Volume 1: Fluid Mechanics最新文献_第5页

Simulations of Tubular UAV With Vectored Thrust in Near-Hovering Regimes in the Presence of Side Winds 具有矢量推力的管状无人机在侧风作用下近盘旋状态的仿真

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-4678

K. Matveev, M. Wheeler

{"title":"Simulations of Tubular UAV With Vectored Thrust in Near-Hovering Regimes in the Presence of Side Winds","authors":"K. Matveev, M. Wheeler","doi":"10.1115/ajkfluids2019-4678","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4678","url":null,"abstract":"\u0000 An innovative unmanned aerial vehicle with a tubular body and a vectored thruster is considered in this study. In order to optimize the vehicle design and develop effective means for its control, aerodynamic characteristics of this vehicle need to be known. Computational fluid dynamics studies employing STAR-CCM+ software have been carried out for this UAV in near-hovering regimes. Aerodynamic simulations employed the SST k–ω turbulence model, γ transition model, and a virtual actuator disk model. After conducting a validation study with a cylinder in axial flow, modeling of the UAV setup was completed for a range of propulsor orientations and cross winds. The aerodynamic phenomena are found to become more complex with increasing the propulsor angle with respect to the main body axis and in stronger cross winds due to interactions between the incident flow, the propulsor jet, and the body surface. At the propulsor deflection angle of 15°, the horizontal aerodynamic force on the body was augmented by 0.02–0.07 of the propulsor thrust magnitude in various wind conditions, whereas the axial downward force increased by 0.01–0.03 of the thrust. In cross winds with the relative velocity magnitude of 0.65, the horizontal aerodynamic force on the body increased by about 0.25 of the propulsor thrust magnitude, while the axial downward force increased by about 0.05 of the thrust.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122235912","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}

引用次数: 0

The Effect of Model Parameters on CFD Simulation of a Thermosyphon 模型参数对热虹吸CFD模拟的影响

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-4896

Huiyu Wang, D. K. Walters, K. Walters

{"title":"The Effect of Model Parameters on CFD Simulation of a Thermosyphon","authors":"Huiyu Wang, D. K. Walters, K. Walters","doi":"10.1115/ajkfluids2019-4896","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4896","url":null,"abstract":"\u0000 Both numerical and experimental studies have previously been carried out to investigate the heat transfer performance of the two-phase closed thermosyphon (TPCT). This paper investigates the performance of a commercially available computational fluid dynamics (CFD) solver (Ansys FLUENT) to predict the complex flow behavior of TPCTs, with special focus on modeling of the mass transfer phase change process. The present study uses four different sets of mass transfer coefficients for condensation and evaporation within a previously documented phase change model to determine their impact on the simulation results. The mass transfer coefficients effectively control the rate of transfer from liquid to vapor phase during evaporation and vice versa during condensation. The choice of coefficients is assumed to represent a balance between numerical accuracy and stability. A baseline simulation is performed for which both the evaporation and condensation coefficients are equal and set to default values. Three additional simulations vary the magnitude of the coefficients and adopt relative values based on density ratio following a recommended method that has been previously found to be effective for these simulations. Initial results show that the case with the highest coefficient of evaporation and coefficient for condensation based on the density ratio is in good agreement with available experimental data of overall thermal resistance of the TPCT., with predictive capability degrading as the values of the coefficients are reduced. Additionally, the 3D CFD models implemented in this study appear to successfully predict the phase change process and vital flow behavior inside the TPCTs, at least in a qualitative sense.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132101974","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}

引用次数: 0

Experimental Study on Drag Reduction Effect With Traveling Wave Control Using PIV Measurement 基于PIV测量的行波控制减阻效果实验研究

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-4855

I. Suzuki, Takaaki Shimura, A. Mitsuishi, K. Iwamoto, A. Murata

引用次数: 3

Design and Modelling of a Cartridge Pressure Amplifier 盒式压力放大器的设计与建模

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-5474

B. Zardin, Giovanni Cillo, P. Zavadinka, Juraj Hanusovsky, M. Borghi

引用次数: 0

The Effects of Nozzle Orientation on Mixing Characteristics of Elliptic Twin Free Jets 喷嘴取向对椭圆双自由射流混合特性的影响

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-5478

Ella M. Morris, Neelakash Biswas, Seyed Sobhan Aleyasin, M. Tachie

{"title":"The Effects of Nozzle Orientation on Mixing Characteristics of Elliptic Twin Free Jets","authors":"Ella M. Morris, Neelakash Biswas, Seyed Sobhan Aleyasin, M. Tachie","doi":"10.1115/ajkfluids2019-5478","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5478","url":null,"abstract":"\u0000 The effects of nozzle orientation on the mixing and turbulent characteristics of elliptical free twin jets were studied experimentally. The experiments were conducted using modified contoured nozzles with a sharp linear contraction. The centers of the nozzle pair had a separation ratio of 5.5. Four nozzle configurations were tested, one twin jet orientated along the minor plane (Twin_Minor), one twin jet orientated along the major plane (Twin_Major), one single jet orientated along the minor plane (Single_Minor) and one single jet orientated along the major plane (Single_Major). In each case, the Reynolds number based on the maximum jet velocity and the equivalent diameter was 10,000. A planar particle image velocimetry system was used to measure the velocity field in the jet symmetry plane. It was observed that the velocity decay rate is not sensitive to nozzle orientation. However, close to the jet exit the spread rate was highest in the minor plane. In addition, contour plots of Reynolds shear stress and turbulence intensities revealed significant differences between the minor and major plane. Velocity profiles showed little variation close to the jet exit, while further downstream the variations between the velocity profiles were more pronounced between the major and minor planes.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"21 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121106429","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}

