• 동력기계공학회지
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• 제10권4호
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• pp.17-24
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• 2006

The turbulent flow field characteristics of a gun-type gas burner with and without a duct were investigated under the isothermal condition of non-combustion. Vectors and mean velocities were measured by hot-wire anemometer system with an X-type hot-wire probe in this paper. The turbulent flow field with a duct seems to cause a counter-clockwise recirculation flow from downstream to upstream due to the unbalance of static pressure between a main jet flow and a duct wall. Moreover, the recirculation flow seems to expand the main jet flow to the radial and to shorten it to the axial. Therefore, the turbulent flow field with a duct increases a radial momentum but decreases a axial momentum. As a result, an axial mean velocity component with a duct above the downstream range of about X/R=1.5 forms a smaller magnitude than that without a duct in the inner part of a burner, but it shows the opposite trend in the outer part.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.717-724
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• 2008

Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source for nuclear hydrogen generation, which can produce hydrogen from water or natural gas. A primary hot gas duct (HGD) as a coaxial double-tube type cross vessel is a key component connecting the reactor pressure vessel and the intermediate heat exchanger for the VHTR. In this study, structural sizing methodology for the primary HGD with a coaxial double-tube of the VHTR that produces heat at temperatures in the order of $950^{\circ}C$ was suggested and a structural pre-sizing of it was carried out as an example.

• 한국압력기기공학회 논문집
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• 제4권2호
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• pp.1-6
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• 2008

Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source for nuclear hydrogen generation. The VHTR can produce hydrogen from heat and water by using a thermo-chemical process or from heat, water, and natural gas by steam reformer technology. A co-axial double-tube primary hot gas duct (HGD) is a key component connecting the reactor pressure vessel and the intermediate heat exchanger (IHX) for the VHTR. In this study, a preliminary design analysis for the primary HGD of the nuclear hydrogen system was carried out. These preliminary design activities include a determination of the size, a strength evaluation and an appropriate material selection. The determination of the size was undertaken based on various engineering concepts, such as a constant flow velocity model, a constant flow rate model, a constant hydraulic head model, and finally a heat balanced model.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.115-120
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• 2001

The present study examined the possibility of $NO_{x}$ reduction in the high temperature industrial furnaces. duct burner of gas turbine cogeneration and two-stage gas turbine combustor. The experimental study was carried out for the diffusion flame of second stage combustor with the variations of oxygen concentration and supplying rate of hot exhaust gas from first stage combustor. It also examined the flammability range and $NO_{x}$ formation of the second stage combustor in which the fuel is supplying into the mixture of oxygen hot exhaust gas from first stage combustor. The results show that the enrichment of oxygen and increase of exhaust gas lead to increase the $NO_{x}$ up to 50 ppm with 23% $O_{2}$ condition.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.296-299
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• 2007

KAERI is in the process of carrying out the Nuclear Hydrogen Development and Demonstration (NHDD) Program. The indirect cycle gas cooled reactors that produce heat at temperatures in the order of $950^{\circ}C$ are being considered in the NHDD program. For the indirect gas cooled reactors, the intermediate hear exchanger (IHX) and hot gas duct (HGD) are the main components. For the NHDD program we are in the process of establishing a conceptual design of the IHX and HGD. The pre-conceptual design activities in this study dealt with a preliminary design of the IHX and the HGD including strength and thermal expansion evaluation of the main components.

• 한국전산유체공학회지
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• 제9권3호
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• pp.49-56
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• 2004

