Abstract
The purpose is to exactly determine a flow state of a thermal plume bymeasurement and analysis of plume spectrum, The behavior of even a laminar plumeis always time-dependent, because the laminar plume sways naturally. Atime-dependent temperature of the thermal plume is measured on the mid-plane, onthe several given height and to the axial direction of the heated wire. Thepower spectrum density (PSD) is obtained from time series data of plumetemperature by the maximum entropy method (MEM). By a criterion of the PSDgradient, a flow state, viz. laminar, transitional or turbulent, in the thermalplume can be quantitatively and exactly determined on the mid-plane, on theseveral given height and to the axial direction of the heated wire. Thiscrieterion for determination of flow state can be applied to any kind of flow.
