• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.3
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• pp.43-53
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• 2022

In this study, analysis of the flow characteristics of pintle-controlled nozzle with split-line TVC system and the thrust performance prediction was performed. The numerical computation was verified by comparing the thrust coefficient derived from the analysis results with the experimental data. By applying the same numerical analysis technique, the flow characteristics of nozzle were confirmed according to operating altitude, pintle stroke position and TVC angle with the 1/10 scale. As the TVC angle increased, thrust loss occurred and the tendency of AF was different depending on the position of the pintle stroke. Based on the analysis results, the relation of thrust coefficient was derived by applying the response surface methods. The thrust performance model with a slight difference of 1.2% on average from the analysis result was generated.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.228-231
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• 1996

In this paper, we calculate the thrust force by the permeance method. we analyze the thrust force vs. displacement and harmonic components of static thrust characteristics of LPM. Microstep reference current for cancelation of the dominent harmonic component is obtained by the analytical method.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.89-91
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• 2004

This paper deals with thrust characteristic by design parameter of linear synchronous reluctance motor(LSynRM). Mover of LSynRM used stator of linear induction machine. Design parameter being teeth width, teeth depth, airgap and displacement, we analyzed thrust characteristic on singleness or complex case. Also, we presented thrust characteristic using finite element method.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.788_789
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• 2009

The cogging force of a permanent-magnet linear motor is a major component of the detent force, but unfortunately makes a ripple in the thrust force and induces undesired vibration and acoustic noise. In this paper, Coupling Particles Swarm Optimization is applied to optimization the shape of permanent magnet linear motor by minimizing the undesired vibration and acoustic noise in the thrust force and also considering the maximum thrust force. The result shows that the 9-pole 10-slot PMLM removes almost of the cogging force while giving a big thrust force.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.337-342
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• 1998

In this paper the lubrication performances of line pivoted pad thrust bearing and point pivoted pad thrust bearing are studied by a numerical analysis. The running characteristic parameters such as nondimensional load carrying capacity nondimensional friciton power loss nondimensional flow rate and film thickness ratios are calculated for various circumferential pivot positions. The results provide a usdful data for the selection of pivot position in a pivoted and thrust bearing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.610-613
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• 1995

In addition to propulsive force to a flying vehicle, a rocket propulsion system can provide moments ro rotatate the flying vehicle and thus provide control of the vehicle's attitude and flight path. By controlling the direction of the thrust vectors, it is possible to control a vehicle's pitch, yaw, and roll motions. In this paper, we will introduce general thrust vector control mechanisms.

• Tribology and Lubricants
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• v.15 no.1
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• pp.24-28
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• 1999

This paper describes a new pivoting technique to improve bearing performance in pivoted pad thrust bearings. This new technique adjusts the pivot line in a line pivoted pad thrust bearing to be parallel to the trailing edge of a sector shaped pad. Bearing performance factors such as load carrying capacity, frictional torque and flow rate are numerically investigated for conventional point-pivoted and line-pivoted pads and for the new parallel-line pivoting technique. It is shown that the load carving capacity can be maximized with the new technique.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.21-21
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• 2000

Thrust Cut-Off 시스템은 로켓 발사체의 분리시의 충격에 의한 비행방향오차 및 비행거리를 감소하고 Pay-Load 부에 추진력을 증가시키고 분리된 추진 기관부의 낙하위치 예측을 용이하게 한다. 이와 같이 중요한 역할을 하게되는 Thrust Cut-Off 시스템에서 스냅링은 핵심적인 역할을 하게 된다. 정상적인 추진체의 작동 시에는 고압의 연소가스를 지탱하고 분리 시에는 쉽게 분리되어 연소가스를 역 분사 시켜야한다.(중략)

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.4
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• pp.18-25
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• 2011

Solid propulsion systems have simple structures compared to other propulsion systems and are suitable for long-term storage. However the systems generally have limits on control of thrust levels. In this paper we suggest control algorithms for combustion chamber pressure of variable thrust solid propulsion systems using special nozzles such as pintle valve. For the pressure control within the chamber, we use a simple pressure change model by considering only mass conservation within the combustion chamber, design a classical algorithm and also a nonlinear controller using the feedback linearization technique. Also we derive the equation of the thrust for an under-expanded one-dimensional nozzle and then design a proportional-intergral controller after linearizing the thrust model for an operating point. Finally, we demonstrate the performance of the controller through a numerical simulation.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.34-41
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• 2014

A feasibility study of thrust control of hybrid propulsion system for lunar exploration is presented. The thrust control experiments were performed by controlling the oxidizer mass flow rate where the thrust modulation is carried by using a ball valve and a stepping motor. The gaseous oxygen (GOX) and the HDPE (High Density PolyEthylene) were used for the oxidizer and solid fuel, respectively. It was found that the thrust levels were stable without much fluctuation during the modulation period, and that the thrust was exactly controlled with target thrust modulation ratio of 53% and 32%.