듀얼 벨 노즐과 E-D 노즐을 결합한 한국형발사체의 비추력 증가

문태석(Taeseok Moon),허환일(Hwanil Huh) 한국추진공학회 2018 한국추진공학회지 Vol.22 No.1

A basic numerical analysis was performed to confirm the possibility of combining a dual bell nozzle and an Expansion-Deflection(E-D) nozzle. The dual bell nozzle was designed based on the first-stage nozzle of the Korean Space Launch Vehicle that is being developed, and the E-D nozzle concept was applied to the dual bell nozzle. The inlet condition was analyzed by applying eight types of frozen flow analysis, and k-ω SST was selected as the turbulence model. The number of optimal grids was obtained as 240,000 through the grid sensitivity analysis. As a result, it was confirmed that the transition altitude increased owing to over-expansion when the E-D nozzle concept was applied to the dual bell nozzle, and the specific impulse gain was obtained at high altitudes compared with the KSLV-II first-stage engine.

Dual-Bell Contour를 갖는 Slot Nozzle의 추력특성

권민찬(Minchan Kwon),V. V. Semenov 한국추진공학회 2013 한국추진공학회 학술대회논문집 Vol.2013 No.12

고정된 팽창비 노즐을 갖는 비행체의 최대 비추력은 노즐 출구 압력이 로켓의 비행궤적 중 일치하는 몇 몇 대기압력 고도에서 갖게 된다. Dual-Bell Contour를 갖는 Slot Nozzle은 고도보정기법의 하나로써 통상적인 Bell Nozzle과 비교하였을 때 지상에서는 약 8% 그리고 고고도에서는 약 3.6%의 추력증가 특성을 갖는 다는 것이 연구결과를 통해 알려졌다. At rigid, fixed-area nozzle with a given expansion ratio the maximum specific impulse is reached when nozzle exit pressure is selected as equal to some atmospheric pressure on trajectory of rocket flight. Slot Nozzle with Dual-Bell contour is one of the altitude compensation methods. The calculations shows the thrust of Slot Nozzle increased to 8% near the Earth and 3.6% in space at equal conditions with conventional Bell Nozzle.

고도 보정용 듀얼 벨 노즐 개발 동향과 기술 분석

최준섭(Junsub Choi),허환일(Hwanil Huh) 한국항공우주학회 2015 韓國航空宇宙學會誌 Vol.43 No.5

듀얼 벨 노즐은 일반적인 벨 형상 노즐의 문제점인 저고도에서의 과대팽창, 고고도에서의 과소팽창을 감소시키며, 이로 인해 손실되는 비추력을 최소화 할 수 있는 노즐이다. 미국의 Rocketdyne사에서는 확장 노즐의 형상에 따른 추력특성을 분석하였고, NASA에서는 고도에 따른 연소실험을 수행하였다. 유럽은 DLR을 중심으로 굴곡각, 노즐 길이, 팽창비 등에 따른 연구를 진행하고 있으며, 러시아의 MAI에서는 팽창부에 슬롯을 추가하여 추력손실을 줄일 수 있는 연구가 진행되고 있다. 아시아에서는 일본, 인도 등에서 연구가 진행되고 있고, 일본의 미쓰비시사에서 슬롯 노즐과 유사한 개념의 기술을 특허로 등록하였다. 본 논문에서는 고도 보정이 가능한 노즐로써 듀얼 벨 노즐의 개념 및 성능과 국외 연구 개발 현황을 정리하였다. 국내에서도 경제성 있는 우주개발을 위해 듀얼 벨 노즐에 대한 연구가 필요하다. Dual-bell nozzle can overcome the performance losses of the conventional bell-shaped nozzles which induced by off-design operations with either over-expanded or under-expanded exhaust flow and minimize the losses of the specific impulse. In United States, Rocketdyne analyzed thrust characteristics according to the shape of the expansion nozzle and NASA conducted hot firing tests with various altitudes. DLR, which is one of the research institute of the Europe, is carrying out research for the different cases of inflection angle, nozzle length and expansion ratio. MAI of Russia applied the slot nozzle to the expansion region in order to reduce the performance losses. In Asia, both the Japan and the India are researching on the dual-bell nozzle and Mitsubishi cooperation of the Japan registered its patent. In this paper, concepts and performance of dual-bell nozzle, which can compensate altitude, are investigated and trends of current research are summarized. It is necessary for Korea to research on the dual-bell nozzle for lucrative space development.

