| This thesis focuses on the discharge coefficient and heat transfer coefficient measurements in in-line arrays of impinging jets for Reynolds numbers (based on the jet diameter d) ranging from 8900 to 31000. Liquid crystal thermography was used to determine the temperature distribution on the target plate. Three spanwise jet distances of p/d=2.0, 3.0 and 4.0, and nine jet to target plate distances of z/d=0.3, 0.4, 0.5, 0.6, 0.8, 1.0, 2.0, 3.0 and infinity were tested for discharge coefficient test. For heat transfer test, three spanwise jet distances of p/d=2.0, 3.0 and 4.0, and four jet to target plate distances of z/d=0.3, 0.5, 1.0 and 2.0 were tested.;The test results indicate that discharge coefficient increased with increasing pitch and jet to target wall distances. For all tested geometries, the area-weighted Nusselt number, Nujet, increases monotonically with the jet Reynolds number. Increasing jet-to-jet spacing (p/d) resulted in reduced heat transfer coefficients. At lower impingement distances, p/d had a greater influence on heat transfer than at higher z/d. Highest averaged Nusselt numbers were found at z/d=1.0 (p/d=2.0) and z/d=2.0 (p/d=3.0 and 4.0). Multiple-jet heat transfer is strongly affected by jet interactions. The inner jets exhibit more changes than the outer jets with altering z/d and p/d. A correlation between the pertinent nondimensional parameters, the Nusselt number, the jet Reynolds number, the jet spanwise distance, p/d, and the jet to target plate distance, z/d, was obtained that encompasses all test data with a reasonable agreement. |
