• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.70-80
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• 2019

Combustion tests using six bi-swirl coaxial injectors with different shapes and recess lengths were performed in a model combustion chamber capable of flame visualization. By utilizing gaseous methane and gaseous oxygen instead of actual propellants, the effects of injector design and experimental conditions on the flame structure and combustion stability were analyzed. It was found that not only the experimental conditions but also the injector geometry such as the recess length and orifice diameter had a considerable influence on the combustion stability. In addition, it was confirmed that the heat release pattern changed with the occurrence of combustion instability.

• Journal of Power System Engineering
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• v.13 no.6
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• pp.43-50
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• 2009

If an internal combustion engine is operated by consolidated control, the minimum fuel consumption is achieved satisfying the demanded objectives. For this, it is necessary that the engine is operated on the ideal operating line which satisfies minimum fuel consumption. In this context of view, there are many tries to achieve given object. However, the parameter in the internal combustion engines are variable and depend on the operating points. Therefore, it is necessary to cope with the uncertainties such that the optimal operating may be possible. From this point of view, this paper gives a controller design method and a robust stability condition for engine torque control which satisfies the given control performance and robust stability in the presence of physical parameter perturbation. Exactly, the present paper considers a robust stability of this 2DOF servosystem with nonlinear type uncertainty in the engine system, and a robust stability condition for the servosystem is introduced. This result guarantees that if the plant uncertainty is in the permissible set defined by the given condition then a gain tuning can be carried out to suppress the influence of the plant uncertainties.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.73-77
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• 2003

Stability rating of KSR-III rocket engine is conducted based on stability rating tests in the course of development of KSR-III rocket engine. Rocket engine is approved to have combustion stabilization ability when it can suppress the external perturbation or pressure oscillation with finite amplitude and recover the original stable combustion. Rocket engine in flight nay be perturbed with unexpectedly large amplitude and thus a designer should not only assure combustion stabilization ability of the engine but also quantify the stabilization capacity. For this, several quantitative parameters and their evaluation are introduced. To verify dynamic stability of KSR-III rocket engine, five stability rating tests have been conducted. Based on these test results, such parameters are quantified and thereby, the stabilization capacity of KSR-III rocket engine is evaluated.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.11
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• pp.1029-1037
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• 2010

If an internal combustion engine is operated by consolidated control, the minimum fuel consumption is achieved and the demanded objectives are satisfied. For this, it is necessary that the engine is operated on the ideal operating line which satisfies minimum fuel consumption. In this context of view, there are many tries to achieve given object. However, the parameters in the internal combustion engines are variable and depend on the operating points. Therefore, it is necessary to cope with the uncertainties such that the optimal operating may be possible. From this point of view, this paper gives a controller design method and a robust stability condition for engine torque control which satisfies the given control performance and robust stability in the presence of physical parameter perturbation. Exactly, in this paper, we consider the robust stability problem of this 2DOF servosystem with nonlinear type uncertainty in the engine system, and a robust stability condition for the servosystem is shown. This result guarantees that if the plant uncertainty is in the permissible set defined by the given condition, then a gain tuning can be carried out to suppress the influence of the plant uncertainties.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.3 s.234
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• pp.384-389
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• 2005

Experimental study of variation of exhaust gas temperature was carried out with the changes of spark timing and exhaust valve timing during the cold start operation of an SI engine. To investigate the effects of these variables on combustion stability, cylinder pressure and exhaust gas temperature were measured and analyzed. Experimental results showed that exhaust gas temperature increased when spark and exhaust valve timings were retarded from the baseline cases. However, combustion stability during cold start deteriorated under the retarded conditions. To increase exhaust gas temperature for fast warmup of catalysts while maintaining combustion stability, an optimal condition for spark and valve timing retard should be appied for the cold start period.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.61-66
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• 2004

The objective of the present study is to develop methodology for the assessment of combustion stability of liquid rocket injectors. To simulate actual combustion occurring inside of a thrust chamber, a fullscale injector has been employed in the study, which bums gaseous oxygen and mixture of methane and propane. The main idea of the experiment is that the mixing mechanism is considered as a dominant factor significantly affecting combustion instability in a fullscale thrust chamber. A single split triplet injector has been used with an open-end cylindrical combustion chamber. The characteristics revealed by excited dynamic pressures in gaseous combustion show degrees of relative acoustic damping depending on operating conditions. Upon test results, the direct comparison between various types of injectors can be realized for the selection of the best design among prospective injectors.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.82-89
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• 2001

This paper concerns lean gas cyclone combustion system adopting distributed inlets with different velocity to promote ignition and burnout properties. Detailed temperature measurements have been achieved under different operating conditions and flue gas compositions and NOx have been measured. Experimental results show that cyclone combustor provided increasing combustion stability and reduction NOx emission level to negligible level.

• Journal of ILASS-Korea
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• v.1 no.3
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• pp.29-36
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• 1996

The present study systematically investigates the effect of evaporation rate on the combustion characteristics and the flame stabilization in a gasoline engine. A constant volume combustion chamber was used to elucidate a basic combustion characteristics and the premixer was installed to control temperature and equivalence ratio. And the maximum pressure, combustion duration and flame propagation according to the evaporation rate were measured to determine the optimal temperature range for evaparating a gasoline fuel. These experimental results indicate that the combustion characteristics such as combustion chamber pressure and combustion duration were deteriorated by decreasing surrounding temperature of fuel injected. It was also found that the overall gasification process for gasoline fuel was strongly influenced by a combustion chamber temperature rather than a premixer temperature.

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.141-145
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• 2004

The objective of the present study is to conduct model combustion tests for various injectors to identify their combustion stability characteristics. Three different double swirl coaxial injectors with variation of a recess length have been tested for the comparative study of CH flame structure and dynamic characteristics. Gaseous oxygen and mixture of gaseous methane and propane have been employed for simulating actual propellants used for a full-scale thrust chamber. Upon test results, the direct comparison between various types of injectors can be realized for the selection of the best design among prospective injectors.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.4
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• pp.11-19
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• 1993

The experimental study was carried out to investigate the stability and the performance characteristics of the aero-valved pulsating combustion system with maximum operating capacity of 60KW. The effect of geometry of combustion system on the stable condition, the flammability limit, the total pressure oscillation amplitude, and the operating frequency can be identified, and the maximum turn-down-ratio is obtained up to 3.3. The total pressure oscillation amplitude can be controlled by tunning the length of the air inlet pipe. The empirical equation with which the operating frequency can be approximated is proposed and the discrepancy is within 5%. The volumetric efficiency is identified to be one of the important parameters determining the upper flammability limit and the maximum value of which is approximately 22%.