A heated and expanded helium is used to pressurize liquid propellants in propellant tanks of propulsion system of liquid propellant launch vehicles. To produce a heated and expanded helium, an hot-gas heat exchanger is used by utilizing heat source from an exhausted gas, which was generated in a gas generator to operate turbine of turbo-pump and dumped out through an exhaust duct of engine. Both experimental and numerical approaches of hot-gas heat exchanger design were conducted in the present study. Experimentally, siliconites - electrical resistance types - were used to simulate the full heat condition instead of an exhausted gas. Cryogenic heat exchangers, which were immersed in a liquid nitrogen pool, were used to feed cryogenic gaseous helium in a hot-gas heat exchanger. Numerical simulation was made using commercially utilized solver - Fluent V.6.0 - to validate experimental results. Helically coiled stainless steel pipe and stainless steel exhausted duct were consisted of tetrahedron unstructured mesh. Helium was a working fluid Inside helical heat coil and regarded as an ideal gas. Realizable k-』 turbulent modeling was adopted to take turbulent mixing effects in consideration. Comparisons between experimental results and numerical solutions are Presented. It is observed that a resulted hot-gas heat exchanger design is reliable based on the comparison of both results.

• 한국추진공학회지
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• 제9권3호
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• pp.1-9
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• 2005

고성능 로켓엔진의 터보펌프를 구동하기 위한 연료 과농 가스발생기에서 연소 불안정 발생시, 음향 모드 공진주파수를 모사하는 방법을 통하여 모사배관을 결정하였다. 관심 음향모드의 몇 파장만을 모사하여 실제 연소시험에 바로 적용할 수 있는 팎은 길이의 배관도 제시하였다. 가스발생기에서의 연소 불안정을 제어하기 위한 하나의 방안으로, 모사배관의 길이를 변경하여 분사기의 동특성과 연소실의 공진 음향 모드를 서로 분리시킴으로써 상호작용이 일어나지 않게 할 수 있다. 이러한 특성은 연소시 험을 통해 확인되었고, 이를 통하여 비행용 가스발생기의 연소시험과 연소불안정 제어를 위한 한 가지 방안으로서 모사배관을 결정하는 방법을 확립하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.139-146
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• 2001

The experimental study was carried out for the diffusion flame characteristics of second stage combustor with the variations of temperature and supplying rate of hot exhaust gas from first stage combustor. It also examined the flame structure and NOx formation of the second stage combustor in which the fuel(natural gas) is supplying into the mixture of oxygen hot exhaust gas from first stage combustor. The results show that the increasement of temperature and flow rate of exhaust gas lead to increase the NOx up to 30ppm with 19% $O_2$ condition

• 대한기계학회논문집A
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• 제33권10호
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• pp.1108-1118
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• 2009

A Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source of the order of $950^{\circ}C$ for nuclear hydrogen generation, which can produce hydrogen from water or natural gas. A primary hot gas duct (HGD) as a coaxial double-tube type cross vessel is a key component connecting a reactor pressure vessel and an intermediate heat exchanger in the VHTR. In this study, a structural sizing methodology for the primary HGD of the VHTR is suggested in order to modulate a flow-induced vibration (FIV). And as an example, a structural sizing of the horizontal HGD with a coaxial double-tube structure was carried out using the suggested method. These activities include a decision of the geometric dimensions, a selection of the material, and an evaluation of the strength of the coaxial double-tube type cross vessel components. Also in order to compare the FIV characteristics of the proposed design cases, a fluid-structure interaction (FSI) analysis was carried out using the ADINA code.

• 항공우주기술
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• 제4권1호
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• pp.171-178
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• 2005

고성능 로켓엔진의 터보펌프를 구동하기 위한 연료 과농 가스발생기에 대하여, 연소 불안정 발생시 모사배관를 각각의 음향모드 공진주파수를 모사하는 방법을 통하여 결정하였다. 관심 있는 음향모드의 몇 파장만을 모사하여 실제 연소시험에 바로 적용할 수 있는 짧은 길이의 배관도 제시하였다. 가스발생기에서의 연소불안정을 제어하기 위한 하나의 방안으로서, 모사배관의 길이를 바꾸어 분사기의 동특성과 연소실의 공진 음향 모드를 서로 분리시켜 상호작용이 일어나지 않게 할 수 있으며, 이러한 특성은 연소시험을 통해 확인되었다. 비행용 가스발생기의 연소시험과 연소불안정 제어를 위한 일련의 방안으로서 모사배관를 결정하는 방법을 확립하였다.