• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.475-478
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• 2005

Ducted rocket produces thrust by 2 steps, primary incomplete combustion in the gas generator, and secondary complete combustion reaction in combustion chamber mixed by air taken through duct. the range of a rocket is determined by the weight of propellant, especially the weight of fuel. So ducted rocket has more efficiency and high terminal speed compared to traditional solid rocket motor. This propulsion system expected to be applied to various kinds of missile for anti-aircraft, anti-ship

• Journal of Aerospace System Engineering
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• v.15 no.3
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• pp.79-86
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• 2021

For a preliminary study on a thrust-throttleable Variable Flow Ducted Rocket, a gas generator and flow control valve were developed, and ground combustion tests were performed. The gas generator and flow control valve operated at the required performance level for parameters, such as heat-resistance, combustion-time, pressure, and temperature. The combustion characteristics of a fuel-rich solid propellant mixed with Boron/MgAl/AP, etc., were also analyzed. A Plunger-type flow control valve was designed to control the discharge flow area, and it was confirmed that the flow control valve was able to control the combustion gas flow rate and pressure. However, due to the reduction of the discharge flow area caused by adhesion of combustion products, the combustion pressure continuously increased. The analysis of the pressure increase is covered in Part 2 of this paper.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.12-19
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• 2022

The propellants used in the gas generator of the ducted rocket are fuel-rich propellants, which contain an excessive amount of metal fuel and a small amount of oxidizing agent compared to general solid rocket propellants. In this paper, boron powder and MgAl(Magnesium-Aluminium alloy) were applied to produce fuel-rich propellants. The optimum formulation was determined by characterizing these metal fuel-rich propellants. Analysis of combustion products in the gas generators confirmed that the fuel-rich propellants containing fine boron powder itself instead of boron-bead could be useful in gas generators.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.8
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• pp.684-691
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• 2015

A sudden increase in combustion pressure is observed in the ducted rocket combustion test equipped with pipe shaped and converging nozzle exhaust tubes. This study aims to understand the physical mechanism of abrupt change in combustion pressure using thermal choking in the exhaust tube. Results confirmed that the thermal choking of the flow inside the exhaust tube was responsible for the sudden increase in combustion pressure. Also, high pressure exponent of solid propellants is critical sensitive to the occurrence of thermal choking exhaust pipe. Additionally, numerical simulation showed that the sudden increase in combustion pressure was less possible in diverging pipe because thermal choking is more reluctant to occur.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.6
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• pp.54-60
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• 2016

Multi-port HDPE and Paraffin firing tests are conducted for hybrid gas generator application of a ducted rocket in the low oxidizer mass flux range. A fuel rich gas of O/F ratio from 0.3 to 0.8, a typical O/F operating range of a ducted rocket gas generator, have been achieved with paraffin fuel implying that the hybrid system can be a potential candidate. It was also found that an almost constant O/F ratio regime exists under $35kg/m^2s$ of the oxidizer mass flux, opening a possibility for the paraffin fuel toward the VFDR gas generator application.

• Journal of Aerospace System Engineering
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• v.15 no.3
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• pp.87-92
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• 2021

In this study, a numerical approach was utilized to observe the phenomena in the ground combustion test of a gas generator for a ducted rocket with a plunger-type flow control device. The design factors were also identified through the analysis. It was observed that the pressure increase without the adhesion of the combustion product at the discharge pipe was quite similar to the analysis assuming a cone-shaped erosive burning effect. The pressure increase in most cases was similar to the analysis results when assuming the change in discharge pipe area due to the adhesion of combustion products. Moreover, it was also established that for a given grain shape and discharge flow area, the effect of the adhesion of combustion products has a significant effect on the combustion chamber pressure for cases over n=0.45.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.375-378
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• 2011

The combustion characteristics of fuel-rich gas generator which could be adopted to Ducted Rocket propulsion system is investigated. The gas generator is designed considering the design requirements of propulsion system then solid fuel, which is developed by reducing the contents of oxidizer and increasing the contents of metallic solid particle, is loaded in the manufactured gas generator. The results of combustion test shows the necessity of the special analysis tool for estimating the gas generator performance where multi-phase flow of fuel-rich gas exists.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.05a
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• pp.43-55
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• 1995

램제트 추진기관의 개념/특징과 현재까지 발전되어 온 여러가지 램제트 추진기관의 기술현황에 대해 기술하였으며 성능, 제작비 등 여러면에서 타 체계와 비교하였다. 또한 실제적 적용분야가 대부분 무기체계 임에 따라 현재까지의 적용현황과 함께 향후 어떻게 적용되고 발전되고자 하는지를 분석하였다. 이로부터 지난 40～50년간 무기체계 임무 및 특성에 따라 액체 램제트, 고체 램제트 및 닥티드 로켓형의 3가지로 발전되어 왔으며, 차세대 유도무기의 성능향상/생존도 향상 측면에서, 즉 고속/장 사거리 능력확보를 위해 램제트 추진기관이 세계적 관심 집중 대상이 되고 있음을 알 수 있었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.93-95
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• 2009

This is a reviewing paper on the ramjet development programs of the U.S.A. and European countries through the presented papers at the ISABE 2005 and Joint Propulsion Conference 2008. Interestingly, the programs which are developing now are only limited on the ducted rocket, neither liquid nor pure solid fuel ramjet.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.293-298
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• 2011

The combustion and flow-rate control characteristics of fuel-rich gas generator which could be adopted to Ducted Rocket propulsion system are investigated. The gas generator is designed considering the design requirements of propulsion system and solid fuel for fuel-rich combustion is developed then adopted to ground test. The results of combustion test show the necessity of the special analysis tool for estimating the gas generator performance where multi-phase flow of fuel-rich gas exists. During the flow-rate control test, characteristics of gas generator pressure with the angle of valve are analyzed and, method to estimate the pressure of gas generator is suggested using the relation between the valve exit area and discharge coefficient.