Detailed Measurement of the Near-Wall Region of a Turbulent Pipe Flow

Durst, F.; Jovanović, J.; Sender, Joachim

doi:10.1007/978-3-642-78823-9_15

Cited by 19 publications

(30 citation statements)

References 5 publications

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“…All measurements were corrected for the spatial integration of the LDV signals due to the finite size of the measurement volumes following a method proposed by Durst et al 10 ͑see also den Toonder 9 ͒. Statistical measurement errors were computed following the procedure of Lumley and Panofsky.…”

Section: The Experimental Conditions and Data Processingmentioning

confidence: 99%

Reynolds number effects in a turbulent pipe flow for low to moderate Re

1997

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We present in this paper high resolution, two-dimensional LDV measurements in a turbulent pipe flow of water over the Reynolds number range 5000-25000. Results for the turbulence statistics up to the fourth moment are presented, as well as power spectra in the near-wall region. These results clearly show that the turbulence statistics scaled on inner variables are Reynolds-number dependent in the aforementioned range of Reynolds numbers. For example, the constants in the dimensionless logarithmic mean-velocity profile are shown to vary with Reynolds number. Our conclusion that turbulence statistics depend on the Reynolds number is consistent with results found in other flow configurations, e.g., a channel flow. Our results for the pipe flow, however, lead nevertheless to quite different tendencies.

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Section: The Experimental Conditions and Data Processingmentioning

confidence: 99%

Reynolds number effects in a turbulent pipe flow for low to moderate Re

1997

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“…The MIR technique is not new; Corino and Brodkey (1969) employed it to measure turbulence structure in a circular tube. Recent applications of the technique include, but are not limited to, those of Durst, Jovanovic, and Sender (1993), Parker and Merati (1996), Cui and Adrian (1997), and Becker et al (2002).…”

Section: Inl Mir Flow Systemmentioning

confidence: 99%

Estimated Uncertainties in the Idaho National Laboratory Matched-Index-of-Refraction Lower Plenum Experiment

McEligot¹,

McIlroy²,

Johnson³

2007

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The purpose of the fluid dynamics experiments in the MIR (Matched-Index-of-Refraction) flow system at Idaho National Laboratory (INL) is to develop benchmark databases for the assessment of Computational Fluid Dynamics (CFD) solutions of the momentum equations, scalar mixing, and turbulence models for typical Very High Temperature Reactor (VHTR) plenum geometries in the limiting case of negligible buoyancy and constant fluid properties. The experiments use optical techniques, primarily particle image velocimetry (PIV) in the INL MIR flow system. The benefit of the MIR technique is that it permits optical measurements to determine flow characteristics in passages and around objects to be obtained without locating a disturbing transducer in the flow field and without distortion of the optical paths. The objective of the present report is to develop understanding of the magnitudes of experimental uncertainties in the results to be obtained in such experiments. Unheated MIR experiments are first steps when the geometry is complicated. One does not want to use a computational technique, which will not even handle constant properties properly. This report addresses the general background, requirements for benchmark databases, estimation of experimental uncertainties in mean velocities and turbulence quantities, the MIR experiment, PIV uncertainties, positioning uncertainties, and other contributing measurement uncertainties.The accuracy of the velocity field determination is ultimately limited by the ability of the scattering particles to follow the unsteady motion of the continuous phase. For the particles in the MIR VHTR experiment, the estimated cutoff frequency is about 40 kHz. The frequency of shedding from the posts in the MIR model is estimated to be of the order of 1 Hz and, therefore, the particles should follow the flow.Based on review of the literature, we estimate that the random uncertainty in measured particle displacement for our system and experiment is about 0.3 pixel for a single realization away from the walls. As an example, we estimated the uncertainties in measurements for the maximum velocity in an inlet jet flow operating at about its minimum flow rate. Consequently, this example would provide worst-case estimates in some senses. For the uncertainty in the mean velocity at this location, one could report With the current MIR model and the 3D PIV system, McIlroy and colleagues examined the effects of sample size for a typical set of measurements. Trends were generally as observed by Uzol and Camci. Preliminary conclusions were that (for this view and processing parameters) about 750 images should be collected to reduce the scatter in mean velocity statistics to between 0.4 and 10% v for velocities greater than about 2 m/s. The trends predicted by an uncertainty analysis are consistent with the observations, but, for the most part, the expected values are less than the scatter observed. Preliminary conclusions from the comparisons are that (1) more samples should be collected than predict...

