ISSN Online: 2377-424X
ISBN Print: 1-56032-797-9
International Heat Transfer Conference 11
APPLICATION OF TEMPERATURE FLUCTUATION MEASUREMENTS TO INSTABILITY AND TRANSITIONS OF AIR FLOW IN A ROTATING CURVED SQUARE CHANNEL
Resumo
A simple technique using a fine thermocouple (12.7 μm wire diameter) for temperature fluctuation measurements of slightly heated air flow in a rotating curved square channel is used to study the laminar-turbulent transition phenomena under the simultaneous action of centrifugal and Coriolis forces caused by curvature and rotation for Reynolds numbers Re = 500 and 104 and rotating speeds n = 0 ~ 350 rpm. At Re = 500, the
destabilizing effects dominate and lead to early transition. At Re = 104, the stabilizing effects dominate and lead to relaminarization process. Laminar-turbulent transition phenomena in a straight square channel flow are also presented as reference. The method is based on the well-known analogy between the axial velocity and temperature fields for air flow in ducts for both
laminar and turbulent flows. The experimental results are
presented in the time domain only for five locations along the horizontal axis of the cross-section. The results are considered to be new and provide a new insight into one aspect of flow transition mechanisms. The general applicability of the method to various fluid mechanics and convection heat transfer problems is pointed out.