Noushin Amini

Fluid Flow Mixing of Turbulent Jets Within a Staggered Rod Bundle

In this investigation, flow mixing between turbulent jets injecting to a channel containing a rod bundle and the channel flows is studied using Particle Image Velocimetry (PIV) and Matched Index of Refraction (MIR) techniques. A specific case of a single impinging jet with a Reynolds number of 13,400 is considered for this analysis. The time-averaged vorticity fields for three different planes within the measurement volume verify the presence of coherent structures within all three fields, specifically in areas close to the jet impingement area and in the shear layer of the jet within the impingement plane. The cumulative effect of the vorticity patterns observed within all measurement planes is believed to have a significant role in the enhancement of mixing within the test section.To further analyze the behavior of the large-scale coherent structures observed in the time-averaged vorticity fields, Proper Orthogonal Decomposition (POD) technique was applied to the PIV velocity fields. The results confirm that the jet flow is the most energetic and the dominant feature of the flow field. Therefore, to further analyze the behavior of some of the relatively smaller-scale coherent structures which could play a significant role in the mixing process, a higher number of modes or a different approach needs to be considered.© 2012 ASME

PIV Measurements of Jet Flow Mixing in the Vicinity of Rod Bundles using Matched-Index of Refraction

In this study, the velocity field of impinging jets within a rod bundle was developed. Velocity measurements were accomplished using Particle Image Velocimetry (PIV). Additionally, Matched-Index of Refraction (MIR) techniques were implemented to allow the visualization of flow characteristics within interior areas of the rod bundle which would typically be obstructed. Such measurements are of importance and essential to the development of new models to predict the systems’ hydraulic behavior.Copyright

PTV Experiments of Subcooled Boiling Flow Through a Rectangular Channel

Experiments were carried out to investigate turbulent sub-cooled boiling flow of Novec-2000 [1] refrigerant through a vertical square channel with one heated wall. Channel dimensions were selected to be similar to those encountered on a Boiling Water Reactor (BWR) channel flow, with an hydraulic diameter of Dh = 8.2 mm. Flow visualization techniques such as Particle Tracking Velocimetry (PTV) and Shadowgraphy were used to measure time-average axial and normal velocities, axial and normal turbulence intensities, and Reynolds Stresses. Results are reported for hydraulic Reynolds numbers at channel inlet of 4638 , 14513 and 24188 for up to thirteen wall heat fluxes (q″ ) ranging from 0.0 to 64.0 kW/m2 . This work is an attempt to enrich the database already collected on turbulent subcooled boiling flow, with the hope that it will be useful in turbulence modeling efforts.Copyright

Experimental Study of Jet Flow Impingement Within a Rod Bundle Using PIV Technique

In this investigation Particle Image Velocimetry technique was implemented to a matched refractive index facility which was placed in a rectangular channel of L:1016 mm×W:76.2 mm×H:76.2 mm. Water was pumped into either one or both of the inlet jets which were entering the channel’s top wall with several different Reynolds numbers. The instantaneous and time-resolved velocity fields were successfully obtained from which several flow characteristics such as vorticity, turbulence instabilities and Reynolds stresses can be calculated.Copyright