A Flying Hot-wire probe For Measurement In Separated Flow

This paper contains a description of the principles of a flying hot-wire system, and outline the advantages and disadvantages of using a hot-wire probe system based on either circular, linear or ‘bean shaped’ curve path. The system developed at Bradford University is based on the bean shaped curve path first utilized at Imperial College. A brief description is given of its operation. The validity of the system was demonstrated by calibration test in which a single normal hot-wire probe was moved in still air. Finally, results are presented for measurements with such a probe behind a backward facing step with height H=120 mm. the results obtained show many of the features observed in similar investigations with laser-Doppler Anemometry, but some new bi-modal phenomena are noticed in the pdf curves in parts of the separated flow region. It is demonstrated that this bi-modal phenomena is consistent with the existence of flip-flop stability situation in the shear layer, which bound the separated flow region.