Experimental investigation of impinging air jet on rough and moving heated plate

Various geometries, design variables and thermal boundary conditions have brought different heat transfer techniques to the agenda. Evaluating these variables in detail, examining their relations with each other, and as a result, determining the optimum heat transfer technique has undoubtedly been one of the important engineering problems. When the heat management techniques that provide high cooling rate in industrial areas are examined, it is seen that the jet cooling technique comes first. In this method, heat transfers are carried out on solid surfaces by means of fluid jets. Jet cooling systems are a system that has been used for a long time in gas turbines and has been used in many industrial areas such as cooling the turbine blades heated by combustion gases reaching high temperatures in modern aircrafts with jet engines, as well as tempering glass plates, dyeing and drying paper and textile products, cooling of electronic circuit elements. . In this thesis, the effect of the air jet impinging on the moving surfaces with different geometric surface properties on the local and average heat transfer on the target plate is experimentally investigated. In the established experimental setup, the movement of the plate to which the fluid is impinged is guided by the movement provided by the stepper motor. With the number of experiments reduced to 18 using the Taguchi experimental design method, experiments are conducted for 6 different Reynolds numbers, 3 different nozzle-plate distances, 3 different plate speeds, 3 different stroke values, 3 different geometry nozzle outlets and 3 different surface roughness conditions. The time-dependent surface temperatures, time-dependent average Nusselt numbers, local Nusselt numbers obtained after the steady state is reached with a high-resolution thermal camera are presented as heat transfer results. Then, comparative graphs and ANOVA test results are presented and evaluated in order to determine the effects of parameters on heat transfer. The results showed that the Reynolds number is the most dominant parameter affecting the heat transfer. The nozzle geometry is the secondary important parameter. After that, roughness, moving the plate and changing the stroke are the effective parameters. The less effective parameter is the nozzle-plate distance.