Bulletin of the American Physical Society
68th Annual Meeting of the APS Division of Fluid Dynamics
Volume 60, Number 21
Sunday–Tuesday, November 22–24, 2015; Boston, Massachusetts
Session E7: High Reynolds Number Experiments |
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Chair: Joseph Katz, Johns Hopkins University Room: 107 |
Sunday, November 22, 2015 4:50PM - 5:03PM |
E7.00001: Investigation of the influence of the subgrid-scale stress on non-intrusive spatial pressure measurement using an isotropic turbulence database Seth Siddle-Mitchell, Xiaofeng Liu, Joseph Katz The instantaneous pressure distribution in a turbulent flow field can be measured non-intrusively by integrating the measured material acceleration using particle image velocimetry (PIV). However, due to the finite spatial resolution of the measurement, the pressure reconstructed from PIV is actually subjected to the effect of spatial filtering. Consequently, the reconstructed pressure is effectively imbedded with the contribution of the sub-grid scale (SGS) stress, which is a term appearing in the filtered Navier-Stokes equation. To quantify the effect of the SGS stress on non-intrusive spatial pressure measurement, we use box filtering to filter three dimensional velocity components in a time-varying isotropic turbulence flow field available to public from the John Hopkins University Turbulence Database (JHTDB). Preliminary results show that the error in the reconstructed instantaneous pressure caused by the SGS stress is about 4.4{\%} of the r.m.s. fluctuation of the filtered isotropic pressure. Correction using similarity SGS modeling reduces the error to 2.1{\%}. [Preview Abstract] |
Sunday, November 22, 2015 5:03PM - 5:16PM |
E7.00002: Experimental studies of vorticity in externally driven flows using electron plasmas N.C. Hurst, J.R. Danielson, C.M. Surko Pure electron plasmas confined in Penning-Malmberg traps offer unique opportunities to study vortex dynamics. The Drift-Poisson equations governing the plasma are isomorphic to the two-dimensional Euler equations for ideal fluid flow, where the electron density is the analog of fluid vorticity\footnote{T. B. Mitchell, C. F. Driscoll, {\it Phys. Fluids } {\bf 8}, 7 (1996).}. In this work, boundary conditions are imposed by biasing segmented electrodes so as to create externally applied flows that advect the vorticity. In this way, for example, one can study the response of a stable, coherent vortex to irrotational shear or strain flows. Advantages of this technique over traditional methods\footnote{R. R. Trieling, et al., {\it J. Fluid Mech.} {\bf 360}, 273-294 (1998).}$^,$\footnote{O. Paireau, et al., {\it J. Fluid Mech.} {\bf 351}, 1-16 (1997).} include precise control of the externally applied flow and the ability to directly measure the vorticity field. Results to be discussed include studies of vortex stripping, destruction, and fission, and breaking of adiabatic invariance in time-dependent external flows. [Preview Abstract] |
Sunday, November 22, 2015 5:16PM - 5:29PM |
E7.00003: Turbulent Deflagrated Flame Interaction with a Fluidic Jet Flow for Deflagration-to-Detonation Flame Acceleration Jessica Chambers, Joseph Mcgarry, Kareem Ahmed Detonation is a high energetic mode of pressure gain combustion. Detonation combustion exploits the pressure rise to augment high flow momentum and thermodynamic cycle efficiencies. The driving mechanism of deflagrated flame acceleration to detonation is turbulence generation and induction. A fluidic jet is an innovative method for the production of turbulence intensities and flame acceleration. Compared to traditional obstacles, the jet reduces the pressure losses and heat soak effects while providing turbulence generation control. The investigation characterizes the turbulent flame-flow interactions. The focus of the study is on classifying the turbulent flame dynamics and the temporal evolution of turbulent flame regime. The turbulent flame-flow interactions are experimentally studied using a LEGO Detonation facility. Advanced high-speed laser diagnostics, particle image velocimetry (PIV), planar laser induced florescence (PLIF), and Schlieren imaging are used in analyzing the physics of the interaction and flame acceleration. Higher turbulence induction is observed within the turbulent flame after contact with the jet, leading to increased flame burning rates. The interaction with the fluidic jet results in turbulent flame transition from the thin reaction zones to the broken reaction regime. [Preview Abstract] |
Sunday, November 22, 2015 5:29PM - 5:42PM |
E7.00004: Variable-Density Co-Flowing Jet Simulations with BHR Daniel M. Israel Recent experiments by the Extreme Fluids team at Los Alamos National Laboratory have examined a jet of SF6 injected into co-flowing air. The experiment is designed to aquire detailed diagnostics for comparision to turbulence models. Simultaneous PIV/PLIF is used to measure the Reynolds stress and velicty-density correlations. In the current work, the BHR RANS model is being implemented in an incompressible variable-density code, and compared to the experimental results. Since the jet is not self-similar, both due to co-flow and variable density effects, careful attenstion is payed to the role of inflow conditions. Also, some multi-jet configurations are explored. [Preview Abstract] |
Sunday, November 22, 2015 5:42PM - 5:55PM |
E7.00005: Experimental study of interfacial structure of a falling liquid film in a vertical pipe Abbas Hasan, Barry Azzopardi, Buddhika Hewakandamby Many studies in the literature provide time series data of the film thickness at one or two points on the pipe wall. Most of these studies focussed on either flat plates or small diameter pipes. The main aim of this paper is to study the characteristics of the interfacial wave structure of falling liquid films (liquid Reynolds numbers: 618-1670) in a large diameter pipe (127 mm) using a Multiple Pin Film Sensor (MPFS) which is capable of providing measurements of film thickness and interfacial waves with excellent resolution in time and in the circumferential and axial directions. Parameters, such as film thicknesses, wave velocities and frequencies were extracted. 3D interfacial wave structures were reconstructed from the film thickness data. Unlike the waves in smaller diameter pipes which are characterised as coherent rings, the waves seen in this study were much localized. The mean film thicknesses are generally in good agreement with published models. The mean film thickness obtained from MPFS was also compared with the conductance ring pairs. There is good agreement between the two methods particularly when the fact that the ring pair technique provides a circumferentially averaged value. [Preview Abstract] |
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