• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.119-122
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• 2009

The purpose of this study is to design of film-cooling ring for the small thrust rocket engine using green propellants(Hydrogen peroxide and kerosene). Cold flow test was carried out to measure the mass flow rate and atomizing characteristic. Required mass flow rate was obtained from thermal analysis of the engine, and measured flow rate 42.25g/s was in the range of permissible coolant flow rate. With the same mass flow rate, cooling ring with more hole and high velocity shows better spray pattern. The result of thermal analysis, cooling ring has enough cooling performance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.374-379
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• 2002

A new active muffler system has been developed and its superior performance on both noise reduction and engine torque increase is demonstrated with experiment. Main characteristic of the proposed muffler system is the use of destructive interference by transmission path difference of divided exhaust pipes to reduce major exhaust noise components thereby overcoming problems of other active exhaust noise control methods. The exhaust pipe is divided into two sections and joined again downstream. One divided pipe has a sliding mechanism to vary its length, which is controlled to make half wavelength transmission path difference for the major engine rpm frequency. In this system one divided pipe is used to control major rpm frequency and its Harmonics and another pipe is used to control noise component double the frequency of rpm. An after-market tuning muffler, which has very simple internal structure and minimal back pressure, is also installed to remove remaining wideband noise. To make the system to be small enough to be practical, conventional muffler is also installed and used in low rpm range and active muffler is only employed in high rpm range. Noise reduction of the proposed system is comparable to conventional passive muffler. The engine dynamo test has proved the proposed system can recover almost all the torque lost by conventional muffler.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.126-132
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• 2011

Fatigue cracks of the turbocharger are often observed for high performance engines under thermal shock tests. Maximum exhaust gas temperature of recently developed gasoline engines could reach approximately $950^{\circ}C$. It's very important to estimate transient temperature histories during thermal shock cycles to predict the stress and the fatigue life of the turbocharger. With these temperature profiles, temperature-dependent material properties and boundary conditions, we could identify critical locations by the application of finite element simulation technologies. In this paper, we applied the reliable analysis approach to the actual turbocharger to predict the weak locations due to the repetitions of plastic strains and compared the results with the crack locations under physical engine test.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.148-153
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• 2008

As the oil price is dramatically jumping up, the consumption of LNG is rapidly expanding and the size of LNG carriers becomes bigger. For LNG ships, the application of DF (Dual-Fuel) engines gradually increases because of high efficiency, which alternatively use diesel or BOG (Boil-Off Gas) from cargo tank as a fuel. The surplus BOG from LNG cargo tank should be exhausted by GCU or liquefied through the BOG reliquefaction system and returned back. This study focused into its operational characteristics through the process simulation using HYSYS and discussed details on the influence of the variations of some operational parameters such as a distribution ratio by the change of fuel mass flow into the DF engine.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.36-42
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• 2004

The Properties of material, C18200 which is used for development of high performance liquid rocket engine combustor chamber were obtained by tension tests. The specimen for regenerative combustor was designed by structural analysis using that Properties. After the designed specimen was manufactured by the same manufacturing process of regenerative combustor. the yielding stress and yielding strain were obtained by strength tests. The properties of C18200 was degraded very much after brazing. The estimation of yielding pressure by structural analysis was almost same as that of strength test. The collector Part was yielded and failed previously than that of cooling channel part during strength test.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.144-147
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• 2017

A hybrid rocket engine capable of thrust throttling and underwater-working was developed for the underwater high-speed vehicle propulsion system. The hybrid rocket engine was designed and made by two types of ground test motor and underwater working motors. An engine performance was verified by the ground tests with the ground test motor and in the case of underwater motors the ground tests and underwater tests were performed. For the underwater operation a two-stage ignition system was adopted and a rupture disc was installed at the end of nozzle for a water-tight just before an ignition. Successful ignition and propulsion were confirmed in the underwater test with the final selected double rupture disc.

