Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena最新文献_第7页

BLEED CONTROL OF PITCHING AIRFOIL AERODYNAMICS BY VORTICITY FLUX MODIFICATION 采用涡量通量修正的俯仰翼型气动排气控制

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.930

John M. Kearney, A. Glezer

{"title":"BLEED CONTROL OF PITCHING AIRFOIL AERODYNAMICS BY VORTICITY FLUX MODIFICATION","authors":"John M. Kearney, A. Glezer","doi":"10.1615/tsfp9.930","DOIUrl":"https://doi.org/10.1615/tsfp9.930","url":null,"abstract":"Distributed active bleed driven by pressure differences across a pitching airfoil is used to regulate the vorticity flux over the airfoil’s surface and thereby to control aerodynamic loads in wind tunnel experiments. The range of pitch angles is varied beyond the static stall margin (14° <  < 22°) of the 2-D VR-7 airfoil at reduced pitching rates up to k = 0.42. Bleed is regulated dynamically using piezoelectric louvers between the model’s pressure side near the trailing edge and the suction surface near the leading edge. The timedependent interactions of the bleed with the cross flow and its effects on the production, accumulation, and advection of vorticity concentrations during the pitch cycle are measured using phase-locked PIV. These interactions mitigate the impact of abrupt transitions between attachment and separation by reducing the peak lift and moment loads that can lead to pitch instabilities. As a result, the stability of the pitch cycle can be improved (negative damping reduced) by as much as E = 1.21 (at k = 0.25). I. OVERVIEW Aerodynamic bleed effected by pressure differences over a lifting surface interacts with the local surface vorticity layer to produce significant changes in vorticity flux and therefore in global aerodynamic forces and moments. Though passive bleed through porous surfaces for flow control was investigated as early as the 1920s (e.g., Lachmann, 1924) and since then by a number of researchers (e.g., Hunter, Viken, Wood, and Bauer, 2001, Han and Leishman, 2004, Lopera, Ng, and Patel, 2004), active distributed bleed by time-dependent regulation of surface porosity for mitigation of adverse aerodynamic effects on static and pitching airfoils has only been demonstrated recently by Kearney and Glezer (2012, 2013, 2014). These investigations revealed that such bleed can modify the formation and advection of surface vorticity concentrations and thereby alter the timing and strength of the dynamic stall vortex and aerodynamic loads during the pitch cycle. Excursions in pitch through the static stall angle can result in high, transitory aerodynamic loads due to the rapid buildup and shedding of vorticity concentrations. When the pitch motion through stall is oscillatory (i.e., during dynamic stall), especially at rapid pitch rates (“reduced” frequencies of k = c/2U∞ ≳ 0.1), the alternating attachment and flow separation produce periodic forcing that can lead to structural instabilities that are manifested by severe torsion or flutter (Carta, 1967, Johnson and Ham, 1972, McCroskey, Carr, and McAlister, 1976, Ericsson and Reding, 1988). Therefore, the occurrence of dynamic stall on the retreating blade imposes limitations on rotorcraft forward flight speeds (Raghav and Komerath, 2013). The earlier work on dynamic stall has indicated that these adverse effects can be mitigated by modifying the evolution of the unsteady vorticity concentrations that arise due to the blade’s motion. The present investigations build on th","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116992830","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

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.1030

Alan Burlot, B. Gréa, F. Godeferd, C. Cambon

引用次数: 0

SPECTRAL ANALYSIS ON REYNOLDS STRESS TRANSPORT EQUATION IN HIGH RE WALL-BOUNDED TURBULENCE 高re壁面湍流中雷诺应力输运方程的谱分析

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.660

Myoungkyu Lee, R. Moser

{"title":"SPECTRAL ANALYSIS ON REYNOLDS STRESS TRANSPORT EQUATION IN HIGH RE WALL-BOUNDED TURBULENCE","authors":"Myoungkyu Lee, R. Moser","doi":"10.1615/tsfp9.660","DOIUrl":"https://doi.org/10.1615/tsfp9.660","url":null,"abstract":"Despite its importance in many applications, the nature of wall-bounded turbulent flow is not well-understood. The dynamics of near-wall turbulence has been well studied, with direct numerical simulation (DNS) making an important contribution. It has been difficult to study the interaction of near-wall and outer-layer turbulence via DNS because the Reynolds numbers available via DNS have not been sufficiently high to exhibit significant scale separation. In the work presented here, we correct that short-coming. We have performed direct numerical simulation(DNS) of turbulent channel flow using a Fourier-Galerkin method in the streamwise(x) and spanwise (z) directions and a BSplines collocation method in the wall-normal (y) direction. The highest Reynolds number based on shear velocity (uτ = √ τw/ρ), Reτ is approximately 5200. To study the scale dependence of the dynamics of the Reynolds stress components, we applied a spectral analysis to the terms in the Reynolds stress transport equation (RSTE). Result shows that the large (or very large) scale motion has an important role in turbulent transport terms. Also, it has been observed that a non-trivial portion of turbulent kinetic energy (TKE) is transported to the near-wall region and dissipated by large scale motion. Introduction Recently, much research has been directed at understanding wall-bounded turbulent flows at high Reynolds number (Re). Recent advances of experimental techniques (Nagib et al., 2004; Kunkel & Marusic, 2006; Westerweel et al., 2013; Bailey et al., 2014) and computing power (Lee et al., 2013; Borrell et al., 2013; El Khoury et al., 2013) provide information not previously available. One of the most important feature of high Re wall-bounded turbulence is the separation of scales between the near wall and outer layer turbulence. Two distinct peaks of the streamwise velocity energy spectral density are observed experimentally: a small-scale peak in the near-wall region and a large-scale peak in the outer region (Hutchins & Marusic, 2007; Monty et al., 2009; Marusic et al., 2010a,b). Two such spectral peaks were confirmed by direct numerical simulation(DNS) by Lee & Moser (2015). Lee & Moser (2015) have also found that there is peak distinction in the spectral density of Reynolds stress, −u′v′, but this has not yet been observed in experiments. Since the DNS can provides such richer data with high fidelity, it is possible to compute higher order terms in three dimensions. In this work, we have focused on the Reynolds stress transport equation (RSTE) which give us information about production, transport and dissipation of the Reynolds stress tenor. However, RSTE is an averaged equation, so it is difficult to study detailed roles of turbulent motions. Hence, we have performed a spectral analysis on each terms in RSTE to observe how the motions in different length scales contribute the transport of Reynolds stresses. To our knowledge, such a spectral analysis of terms in RSTE has no","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113980366","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: 14

