Recent Publications: Kyosung Choo

Dr. Kyosung Choo, assistant professor in the Department of Mechanical and Industrial Engineering, has produced three publications this year in two different scientific journals.

Below is information on each publication followed by an abstract.

Friedrich B. K., A.W. Glaspell, K. Choo, The Effect of Volumetric Quality on Heat Transfer and Fluid Flow Characteristics of Air-assistant Jet Impingement, Int. Journal of Heat and Mass Transfer 101 (2016) 261-266.

Heat transfer characteristics of air-assistant water jet impingement was experimentally investigated under a fixed water flow rate condition. Water and air were used as the test fluids. The effects of volumetric quality (β = 0–0.9) on the Nusselt number and pressure were considered. The results showed that the stagnation Nusselt number increased with volumetric quality, attained a maximum value at around 0.8 of the volumetric quality, and then decreased. The stagnation Nusselt number of the air-assistant water jet impingement is governed by the stagnation pressure. Based on the experimental results, a new correlation for the normalized stagnation Nusselt number is developed as a function of the normalized stagnation pressure alone. In addition, the lateral variation of Nusselt number is governed by hydraulic jump radius.

K. Choo, Friedrich B. K., A.W. Glaspell, K. Schilling, The Influence of Nozzle-to-plate Spacing on Heat Transfer and Fluid Flow of Submerged Jet Impingement, Int. Journal of Heat and Mass Transfer 97 (2016), 66 69.

In this study, heat transfer and fluid flow characteristics of a submerged jet impinging on a flat plate surface are experimentally investigated. The working fluids are air and water. The effects of a wide range of nozzle-to-plate spacing (H/= 0.1 − 40) on the Nusselt number and pressure at stagnation point are considered. The results show that the Nusselt number and pressure are divided into three regions; region (I) jet deflection region (H/⩽ 0.6), region (II) potential core region (0.6 < H/⩽ 7), and region (III) free jet region (7 < H/⩽ 40). In region I, the Nusselt number and pressure drastically increase with decreasing the nozzle-to-plate spacing. In region II, the effect of the nozzle-to-plate spacing is negligible on the Nusselt number and pressure. In region III, the Nusselt number and pressure monotonically decrease with increasing the nozzle-to-plate spacing. Based on the experimental results, new correlations for the normalized stagnation Nusselt number and pressure are developed as a function of the nozzle-to-plate spacing alone.

K. Choo, and S. J. Kim, The influence of nozzle diameter on the circular hydraulic jump of liquid jet impingement,” Experimental Thermal and Fluid Science 72 (2016) 12-17.

In this study, the circular hydraulic jump of jet impingement cooling was experimentally investigated using water as the test fluid. The effects of nozzle diameter (0.381, 0.506, 1, 2, 3.9, 6.7, 8 mm) on the hydraulic jump radius were considered. The results indicate that the dimensionless hydraulic jump radius (rhj/d) is independent of the nozzle diameter under fixed impingement power conditions, while the dimensionless hydraulic jump radius increases with decreasing nozzle diameter under fixed jet Reynolds number conditions. Based on the experimental results, a new correlation for the hydraulic jump radius is proposed as a function of the impingement power alone. It is shown that the proposed empirical correlation for the dimensionless hydraulic jump radius has the same form as that derived from a dimensional analysis of the conservation equations. In addition, the results clearly show that the dimensionless hydraulic jump radius depends on two dimensionless groups, jet Reynolds and Froude numbers, rather than just one, jet Reynolds number.