• Advances in aircraft and spacecraft science
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• v.10 no.1
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• pp.1-18
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• 2023

This paper investigates the integrated control of an air-breathing hypersonic vehicle considering the safety of propulsion system under acceleration. First, the vehicle/engine coupling model that contains a control-oriented vehicle model and a quasi-one-dimensional dual-mode scramjet model is established. Next, the coupling process of the integrated control system is introduced in detail. Based on the coupling model, the integrated control framework is studied and an integrated control system including acceleration command generator, vehicle attitude control loop and engine multivariable control loop is discussed. Then, the effectiveness and superiority of the integrated control system are verified through the comparison of normal case and limiting case of an air-breathing hypersonic scramjet coupling model. Finally, the main results show that under normal acceleration case and limiting acceleration case, the integrated control system can track the altitude and speed of the vehicle extremely well and adjust the angle deflection of elevator to offset the thrust moment to maintain the attitude stability of the vehicle, while assigning the two-stage fuel equivalent ratio to meet the thrust performance and safety margin of the engine. Meanwhile, the high-acceleration requirement of the air-breathing hypersonic vehicle makes the propulsion system operating closer to the extreme dangerous conditions. The above contents demonstrate that considering the propulsion system safety will make integrated control system more real and meaningful.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.72-78
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• 2003

In the present paper, computational studies on the hydrodynamic behavior of the inducer for the rocket-engine turbopump are presented including the effect of the mass flow rate. As the mass flow rate is increased, the inducer showed better performance with weak back flows which may have deleterious effects upon the anti-cavitation ability. But the adopted inducer showed low head rise with high volume flow rates, which may be caused by the small passage area near the trailing edge. The static pressure distributions at the shroud surface are compared with experimental results showing very good agreements except near the leading edge where strong back flows are present. The overall performance of the inducer such as, efficiency, head rise is also compared with experiments. The computational results are generally in good agreements with experimental ones near the design point, but two results show discrepancy at the high flow rate.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.448-451
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• 2008

Three methods of nozzle flow analysis, frozen-equilibrium, shifting-equilibrium and non-equilibrium approaches, were used to rocket nozzle flow, those were coupled with the methods of computational fluid dynamics code. For a design of high temperature rocket nozzle, chemical equilibrium analysis which shares the same numerical characteristics with frozen flow analysis can be an efficient design tool for predicting maximum thermodynamic performance of the nozzle. Frozen fluid analysis presents the minimum performance of the nozzle because of no consideration for the energy recovery. On the other hand, the case of chemical-equilibrium analysis is able to forecast the maximum performance of the nozzle due to consideration for the energy recovery that is produced for the fast reaction velocity compared with velocity of moving fluid. In this study, using the chemical equilibrium flow analysis code that is combined the modified frozen-equilibrium and the chemical-equilibrium. In order to understand the thermochemical characteristic components and the accompanying energy recovery, shifting-equilibrium flow analysis was carried out for the 30 $ton_f$-class KARI liquid rocket engine nozzle together with frozen flow. The performance evaluation based on the 30 $ton_f$-class KARI LRE nozzle flow analyses will provide an understanding of the thermochemical process in the nozzle and performances of nozzle.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.3
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• pp.297-308
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• 2017

One of the major engine thermal management system(TMS) strategies for improving fuel economy is to operate the engine in high temperatures. Therefore, this work performed a numerical and experimental study to examine the effect of several different STOs(Starting Temperature of Opening) of wax-thermostat, ranging from $85^{\circ}C$ to $105^{\circ}C$, of gasoline engine on fuel economy and emission characteristics. In this study, a gasoline car equipped with waxthermostat was tested and simulated under FTP-75 and HWFET mode. CRUISE $M^{TM}$ was used to simulate vehicle dynamics, transient engine performance and TMS. The test results showed fuel savings for both drive cycles due to higher STO of $100^{\circ}C$, which is slightly worse than that of $90^{\circ}C$ and amounts between 0.34 and 0.475 %. These controversial results are attributed to experimental errors and uncertainty. The computational results for three STOs, $85^{\circ}C$, $95^{\circ}C$ and $105^{\circ}C$, showed that fuel savings attributed to the application of higher STOs of $95^{\circ}C$ and $105^{\circ}C$ are relatively small and range from 0.306 to 0.363 %. It is also found that the amount of HC and CO emissions from the tailpipe tends to decrease with higher engine coolant temperature because of faster catalyst light-off and improved combustion.