Heat transfer correlation for hexagonal and in-line arrays of impinging jets

The paper reports on the results of heat transfer measurements in hexagonal and in-line arrays of impinging jets for Reynolds numbers (based on the nozzle diameter Dm) ranging from 5 × 103 to 2 × 104. Liquid crystal thermography (LCT) was used to determine the temperature distribution on the flat impingement plate. The distance between the impingement plate and the nozzle exit plane varied between 3Dm and 10Dm, while the spacing between the nozzles varied between 2Dm and 6Dm. The experiments indicate that the multiple-jet heat transfer is strongly influenced by jet interactions, which, in turn, depend on the parameters mentioned above. The data set was used to construct a new correlation for the (area-averaged) Nusselt number that takes the interactions into account.