• Journal of the Korean Society of Propulsion Engineers
• /
• v.20 no.3
• /
• pp.103-110
• /
• 2016

A performance analysis program of a disk type fluidic valve was developed to predict a chamber pressure and a response time. A parametric study of this device was performed by using scattering plot method. A sensitivity of Mach number at a nozzle outlet showed the highest value about a outlet diameter of nozzle. An inlet flow rate is the most important parameter to design the fluidic valve because it has high sensitivity value both a outlet velocity and a response time.

• Structural Engineering and Mechanics
• /
• v.47 no.2
• /
• pp.149-166
• /
• 2013

Flexible behaviors in new aerospace structures can lead to a degradation of their control and guidance system and undesired performance. The objectives of the current work are to analyze the vibration resulting from the propulsion force on a Single Stage to Orbit (SSTO) launch vehicle (LV). This is modeled as a follower force on a free-free Euler-Bernoulli beam consisting of two concentrated masses at the two free ends. Once the effects on the oscillation of the actuators are studied, a solution to reduce these oscillations will also be developed. To pursue this goal, the stability of the beam model is studied using Ritz method. It is determined that the transverse and rotary inertia of the concentrated masses cause a change in the critical follower force. A new dynamic model and an adaptive control system for an SSTO LV have been developed that allow the aerospace structure to run on its maximum bearable propulsion force with the optimum effects on the oscillation of its actuators. Simulation results show that such a control model provides an effective way to reduce the undesirable oscillations of the actuators.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.8 no.1 s.20
• /
• pp.49-55
• /
• 2005

Due to small and light mission payloads, subsystems and propulsion system, small sized UAVs come to be available for reconnaissance that have been performed by aircraft and huge UAVs. The objective of this study is to develop an efficient propulsion system for small reconnaissance UAVs. A glow engine was modified for an efficient and robust 4-stroke gasoline engine with carburetor, new electronic control unit and lubrication system. Engine modification technique and small engine performance test stand are capable of economical method for military UAVs.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.413-418
• /
• 2008

Flow instability in the rocket turbo pump system can be caused by various reasons such as valve, orifice and venturi, etc. The inception of cavitation, especially in the propellant feeding system, is the primary cause of the mass flow and pressure oscillation due to cyclic formation and depletion of cavitation. Meanwhile, the main propellant in liquid rocket engine is the cryogenic one, which is very sensitive to temperature variation, and the variation of propellant properties caused by thermodynamic effect should be accounted for in the flow analysis. The present study focuses on the formation of cryogenic cavitations by adopting IDM model suggested by Shyy and coworkers. Also, the flow instability was investigated in the downstream of orifice by using a developed numerical code. Calculation results show that cryogenic cavitations can lead to flow instability resulting in mass flow fluctuations due to pressure oscillations. And the prediction of cavitations in cryogenic fluid is of vital importance in designing feeding system of LRE.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.255-259
• /
• 2008

This paper presents the spray characteristics of the oxidizer rich preburner injector which can be used in the high-thrust rocket system. We designed the basic shape of the liquid-liquid coaxial swirl injector for the rocket oxidizer rich preburner injection system. To understand the spray angle variation with the high pressure environment, the spray visualization in the high pressure chamber was preformed. Also we measured the droplet velocity, the Sauter Mean Diameter(SMD), the volume flux and the number density with the PDPA system by using water in atmospheric pressure. The results show that the spray angle is reduced by increasing ambient pressure and maximum droplet velocity is shown from a nozzle tip and then the droplet velocity decreases as a spray moves to the downstream. The SMD decreases on the axial distance from 20 mm to 50 mm but it increases over 50 mm. That is due to the increasing number of collision with each droplet and interaction with ambient air on going downstream direction.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.22 no.3
• /
• pp.1-7
• /
• 2018

A combustion test for a supersonic combustor was conducted using a direct-connected type supersonic combustor test facility. The facility was verified for the capability of simulating required flow conditions. The test condition was maintained at Mach 2.0, $915^{\circ}C$ and 496 kPa for 15 s. Using gaseous hydrogen as the fuel, the combustor model was also tested for its ignition and flame holding capability at the fuel equivalence ratio of 0.12. Combustion efficiency was 71%, and the supersonic flow regime was obtained at this test condition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.243-246
• /
• 2008

This paper is to consider analytical thermodynamic modeling of bipropellant propulsion system. The objective of thermodynamic modeling is to predict thermodynamic conditions such as pressures, temperatures and densities in the pressurant tank and the propellant tank in which heat and mass transfer occur. In this paper also it shows analytic equations that calculate the evolution of ullage volume and interface areas. Since the ullage interface areas are time-varying,(the liquid propellant volume decreases as the rocket engine is firing; the change of ullage volume correspond to the change of liquid propellant volume) for a numerical convenience non-dimensionalized correlations are commonly used in most literatures with limitations; a few percentages of inherent error. The analytic equations are derived from analytic geometry, subsequently without inherent error. Those equations are important to calculate the heat transfer areas in the heat transfer equations. It presents the comparison result of both analytic equations and correlation method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.506-510
• /
• 2008

Ramjets are capable of much higher specific impulse than liquid rocket engines for high speed flight in the atmosphere. Ramjets, however, cannot generate thrust at low flight speed. Therefore, an additional propulsion device to accelerate the ramjet vehicle to a supersonic speed is required. In this study, we propose a novel ramjet propulsion system with a $H_2O_2$/Kerosene rocket as the accelerator for initial stage. In order to test the feasibility of this concept, consecutive reactors was built; one for the decomposition of $H_2O_2$ and the other for kerosene combustion. Decomposed $H_2O_2$ jet was injected to combustor through converging nozzle from gas generator and over this hot oxygen jet, kerosene was injected by spay injector. Through the various test cases, hypergolic ignition test was carried out and steady combustion was achieved.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.21 no.5
• /
• pp.88-96
• /
• 2017

As a part of the development procedures of scramjet engine with a regenerative cooling system, this experiment was performed using air-assist type injectors for scramjet engine. Two types of injectors were used in this experiment with the 90 and 60 degrees of the injection angle to the main flow. Mie-scattering was used for spray visualization and PDPA was used for the measurement of the atomization characteristics. It was found that increasing the pressure of supplied gas and the distance from nozzle tip led to the enhancement atomization characteristics and the injector with 60 degrees injection angle has better atomization characteristics than 90 degrees injector.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.43 no.8
• /
• pp.712-721
• /
• 2015

Pulse Detonation Engine (PDE) has been considered as a future propulsion system for broad range of operation and higher thermal efficiency. Various subsystem technologies have been studied for more than decade to improve the performance of the potential system. New valve systems has been developed for the stable operation at high frequency including inflow-driven valve, rotary valve and valveless system. To foster the detonation initiation with a little ignition energy, plasma ignition method and DDT (deflagration to detonation transition) acceleration method such as swept ramp mechanism have been studied. Fluidic nozzle system and other nozzle system are the ongoing research topics to maximize the propulsion performance of the PDE. Present paper introduces the state of the art of PDE subsystem technologies developed in recent years.