Abstract
The aim of this article is to study the flow and heat transfer characteristics of row of jet impingements with simulated cross-flow. Elongated orifices with an aspect ratio of orifice length to orifice width at AR=4 was studied and compared with the case of circular orifices (AR=1) under the same cross-section area. Four of impinging jets with inline arrangement impinge on inner surface of wind tunnel with rectangular cross-section having height of two times of equivalent diameter of orifice. Two differences of cross-flow velocities corresponding to velocity ratios (jet velocity/cross-flow velocity), VR=3 and 7, and attacking angle defined as angle of major axis of elongated orifice to cross-flow direction at θ=0°, 15° and 45° were examined. In order to measure the heat transfer on the impinged surface, temperature distributions were monitored using Thermochromic Liquid Crystal sheet (TLCs), and heat transfer coefficient distributions were evaluated using an image processing method. The flow characteristics on the impingement surface were visualized using the oil film technique. The numerical simulation was also employed to gain insight into the fluid flow. Results show that the θ=0°can minimize the cross-flow effect, and the area of high heat transfer is extended in upstream region of jet impingement.
