• Title/Summary/Keyword: Nozzle area ratio

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Preparation and characterization of Environmental Functional Nanofibers by electrospun nanofibers-Dry sorption material for indoor CO2 capture (정전방사를 통한 환경기능성 미세섬유 제조 및 특성분석 - 실내환경 CO2 포집용 건식흡착소재)

  • Kim, Eun Joo;Park, Kyung-Ryul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.12
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    • pp.938-943
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    • 2018
  • Thin nano-sized fibres were prepared by an electrospinning method. The spinning appratus consisted of pump for polymer injection, nozzle and nozzle rotus, and an aluminum plate collected the polymer fibers. Its surface was chemically modified for selective improved adsorption of carbon monoxide at indoor level. The chemical activation enabled to form the fibres 250-350 nm in thickness with pore sizes distributed between 0.6 and 0.7 nm and an average specific surface area of $569m^2/g$. The adsorption capacities of pure (100%) and indoor (0.3%) $CO_2$, of which level frequently appears, at the ambient condition were improved from 1.08 and 0.013 to 2.2 and 0.144 mmol/g, respectively. It was found that the adsorption amount of $CO_2$ adsorbed by the chemically activated carbon nanofiber prepared through chemical activation would vary depending on the ratio of specific surface area and micropores. In particular, chemical interaction between adsorbent surface and gas molecules could enhance the selective capture of weak acidic $CO_2$.

An Experimental Study of Film Cooling Characteristics at Supersonic Free Stream Conditions (초음속 주유동 환경에서의 막냉각 특성 시험 연구)

  • Kim, Manshik;Lee, Dong Min
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.4
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    • pp.342-348
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    • 2017
  • In this paper, film cooling characteristics at supersonic free stream conditions were examined experimentally by applying an IR-thermography. Film cooling experiments were carried out in a free-jet facility at Mach number of 3.0 and with unit Reynolds number of $42.53{\times}10^6$ and $69.35{\times}10^6$ using wedge shaped film cooling model which has a converging film cooling nozzle. Film cooling efficiency was calculated by measuring the surface temperature of PEEK(Polyether Ether Ketone) and the effects of angle of attack and blowing ratios on the film cooling efficiency were examined. The measured wall temperature was significantly reduced by the film cooling flow compared with the results without the film cooling flow. The usefulness of film cooling was also confirmed by the surface heat flux calculated using the surface temperature history of PEEK. As the blowing ratio increases the protected area of PEEK was also expanded along the direction of free stream and film cooling flow.

A Study on Buzz Margin Control in Supersonic Engine Intake using PID Controller (PID 제어기를 이용한 초음속 엔진 흡입구의 버즈마진 제어에 관한 연구)

  • Kong, Chang-Duk;Ki, Ja-Young;Kho, Seong-Hee;Kang, Myoung-Cheol
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.05a
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    • pp.88-92
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    • 2009
  • Total pressure recovery ratio in intake is crucial factor to the operational characteristics of supersonic propulsion system because it does not compress inlet air mechanically by compressor, but does compress inlet air by ram compression. As the result of that the dynamic characteristic analysis of engine was performed before the controller was designed, it could be ascertained when the AoA of flight vehicle increases, the buzz margin decreases so that the shock wave produced outside intake in the specified area according to flight operation's characteristics. Therefore the PID control algorithm was designed to be controlled buzz margin that the characteristic of shock wave could meet the requirement of performance in intake. The PID controller was designed that the buzz margin value is being positive number using the control variables; fuel flow and nozzle throat area.

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Computational Study on Design of the AIG for the Enhancement of Ammonia Injection in the SCR System (SCR 시스템 내 암모니아 분사 균일도 개선을 위한 AIG 설계에 관한 해석적 연구)

  • Seo, Moon-Hyeok;Chang, Hyuksang
    • Clean Technology
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    • v.18 no.4
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    • pp.410-418
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    • 2012
  • The performance of the ammonia injection gun (AIG) used for maximizing the utilization of reducing agent in the selective catalytic reduction (SCR) system is decided by several parameters such as the pattern of flow distribution, geometry of the air distribution manifold (ADM) and the array and geometry of nozzles. In the study, the uniformity of jet flows from the nozzles in AIG was analyzed statistically by using the computational fluid dynamics (CFD) method to evaluate the role of design parameters on the performance of the SCR system. The uniformity of jet flows from the nozzles is being deteriorated with increasing the supplying flow rate to the AIG. Distribution rates to each branch pipe become lower with decreasing distance to the header, and flow rates from nozzle are also reduced with decreasing distance to the header. The uniformity of jet flows from nozzles becomes stable significantly when the ratio of summative area of nozzles to each sectional area of the branch pipe is below 0.5.

