High Reynolds number experimentation in the US Navy's William B Morgan Large Cavitation Channel

Etter, R. J.; Cutbirth, J. Michael; Ceccio, Steven L.; Dowling, David R.; Perlin, Marc

doi:10.1088/0957-0233/16/9/001

Cited by 36 publications

(21 citation statements)

References 8 publications

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“…In addition, the Surface Layer Turbulence and Environmental Science Test (SLTEST) facility in Utah (Metzger & Klewicki 2001) has provided high quality data in the atmospheric boundary layer, which has been invaluable for studying the behaviour at Reynolds numbers one or two orders of magnitude larger than what is possible in the laboratory. Other, more general purpose facilities, have also been employed to study high Reynolds number boundary layer flows, including the NASA Ames Full-Scale Aerodynamics Facility (Saddoughi & Veeravalli 1994), DNW, the German-Dutch wind tunnel (Fernholz et al 1995) and the US Navy's William B. Morgan Large Cavitation Channel (Etter et al 2005;Winkel et al 2010). One of the main questions that has arisen from these studies is the scaling of the streamwise Reynolds stress u 2 , particularly the behaviour of the near-wall peak found at about z + = 15.…”

Section: Introductionmentioning

confidence: 99%

Spatial resolution correction for wall-bounded turbulence measurements

et al. 2011

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A correction for streamwise Reynolds stress data acquired with insufficient spatial resolution is proposed for wall-bounded flows. The method is based on the attached eddy hypothesis to account for spatial filtering effects at all wall-normal positions. This analysis reveals that outside the near-wall region the spatial filtering effect scales inversely with the distance from the wall, in contrast to the commonly assumed scaling with the viscous length scale. The new formulation is shown to work very well for data taken over a wide range of Reynolds numbers and wire lengths.

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Section: Introductionmentioning

confidence: 99%

Spatial resolution correction for wall-bounded turbulence measurements

et al. 2011

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“…The first LDV system, a stationary single-component LDV system described by Etter et al (2005), acquired the streamwise velocity component at a single reference point located 5 cm upstream of the model leading edge and 31 cm below the test model centreline. The second LDV system, also described by Etter et al (2005), was a traverse mounted two-component LDV system. The traversing LDV system was positioned to acquire the streamwise and wall-normal velocity components through the entire boundary layer at four streamwise locations (X = 1.78, 2.09, 5.94 and 9.94 m).…”

Section: B R Elbing and Othersmentioning

confidence: 99%

On the scaling of air layer drag reduction

et al. 2013

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Air-induced drag reduction was investigated on a 12.9 m long flat plate test model at a free stream speed of 6.3 m s −1 . Measurements of the local skin friction, phase velocity profiles (liquid and gas) and void fraction profiles were acquired at downstream distances to 11.5 m, which yielded downstream-distance-based Reynolds numbers above 80 million. Air was injected within the boundary layer behind a 13 mm backward facing step (BFS) while the incoming boundary layer was perturbed with vortex generators in various configurations immediately upstream of the BFS. Measurements confirmed that air layer drag reduction (ALDR) is sensitive to upstream disturbances, but a clean boundary layer separation line (i.e. the BFS) reduces such sensitivity. Empirical scaling of the experimental data was investigated for: (a) the critical air flux required to establish ALDR; (b) void fraction profiles; and (c) the interfacial velocity profiles. A scaling of the critical air flux for ALDR was developed from balancing shear-induced lift forces and buoyancy forces on a single bubble within a shear flow. The resulting scaling successfully collapses ALDR results from the current and past studies over a range of flow conditions and test model configurations. The interfacial velocity and void fraction profiles were acquired and scaled within the bubble drag reduction (BDR), ALDR and transitional ALDR regimes. The BDR interfacial velocity profile revealed that there was slip between phases. The ALDR results showed that the air layer thickness was nominally three-quarters of the total volumetric flux (per unit span) of air injected divided by the free stream speed. Furthermore, the air layer had an average void fraction of 0.75 and a velocity of approximately 0.2 times the free stream speed. Beyond the air layer was a bubbly mixture that scaled in a similar fashion to the BDR results. Transitional ALDR results indicate that this regime was comprised of intermittent generation and subsequent fragmentation of an air layer, with the resulting drag reduction determined by the fraction of time that an air layer was present.

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“…The free-stream tunnel speeds tested ranged from 6.5 to 20 m/s. Additional LCC facility details can be found in Etter et al (2005). These experiments were conducted as part of DARPA's Friction Drag Reduction (FDR) program.…”

Section: Conclusion For Pdr Over Rough Surfacesmentioning

confidence: 99%

Quarterly Performance/Technical Report of the National Marrow Donor Program

Setterholm¹

2008

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Background: This effort accompanied the DARPA Friction Drag Reduction Program (ATOITTO) effort at the University of Michigan funded under contract HR-001 1-04-1-001 "High Reynolds Number Micro-bubble and Polymer Drag Reduction Experiments" for flows over smooth surfaces. The details of that effort can be found in the final technical report for that project. The purpose of the additional investigation was to examine the physics and engineering of friction drag reduction methods for turbulent boundary layers (TBL) found in hydrodynamic flows over rough surfaces. Two methods of friction drag reduction (FDR) were examined: & Polymer Drag Reduction-solutions containing extensible, long-chain molecules are injected into a TBL. The polymer molecules interact with the underlying turbulent flow and lead to a reduction of the correlated velocity fluctuations and, hence, a reduction of the turbulent transport of momentum across the TBL. This leads to local drag reduction of up to --70% for TBL flows over smooth surfaces compared to a flow without polymer injection. 0Air Layer Drag Reduction-air is injected into the TBL with the aim of creating a stable gas layer of very high void fraction (> 80% void fraction), separating the liquid flow from the solid surface. This results in friction drag reductions of over 80% compared to the friction drag without air layers.Reduction of drag on marine transportation systems can reduce fuel cost and increase ship performance, including maximum speed, range between refueling, and increased payload. Currently, reduction in fuel cost is the primary driving force behind dragreduction research efforts because the world's non-military fleet consumed nearly 280 million tons of fuel as of 2006 and, as of 2005, the U.S. military was the world's largest consumer of diesel fuel.

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High Reynolds number experimentation in the US Navy's William B Morgan Large Cavitation Channel

Cited by 36 publications

References 8 publications

Spatial resolution correction for wall-bounded turbulence measurements

Spatial resolution correction for wall-bounded turbulence measurements

On the scaling of air layer drag reduction

Quarterly Performance/Technical Report of the National Marrow Donor Program

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