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“…The MIR technique is not new itself; Corino and Brodkey [1969] employed it to measure turbulence structure in a circular tube earlier. Recent applications of the technique include, but are not limited to, those of Durst, Jovanovic and Sender [1993], Parker and Merati [1996], Cui and Adrian [1997] and Becker et al [2002]. [Thompson, Bouchery and Lowney, 1995] and a simple demonstration of the benefits with transparent models having curved interfaces…”

Section: Ineel Matched-index-of-refraction Flow Systemmentioning

confidence: 99%

Development Of An Experiment For Measuring Flow Phenomena Occurring In A Lower Plenum For VHTR CFD Assessment

McEligot¹,

Condie²,

Creery³

et al. 2005

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The objective of the present report is to document the design of our first experiment to measure generic flow phenomena expected to occur in the lower plenum of a typical prismatic VHTR (Very High Temperature Reactor) concept. In the process, fabrication sketches are provided for the use of CFD (computational fluid dynamics) analysts wishing to employ the data for assessment of their proposed codes. The general approach of the project is to develop new benchmark experiments for assessment in parallel with CFD and coupled CFD/systems code calculations for the same geometry. One aspect of the complex flow in a prismatic VHTR is being addressed: flow and thermal mixing in the lower plenum ("hot streaking" issue). Current prismatic VHTR concepts were examined to identify their proposed flow conditions and geometries over the range from normal operation to decay heat removal in a pressurized cooldown. Approximate analyses were applied to determine key non-dimensional parameters and their magnitudes over this operating range. The flow in the lower plenum can locally be considered to be a situation of multiple jets into a confined crossflow --with obstructions. Flow is expected to be turbulent with momentum-dominated turbulent jets entering; buoyancy influences are estimated to be negligible in normal full power operation. Experiments are needed for the combined features of the lower plenum flows. Missing from the typical jet experiments available are interactions with nearby circular posts and with vertical posts in the vicinity of vertical walls -with near stagnant surroundings at one extreme and significant crossflow at the other.Unheated MIR (Matched-Index-of-Refraction) experiments are first steps when the geometry is complicated. One does not want to use a computational technique which will not even handle constant properties properly. The purpose of the fluid dynamics experiments is to develop benchmark databases for the assessment of CFD solutions of the momentum equations, scalar mixing and turbulence models for typical VHTR plenum geometries in the limiting case of negligible buoyancy and constant fluid properties. As indicated by the scaling studies, in normal full power operation of a typical VHTR conceptual design, buoyancy influences should be negligible in the lower plenum. The MIR experiment will simulate flow features of the paths of jets as they mix in flowing through the array of posts in a lower plenum en route to the single exit duct. The conceptual design for such an experiment is described and the development of the final apparatus is presented. Fabrication sketches are provided in Appendix A for the use of CFD analysts wishing to employ the data for assessment of their proposed codes. iv v

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Detailed Measurement of the Near-Wall Region of a Turbulent Pipe Flow

Cited by 19 publications

References 5 publications

Reynolds number effects in a turbulent pipe flow for low to moderate Re

Reynolds number effects in a turbulent pipe flow for low to moderate Re

Estimated Uncertainties in the Idaho National Laboratory Matched-Index-of-Refraction Lower Plenum Experiment

Development Of An Experiment For Measuring Flow Phenomena Occurring In A Lower Plenum For VHTR CFD Assessment

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