이류체 노즐을 이용한 연삭 공구 세정에 대한 연구

이종진(Jongjin Lee),박근환(Keunhwan Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

This paper describes an experimental study on the cleaning of edge grinding tools using a dual-fluid nozzle. For cleaning with the dual-fluid nozzle, the dropletized ultra-pure water must be smaller than the particles. The dropletization is achieved through the pressure of nitrogen and ultrapure water. We have manufactured a dual-fluid nozzle. To demonstrate the droplet effect, the pressure of nitrogen and ultrapure water was set to 5 bar-5 bar. In this paper, cleaning forces by distance and the cleaning method is explained. The distance was set to 5mm and 10mm. We prove particle removal efficiency through a high-speed camera. The dual-fluid nozzle used 5.208 liters per minute of water. water. Existing nozzles used 7.11 liters per minute of water. This saves 26.75 percent of water. This means that cleaning with the dual-fluid nozzle is more useful.

이류체 노즐을 이용한 연삭 공구 세정에 대한 연구

이종진(Jongjin Lee),박근환(Keunhwan Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

This paper describes an experimental study on the cleaning of edge grinding tools using a dual-fluid nozzle. For cleaning with the dual-fluid nozzle, the dropletized ultra-pure water must be smaller than the particles. The dropletization is achieved through the pressure of nitrogen and ultrapure water. We have manufactured a dual-fluid nozzle. To demonstrate the droplet effect, the pressure of nitrogen and ultrapure water was set to 5 bar-5 bar. In this paper, cleaning forces by distance and the cleaning method is explained. The distance was set to 5mm and 10mm. We prove particle removal efficiency through a high-speed camera. The dual-fluid nozzle used 5.208 liters per minute of water. water. Existing nozzles used 7.11 liters per minute of water. This saves 26.75 percent of water. This means that cleaning with the dual-fluid nozzle is more useful.

Influence of air injection nozzles on filter cleaning performance of pulse-jet bag filter

Shim, Joonmok,Joe, Yun-Haeng,Park, Hyun-Seol Elsevier Sequoia 2017 Powder technology Vol.322 No.-

<P><B>Abstract</B></P> <P>The filter cleaning performance of different air injection nozzles installed in a pulse-jet bag filter dust collector were compared. The examined nozzles were a hole nozzle, a nipple nozzle, and a dual-slit injector. The latter is an air injection nozzle with two circumferential slits, which was newly designed in this study to introduce large volumes of cleaning air with a small amount of compressed air, thereby significantly improving the filter cleaning efficiency. When the dual-slit injector was applied under a 2.0m/min filtration velocity, superior filter cleaning performance and lower dust emission were observed compared to those for the hole and nipple nozzles. In addition, there was little difference in filter cleaning efficiency according to pulsing air pressure, indicating that low and high pulse pressures can yield similar levels of filter cleaning performance when the dual-slit injector is employed; thus, the pulsing energy for filter regeneration can be reduced. Under a 4.0m/min filtration velocity, neither the hole nor nipple nozzle yielded effective filter cleaning, generating a higher pressure drop and a significantly reduced pulse-jet cleaning interval. On the other hand, the dual-slit injector applied to the pulse-jet bag filter maintained stable filter cleaning performance, even under the high filtration velocity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The influence of pulsing air injection nozzle on the performance of a pulse-jet bag filter was examined. </LI> <LI> A dual-slit injector was proposed and compared to two other nozzles. </LI> <LI> The dual-slit injector exhibited superior filter cleaning efficiency and lower dust emission. </LI> <LI> The dual-slit injector can work well under relatively low pulsing air pressure. </LI> <LI> The dual-slit injector can reduce the energy consumption for filter cleaning of a bag filter dust collector. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

