• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.139-143
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• 2007

The overall results of combustion tests performed for a 30 tonf-class full-scale combustion chambers of a liquid rocket engine were described. The combustion chambers have chamber pressure of 53${\sim}$60 bar and propellant mass flow rate of 89 kg/so The combustion chamber is composed of mixing head, SUS baffle, baffle injector, ablative chamber, channel cooling chamber and regenerative cooling chamber. The test results show that the combustion characteristic velocity is in the range of 1673${\sim}$1730 m/sec and the specific impulse of the combustion chamber is in the range of 254${\sim}$263 sec. As the recess number of the injectors increases, the combustion characteristic velocity increases. And as the combustion characteristic velocity increases, the specific impulse of the combustion chamber also increases.

• Journal of the korean Society of Automotive Engineers
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• v.4 no.2
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• pp.58-68
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• 1982

It is well known to diesel engineers that the heat release pattern is one of the most important factors affecting engine performance. Thorough research in heat release pattern has materially helped the progress in high-speed diesel engine development . This paper is based on the research conducted at KAIST and Daewoo Heavy Industry last year. The purpose of this paper is to determine the heat release pattern in combustion chamber of MAN M type, the famous low-noise engine. Thermodynamic cycle simulation was performed using Whitehous-Way's heat release pattern with modified coefficients and Annand's heat transfer model. Instantaneous temperature and pressure of gas in cylinder could be determined by the numerical solution of simultaneous equation of mass conservation, equation of energy conservation, and state equation of ideal gas. Calculated results were compared with measured values in some details emphasizing upon the factors affecting rate of heat release. The agreement was fairly good and revealed why M type should have lower burning velocity at the early part of combustion in spite of high injection rate. Additional results by parametric studies were given in relation to fuel injection conditions for further application to engine development.

• Journal of ILASS-Korea
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• v.22 no.4
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• pp.203-209
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• 2017

The International maritime organization(IMO), in an effort to slow down the global warming, proposes reduction in ship's speed as a way to lower the rate emissions from ships. In addition, since ship's fuel cost have been increased, the shipping volumes, fuel-saving technology are being required urgently. Therefore, in this present study, a method of reducing the fuel cost that can improve the performance of the diesel engine was tried by introducing a predetermined amount (0.1~0.3% of the mass amount of fuel used) of hydrogen fuel additive. The experimental conditions of the test engine were 1500rpm and torque BMEP-10b ar. The engine performances (power output, fuel consumption rate, p-max, exhaust temperature) were compared before and after addition of hydrogen fuel additives. This experimental study confirmed reducing at least 2% fuel consumption and 2.19% NOx emission.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.7
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• pp.2421-2429
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• 1996

The objective of this research is to apply effect of the pre-mixed combustion quantity and smoke emission in diesel engine. According as air fuel ratio is increased, emission of smoke concentration is linearly reduced. As Injection timing is advanced, smoke concentration is remarkably reduced. It is considered to be the primary cause of the increase in the premixed combustible mixture during long ignition delay period with advancing injection timing. Smoke is increased with increasing engine speed, so it is considered to be the primary cause of the increase of the mass of fuel injected. Smoke is decreased according to the increase of methanol volume ratio. It is considered that the primary cause of the increase in the quantity of pre-mixed combustion.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.144-152
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• 1996

In the sequential MPI system with one injection for each cycle, engine performance is influenced by the mixture conditions. It can be said that engine performance is improved by being better identical mixture formation conditions for all cylinders. As the fuel injection timing to the intake port effects on the mixture formation conditions and the engine performance, injection timing must be better adjusted to engine requirements. Engine behavior was clearly different depending on the injection time during intake storke. Therefore it was studied that injection timing of fuel effects on the engine performance I. e. combustion stability, COV(imep), A/F excursion, CO,HC emission concentration and fuel consumption. It was found that late intake-synchronous injection was deteriorated the combustion characteristics and performance characteristics, while early intake-synchronous infection resulted in favorable engine behavior.

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.1
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• pp.35-46
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• 1992

In this study, we calculated gas flow fields and distribution of fuel droplet and mass fraction using the CONCHAS-SPRAY code which modified to execute in IBM PC and changed three important factors, injection rate pattern (BASIC, I, II, III), different bowl shape and spray type. Especially vortices which be influenced by fuel-air mixing process, evaporation and flame propagation are generated more strongly in the bowl-piston type combustion chamber than in the flat-piston type. As the spray type changes, it is found that conical type produced large and strong vortices and fuel droplets are effictively diffused into the entire combustion chamber. As the injection rate pattern changes I, II, III based on BASIC type, we confirmed that End-of-Injection Effect strongly influence on droplets life time.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.1
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• pp.62-69
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• 2000

Present study deals with performance analysis of an inert gas generator (IGG) which can be used as effective means to suppress fire. The IGG uses a turbo-jet engine to generate inert gas for fire extinguishing. It is generally known that a less degree of oxygen content in the product of combustion will increase the effectiveness of fire extinguishing. An inert gas generator system with water injection has advantages of suffocating and cooling effects that are very important factors for fire extinguishing. Some aspects of influencing parameters, such as, air excess coefficient, compressor pressure ratio, air temperature before combustion chamber, gas temperature after combustion chamber, mass flow rate of water injection etc. on the performance of IGG system are investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.253-257
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• 2003

Theoretical-numerical analysis of wave instability is conducted with parametric response function model. Fluctuating instantaneous mass evaporation rate functionally coupled with pressure perturbations with phase lag is assumed to examine the validity of the method. With sufficiently large amplitude and less phase lag to perturbation, combustion response is resonant to pressure waves, unstable waves are amplified, and the system is driven to instability. Magnitude of response is a crucial instability parameter in the determination of a stability margins and makes a critical change of balancing conditions between the amplifying and damping acoustic energies. In the phase regime the unstable waves are amplified, whereas, the acoustic waves are attenuated in the out-of-phase regime. In the intermediate regime, no distinct tendency of unstable waves was determined.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.338-343
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• 2003

Computations were performed to investigate the spray characteristics of the twin fluid nozzle in three stage heavy-oil combustion burner. The burner geometry and flow conditions were provided by a burner company. The goal of the study is to estimate mean droplet size, initial velocity and spread factor of the nozzle through comparison between experiments and numerical analyses. Air stage ratio is 2:4:4 by mass, and O2 in exhaust gas is about 4 % by volume. Here, the agreement between the experiment and numerical analyses is evaluated by NOx generation. Spray characteristics will be linearly interpolated between fuel consumption rate l20L/h and 240 L/h.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.282-287
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• 2004

Unielement combustion tests were conducted using coaxial bi-swirl injectors. Major experimental parameters were a recess length and a fuel-side swirl chamber. Combustion efficiency mainly depends on a mixing mechanism for the present coaxial swirl injectors. Low-frequency pressure excitations around 200Hz were observed for all injectors. However, dynamic behaviors considerably differ for an external and an internal mixing case controlled by a recess length. The internal mixing induces mixture to be biased at a specific frequency in a mass flow rate, which results in a relatively high amplitude of pressure fluctuations but results for the external mixing case show that fuel and oxidizer mixture flow carries more complicated, multiple wave characteristics due to broad mixing region as well as disintegration and merging phenomena of propellant films.