引用次数: 2

Numerical Simulation of Influences of the Body’s Presence on Flow Around the Wings in Insect Flapping Flight 昆虫扑翼飞行中身体存在对翼周流动影响的数值模拟

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-5176

Kohei Yamauchi, T. Fukui, K. Morinishi

{"title":"Numerical Simulation of Influences of the Body’s Presence on Flow Around the Wings in Insect Flapping Flight","authors":"Kohei Yamauchi, T. Fukui, K. Morinishi","doi":"10.1115/ajkfluids2019-5176","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5176","url":null,"abstract":"\u0000 In this research, we numerically investigated the influences of the body’s presence on flow around the hovering fruit fly with regularized lattice Boltzmann method. In recent years, insect’s flapping flight system has been investigated because their superior flight mechanisms are expected to improve the flight abilities of micro air vehicles. Because of the simplification of experimental equipment and computational simulation, the insect model without body is often used to investigate the flow around the hovering flight insect. However, the gap between the wing and body can significantly change the flow around the wing root. Thus, we conducted investigations of the influences of the body’s presence on the vortical flow structure and cycle-averaged lift coefficient. As a result, the aerodynamic forces on the wings were enhanced by the body’s presence. The flow at the gap between wing and body enhanced the vortex strength and aerodynamic forces on the wing root region. Also, the cycle-averaged lift coefficient of the with body model was slightly higher than that of the without body model. If the wing’s flapping motion or the shape of the wing is changed, the effects of the body’s presence will cause different flow around the wing root. Therefore, it is necessary to take body’s presence into consideration.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127243396","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}

引用次数: 1

Computational Fluid Dynamics Modelling of a Load Sensing Proportional Valve 负载敏感比例阀的计算流体动力学建模

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-4708

A. Corvaglia, Giorgio Altare, Roberto Finesso, M. Rundo

引用次数: 3

Flow Measurement in Stented Left Coronary Artery Models 左冠状动脉支架模型的血流测量

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-5154

Kensuke Ono, K. Yamamoto, T. Tsukahara, M. Motosuke, H. Kawamoto, S. Tahara, Kentaro Tanaka, S. Nakamura

引用次数: 0

Experimental Investigations on Friction Drag Reduction on an Airfoil by Passive Blowing 被动吹气减阻翼型的实验研究

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-5068

Shiho Hirokawa, Kaoruko Eto, K. Fukagata, N. Tokugawa

引用次数: 1

Flow Visualization and Drag Measurement of a Circular Cylinder in Compressible Flow at Reynolds Number Between 1000 and 5000 雷诺数为1000 ~ 5000的可压缩圆柱体流动显示与阻力测量

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-5164

K. Kusama, A. Noguchi, T. Nagata, A. Komuro, T. Nonomura, A. Ando, Keisuke Asai

{"title":"Flow Visualization and Drag Measurement of a Circular Cylinder in Compressible Flow at Reynolds Number Between 1000 and 5000","authors":"K. Kusama, A. Noguchi, T. Nagata, A. Komuro, T. Nonomura, A. Ando, Keisuke Asai","doi":"10.1115/ajkfluids2019-5164","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5164","url":null,"abstract":"\u0000 In this study, a compressible low-Reynolds number flow over a circular cylinder was investigated by schlieren visualization and the force measurement. A Reynolds number based on freestream quantities and a diameter of a cylinder is set to be 1000 ≤ Re ≤ 5000 and a Mach number is set to be 0.1 ≤ M ≤ 0.5 by using the low-pressure wind tunnel. From the schlieren visualization, frequency of the vortex shedding was obtained by performing frequency analysis on the time series schlieren images. Near wake structure by the circular cylinder is measured by time-averaged schlieren image. Even though M is less than 0.5, the structure of the flow fields changes depending on M. The effect of M on the scale of wake structure depends on Re. Under the condition at Re of 1000–3000, the scale becomes large as M increases more than 0.2. On the other hand, under the condition that Re is 4000–5000, it becomes small as M increase 0.3 or more St is revealed to be decrease for Re of 2000–3000 with increasing M, and St increases at Re of 4000–5000. From the force measurement, drag coefficient (Cd) and pressure distribution on a circular cylinder (Cp) obtained. The effect of M on Cd does not depend on Re, and Cd also increases as M increases. The effect of Re on Cd is also observed that Cd increases as Re increases and this trend doesn’t depend on M. The Cp decrease with Re increase. The M effect on Cp is that the range of Cp is enlarged with M increase.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131001293","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}

引用次数: 0