Investigation of Flow and Heat Transfer Characteristics of Annular Impinging Jet

摘要

Flow and heat transfer characteristics of impinging jet from annular pipe were experimentally and numerically investigated. To generate annular jet, the cylindrical rod with 12.7 mm in diameter was inserted at center of pipe nozzle which has inner diameter (D) of 28.6 mm. The jet-to-plate distance (H) was examined in the range of 2D, 4D, 6D and 8D. The jet Reynolds number was fixed for all experiments at Re=20,000 based on averaged velocity and pipe inner diameter. The conventional jet was also studied for comparison. The temperature distribution on the impingement surface was measured using an infrared camera. The numerical simulation was carried out to visualize the flow behavior. The results show that the heat transfer of annular jet is higher than that the case of conventional pipe jet at low jet-to-plate distance (H=2D); however, the ones of annular and conventional jet are comparable when jet-to-plate distance becomes higher than H=6D.