독일 DLR의 듀얼 벨 노즐 특성 및 핵심 변수

김정훈(Jeonghoon Kim),허환일(Hwanil Huh) 한국항공우주학회 2015 韓國航空宇宙學會誌 Vol.43 No.11

효율적인 추진기관 개발을 위해 여러 종류의 고도 보정 노즐에 대한 연구가 진행되고 있다. 본 논문에서는 향후 듀얼 벨 노즐 연구를 위한 기초자료로서의 활용을 위해 독일 DLR에서 수행한 연구내용을 바탕으로 듀얼 벨 노즐의 주요 특성을 조사하고 핵심 변수를 도출하였다. DLR은 다양한 실험을 통해 변곡각과 천이 NPR은 비례한다는 것과 확장부 길이와 측하중은 비례하지만 천이 NPR과 천이 지속시간과는 반비례한다는 것을 밝혔다. 성능 예측과정을 통해 노즐의 형상이 결정될 수 있고 요구 성능에 맞게 변수간의 최적화가 필요하다. Various types of altitude compensation nozzles have been investigated to develop an effective propulsion system. In order to obtain baseline data for future study of dual bell nozzles, main characteristics and key parameters of dual bell nozzles are summarized and described by analysing DLR dual bell nozzles. DLRs experimental researches show that inflection angle is proportional to transition NPR, and extension length is proportional to side load, but inversely proportional to transition NPR and transition duration. Therefore, the nozzle geometry can be determined through the performance prediction process and thus the optimization process is required to meet performance requirements between parameters.

Study on wall pressure and hysteresis behaviors of a novel dual-bell nozzle

Ke Xin Wu,Gerald Canaan Sohn,Ruoyu Deng,Hao Jia,Heuy Dong Kim,Xianghui Su 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

The dual-bell nozzle is a kind of altitude adaptive nozzle for improving the performance of space launchers as well as future reusable launch vehicles. Numerical investigations have been conducted on a planar dual-bell nozzle to illustrate the flow characteristics at sea level, “sneak” transition, and altitude modes, respectively. Findings from computational fluid dynamics have been contrasted with experimental data from the open literature. The normalized pressure distributions along the dual-bell nozzle wall for different turbulence models are compared to the pressure measurements taken during the experiment by fixing the nozzle pressure ratio (NPR) at 29.8. The NPR value gradually rises across a large range from 6 to 55 to explore the evolution of the flow characteristics. The pressure distributions along the nozzle wall and shock position have been investigated. The hysteretic behaviors occur in dual-bell nozzles close to the contour inflection. The wall pressure and hysteresis behaviors have been expounded in detail.

듀얼 벨 노즐 전산수치해석을 위한 난류 모델 평가

김정훈(Jeonghoon Kim),허환일(Hwanil Huh) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5

듀얼 벨 노즐의 해석에 적합한 난류 모델을 선정하기 위해 수치 연구를 수행하였다. 듀얼 벨 노즐은 KSLV-II를 기반으로 설계하였다. CEA 코드를 이용하여 노즐 내부 유동의 화학조성을 계산하였고, 지상조건에 대해 8화학종 동결유동 해석을 진행하였다. 난류 모델은 S-A, Standard k-ε, SST k-ω 모델을 사용하였다. 난류 모델에 따른 노즐 벽 압력 분포 및 성능 계산을 통해 난류 모델의 적절성을 평가하였다. 해석 결과, 가장 박리를 잘 예측하면서 성능적인 측면에서도 오차가 적은 SST k-ω 모델이 듀얼 벨 노즐 해석에 적합하다고 판단된다. Three turbulence models were evaluated for numerical analysis of a dual bell nozzle. Dual bell nozzle was designed based on the KSLV-II vehicle. Chemical compositions of flow in nozzle was calculated by using CEA code and frozen flow analysis of 8 species was carried out at sea level condition. Turbulence models used were S-A, Standard k-ε and SST k-ω model. Appropriateness of turbulence models was assessed by comparing nozzle wall pressure distribution and performance calculation. Results show that SST k-ω model, which predicts the separation properly and has less error in a performance aspect, is the most suitable to analyze dual bell nozzles.

한국형발사체를 기반으로 한 듀얼 벨 노즐의 전산수치해석 기초 결과

김정훈(Jeonghoon Kim),최준섭(Junsub Choi),허환일(Hwanil Huh) 한국추진공학회 2016 한국추진공학회지 Vol.20 No.6

Numerical analysis was conducted as a preliminary study for evaluating the dual bell nozzle. For future parametric studies, a dual bell nozzle was designed, and thereafter inlet condition, turbulence model, and the number of optimum grids were determined. Dual bell nozzle was designed based on the KSLV-II first stage nozzle. Inlet condition was determined to frozen flow model of non-reacting eight species by comparing with the design values. SST k-ω model turned out to be suitable as turbulence model. About 150 thousand of the grids were selected after grid sensitivity tests. Based on the results determined in this study, we plan to investigate performance gain of the KSLV-II by adopting a proposed dual bell nozzle.