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@ARTICLE{Krmer:31559,
      author       = {Krämer, M. and Afchine, A.},
      title        = {{S}ampling characteristics of inlets operated at low
                      ${U}/{U}_{O}$ ratios: new insights from computational fluid
                      dynamics ({CFX}) modeling},
      journal      = {Journal of aerosol science},
      volume       = {35},
      issn         = {0021-8502},
      address      = {Amsterdam},
      publisher    = {Elsevier},
      reportid     = {PreJuSER-31559},
      pages        = {683 - 694},
      year         = {2004},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {Belyaev and Levin (Journal of Aerosol Science, 5 (1974)
                      325) $(B\&L)$ empirically derived a function for aspiration
                      efficiencies A of thin-walled inlets operated at low
                      velocity ratios U/U-0 (U flow velocity inside the inlet, U-0
                      velocity of the free flow). This function, which is
                      especially applicable for particle sampling on fast,
                      high-altitude aircraft, has not been experimentally or
                      theoretically verified.By means of the computational fluid
                      dynamics model (CFX), we evaluate this $B\&L$ function by
                      explicitly determining inlet aspiration efficiencies over a
                      wide range of high-altitude airborne applications. We find
                      good agreement in the range where $B\&L$ performed their
                      measurements (U/U-0 = 0.18-0.2, particle Stokes numbers Stk
                      > 0.1), but for lower U/U-0 and smaller Stk the $B\&L$
                      function deviates from the CFX results. Therefore, we
                      provide here a modified $B\&L$ function covering the ranges
                      U/U-0 = 0.007-0.2 and Stk > 0.001:A(Stk) = (a Stk + b)/(a
                      Stk + 1 + b) (U-0/U) + c(U/U-0) a = 1.26, b = 0.27, c =
                      0.50, (a) U/U-0 < 0.2, (b) Stk > 0.001.In addition, we used
                      CFX to analyze the performance of a short inlet and
                      demonstrate the strong sensitivity of the sampling
                      characteristics to the inlet design, i.e. the particle
                      transmission efficiency changes from zero for a standard
                      inlet to $30\%$ for a short inlet and the aspiration
                      efficiencies of smaller particles are lower by approximately
                      a factor of two when sampled with the short in comparison to
                      the standard inlet. (C) 2003 Elsevier Ltd. All rights
                      reserved.},
      keywords     = {J (WoSType)},
      cin          = {ICG-I},
      ddc          = {530},
      cid          = {I:(DE-Juel1)VDB47},
      pnm          = {Chemie und Dynamik der Geo-Biosphäre},
      pid          = {G:(DE-Juel1)FUEK257},
      shelfmark    = {Engineering, Chemical / Environmental Sciences /
                      Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000222167000002},
      doi          = {10.1016/j.jaerosci.2003.11.011},
      url          = {https://juser.fz-juelich.de/record/31559},
}