Frequency-dependent heat transfer enhancement from rectangular heated block array in a pulsating channel flow

The effect of pulsating flow on convective heat transfer from periodically spaced blocks in tandem on a channel wall is experimentally investigated. The spacing l between repeated blocks varied from l/L = 0.3 to 0.6 where L is the block pitch. The experiments are carried out in the range of 10 Hz < f _F < 100 Hz and 0.2 < A < 0.3. A pulsating flow is imposed by an acoustic woofer at the channel inlet and a constant heat is generated at each protruding block. The impact of the important governing parameters such as the Reynolds number, the Strouhal number and the inter-block spacing on heat transfer rate from heated blocks is examined in detail. The experimental results show that thermal transport from the blocks is greatly affected by the frequency, the amplitude of the flow pulsation, the inter-block spacing and the Reynolds number. Thermal resonance frequency which shows a maximum heat transfer coincides well with the inverse of traveling time of a fluid parcel that can be determined from the block periodicity and the Reynolds number.