A nozzle is a device that splits liquid into fine droplets to spray them into the surrounding space. It has been widely used in various systems and devices including cooling, dust collection and spray systems. The tangential pressure swirl nozzle finds particularly wide use in various industrial and agricultural fields such as combustion engines, spray drying, cooling, plating, etc., due to its simple structure and good spray properties. Therefore, investigating the factors influencing the water spray characteristics of tangential pressure swirl nozzles is of great importance for proper installation and use of nozzles.

So far, the effect of the swirl chamber diameter, outlet diameter and swirl chamber cone angle on the water spray characteristics of a tangential pressure swirl nozzle has been studied, but that of the liquid incidence angle has not been considered.

Kim Song Won, a section head at the Faculty of Thermal Engineering, has experimentally studied the spray distribution, spray angle, etc. of a tangential pressure swirl nozzle and carried out a CFD simulation to analyze the effect of liquid incidence angle on the spray characteristics and determine the optimum incidence angle.

Through the study, he has concluded that it is necessary to take measures to prevent U-tube bundles from sagging down in the design and manufacture of reheater bundles.

For more information, you can refer to his paper “Experimental and CFD Study on Spray Characteristics of Tangential Pressure Swirl Nozzle” in “Proceedings of KUTIC-2025”.

Many programs have been in use for accurate evaluation of the efficiency of thermal systems and for their optimal design. Cyclepad is a good example. It has been developed for an analysis and the optimal design of different thermodynamic cycles.

However, Cyclepad has the disadvantage of needing the input and output of each computational module to be single phase only. Therefore, it failed to support accurate analyses of systems using wet steam and accurate calculation of the thermal properties of the working fluid at the transition points.

In addition to Cyclepad, some other programs for optimizing a second-order system using different optimization algorithms have also been developed, but they have not proved to be useful.

Pak Myong Guk, an institute head at the Faculty of Thermal Engineering, has proposed an improved random tunneling algorithm (RTA) to effectively solve a constrained mixed-variable global optimization problem, and based on it, he has conducted a thermal sequence efficiency analysis of the Rankine cycle and developed an optimization system for it.

With CAD technique introduced, the newly-developed program is effective for designing various Rankine cycles and for optimizing the efficiency of the Rankine cycle by applying improved IRTA.

For further details, you can refer to his paper “Development of Rankine Cycle Optimization CAD” in “Proceedings of KUTIC-2025”.

In recent years, many modal identification methods based on continuous wavelet transform have been developed. The time variation of the instantaneous amplitude and phase of each mode component within measured signals can be observed on time-frequency planes, where measured signals are decomposed to a series of curves called ridges which directly express the amplitude and phase of each mode component at the time of wavelet analysis. Thus, the extraction of ridges and the value of the CWT along the ridges are used to identify modal parameters.

What is important here is to determine ridges. When the frequency window of a wavelet function includes only one natural frequency, ridges accurately represent modal parameters. Therefore, ridges have to be considered carefully in the application of this method.

Ri Yong Ho, a researcher at the School of Science and Engineering, mathematically investigated the distortion of a ridge when the frequency window of wavelet function includes two closely-spaced natural frequencies.

He demonstrated the correctness of the analytical result in detail through numerical simulation.

If further information is needed, you can refer to his paper “Research of Characteristics of a Ridge for the Closely Spaced Two Modes in Time-Frequency Domain” in “Proceedings of KUTIC-2025”.