An analysis of flow and heat transfer in separated flows over blocked surface

摘要

The flow and heat transfer characteristics of flat and blocked surfaces were experimentally examined under the influence of the free stream velocity of 3, 5, 10 and 15 m/s encompassing laminar, transitional and turbulent flows. A constant-temperature hot wire anemometer was used for the velocity and turbulent intensity measurements, and copper-constant thermocouples and a micro-manometer for temperature and static pressures measurements, respectively. The flow over blocked surface separated in front of the first block and attached on it, then circulated between blocks, and then reattached behind the last block. The results showed that the flow separation before the first block occurred earlier in laminar-laminar separated-reattached flow than the transitional and turbulent flows and turbulent-turbulent separated-reattached flow leading to a shorter reattachment region with high free-stream turbulence. The presence of the separation and reattachment caused the heat transfer enhancement, which was more pronounced in the laminar flow and new empirical equations were developed for the local Stanton numbers.