Analysis on the Internal Flow of the Hydraulic Dual Chambers Applying Various Orifice (다양한 오리피스를 이용한 연결형 공압 챔버 내부 유동 해석)

  • Cho, Kihong;Park, Jungho;Kim, Euiyong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.18 no.1
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    • pp.58-64
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    • 2014
  • Hydraulic dual chamber, as the simulator for a dual pulse rocket motor, was tested by a high pressure device with various orifice-hole size being applied. Pressure difference occurs between 1st chamber and 2nd chamber depending on area ratio of the orifice to nozzle throat. Studying a design configuration of the orifice is essential to the motor development because pressure difference severely affects the rocket motor performance. It is noticed in this study that energy dissipation is caused by the vortex flow originating from the orifice as the 2nd chamber is operated. The flow field is simulated by a commercial computational fluid dynamics program, ANSYS FLUENT V14.5.

Analysis of Unsteady Combustion Performance in Solid Rocket Motor with Pintle (핀틀을 장착한 고체추진기관의 비정상 연소 성능 분석)

  • Ki, Taeseok;Ha, Dongsung;Jin, Jungkun;Lee, Hosung;Yoon, Hyungull
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.1
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    • pp.68-75
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    • 2015
  • In this paper, unsteady characteristics of pressure in solid rocket motor were analyzed by using response of pintle actuation, pressure and thrust data from ground test. Pressure and thrust in solid rocket motor can be controlled in real time by varying nozzle throat area with pintle, installed in the valve. Unsteady characteristics of pressure can be observed in this system occurred by various reasons. Two critical reasons, error of pintle actuation and ablation of center tube, are found and effects of each reason can be analyzed individually by re-prediction of pressure with response of pintle actuation and analyzing thrust to pressure ratio.

Development and Launching Test of 10N Class Liquid Propellant Rocket (10뉴턴급 추진력의 액체로켓 개발 및 발사시험)

  • Lee, Jung-Sub;Choi, Won-June;Kim, Min-Ki;Moon, Ki-Hyun;Song, Seong-Hwan;Kwon, Se-Jin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.11a
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    • pp.375-379
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    • 2008
  • In this paper, a 10N class liquid propellant rocket utilizing a dissolving reaction of hydrogen peroxide is constructed and tested. Through a series of designs, seven orifices with a diameter of 200 ${\mu}m$ and a nozzle with a neck of 2.5mm in diameter and area ratio of 2.56 were made. The platinum coated on Isolite was used for catalyst. 90wt% peroxide pressed at 20 bar by nitrogen gas was used for performance evaluation. The length of the catalyst bed and the load of platinum was taken as the parameters for this experiment. For the catalyst support length of 4cm loaded on 5wt% platinum, satisfactory $c^*$ efficiency and stable thrust was observed. The light weight body of the rocket was composed of aluminum. Rocket rose about 10m with relatively constant velocity in launching test.

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Comparison of Pesticide Residues in Perilla Leaf, Lettuce and Kale by Morphological Characteristics of Plant (형태적 특성이 다른 들깻잎, 상추, 케일 중 농약 잔류량 비교)

  • Son, Kyeong-Ae;Im, Geon-Jae;Hong, Su-Myeong;Kim, Jin Bae;Ihm, Yang Bin;Ko, Hyeon Seok;Kim, Jang Eok
    • The Korean Journal of Pesticide Science
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    • v.16 no.4
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    • pp.336-342
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    • 2012
  • This study was carried out in order to compare the residue levels of pesticides among lettuce, kale and perilla leaf depending on the morphological characteristics of plant. Residue levels were investigated at the zero, second, fifth days after last application, 9 species of systemic or non-systemic pesticide were twice applied with 7 days interval by knapsack power sprayer with 2 heads fan shape nozzle. Ratios of leaf area to weight ($cm^2$ $g^{-1}$) were 58 of perilla leaf, 27 of lettuce and 23 of kale. Ratios of leaf area to weight of perilla leaf was 2.1 times higher than that of lettuce. Residue levels of perilla leaf were 1.3 to 2.3 times higher than those of lettuce at the day of spraying and 1.3 to 3.3 times higher at the fifth day. Therefore the differences of pesticide residues between perilla leaf and lettuce were affected by the ratio of leaf area to weight. Residue levels in lettuce were 2.4 to 7.3 times higher than those in kale at the day of spraying because the adhesive effect of pesticide particles on kale leaf was low.