Conditional analysis in a turbulent boundary layer with strong density differences

Design of thermal-anemometry-based probes for the simultaneous measurement of velocity and gas concentration in turbulent flows

“…(ii) Probes with separation distances small enough that thermal interference effects are likely (s/d hot ≤ 10), which herein are referred to as interference probes, appear to be necessary in He/air mixtures. For most of these probes, s/d hot is approximately 1 or 2, but Harion et al [5] (and related works [6,[15][16][17][18]), designed a probe in which s/d hot = 10, and in which interference effects were considered to be of secondary importance due to the large diameter ratio of the sensing elements. Interference probes do not appear to be necessary in other gas mixtures, as evidenced by the work of McQuaid and Wright [9] and Sakai et al [19].…”

“…Then, in section 4, we present the details and results of an experimental investigation into the design of thermal-anemometry-based probes capable of making measurements in He/air mixtures. The present work specifically focuses on such probes since (i) helium is generally an attractive gas for studying flows of heterogeneous mixtures (as it is inert, non-toxic, and relatively inexpensive), and (ii) its relatively low density and Schmidt number makes it useful for studying variable-density flows (as is the case for many of the works cited in table 1 [8,[10][11][12][14][15][16][17][18]) or differential diffusion. Finally, the conclusions and future work are discussed in section 5.…”