• Journal of the Korean Society of Propulsion Engineers
• /
• v.12 no.1
• /
• pp.44-50
• /
• 2008

In this study a turboshaft engine for a helicopter propulsion system was modeled using SIMULINK and the components' maps were generated from the limited performance deck data provided by engine supplier using a hybrid method with the genetic algorithms and the system identification method. In order to verify the SIMULINK performance model and the component maps generated by the hybrid method, the steady-state performance analysis results were compared with the performance data provided by engine manufacturer. In this investigation, it was confirmed that the analysis results by the proposed model are closely met with those by engine manufacturer's data.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.238-238
• /
• 2012

Report is devoted to place and role of numerical simulation in design of rocket propulsion systems. In introduction advanced solutions in liquid propellant rocket engines design are presented. Further essence of design process described briefly. The central place of method of solution of direct problem in design process was shown. Numerical simulation for solving direct problem of fluid dynamic was used as the alternative to theoretical and experimental approaches. Main features of numerical models of processes in propulsion systems were observed. Some results of simulation and (or) design of different types of chemical propulsion system were presented also. The combined rocket engine, rocket engine with injection of after-turbine gas into supersonic part of the nozzle, solid propellant engine and hybrid propulsion engine are under consideration.

• Journal of Aerospace System Engineering
• /
• v.16 no.3
• /
• pp.42-51
• /
• 2022

An eVTOL aircraft, which is required to operate with low pollution/low noise in urban environments, mostly use battery-powered electric propulsion systems as power sources, not traditional propulsion systems such as reciprocating or turbine engines. Accordingly, certification preparation for the electric propulsion system and securing the safety of the electric propulsion system, are important issues. In the U.S., special technical standards equivalent to FAR Part 33 were issued to certify electric engines, and in Europe, various special conditions were established to certify electric propulsion systems. Thus, in Korea, the technical standards for the electric propulsion system for eVTOL aircraft must also be prepared in line with the U.S. and Europe. In this paper, SC E-19, the technical standard of the electric/hybrid propulsion system (EHPS) in special conditions, was analyzed. Additionally, securing the safety of the electric propulsion system of the aircraft are proposed, through the collaboration of SC E-19 technical standards with the existing aircraft safety evaluation procedure ARP 4761. Finally, through a case study of the Ehang 184 electric propulsion system, it has been confirmed that the proposed safety assurance method is applicable at the aircraft level.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.11a
• /
• pp.251-254
• /
• 2008

Ground firing test facility and test field for firing test of hybrid rocket engine were constructed. Ground firing test facility were composed of hybrid rocket engine, thrust stand, oxidizer storage/supply system, control system and data acquisition system. Firing tests of thrust 50 kgf class were conducted. Stable performance data was obtained and operational reliability of ground firing test facility were found.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.12 no.1
• /
• pp.918-927
• /
• 2020

Flows induced by hybrid CRP pod propulsion systems (CRP-POD) are fundamentally characterized by unsteadiness. This work presents a numerical study on the unsteady flow of a CRP-POD at behind-hull condition based on CFD (Computational Fluid Dynamics). Unsteady RANS method is adopted, coupled with SST k-u turbulence model and sliding mesh method. The propeller thrusts and torques obtained by CFD is validated by model tests and acceptable agreements are obtained. The time histories of shingle-blade loads and pressures near the hull surface are recorded for the analysis of unsteady flow features. The cases of forward propeller alone and aft propeller alone are also computed to distinguish the hull-propeller interaction and propeller-propeller interaction. The results show the blade loads of both forward and aft propellers strongly fluctuate with phase angles. For the forward propeller, the blade load fluctuation is mainly governed by the hull-propeller interaction, while the aft blade load is remarkably affected by the propeller-propeller interaction in terms of the load average and fluctuation pattern. The fields of pressure, vorticity and velocity are also analyzed to reveal the unsteady flow features.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.14 no.6
• /
• pp.1-8
• /
• 2010

In this paper, we present some results of technical surveys, power analyses, and weight estimation on electric propulsion systems for 1-ton class Personal Air Vehicles(PAV) applications. When hybrid electric propulsion is adopted, its power performance using fuel cells and batteries in inferior to that of internal combustion engines. However, hybrid electric propulsion systems may replace IC engines when energy density and power density reach 0.75 kW$^*$hr/kg and 2.5 kW/kg, respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.05a
• /
• pp.97-100
• /
• 2008

A hybrid sounding rocket carrying about 10kg payload reaching up to 15km altitude has been designed. The commercial seamless aluminium tube and liquid ${N_2}O$ without pressurization devices were chosen as rocket motor case and oxidizer supply system respectively. A hybrid rocket engine performing required propulsion impulse is designed with time dependent internal ballistic scheme. Engine performance, aerodynamic characteristics, and trajectory were predicted by a integral technique of internal ballistics and external ballistics. The design results were evaluated by comparison with previous experimental data, technical reports, and literatures.

• Journal of Aerospace System Engineering
• /
• v.10 no.3
• /
• pp.23-31
• /
• 2016

The intermediate mixing chamber is one of various methods for improving the regression rate and combustion efficiency of the hybrid rocket. The mixing chamber with its non-combustible material makes the propulsion performance increase, but it leads to a low fuel-loading density in the combustion chamber; therefore, this performance-related trade-off between the mixing chamber and the low fuel-loading density was studied. In this study, the trade-off was conducted by comparing the intermediate-mixing-chamber case with a w/o-mixing-chamber case. The small hybrid-sounding rocket is designed with internal ballistics for comparing the rocket length to the weight. In addition, an external ballistic analysis was conducted for comparing the performances of the w/- and w/o-mixing-chamber cases. As a result, the intermediate-mixing-chamber case shows that the length and the weight were decreased to 12 % and 8 %, respectively; furthermore, when compared with the normal cases, the estimated altitude result of the w/-mixing-chamber case was increased to approximately 75 m.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.5
• /
• pp.429-436
• /
• 2016

Currently, many studies on green ships are under way. Fuel cell (FC) ships are of interest as future low-emission, fuel-efficient vessels. In this paper, a hybrid power management system for an FC ship was designed. The system consists of an FC, a battery, a unidirectional DC/DC converter, a bidirectional DC/DC converter, a filter, an inverter, and a propulsion component. To design the system, we analyze electric sources and converters, and create PLECS models of hybrid power management system. Then, we check the cold start sequence and perform a simulation to understand the characteristics of the hybrid power management system in an FC ship.

• Journal of Power System Engineering
• /
• v.22 no.1
• /
• pp.41-47
• /
• 2018

This paper analyzes the output characteristics of a self excited induction generator with isolated mode according to change of its speeds and loads for building a hybrid electric propulsion system in special purpose ships by using power take off. The induction generators are being considered as an alternative choice to the well-developed generators because of their lower unit cost, inherent ruggedness, operational and maintenance simplicity. However, the generator working by stand alone has a few problems that the reactive power is required to establish the air gap magnetic flux, and the induced voltage and magnetizing current fluctuate when the load is varied. In spite of its advantages, basic design data of the capacitor bank and behaviors of the output characteristics of the generator are not sufficient for the system. Based on the operating condition(speed range of main engine) of the target boat, a reduced experimental equipment system was constructed to analyze the output characteristics of the SEIG. And a suitable capacitor bank of a stand-alone generator and its output characteristics under various loads was investigated in detail through these experiments. According to the experimental result, it was confirmed that the capacitor bank should be $70{\mu}F{\sim}100{\mu}F$, and the proper SEIG induced voltage should be DC 80 V ~ 250 V in order to storage electrical energy into a battery.