novel one-dimensional slug tracking mechanistic model for unsteady, upward gas-liquid slug flow in inclined pipes is presented. The model stems from the first principles of mass and momentum conservation applied to a slug unit cell consisting of a slug body of liquid and a region of stratified flow containing an elongated bubble and a liquid film. The slug body front and rear are treated as surfaces of discontinuity where mass and momentum balances or “jump laws” are prescribed. The former is commonly applied in mechanistic models for slug flow, whereas the latter is typically overlooked, thereby leading to the assumption of a continuous pressure profile at these points or to the adoption of a pressure drop due to the fluid acceleration on a heuristic basis. Our analysis shows that this pressure change arises formally from the momentum jump law at the slug body front. The flow is assumed to be isothermal, the gas is compressible, the pressure drop in the elongated bubble region is accounted for, the film thickness is considered uniform, and weight effects in the pressure from the interface level are included. Besides specifying momentum jump laws at both borders of the slug body, another novel feature of the present model is that we avoid adopting the quasi-steady approximation for the elongated bubble-liquid film region, and thus the unsteady terms in the mass and momentum balances are kept. The present model requires empirical correlations for the slug body length and the elongated bubble nose velocity. The non-linear equations are discretized and solved simultaneously for all the slug unit cells filling the pipe. Time-space variation of the slug body and film lengths, liquid holdup and void fraction, and pressures, among other quantities, can be predicted, and model performance is evaluated by comparing with data in the literature.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130709995","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":"IMECE2021 Front Matter","authors":"","doi":"10.1115/imece2021-fm10","DOIUrl":"https://doi.org/10.1115/imece2021-fm10","url":null,"abstract":"\u0000 The front matter for this proceedings is available by clicking on the PDF icon.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133487264","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":"Design of Air-Jet Flow Frame to Control Bug’s Flight Path to Prevent Collision on LIDAR Covers","authors":"Zahra Sadeghizadeh, E. Romero, Gerardo Carbajal","doi":"10.1115/imece2021-73863","DOIUrl":"https://doi.org/10.1115/imece2021-73863","url":null,"abstract":"\u0000 Environmental factors such as vibration, high air temperature, rain, haze conditions, or insects’ debris on the sensor may negatively impact the performance of light detection and ranging (LIDAR) sensor. For instance, at high velocity, especially on summer nights, the bugs strike on the LIDAR cover surface and accumulate over time, blocking the sensor visibility. As a result, the sensor measurement becomes obscured by insects splashing on the LIDAR cover, resulting in a critical loss of performance in LIDAR sensor readings. One approach to resolve this problem is to keep insects away from hitting the sensor cover. To change the insects’ flight path, it is possible to implement a non-invasive method such as applying high momentum air-jet adjacent to the LIDAR cover to deflect the bugs away from the surface. This non-invasive mechanism can control the airflow near the front surface of the sensor to prevent insect collision on the surface. This study designed and fabricated a custom-made air-jet to modify the airflow trajectory on the sensor’s front surface and used nylon pellets as insects. With this design, it is possible to control the resultant upstream airflow before impacting the LIDAR surface, consequently preventing insects or other particles from colliding the sensor cover. The resulting upstream flow depends on the air-jet flow and free stream velocity ahead of the sensor. Highspeed imaging studies have been applied to determine the effectiveness of the air-jet design in altering the nylon pellets’ flight. High-speed imaging shows how different operating conditions affect the nylon pellets path on LIDAR cover. The controlling parameters in this experimental study are free stream air velocity and orientation of air-jet velocity.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124802130","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 Computational Study of the Evolution of Fabri-Choke in a Two-Dimensional Supersonic Ejector","authors":"S. C. V., V. Lijo","doi":"10.1115/imece2021-70919","DOIUrl":"https://doi.org/10.1115/imece2021-70919","url":null,"abstract":"\u0000 An ejector refrigeration system (ERS) can significantly reduce electricity consumption compared to traditional compressor-based systems. Fabri-choking is an indication of an ejector operating in the idealized condition with a maximum entrainment ratio. Backpressure has a significant influence on ejector performance. Severe degradation in performance is observed when the backpressure increases from the design value. Until now, many works have been performed to design and evaluate the ejector systems. In the majority of these works, it is assumed that the ejector is working with fixed designed backpressure, which gives maximum performance. In almost all of the practical applications of ERS, the backpressure varies, mainly as the cooling load requirement changes. In such practical applications, the flow in the ejector is very interesting, and this paper takes a new look at the transient operation of an ejector with varying backpressure. In the present study, numerical simulations have been used to provide detailed flow physics and, in particular, the occurrence of Fabri-choke in a supersonic ejector. The results obtained reveal compound choking, multiple evolutions of Fabri-choke, and its relation to wave reflections. Results showed that the first and second occurrences of Fabri-choke occurred when the backpressure is reduced by 6.0% and 8.0%, respectively. Methods to ascertain Fabri-choke in numerical simulations and experimental studies were also separately addressed.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124816095","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 Study of Gas-Liquid Mass Transfer in a Rectangular Microchannel by Digital Image Analysis Method","authors":"Shuo Yang, G. Kong, Zan Wu","doi":"10.1115/imece2021-69095","DOIUrl":"https://doi.org/10.1115/imece2021-69095","url":null,"abstract":"\u0000 Study of mass transfer in microchannels is indispensable for the design of microreactors. Gas-phase volume monitoring method has been widely used to study the mass transfer process. When using this method, bubble length was measured in most studies to calculate the bubble volume by assuming a symmetrical bubble shape. Therefore, this method is not suitable for asymmetric bubbles. The present study focuses on the mass transfer of CO2 bubbles in a flat rectangular microchannel by using the method of digital image analysis (DIA), especially for deformed bubbles. The dynamics of gas-liquid flow at different volumetric flow rates were observed by a high-speed recording system. Flow patterns were mapped and scaling laws were given for bubble size and bubble velocity. The results showed that the bubble volume increases as gas flow rate increases, while decreases as liquid flow rate increases. It can be explained by the bubble breakup mechanism. Besides, the bubble velocity increases as gas and liquid flow rates increase. The mass transfer of CO2 from bubbles to liquid slugs was quantitatively characterized by volumetric mass transfer coefficient kLa. The results showed that kLa and kL increase with increasing of superficial gas and liquid velocities. The same tendencies can be found in the literature. Finally, new mass transfer correlations were proposed. Predictions from the correlations showed a good agreement with the experimental data.","PeriodicalId":112698,"journal":{"name":"Volume 10: Fluids Engineering","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129514119","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}