No abstract

In-line leukocyte reduction filters (LRF) are available for use with an automated plateletpheresis (PPH) system. Initially, 62% of PPH units produced with such a filter (LRF6, N = 29) had postfiltration (POF) white blood cell (WBC) counts < 5 x 10(6), with a mean POF WBC of 42 x 10(6). In an attempt to decrease POF WBCs, PPH were rested 30 to 60 minutes before filtration with LRF6. A new, larger-volume LRF (LRF10) was also assessed for its efficiency of leukodepletion. A total of 625 PPH, 490 filtered with LRF6 and 135 with LRF10, were evaluated using prefiltration (PRF) and POF samples. Mean prefiltration WBC loads averaged 80 x 10(6) (range, 60-88 x 10(6)) using seven combinations of filters, collection software, and PRF rest periods. Ninety-three percent of PPH units rested prior to filtration with LRF6 (N = 237) had < 5 x 10(6) WBC POF, with a mean of 5 x 10(6) WBC POF. All PPH units filtered with LRF10 (N = 135), whether rested or not, had < 5 x 10(6) WBC POF, with a mean WBC count of 0.2 x 10(6) POF. Mean platelet (PLT) yields POF ranged from 3.1 to 3.4 x 10(11). A PRF rest decreased mean POF WBC counts in products filtered with LRF6. The LRF10 consistently produced PPH with < 5 x 10(6) WBC POF. Blood centers must thoroughly validate equipment utilized in the production of blood components.

No abstract

Pin fin arrays are common features in the trailing edge region of turbine blades, and provide both structural integrity and increases in heat removal rates. Aforementioned pins act as fins by increasing the flow-wetted area, while also introducing complex flow structures such as von Kármán vortex shedding and horseshoe vortex systems; both directly affecting the global and local heat transfer characteristics over the endwall. The present study utilizes a wind tunnel to investigate the row to row interactions throughout a pin fin array comprised of four staggered rows, with spanwise and streamwise pitches of 2.5 pin diameters with a focus on the flow field downstream of the first row. The channel height to pin diameter ratio of 2. The Reynolds numbers tested based on pin diameter and local maximum velocity are 10,000 and 30,000. PIV is used as the experimental method of choice for acquiring quantitative flow data to study the flow field and derive high fidelity turbulence data and vortex structures with respect to the effects of the upstream rows on the pin fins downstream; this describes the underlying flow physics that drive the local Nusselt Number distribution on the cooled surface. Also, it was found that the wake structure varies over the two Reynolds Numbers significantly due to increased flow instabilities which promote shear layer separation and vortex formation. Flow acceleration due to neighboring pins confines the vortex formation in spanwise direction. The distribution of turbulent kinetic energy and the contribution of all Reynolds Stress Tensor components is reported. The turbulent scheme in the wake region is particularly anisotropic. The test section pressure drop is in agreement with literature for 30,000 Reynolds Number, but larger for smaller Reynolds Numbers. A thorough RANS simulation of the baseline case was conducted by carefully adjusting the turbulence model parameters to accurately reflect this particular experimental setup. The numerical results are in good agreement with heat transfer results and thus are utilized to further understand the underlying flow physics. However, the shear layer breakdown is underpredicted in numerical results resulting in shielded regions in the wake of the pin with artificially low heat transfer. The findings of the study contribute to better understanding of the underlying flow physics in a pin fin cooled airfoil and assist design engineers in making better internal cooling geometries.