Research PaperExperimental study on cooling performance of multiple impinging jets with different nozzle arrangements in a ground fast cooling simulation device

- A ground fast cooling simulation device with multiple impinging jets is built.
- Oil film visualization is conducted with 3 different nozzle arrangements.
- Cooling performance comparisons are made under different working conditions.
- An overall performance evaluation indicator RU ratio is proposed for future use.

In this paper, the cooling performance of multiple impinging jets with different nozzle arrangements in a ground fast cooling simulation device is studied in experiments. An introduction is given firstly on a self-designed cooling simulation device capable of testing large test pieces. 3 nozzle arrangements with different nozzle numbers and the same total area are used. Secondly, oil-film flow visualization results are shown and comparisons on cooling rate and uniformity are made based on the cooling curves under different conditions. Reasons for the complicated variations of the cooling performance are discussed. Due to the complicated interactions caused by the multiple jets, nozzle arrangement is found to determine the basic flow field and cooling performances of different nozzle arrangements are greatly dependent on tank pressure and nozzle height conditions. Finally, an overall performance evaluation indictor RU ratio is proposed. RU ratio is flexible in weighing both the cooling rate and cooling uniformity. Based on the evaluation result, the N-4 nozzle arrangements proves to be the best when nozzle height H = 5 cm and H = 7.5 cm while the N-16 arrangement is the optimum when H = 3.5 cm. It's also found that additional information of controlling strategies can be obtained by using the RU ratio to evaluate performances of nozzle arrangements under different working conditions.