SCALAR DISPERSION BY COHERENT STRUCTURES 相干结构的标量色散

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.740

C. Vanderwel, S. Tavoularis

引用次数: 3

LARGE-SCALE MOTIONS IN TURBULENT CHANNEL FLOW WITH SLIP CONDITION 滑移条件下湍流沟道大尺度运动

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.30

Minwoo Yoon, 윤민

引用次数: 0

DNS OF A FULLY DEVELOPED TURBULENT POROUS CHANNEL FLOW BY THE LATTICE BOLTZMANN METHOD 用晶格玻尔兹曼方法计算完全发育的湍流多孔通道流动的DNS

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.310

Y. Kuwata, K. Suga

{"title":"DNS OF A FULLY DEVELOPED TURBULENT POROUS CHANNEL FLOW BY THE LATTICE BOLTZMANN METHOD","authors":"Y. Kuwata, K. Suga","doi":"10.1615/tsfp9.310","DOIUrl":"https://doi.org/10.1615/tsfp9.310","url":null,"abstract":"To understand the turbulent flow physics over permeable porous surfaces, a direct numerical simulation (DNS) of a turbulent channel flow over a porous layer is performed by the D3Q27 multiple-relaxation time lattice Boltzmann method. The bulk mean Reynolds number is 3000 and the presently considered porous layer, whose porosity is 0.71, consists of staggered cube arrays. Using the DNS results, the phenomenological discussions through the twopoint autocorrelation, one-dimensional energy spectrum and proper orthogonal decomposition (POD) analyses are carried out. The reason why the streaky structure over the porous layer becomes shorter, wider and obscurer than that near the solid wall are discussed. It is found that the low wavenumber turbulence is enhanced over the porous layer. This low wavenumber large-scale motions are considered to stem from the Kelvin-Helmholtz instability due to the weakened wall-blocking effect and the strong shear over the porous layer. BACKGROUND Due to its high heat and mass transfer efficiency, porous structures commonly play important role in industrial fields and thus understanding and modelling the flows over porous media are industrially crucial issues. To understand the turbulent flow physics over permeable porous surfaces, partially direct numerical simulations (DNSs) of turbulent channel flows over porous layers were performed by Breugem et al.(2006). Although they solved the turbulent flows directly in the clear channel region, they applied the volume averaged momentum equation to the porous regions. Since their simulations did not take account of the influence of not only the porous structure but also the dispersion, the predicted turbulence phenomena around and inside the porous layers might not be exactly correct. Recently, Chandesris et al. (2013) performed a full DNS study for a low Prandtl number (Pr=0.1) heat transfer field with the same flow conditions as those of Breugem et al. (2006). Although they resolved the model porous structure, it was an unrealistically revitating structure. Since their focus was on heat transfer, they did not provide further information on the turbulent flow physics than that by Breugem et al. (2006). The turbulent porous channel flows were also investigated experimentally by Suga et al.(2010 and 2011), however, due to the difficulty of the measurements inside the porous media, the measurements were limited to the clear channel regions. Accordingly, as far as the authors know, there is no study on the precise turbulence structure in the interface region over the porous layer. Therefore in this study, a DNS study of a turbulent channel flow over a porous layer is performed. To directly treat the porous structure, the D3Q27 multiple relaxation time lattice Boltzmann method of Suga et al.(2015) is employed. NUMERICAL SCHEME The present DNS is performed by the D3Q27 multiple relaxation time lattice Boltzmann method (MRT-LBM) (Suga et al.,2015) whose time evolution equation is | f ","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125437823","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

ON THE INFLUENCE OF PRESSURE VARIATION ON IGNITION AND MIXING PROCESSES IN A REACTING SHOCK-BUBBLE INTERACTION 激波-气泡反应相互作用中压力变化对点火和混合过程的影响

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.150

Felix Diegelmann, J. Matheis, V. Tritschler, S. Hickel, N. Adams

引用次数: 0

INERTIAL LOGARITHMIC LAYER PROPERTIES AND SELF-SIMILAR MEAN DYNAMICS 惯性对数层性质和自相似平均动力学

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.460

J. Klewicki, C. Morrill-Winter, A. Zhou

引用次数: 5

COMPRESSIBILITY EFFECTS ON TURBULENT SHEAR FLOWS 可压缩性对湍流剪切流的影响

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.630

N. Sandham

引用次数: 0

TURBULENCE MODIFICATION IN POLYDISPERSE, WALL-BOUNDED TURBULENCE 多分散、壁面湍流中的湍流修正

Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena Pub Date : 1900-01-01 DOI: 10.1615/tsfp9.1140

D. Richter, Omar Garcia, Christopher Astephen

引用次数: 0