ISSN Online: 2377-424X
International Heat Transfer Conference 12
Effects of Adverse Pressure Gradient on Heat Transfer in Turbulent Boundary Layer
Resumo
A thermal turbulent boundary layer subjected to a sustained adverse pressure gradient is experimentally investigated.
The conventional thermal law of the wall does not hold in the fully turbulent region. Moreover, turbulent
Prandtl number decreases in this region. These findings indicate that heat transfer is greatly enhanced under the
APG conditions. However, r.m.s. intensities of temperature fluctuation in the APG flows remain unchanged in
comparison with the ZPG flow. This should indicate that the wall-normal fluctuation, which remains unchanged in
the APG flow, definitely controls the heat transfer from the wall even in complex flows. Waveforms of temperature
fluctuations and their spectra indicate that the time scales of thermal field in the APG flow increase in the near
wall region. This characteristic conforms to the result of the velocity field. Higher-order moments and p.d.f.s of
temperature fluctuations are not greatly affected in the near wall region by imposing APG flows.