• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.141-144
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• 2008

Atomization characteristics and spatial distribution of the spray emanating from an injector of liquid-propellant thruster are investigated by using dual-mode phase Doppler anemometry (DPDA). Spray characteristic parameters such as the mean velocity, Sauter mean diameter (SMD), and velocity fluctuation are measured at various locations along the spray axis as well as on the radial direction. Those data are quantified in radial profile and also used to scrutinize the correlation between diameter and turbulence intensity of spray droplets. For the better visual grasp, dynamic behavior of spray droplets along the spray stream is presented through the velocity vectors projected on the plane of geometric axis of nozzle orifice and radial coordinate.

• Journal of Ship and Ocean Technology
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• v.6 no.1
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• pp.27-33
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• 2002

Recently, the application of the electric propulsion system becomes popular because of its advantage over conventional propulsion. However, the complicated flow mechanism and interaction around the azimuth thruster are not fully understood yet, and the studies on the powering performance characteristics with azimuth/pod thrusters are now in progress. The experimental method developed in KRISO(Korea Research Institute of Ships & Ocean Engineering) is introduced and the results of the powering performance tests, consisting of resistance, self-propulsion and propeller open water tests for a cable layer with two azimuth thrusters are presented. For the analysis of powering performance with azimuth thrusters, it is necessary to evaluate the thrust/drag for components of a thruster unit, Extrapolation results could differ according to the various definitions of the propulsion unit; that is the pod, thruster leg and/or nozzle can be treated as hull appendages or as part of propulsion unit, The powering performances based on several definitions are investigated for this vessel. The results of the measurements for the 3-dimensional velocity distribution on the propeller plane are presented to understand the basis of the difference in propulsion characteristics due to the propeller rotational directions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.401-405
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• 2017

Continuous variable thrusters require precise thrust control to change the position or attitude of the aircraft and to control the pressure inside the combustion chamber. For this purpose, the thrust is adjusted by moving the pintle structure near the nozzle neck inside the combustion chamber by moving the pintle structure forward and backward, and the actuator is used to move the pintle structure. In this paper, we developed a actuator system for continuous variable thruster and load test system to simulate the load under operating conditions. Also, the performance test of the actuator was performed using the developed load test system

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.113-116
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• 2008

Pseudo-3D Spatial distribution of spray droplets is investigated by using Dual-mode Phase Doppler Anemometry (DPDA) in order to examine the disintegration and spreading behavior of spray exiting from liquid-thruster injector. Spray injected from nozzle orifice with length-to-diameter ratio $(L/d_o)$ of 1.67 and at the injection pressure of 27.6 bar is aligned to the vertical. Vertical and horizontal mean velocities of droplets, Arithmetic Mean Diameter (AMD), Sauter Mean Diameter (SMD), and volumetric flux decrease as droplets travel from center/upstream toward outer region/downstream of spray.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.189-192
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• 2011

In solid rockets, a pintle thruster is a modulatable thrust device which controlls nozzle throat area. In this study, effect of bore on aerodynamic loads in a SNECMA modulatable thruster was carried out. Existence of bore resulted in reduced aerodynamic load.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.2
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• pp.1-9
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• 2012

Applicability of regenerative cooling in 2,500 N-class bipropellant thruster using hydrogen peroxide and kerosene was considered for improvement of performance and application in various missions. Calculation was performed by one dimensional approach using hydrogen peroxide as a coolant. The heat flux of thruster at nozzle throat was estimated at 18 - 20 MW/$m^2$. Designed cooling channel width and height were 2.5 mm and 0.5 mm, respectively. Based on designed cooling channel configuration, flat plate model was manufactured and tested for estimation of pressure drop in cooling channel, and CFD analysis was compared with the test result. The maximum error between CFD analysis and experimental result was approximately 13% and average error was approximately 5%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1071-1078
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• 2015

Numerical computations were performed to investigate the effects of pintle stroke, altitude, and bore on the performance of an external pintle thruster. Results show that under-expansion flow occurs always, independent of pintle stroke. An external pintle thruster shows good performance in that it is capable of good amount of thrust control, while aerodynamic loads are increased due to shock waves on the pintle support. When altitude is increased to 20 km, the nozzle exit velocity, Mach number, thrust as well as aerodynamic loads are increased. Bore increases aerodynamic load 5.9%, and therefore pintle shape without bore is preferred for lower aerodynamic load of a pintle in order to actuate the pintle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.540-543
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• 2011

This work is devoted to an experimental investigation on conceptual design of dual consecutive stage micro plasma thruster (${\mu}PT$). Optimization study on the thruster configuration has been performed for various electrode gap distances from 1 mm to 2 mm and the hole diameter from 0.3 mm to 2 mm depending on desired operating conditions and corresponding nozzle design requirement. The operation of ${\mu}PT$ at low pressure from $10^{-1}$ Torr to $10^{-4}$ Torr and at various argon flow rates ranging from 5 sccm to 300 sccm has been studied to understand the physic of plasma and the gas dynamics in details. The specific impulse can reach up to 3000-4000 seconds at low power consumptions from 1 to 5 W. Image of exhaust plume from ${\mu}PT$ will be provided and electrical characteristics is also mentioned in this paper.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.616-617
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• 2010

Nemerical analysis was carried out for a patented SNECMA modulatable thrust device. By adopting aerospike-like nozzle and a moving needle, proposed modulatable thrust device are capable of delivering optimal thrust according to the altitude.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.3-3
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• 2000

저추진력 추력기라는 것은 추력이 수 N 정도, 노즐출구직경이 수 mm 정도의 소형추력기를 의미하며, 주로 인공위성을 비롯한 우주 비행체의 자세제어, 궤도천이 등의 목적을 위해 사용된다. 따라서, 저추진력 추력기의 일반적인 작동환경은 연속체 영역, 천이영역(transition flow regime), 희박영역(rarefied flow regime)을 모두 포함하므로, 기존의 연속체 유체역학에서 사용되는 Navier-Stokes 방정식을 사용할 수 없고, 분자들의 미시적인 움직임과 내부 에너지 분포를 고려한 Boltzmann 방정식을 이용한 해석을 수행하여야 한다.(중략)